Tunable blue-emitting lead halide perovskites
阅读说明：本技术 可调的发蓝光的铅卤化物钙钛矿 (Tunable blue-emitting lead halide perovskites ) 是由 酒井信世 伯纳德·威戈 亨利·詹姆斯·施耐德 于 2019-07-12 设计创作，主要内容包括：本发明涉及钙钛矿化合物,该钙钛矿化合物在可见光谱的蓝光区域具有出奇好的发射性质,特别是光致发光发射性质。这些钙钛矿包含阳离子的混合物或卤离子的混合物,或包括这两者的混合物。本发明还涉及：包含本发明的钙钛矿类型的光活性材料；包括本发明的光活性材料的光电器件；产生蓝光的方法；以及本发明的光活性材料在发射蓝光或作为磷光体的用途。(The present invention relates to perovskite compounds having surprisingly good emission properties, in particular photoluminescent emission properties, in the blue region of the visible spectrum. These perovskites comprise a mixture of cations or a mixture of halide ions, or a mixture including both. The invention also relates to: comprising a perovskite-type photoactive material of the present invention; an optoelectronic device comprising the photoactive material of the present invention; a method of generating blue light; and the use of the photoactive materials of the present invention in emitting blue light or as phosphors.)
1. Perovskite of formula (I)
[RbxCs(1-x)][Pb][BryCl(1-y)]3 (I)
Wherein
x is greater than 0 and less than 1, and
y is greater than 0 and less than 1.
2. Perovskite of formula (I) according to claim 1, wherein x is comprised between 0.2 and 0.8, preferably between 0.3 and 0.7.
3. Perovskite of formula (I) according to any of the preceding claims, wherein y is from 0.2 to 0.8, preferably from 0.3 to 0.7.
4. Perovskite of formula (I) according to any of the preceding claims, wherein x is from 0.35 to 0.65 and y is from 0.4 to 0.6, preferably wherein x is from 0.35 to 0.45 and y is from 0.4 to 0.6.
5. Mixed perovskites of formula (II)
{[A]2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-a (II)
Wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
a is greater than 0 and less than 1;
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
6. A mixture, comprising:
(a) formula [ A ]]2[M][X]4The compound of (a) to (b),
wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
and
(b) formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Of (a) a compound
Wherein
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
7. The mixed perovskite of formula (II) according to claim 5 or the mixture according to claim 6, wherein each A cation is selected from C2-10Alkylammonium ion, C2-10Alkenyl ammonium ion, C1-10Alkyl imine ion, C3-10Cycloalkylammonium ion and C3-10Cycloalkylimide ion, above C2-10Alkyl ammonium ion、C2-10Alkenyl ammonium ion, C1-10Alkyl imine ion, C3-10Cycloalkylammonium ion and C3-10The cycloalkyliminium is optionally substituted with one or more groups selected from amino, C1-6Alkylamino, imino, C1-6Alkylimino radical, C1-6Alkyl radical, C2-6Alkenyl radical, C3-6Cycloalkyl and C6-12A substituent of an aryl group.
8. The mixed perovskite of formula (II) according to any one of claims 5 to 7 or the mixture according to claim 6 or 7, wherein each A cation is C optionally substituted with one, two or three amino or imino groups1-10Alkyl primary ammonium cations.
9. The mixed perovskite of formula (II) according to any of claims 5 to 8 or the mixture according to any of claims 6 to 8, wherein each a cation is selected from ethylammonium ion, propylammonium ion, butylammonium ion, pentylammonium ion, hexylammonium ion, heptylammonium ion, octylammonium ion, benzylammonium ion, phenethylammonium ion, benzylammonium ion, naphthylmethylammonium ion and guanidinium.
10. The mixed perovskite of formula (II) according to any one of claims 5 to 9 or the mixture according to any one of claims 6 to 9, wherein each a cation is a butylammonium ion.
11. The mixed perovskite of formula (II) according to any one of claims 5 to 10 or the mixture according to any one of claims 6 to 10, wherein each M cation is selected from Ca2+、Sr2+、Cd2+、Cu2+、Ni2+、Mn2+、Fe2+、Co2+、Pd2 +、Ge2+、Sn2+、Pb2+、Yb2+And Eu2+Preferably Pb2+。
12. The mixed perovskite of formula (II) according to any one of claims 5 to 11 or the mixture according to any one of claims 6 to 11, wherein each X anion is selected from F-、Cl-、Br-And I-Preferably Cl-Or Br-。
13. The mixed perovskite of formula (II) according to any one of claims 5 to 12 or the mixture according to any one of claims 6 to 12, wherein [ X [ ]]From Cl-Or Br-Consists of a single X anion.
14. The mixed perovskite of formula (II) according to any one of claims 5 to 13 or the mixture according to any one of claims 6 to 13, wherein b and c are both greater than 0 and less than 1.
15. The mixed perovskite of formula (II) according to any one of claims 5 to 14 or the mixture according to any one of claims 6 to 14, wherein b is 0.2 to 0.8, preferably 0.3 to 0.7.
16. The mixed perovskite of formula (II) according to any one of claims 5 to 15 or the mixture according to any one of claims 6 to 15, wherein c is 0.01 to 0.99.
17. The mixed perovskite of formula (II) according to any one of claims 5 to 16 or the mixture according to any one of claims 6 to 16, wherein c is 0.2 to 0.8, preferably 0.3 to 0.7.
18. The mixed perovskite of formula (II) according to any of claims 5 to 17, wherein a is 0.05 to 0.5.
19. A photoactive material, comprising: a perovskite of formula (I) as defined in any one of claims 1 to 4; and/or a mixed perovskite of formula (II) as defined in any one of claims 5 to 18; and/or a mixture as defined in any one of claims 5 to 17.
20. The photoactive material of claim 19, wherein the compound of formula (I) and/or the compound of formula (II) is a crystalline or a polycrystalline compound.
21. The photoactive material of claim 19 or 20, further comprising a porous scaffold.
22. The photoactive material of any one of claims 19-21, further comprising a host material.
23. Use of the following substances for emitting blue light: a perovskite of formula (I) as defined in any one of claims 1 to 4; and/or a mixed perovskite of formula (II) as defined in any one of claims 5 to 18; and/or a mixture as defined in any one of claims 5 to 17; and/or a photoactive material as defined in any one of claims 19 to 21.
24. Use according to claim 23, wherein the use is the emission of blue light with a peak emission wavelength of 450 to 495nm, preferably 460 to 490 nm.
25. A method of producing blue light, the method comprising inducing blue light emission from: a perovskite of formula (I) as defined in any one of claims 1 to 4; and/or a mixed perovskite of formula (II) as defined in any one of claims 5 to 18; and/or a mixture as defined in any one of claims 5 to 17; and/or a photoactive material as defined in any one of claims 19 to 21.
26. A method according to claim 25, wherein the blue light has a peak emission wavelength of 450 to 495nm, preferably 460 to 490 nm.
27. An optoelectronic device, preferably a photovoltaic device or a light emitting device, comprising a photoactive material as defined in any one of claims 19 to 21.
28. An optoelectronic device according to claim 27, wherein the photoactive material is arranged in a layer.
29. An optoelectronic device according to claim 28, wherein the layer of photoactive material has a thickness of at least 2 nm.
30. An optoelectronic device according to any one of claims 27 to 29, wherein the optoelectronic device comprises:
(a) an n-type region comprising at least one n-type layer;
(b) a p-type region comprising at least one p-type layer; and disposed between the n-type region and the p-type region:
(c) a layer of the photoactive material.
31. An optoelectronic device according to any one of claims 27 to 30, wherein the optoelectronic device is a light emitting device, a photovoltaic device, a photodiode, a photodetector or a photosensor; preferably a light emitting device or a photovoltaic device, and more preferably an LED or a solar cell.
32. Use of a photoactive material as defined in any one of claims 19 to 22 as a phosphor.
Technical Field
The present invention provides compounds of the formula [ RbxCs(1-x)][Pb][BryCl(1-y)]3Wherein x and y are each greater than 0 and less than 1. The invention also provides the formula { [ A { ]]2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-aWherein a is greater than 0 and less than 1, b and c are 0 to 1, and at least one of b and c is greater than 0 and less than 1. The present invention further provides a composition comprising (a) formula [ A]2[M][X]4With (b) a compound of the formula [ RbbCs(1-b)][Pb][BrcCl(1-c)]3A mixture of compounds of (a). Photoactive materials and optoelectronic devices comprising the perovskites, mixed perovskites and mixtures of the invention are also provided. Also provided is the use of the perovskite, mixed perovskite or mixture in the emission of blue light, and a method of producing blue light using the perovskite, mixed perovskite or mixture. Also provided is the use of the photoactive material of the present invention as a phosphor.
Background
There is a great worldwide demand for optically active semiconductor materials which convert electrical energy into light and which convert light into electrical energy. Such materials are useful in a wide range of semiconductor devices including light emitting devices. For example, luminescent materials may be used in the production of fluorescent screens and Light Emitting Diodes (LEDs), among other applications. The production of light absorbing devices, including solar cells, places a great demand on light absorbing materials.
Currently, organic substances are widely used to manufacture optoelectronic devices such as LEDs. However, organic substances have the disadvantage that they tend to emit weakly in the blue region of the spectrum. Organic leds (oleds) typically achieve 20% conversion efficiency in the red and green regions of the visible emission spectrum. However, they often only achieve conversion efficiencies of up to 10% in the blue region of the visible emission spectrum. One key reason is that efficient red and green emission in OLEDs relies on radiative recombination of all singlet and triplet excitons. The common spin-forbidden triplet-triplet electron transition in organic emitters can be made possible by the introduction of phosphorescent metal complexes. However, suitable metal complexes are often not available or lack stability and efficiency in the blue region of the spectrum.
Inorganic materials such as perovskites do not encounter spin-forbidden transition difficulties to the same extent. Accordingly, there has been great interest in providing inorganic photoactive materials that emit strongly in the blue region of the spectrum.
Lead halide perovskites are highly emissive semiconductor materials with potential in such applications. The lead halide perovskite being of the formula AMX3Wherein M is lead and X is a halide. Because many other semiconductors differ, their band gap can be fine-tuned by varying the composition of the lead halide perovskite, and therefore is of high interest. For example, by adjusting the halide ion composition, CsPb (X) having a general composition can be madeaY1-a)3The band gap of cesium-based perovskites of (i) varies across the visible electromagnetic spectrum, where X and Y are different halides (Li et al, "high effective perovskite nanocrystalline light-emitting diodes enabled by a random cross-linking method", ad.
In addition to mixed halides, another strategy for altering the band gap of lead halide perovskites is to alter the general APbX3Constituent A cations (Linaburg et al, "Cs 1-xRbxPbCl3 and Cs1-xRbxPbBr3 solid solutions: understating octating cementing in lead halide cations". chem. Mater.,29, 3507-. For example, the inventors have previously investigated the effect of altering the a cation. Application WO2017/089819 describes a crystalline compound comprising: (i) cs+(ii) a (ii) Formamidine ion (FA); (iii) one or more metal or metalloid divalent cations (B); and (iv) two or more different halide anions. This document specifically illustrates the formula FAxCs(1-x)B(I(1-x)Brx)3The crystalline compound of (1). These compounds exhibit a bandgap of about 1.75eV (about 700nm, in the red region of the spectrum).
However, CsPbX was found to be directed3The addition of FA cations to the perovskite narrows the band gap and thus shifts the emission into the red region of the spectrum. This is disadvantageous in attempts to produce blue-emitting perovskites. Furthermore, the presence of organic ammonium ions (especially FA) in organic-inorganic perovskites can lead to thermal decomposition of the compounds at relatively low temperatures (below 200 ℃). In contrast, inorganic Cs-based perovskites (such as CsPbBr)3And CsPbI3) Thermal decomposition does not occur until the temperature rises above 350 ℃ (Sutton et al, Advanced Energy Materials,2016,6 (8)).
The best perovskite solar cell currently available utilizes methylammonium ion (MA)+) Formamidine ion (FA)+) Cesium (Cs)+) And mixtures thereof as the a cation, owing to the interesting optoelectronic properties observed in these substances.
None of the above strategies produces efficient and stable blue emitters. In fact, lead halide perovskites that emit in the blue region of the visible spectrum encounter great difficulty.
The photoluminescence quantum efficiency of lead halide perovskites depends largely on their composition. It has been observed that mixed halide perovskites generally have a specific structure such as CsPbBr3Or CsPbI3Such monohalide perovskites are less quantum efficient. Having a general composition CsPb (Br)aCl1-a)3The photoluminescent efficiency of the perovskites of (a) decreases rapidly with chloride addition (i.e., "a" decreases from 1, see, e.g., Sadhanala et al, Nano letters,2015,15(9), pp. 6095-6101). Thus, while mixing halides does shift the band gap toward the blue region of the visible spectrum, the emission efficiency drops too low to provide a useful semiconductor material.
Furthermore, lead halide perovskites may be unstable (a. louudice, s. saris, e.oveisi, d.t.l.alexander, r.buonsani, angelw.chem.int.ed.2017, 56,10696, Bryant et al, Energy environ.sci.,2016,9, 1655-. They degrade when exposed to ultraviolet light and atmospheric substances such as water and oxygen. One of the degradation pathways observed when using mixtures of ions is ion separation or segregation. This phenomenon is particularly observed in the presence of mixtures of halide ions, since separation can occur in phases having different halide ion compositions. This decay pathway is particularly prominent in the known blue-emitting mixed halide perovskites (Li et al, "high effective perovskite light-emitting diodes enabled by a random cross-linking method", Ad. Mater.,28,3528, 3534, 2017). It is also known that the chemical and structural stability of perovskites varies with the presence of a cations.
Therefore, there is still a need for a stable, efficient blue-emitting inorganic semiconductor material.
Disclosure of Invention
The inventors now provide stable, tunable, blue-emitting inorganic perovskite materials capable of emitting light in the blue region of the visible spectrum with surprisingly high photoluminescence quantum efficiency (PLQE).
In a first embodiment, the inventors provide perovskites of formula (I)
[RbxCs(1-x)][Pb][BryCl(1-y)]3 (I)
Wherein x is greater than 0 and less than 1 and y is greater than 0 and less than 1. It was found that the mixed bromide and chloride ions in the cesium-rubidium mixed cation lead halide perovskite gave products with surprisingly high photoluminescence quantum efficiency (PLQE, also known as photoluminescence quantum yield, PLQY) in the blue region of the spectrum. That is, these materials emit surprisingly intense light at wavelengths in the blue region of the visible spectrum. The blue light region is a region of about 450nm to about 495 nm. Furthermore, the wavelength can be adjusted by the composition of the compound of formula (I).
In a second embodiment, the inventors provide a mixed perovskite of formula (II)
{[A]2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-a (II)
Wherein [ A ] comprises one or more A cations, which are organic monovalent cations; [ M ] comprises one or more M cations, which are metal or metalloid divalent cations; [ X ] comprises one or more X anions which are halide anions; a is greater than 0 and less than 1; b and c are 0 to 1; and at least one of b and c is greater than 0 and less than 1.
The inventors also provide a mixture comprising:
(a) formula [ A ]]2[M][X]4The compound of (a) to (b),
wherein [ A ] comprises one or more A cations, which are organic monovalent cations;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations; and [ X ] comprises one or more X anions, said X anions being halide anions;
and
(b) formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Of (a) a compound
Wherein b and c are 0 to 1, and at least one of b and c is greater than 0 and less than 1.
Surprisingly, it was found that [ A]2[M][X]4The presence of a substance in combination with a mixed halide or mixed cation lead halide perovskite will produce a product with a strong blue emission.
However, in a preferred aspect, formula (II) { [ A ]]2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-aThe mixed perovskite of (a) includes mixed halide lead perovskite, wherein b and c are both greater than 0 and less than 1, and may be, for example, from 0.01 to 0.99. This further enhances PLQE of the compound.
In another preferred aspect, comprises (a) formula [ A]2[M][X]4And (b) a compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3The compound of (1)The mixture includes mixed halide lead perovskite wherein b and c are both greater than 0 and less than 1 and may be, for example, from 0.01 to 0.99. This further improves the PLQE of the mixture.
The perovskites of formula (I), mixed perovskites of formula (II), and mixtures thereof described herein exhibit intense and stable emission in the blue region of the visible spectrum. Accordingly, the present invention provides a perovskite of formula (I), a mixed perovskite of formula (II) or a perovskite comprising (a) formula [ A]2[M][X]4And (b) a compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3The use of a mixture of compounds of (a) for emitting blue light, preferably for emitting light having a wavelength of 450 to 495 nm. In particular, the present invention provides the use wherein the use is of blue light emitting a peak photoluminescence wavelength of 450nm to 495nm, preferably 460nm to 490 nm.
Similarly, the present invention provides a method of producing blue light, the method comprising inducing a perovskite of formula (I) of the invention, and/or a mixed perovskite of formula (II) and/or comprising (a) formula [ A ]]2[M][X]4And (b) a compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3The mixture of compounds and/or the photoactive material of (a) emits blue light. In this method, the emitted light typically has a wavelength of 450nm to 495 nm. In particular, the emitted light typically has a peak emission wavelength, e.g. a peak photoluminescence wavelength, of 450 to 495nm, preferably 460 to 490 nm.
The advantageous tunable emission properties and stability of the perovskite compounds and mixtures of the present invention make them useful as photoactive materials. Such photoactive materials may emit strongly in the blue region of the visible spectrum and also have the advantages of inorganic perovskites such as stability at high temperatures. Thus, the perovskite compounds and mixtures of the present invention may be used in a wide range of environments. Accordingly, the present invention provides a photoactive material comprising a perovskite of formula (I) as defined herein; and/or a mixed perovskite of formula (II) as defined herein; and/or mixtures as defined herein.
In addition to advantageous physical and optical properties, the photoactive materials of the present invention may be conveniently formed as layers, deposited on a support, and otherwise fabricated into a device. Accordingly, the present invention further provides an optoelectronic device, preferably a photovoltaic device or a light emitting device, comprising a photoactive material as defined herein.
The photoactive materials of the present invention may be advantageously used as phosphors in view of their ability to emit surprisingly strongly in the blue region of the spectrum. Accordingly, the present invention provides the use of a photoactive material as defined herein as a phosphor, for example as a phosphor emitting light at a wavelength of 450nm to 495 nm. In particular, the emitted light typically has a peak emission wavelength, e.g. a peak photoluminescence wavelength, of 450 to 495nm, preferably 460 to 490 nm.
Drawings
FIG. 1: CsPb (Br)1-xClx)3Absorption spectrum (a) and normalized steady state photoluminescence spectrum (b) of the thin film.
FIG. 2: from CsPb (Br)0.5Cl0.5)3With different concentrations (BA)2PbBr4(left side) and (BA)2PbBr2Cl2(right) absorption spectra (a and c) and normalized steady-state photoluminescence spectra (b and d) of the prepared perovskite thin film.
FIG. 3: cs1-xRbxPb(Br0.5Cl0.5)3Absorption spectrum (a) and normalized steady state photoluminescence spectrum (b) of the thin film.
FIG. 4: is provided with (BA)2PbBr4And do not (BA)2PbBr4Cs of (A)0.6Rb0.4Pb(Br0.5Cl0.5)3Absorption spectrum (a) and normalized steady state photoluminescence spectrum (b) of the thin film.
FIG. 5: prepared from different antisolvents for solvent quenching ((BA)2PbBr4)0.1(Cs0.6Rb0.4Pb(Br0.5Cl0.5)3)0.9Steady state photoluminescence spectra of the thin film.
FIG. 6: cs1-xRbxPbBr3Absorption spectrum (a) and normalized steady state photoluminescence spectrum (b) of the thin film.
FIG. 7: (CsPbBr)3)1-x((BA)2PbBr4)xAbsorption spectrum (a) and normalized steady state photoluminescence spectrum (b) of the thin film.
FIG. 8: cs1-xRbxPb(I0.45Br0.55)3Steady state photoluminescence spectra of the thin film.
FIG. 9: ("A")2PbBr4)0.1(Cs0.6Rb0.4Pb(Br0.5Cl0.5)3)0.9Steady state photoluminescence spectra of the films, where "a" is ethylamine, butylamine, and phenylethylamine.
FIG. 10: (Cs)0.6Rb0.4)Pb(Br0.5Cl0.5)3Photoluminescence peak position under uv irradiation for a period of up to 60 minutes.
FIG. 11: ((BA)2Pb(Br2Cl2)4)0.33(CsPbBr3)0.67And ((BA)2Pb(Br2Cl2)4)0.33(Cs0.4Rb0.6PbBr3)0.67A Steady State Photoluminescence (SSPL) spectrum and an absorption spectrum of the thin film.
Detailed Description
The present invention provides surprisingly strongly blue-emitting perovskite materials. In particular, the invention provides compounds of formula (I) [ Rb ]xCs(1-x)][Pb][BryCl(1-y)]3A compound of (1); formula (II) { [ A { []2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-aA compound of (1); and comprises (a) formula [ A]2[M][X]4And (b) a compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3A mixture of compounds of (a). The invention further provides a photovoltaic material comprising one or more of the above perovskite materials, as well as devices comprising such materials.
The compounds of the present invention emit in the blue region of the spectrum. Thus, in one embodiment, the compounds of the invention have a peak emission wavelength of 500nm or less, for example 495nm or less. In a preferred embodiment, the compounds of the invention have a peak emission wavelength in the range from 450nm to 500nm, preferably from 455nm to 495nm, particularly preferably from 460nm to 490 nm.
Aspects of these materials, their use, and suitable methods of making them are discussed in more detail below.
Definition of
"Compound of the invention" means a compound of formula (I), a compound of formula (II) and a compound comprising (a) formula [ A]2[M][X]4And (b) a compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Any or all of the mixtures of compounds of (a).
As used herein, the term "perovskite" refers to a perovskite having a chemical structure with CaTiO3Or a material comprising a layer or region having a three-dimensional crystal structure related to the three-dimensional crystal structure of (a) a titanium oxide (CaTiO)3The material of the material layer or region of the structure-related structure of (a). With CaTiO3The three-dimensional crystal structure-related material of (a) may be referred to as having a "3D perovskite structure", and thus, the perovskite according to this definition may be referred to as a "3D perovskite". CaTiO3Can be represented by the formula ABX3Wherein A and B are different sized cations and X is an anion. In the unit cell, the a cation is at (0, 0, 0), the B cation is at (1/2, 1/2, 1/2), and the X anion is at (1/2, 1/2, 0). The a cations are generally larger than the B cations. Those skilled in the art will appreciate that when A, B and X are varied, the different ion sizes may cause the structure of the perovskite material to change from CaTiO3The structure used is distorted to a distorted structure with low symmetry. If the material comprises a material having a chemical bond with CaTiO3The symmetry will also be lower for the layers of the structure related structure of (1). Materials comprising layers or regions of perovskite material are well known. With respect to the material comprising the perovskite material layer, K is used2NiF4The material structure of the-type structure includes a layer of perovskite material. The general formula is A2BX4Is referred to in the art as a "2D layered perovskite" which differs structurally from conventional 3D perovskites. Exemplary 2D layered perovskites include K2NiF4And (butylammonium)2PbBr4。
Thus, the term "perovskite" does not refer exclusively to bulk CaTiO3A type three-dimensional perovskite structure. The three-dimensional perovskite may be contained in a larger crystal structure. For example, a three-dimensional perovskite may be a small region within a larger crystal structure. For example, referred to as a 0D/3D structure. Such structures comprise (a) zero-dimensional or "0D" regions, having a class K4CdCl6Structure; and (b) a region having a three-dimensional perovskite structure therein (having a structure similar to that of CaTiO)3A three-dimensional crystal structure related to the three-dimensional crystal structure of (a). Such structures are intended to be covered by the appended claims. Thus, for example, a perovskite of the invention may comprise a region consisting of a three-dimensional perovskite, and the three-dimensional perovskite in that region may for example have formula (I) as defined herein.
The skilled person will appreciate that the 3D perovskite material may be of the formula [ a][B][X]3Is represented by the formula (I), wherein]Is at least one cation, [ B ]]Is at least one cation, and [ X]Is at least one anion. When the perovskite comprises more than one a cation, the different a cations may be distributed over the a sites in an ordered or disordered manner. When the perovskite comprises more than one B cation, the different B cations may be distributed over the B sites in an ordered or disordered manner. When the perovskite comprises more than one X anion, the different X anions may be distributed over the X sites in an ordered or disordered manner. The perovskite comprising more than one A cation, more than one B cation, or more than one X cation will be less symmetric than CaTiO3The symmetry of (a).
As used herein, the term "mixed perovskite" refers to a mixture having a certain ratio of the formula [ A][B][X]3And a proportion of a perovskite of the formula [ A ]]2[B][X]4A perovskite compound of perovskite of (a). Thus, calcium is mixedThe titanium ore may comprise the formula [ A ] which may be in two or more layers][B][X]3Layers of perovskite materials are represented, and may further comprise at least one intermediate layer of type a cations. Materials having these structures are well known. [ A ]][B][X]3A, B and the X cation in the component can be reacted with [ A ]]2[B][X]4A, B and the X cation in the component are the same or different. A solid solution may be formed.
As used herein, the term "metal halide perovskite" is a perovskite in which the formula comprises at least one metal cation and at least one halide anion. They may have the formula [ A ] as defined above][B][X]3Or [ A ]]2[B][X]4However, each B is typically as in [ A ]][M][X]3Or [ A ]]2[M][X]4Wherein M represents at least one metal, wherein X represents a halide.
As used herein, the term "mixed halide perovskite" refers to a perovskite or mixed perovskite containing at least two types of halide anions.
As used herein, the term "mixed cation perovskite" refers to a perovskite or mixed perovskite containing at least two types of a cations.
As used herein, the term "optionally substituted" means that the group in question may or may not bear a substituent, i.e. it may be unsubstituted or substituted. For example, the group may carry 0, 1, 2, 3 or more substituents; typically with 0, 1 or 2 substituents. The substituents may be generally selected from substituted or unsubstituted C1-C20Alkyl, substituted or unsubstituted aryl (as defined herein), cyano, amino, C1-C10Alkylamino radical, di (C)1-C10) Alkylamino, arylamino, diarylamino, arylalkylamino, (acyl) amino (amidi), amido (acylamido), hydroxy, oxo, halo, carboxy, ester, acyl, acyloxy, C1-C20Alkoxy, aryloxy, haloalkyl, sulfonic acid, mercapto (i.e. thiol, -SH), C1-C10Alkylthio, arylthio and sulfonyl.
As used hereinAlkyl groups may be substituted or unsubstituted straight or branched chain saturated groups, typically substituted or unsubstituted straight chain saturated groups, more often unsubstituted straight chain saturated groups. The alkyl group typically contains 1 to 20 carbon atoms, typically 1 to 10 carbon atoms. C1-10Alkyl is an unsubstituted or substituted, straight or branched chain, saturated hydrocarbon group having 1 to 10 carbon atoms. C1-6Alkyl is an unsubstituted or substituted, straight or branched chain, saturated hydrocarbon radical having from 1 to 6 carbon atoms. Typically, it is, for example, methyl, ethyl, propyl, isopropyl, n-propyl, butyl, tert-butyl, sec-butyl, n-butyl, pentyl or hexyl. Usually the alkyl group is C1-4An alkyl group. If the term "alkyl" is used anywhere herein without a prefix designating a number of carbon atoms, the number of carbon atoms is typically from 1 to 20 (this also applies to any other organic group mentioned herein).
As used herein, an alkenyl group can be a substituted or unsubstituted, straight or branched chain unsaturated group, which is typically a substituted or unsubstituted, straight chain unsaturated group, more often an unsubstituted, straight chain unsaturated group. An alkenyl group may comprise one or more carbon-carbon double bonds, for example one, two or three double bonds. Typically, an alkenyl group contains one double bond. Alkenyl groups typically contain 2 to 20 carbon atoms, typically 2 to 10 carbon atoms. C2-10An alkenyl group is an unsubstituted or substituted, straight or branched chain, unsaturated hydrocarbon group having 2 to 10 carbon atoms. C2-6The alkenyl group is an unsubstituted or substituted straight or branched chain unsaturated hydrocarbon group having 2 to 6 carbon atoms. Typically it is, for example, ethenyl, propenyl, prop-1-enyl, prop-2-enyl, butenyl, but-1-enyl, but-2-enyl, but-4-enyl, pentenyl, pent-1-enyl, pent-2-enyl, pent-3-enyl, pent-4-enyl, hexenyl, hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl or hex-5-enyl.
As used herein, a cycloalkyl group can be a substituted or unsubstituted cyclic saturated group, and it is typically an unsubstituted cyclic saturated group. Cycloalkyl groups typically contain 3 to 20 carbon atoms. C3-10Cycloalkyl is unsubstituted or substituted cyclic saturated having 3 to 10 carbon atomsAnd a hydrocarbon group. C3-6Cycloalkyl is an unsubstituted or substituted cyclic saturated hydrocarbon group having 3 to 6 carbon atoms. Typically it is, for example, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.
As used herein, a cycloalkenyl group can be a substituted or unsubstituted cyclic unsaturated group, which is typically an unsubstituted cyclic unsaturated group. Cycloalkenyl groups typically contain 3 to 20 carbon atoms. Cycloalkenyl groups may contain one or more double bonds (depending on the number of carbon atoms present in the ring). C4-10Cycloalkenyl is an unsubstituted or substituted cyclic unsaturated hydrocarbon radical having from 4 to 10 carbon atoms. C4-10Cycloalkenyl is an unsubstituted or substituted cyclic unsaturated hydrocarbon radical having from 3 to 6 carbon atoms. Typically it is, for example, cyclobutenyl, cyclopentenyl or cyclohexenyl.
As used herein, aryl is a substituted or unsubstituted monocyclic or bicyclic aromatic group, typically containing from 6 to 14 carbon atoms, typically from 6 to 12 carbon atoms, preferably from 6 to 10 carbon atoms in the ring portion. C6-12Aryl is a substituted or unsubstituted, monocyclic or bicyclic aromatic radical containing from 6 to 12 carbon atoms. Examples include phenyl, naphthyl, indenyl, and indanyl.
As used herein, an amino group is of the formula-NR2Wherein each R is a substituent. R is typically selected from hydrogen, alkyl, alkenyl, cycloalkyl or aryl, wherein alkyl, alkenyl, cycloalkyl and aryl are each as defined herein. Typically, each R is selected from hydrogen, C1-10Alkyl radical, C2-10Alkenyl and C3-10A cycloalkyl group. Preferably, each R is selected from hydrogen, C1-6Alkyl radical, C2-6Alkenyl and C3-6A cycloalkyl group. More preferably, each R is selected from hydrogen and C1-6An alkyl group.
A typical amino group is an alkylamino group which is of the formula-NR2Wherein at least one R is an alkyl group as defined herein. C1-6An alkylamino group is an alkylamino group containing 1 to 6 carbon atoms.
As used herein, an imine (imino) group is of the formula R2A group of C ═ N-or-C (r) ═ NR,wherein each R is a substituent. That is, an imine group is a group containing a C ═ N moiety, having a radical moiety (radial mobility) on or attached to the N atom of the C ═ N bond. R is as defined herein: that is, R is typically selected from hydrogen, alkyl, alkenyl, cycloalkyl, or aryl, wherein alkyl, alkenyl, cycloalkyl, and aryl are each as defined herein. Typically, each R is selected from hydrogen, C1-10Alkyl radical, C2-10Alkenyl and C3-10A cycloalkyl group. Preferably, each R is selected from hydrogen, C1-6Alkyl radical, C2-6Alkenyl and C3-6A cycloalkyl group. More preferably, each R is selected from hydrogen and C1-6An alkyl group.
Typical imine groups are alkylimino groups which are of the formula R2A group of C ═ N-or-C (R) ═ NR, where at least one R is an alkyl group as defined herein. C1-6An alkylimino group is an alkylimino group in which the R substituent contains 1 to 6 carbon atoms.
As used herein, the term "bandgap" refers to the energy difference between the top of the valence band and the bottom of the conduction band in a material. Of course, the skilled person can readily measure the band gap of semiconductors (including perovskites) using well known methods, which do not require undue experimentation. For example, the bandgap of a semiconductor can be estimated by constructing a photovoltaic diode or solar cell from the semiconductor and determining the photovoltaic spectrum of action. Alternatively, the band gap is estimated by measuring the light absorption spectrum via transmission spectroscopy photometry or photothermal deflection spectroscopy. The band gap can be determined by making a Tauc map, as described in Tauc, J., Gribiovici, R. & Vancu, a. optical Properties and Electronic Structure of Amorphous germanium. Phys. Status Solidi 15,627-637(1966), in which the square of the product of the absorption coefficient times the photon energy is plotted on the Y-axis against the photon energy on the x-axis, where the straight line intercept of the absorption edge to the x-axis gives the optical band gap of the semiconductor. Alternatively, the optical bandgap may be estimated by the starting value of the incident photon-to-electron conversion efficiency, as in [ Barkhouse DAR, Gunawan O, Gokmen T, Todorov TK, Mitzi DB. device characteristics of a 10.1% hydrozineprocessed Cu2ZnSn (Se, S)4 sodium cell. progress in Photomagnetism: Research and Applications 2012; published online DOI:10.1002/pip.1160 ].
As used herein, the term "layer" refers to any structure that is substantially laminar in form (e.g., extends substantially in two perpendicular directions, but is limited in extension in a third perpendicular direction). The thickness of the layer may vary over the range of the layer. Typically, the layer has an approximately constant thickness. As used herein, "thickness" of a layer refers to the average thickness of the layer. The thickness of the layer can be easily measured, for example by measuring the cross-section of the film using a microscope such as an electron microscope, or by surface profilometry, for example using a stylus profilometer.
As used herein, the term "porous" refers to a material having pores disposed therein. Thus, for example, in a porous material, a pore is a volume within the scaffold where no material is present. The pores in the material may include "closed" pores and open pores. Closed cells are pores in the material that do not communicate with a cavity, i.e., pores that are isolated within the material and are not connected to any other pores, and therefore cannot be accessed by fluids to which the material is exposed. On the other hand, the "openings" allow the entry of such liquids. The concepts of open and closed porosity are discussed in detail in J.Rouquerol et al, "Recommendations for the Characterization of holes Solids", Pure & appl.chem., Vol.66, No.8, pp.1739-1758,1994. Thus, porosity refers to the fraction of the total volume of the porous material in which fluid flow can effectively occur. Therefore, it does not include closed cells. The term "open porosity" is interchangeable with the terms "interconnected porosity" and "effective porosity" and is commonly reduced in the art to "porosity". Thus, as used herein, the term "without open porosity" refers to a material without effective porosity. As used herein, the term "non-porous" refers to a porous material that is free of any porosity, i.e., no open porosity and also no closed porosity.
As used herein, the term "semiconductor" or "semiconductor material" refers to a material having a conductivity of an order between that of a conductor and an insulator. The semiconductor may be a negative (n) -type semiconductor, a positive (p) -type semiconductor, or an intrinsic (i) -semiconductor. The semiconductor may have a bandgap (measured at 300K) of 0.5eV to 3.5eV, for example 0.5eV to 2.5eV or 1.0 to 2.0 eV.
As used herein, the term "n-type region" refers to a region of one or more electron transporting (i.e., n-type) materials. Similarly, the term "n-type layer" refers to a layer of electron transporting (i.e., n-type) material. The electron transporting (i.e., n-type) material may be a single electron transporting compound or elemental material, or a mixture of two or more electron transporting compounds or elemental materials. The electron transport compound or elemental material may be undoped or doped with one or more doping elements.
As used herein, the term "p-type region" refers to a region of one or more hole transporting (i.e., p-type) materials. Similarly, the term "p-type layer" refers to a layer of hole transporting (i.e., p-type) material. The hole transporting (i.e., p-type) material can be a single hole transporting compound or elemental material, or a mixture of two or more hole transporting compounds or elemental materials. The hole transport compound or elemental material may be undoped or doped with one or more doping elements.
As used herein, the term "disposed on" … … means that one component is provided or placed on another component. The first component may be provided or placed directly on the second component, or there may be a third component interposed between the first and second components. For example, if a first layer is disposed on a second layer, this includes the case where there is an intermediate third layer between the first layer and the second layer. However, generally, "disposed/disposed on … … refers to placing one component directly on another component.
As used herein, the term "electrode material" refers to any material suitable for use in an electrode. The electrode material will have a high electrical conductivity. As used herein, the term "electrode" means a region or layer that consists of or consists essentially of an electrode material.
As used herein, the term "optoelectronic device" refers to a device that emits, controls, detects, or emits light. Light is understood to include any electromagnetic radiation. Examples of optoelectronic devices include photovoltaic devices, photodiodes, solar cells, photodetectors, phototransistors, photomultiplier tubes, photoresistors, color-developing devices, phototransistors, light-emitting devices, light-emitting diodes, and charge injection lasers.
As used herein, the term "phosphor" refers to a material that absorbs photons of a first energy and emits photons of a second energy, wherein the second energy is lower than the first energy. For example, the phosphor may absorb photons having a wavelength of 405nm and emit photons having a wavelength of 467 nm.
The term "consisting essentially of … …" refers to a composition that includes the components consisting essentially of, as well as other components, provided that the other components do not materially affect the basic characteristics of the composition. Generally, a composition consisting essentially of certain components will include greater than or equal to 95 wt% of these components or greater than or equal to 99 wt% of these components.
Perovskite of formula (I)
In a first aspect, the present invention provides perovskites of formula (I)
[RbxCs(1-x)][Pb][BryCl(1-y)]3 (I)
Wherein x is greater than 0 and less than 1 and y is greater than 0 and less than 1.
The advantages of these particular compounds can be seen from the table in the examples section below by comparing mixed cationic lead halide perovskites with mixed halide lead halide perovskites with the presently claimed materials.
Table 1 shows photoluminescence quantum yield (PLQY, a measure of luminescence intensity) as a function of mixed halide perovskite CsPb (Br/Cl)3Change of the content of chloride ion. The absorbance and emission of the mixed halide perovskite is also shown in fig. 1. It can be seen that as the amount of chloride ions in the perovskite increases from 0 to 70% of the total amount of halide ions, the emission peak wavelength decreases. That is, the emission of the resulting perovskite shifts towards the blue region of the spectrum. However, PLQY decreases significantly with increasing chloride ion content. It can be seen that the emission efficiency of the cesium lead halide perovskite containing 50% chloride and 50% bromide (as a percentage of the total halide) is only about that of pure cesium lead bromideHalf of perovskite.
Table 6 shows PLQY with mixed cation perovskite (Cs/Rb) PbBr3Variation in rubidium content. The absorption and emission characteristics of these substances are also shown in fig. 6. It can be seen that there is little change in the peak emission wavelength as the amount of rubidium in the perovskite increases from 0 to 70% of the total monovalent cation content. Thus, there is no tendency for the emission wavelength to move towards the blue region of the spectrum.
However, surprisingly, table 3 shows that the compounds of formula (I) as defined herein have tunable emission wavelengths in the blue region of the spectrum at good PLQY. Peak emission wavelength and PLQY are shown with mixed halide mixed cation perovskite (Cs/Rb) Pb (Br)0.5Cl0.5))3The content of rubidium in the product changes. It can be seen that as the rubidium content increases from 0 to 20% of the total monovalent cation content, the emission wavelength will shift slightly toward the blue region of the spectrum and the emission efficiency PLQY will increase. It is also possible to see that a perovskite having this formula containing 70% (as a percentage of the total monovalent cation content) of rubidium emits at 464nm, very deep into the blue region of the spectrum. As can be seen from the absorbance data of this substance shown in FIG. 3a, Cs is0.3Rb0.7Pb(Br0.5Cl0.5))3The substance has a strong absorption at about 450 nm. Strong absorption characteristics in the blue region of the spectrum are most useful in applications where absorption of visible light is required, such as in materials used in solar cell fabrication.
For comparison, FIG. 8 shows mixed cation and mixed halide lead perovskite Cs1-xRbxPb(I0.45Br0.55)3Absolute photoluminescence intensity (indication of PLQY). The rubidium-free perovskite exhibits a broad emission peak extending between about 600nm and 640nm in the orange-red region of the visible spectrum. However, as the rubidium content increases above 0% of the total monovalent cation content, the peak emission wavelength may shift further toward the red region of the spectrum, rather than the blue region. The peak emission wavelength began to be visible when the rubidium content increased from 0.05% to 30% of the total monovalent cation contentThe red region of the spectrum shifts to the orange region and photoluminescence decreases (a decrease in the size of the peak is observed). Thus, Cs1-xRbxPb(I0.45Br0.55)3Does not exhibit the same behaviour as the compound of formula (I) with respect to rubidium content.
Thus, in one embodiment, the compounds of the invention, in particular the perovskites of formula (I), have a chemical structure with CsPbBr3Or CsPbCl3PLQY which is the same or better than them.
Furthermore, the perovskite of formula (I) may emit light having a wavelength of less than 500 nm. For example, the perovskite of formula (I) may emit light having a wavelength of 450nm to 495nm, preferably about 455 to 495nm, more preferably about 460nm to 490nm, more preferably 460nm to 485nm, more preferably from 465nm to 480 nm. Of course, this does not exclude that the perovskite may emit light with other wavelengths.
The perovskite of formula (I) may have a peak emission wavelength, for example a peak photoluminescence emission wavelength, of less than 500 nm. In general, the perovskite of formula (I) may have a peak emission wavelength, for example a peak photoluminescence emission wavelength, of from 450nm to 495nm, preferably from about 455nm to 495nm, more preferably from about 460nm to 490nm, more preferably from about 460nm to 485nm, most preferably from 465nm to 480 nm.
Furthermore, the photoluminescence of the compounds of formula (I) is highly stable. It is known that the peak photoluminescence wavelength of perovskite minerals containing more than one type of halide ions tends to shift over time, typically due to the segregation of halide ions. However, the compounds of formula (I) resist such shifts. FIG. 10 shows (Cs)0.6Rb0.4)Pb(Br0.5Cl0.5)3Photoluminescence peak positions after different periods of exposure to uv light. The position of the photoluminescence peak remains unchanged even at exposures of up to 60 minutes. Although this data is not shown in fig. 10, exposure for more than 60 minutes did not result in significant changes in the photoluminescence peak positions.
Thus, in one embodiment, the compounds of the invention, in particular the perovskites of formula (I), have a photoluminescence peak position that remains constant upon exposure to UV light (e.g. 365nm light) for at least 30 minutes or at least 60 minutes.
Typically, each of Rb, Cs, Cl and Br is present in non-negligible amounts. Thus, typically, in formula (I) [ RbxCs(1-x)][Pb][BryCl(1-y)]3In the perovskite of (a), x is greater than 0.01. Preferably, x is greater than 0.05, such as greater than 0.1 or 0.15.
Typically, x is from 0.01 to 0.99. Preferably, x is from 0.05 to 0.95, more preferably from 0.1 to 0.9. In one embodiment, x is 0.1 to 0.5. In another embodiment, x is from 0.2 to 0.8, preferably from 0.3 to 0.7. Preferably, x is from 0.35 to 0.65; particularly preferably, x is from 0.35 to 0.5, for example from 0.35 to 0.45. For example, x may be 0.4.
Typically, y is greater than 0.01. Preferably y is greater than 0.05, for example greater than 0.1 or 0.2.
Typically, y is from 0.01 to 0.99. Preferably, y is from 0.05 to 0.95, more preferably from 0.1 to 0.9. In one embodiment, y is from 0.1 to 0.9, preferably from 0.2 to 0.8, more preferably from 0.3 to 0.7. In a particularly preferred embodiment, y is from 0.4 to 0.6, for example from 0.45 to 0.55. For example, y may be 0.5.
Thus, typically, x is from 0.01 to 0.99 and y is from 0.01 to 0.99. Preferably, x is 0.05 to 0.95 and y is 0.05 to 0.95. Particularly preferably, x is 0.1 to 0.9 and y is 0.1 to 0.9. In a particularly preferred embodiment, x is from 0.35 to 0.65 and y is from 0.4 to 0.6. For example, x is 0.35 to 0.45 and y is 0.4 to 0.6 or 0.45 to 0.55. Thus, for example, x may be 0.4 and y 0.5.
It has been found that the compounds of formula (I) emit blue light in a stable manner with surprisingly good photoluminescence quantum yields. Accordingly, the present invention provides the use of a perovskite of formula (I) for emitting blue light:
[RbxCs(1-x)][Pb][BryCl(1-y)]3 (I)
wherein x is greater than 0 and less than 1, and y is greater than 0 and less than 1. Typically, the perovskite of formula (I) is used to emit light having a field of less than 500nm, for example from about 450nm to 495nm, preferably from about 455nm to 495nm, more preferably from about 460nm to 490nm, more preferably from 460nm to 485nm, most preferably from 465nm to 480 nm. For example, the perovskite of formula (I) may be used to emit light having a peak emission wavelength (e.g. peak photoluminescent emission wavelength) of less than 500nm, for example from about 450nm to 495nm, preferably from about 455nm to 495nm, more preferably from about 460nm to 490nm, more preferably from 460nm to 485nm, most preferably from 465nm to 480 nm.
In the use of the compounds of formula (I) according to the invention, x is generally from 0.1 to 0.9 and y is from 0.1 to 0.9. In a preferred embodiment, x is from 0.35 to 0.65 and y is from 0.4 to 0.6. For example, x is 0.35 to 0.45 and y is 0.4 to 0.6 or 0.45 to 0.55.
For example, described herein is the use of a compound of formula (I) for emitting light having a wavelength of 460nm to 485nm
[RbxCs(1-x)][Pb][BryCl(1-y)]3 (I)
Wherein x is 0.35 to 0.65 and y is 0.4 to 0.6; preferably, wherein x is 0.35 to 0.45 and y is 0.45 to 0.55.
Perovskite of formula (II)
In a second aspect, the present invention provides a mixed perovskite of formula (II)
{[A]2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-a (II)
Wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
a is greater than 0 and less than 1;
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
The mixed perovskite of formula (II) may also be referred to as "mixed 2D/3D perovskite". However, although they have mixed 2D/3D structures, these mixed compounds may be composed of a single crystalline material, rather than multiple crystalline materials each having a different chemical composition. These mixed size perovskites are commonly referred to as Ruddlesden-Popper phases and are described in detail in "Ruddlesden-Popper hybrid lead oxide perovskite 2D homologus semiconductors", Stoumpos et al, chem.mater; 2016,28,2852 and 2867 ".
In another aspect, the present invention provides a mixture comprising:
(a) formula [ A ]]2[M][X]4The compound of (a) to (b),
wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
and
(b) formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Of (a) a compound
Wherein
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
"mixture" may refer to the physical admixture of two component compounds of a mixture. For example, the mixture may include formula [ A ] both in powder form or in crystalline form]2[M][X]4A compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Wherein particles (e.g. powder or crystals) of one component are distributed in particles of the other component. For example, formula [ A]2[M][X]4Particles of a compound of formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3The particles of the compound(s) may be co-localized, such as on a substrateIn a medium or on a substrate.
In another embodiment, the mixture can include a crystalline material comprising the formula [ A]2[M][X]4A compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Crystal grains of the compound of (1).
The mixed perovskites and mixtures of formula (II) according to the invention have the same surprising advantages as the compounds of formula (I). That is, they exhibit surprisingly effective emission and absorption in the blue region of the visible spectrum, and their peak emission wavelengths can be tuned by tuning.
These advantages are confirmed by the data in the table shown in the examples section below.
Table 7 and fig. 7 show the emission characteristics of mixed 2D/3D perovskites outside the scope of the invention, where b is 0 and c is 1. It can be seen that these substances all emit outside the blue region of the spectrum. And, despite the increase [ A ]]2[M][X]4The amount of substance still fails to tune the emission spectrum into the blue region of visible light. Introduction of [ A]2[M][X]4(where x ═ 0.05, 0.1, and 0.3) do increase the peak emission wavelength, moving it towards the red region. Further increase of [ A ]]2[M][X]4Is such that x is 0.5, which does shift the emission wavelength slightly towards the blue region of the spectrum. However, the 519nm peak position was still strongly in the green region, and the PLQY of this material was only CsPbBr3Half of PLQY for 3D perovskite minerals.
In contrast, the data in Table 2 and FIG. 2 indicate [ A ]]2[M][X]4And CsPb (Br)0.5Cl0.5)3Provides a substance that emits in the blue region of the visible spectrum and is tunable between at least 482nm and 476 nm. Moreover, PLQY of this class is surprisingly high: (CsPb (Br)0.5Cl0.5)3)0.7((BA)2PbBr4)0.3Emits at 476nm deep into the blue region, and has an emission efficiency ratio CsPb (Br)0.5Cl0.5)3High. BA is butyl aluminium.
The effects of the mixed halide ion species shown in table 2 and fig. 2 can also be observed in the mixed monovalent cation species. Table 4 shows ((BA)2PbBr4)x(Cs0.6Rb0.4Pb(Br0.5Cl0.5)3)1-xThe emission characteristic of (1). When x increases from 0 to 0.1 (i.e. upon introduction [ A ]]2[M][X]4Substance), the PLQY of the substance is more than doubled. Also, as shown by the photoluminescence spectrum in fig. 4(b), although the peak emission wavelength is shifted to 480nm (still in the blue region of the spectrum), the emission spectrum is broadened, and emission at low wavelengths, even below 450nm, is observed.
FIG. 11 and Table 8 also illustrate thatbCs(1-b)][Pb][BrcCl(1-c)]3The effect of mixing the monovalent cation fraction in the fraction. An increase in b from 0 to 0.4 causes a sharp shift in the photoluminescence peak position from 489 to 478 and a significant increase in the photoluminescence quantum yield. The combination of blue shift and PLQY increase is unusual and very advantageous for producing blue light.
Thus, in one embodiment, the compounds of the invention, in particular the mixed perovskites of formula (II) and the mixtures of the invention, have a PLQY equal to or greater than CsPbBr3Or CsPbCl3The PLQY of (1). In a preferred embodiment, the mixed perovskite of formula (II) and the mixture of the invention have a PLQY equal to or greater than CsPb (Br)cCl1-c)3Wherein c is greater than 0 and less than 1. In another preferred embodiment, the mixed perovskite of formula (II) and the mixture of the invention have a PLQY equal to or greater than CsbRb1-bPbBr3Wherein b is greater than 0 and less than 1. In another preferred embodiment, the mixed perovskite of formula (II) and the mixture of the invention have a PLQY equal to or greater than CsbRb1-bPbCl3Wherein b is greater than 0 and less than 1.
In a particular embodiment of the invention, the mixed perovskite of formula (II) and the mixture of the invention have a PLQY equal to or greater than CsbRb1-bPb(BrcCl1-c)3Wherein b and c are both greater than 0 and less than 1.
Thus, in general, the mixed perovskites of formula (II) of the present invention and the above mixtures emit light in the blue region of the visible spectrum. For example, the mixed perovskite of formula (II) and the above mixture may emit light having a wavelength of 450nm to 495nm, preferably 460nm to 495nm, and more preferably 465nm to 490 nm. In some cases, the mixed perovskite of formula (II) and the above-described mixtures may emit light having a wavelength of 470nm to 490nm or 475nm to 490 nm. Of course, the mixed perovskites of formula (II) of the present invention and the above-described mixtures may emit light having other wavelengths. The mixed perovskite of formula (II) of the present invention and the above-described mixture may have a peak emission wavelength, for example a photoluminescence peak emission wavelength, of less than 500nm, preferably from 450nm to 495nm, preferably from 460nm to 495nm, more preferably from 465nm to 490 nm. In certain instances, the mixed perovskites of formula (II) of the present invention and the above-described mixtures may have a peak emission wavelength of 470nm to 490nm or 475nm to 490nm, such as a photoluminescence peak emission wavelength.
Thus, the mixed perovskites of formula (II) of the present invention and the above mixtures can be used to emit light in the blue region of the visible spectrum. The present invention therefore provides the use of a mixed perovskite of formula (II) for emitting blue light
{[A]2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-a (II)
Wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
a is greater than 0 and less than 1;
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
Typically, the mixed perovskite of formula (II) is used to emit light at wavelengths of less than 500 nm. For example, the mixed perovskite of formula (II) may be used to emit light having a wavelength of about 450 to 495nm, preferably 460 to 495nm, more preferably 465 to 490nm, for example 470 to 490nm or 475 to 490 nm. The mixed perovskite of formula (II) may in particular be used for emitting a peak emission wavelength (e.g. a photoluminescence peak emission wavelength) of less than 500nm, preferably from 450nm to 495nm, preferably from 460nm to 495nm, more preferably from 465nm to 490 nm; such as 470nm to 490nm or 475nm to 490 nm.
Similarly, the present invention provides the use of a mixture comprising:
(a) formula [ A ]]2[M][X]4The compound of (a) to (b),
wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
and
(b) formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Of (a) a compound
Wherein
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
Typically, the mixture is used to emit light having a wavelength of less than 500 nm. For example, the mixture may be used to emit light having a wavelength of from about 450nm to 495nm, preferably from 460nm to 495nm, more preferably from 465nm to 490nm, for example from 470nm to 490nm or from 475nm to 490 nm. The mixture may in particular be used for emission peak emission wavelengths (e.g. photoluminescence peak emission wavelengths) of less than 500nm, preferably 450nm to 495nm, preferably 460nm to 495nm, more preferably 465nm to 490 nm; such as 470nm to 490nm or 475nm to 490 nm.
In the mixed perovskites of formula (II) of the present invention and the above mixtures, the 3D perovskite component comprises a mixture of halide ions and/or a mixture of monovalent cations. Typically, the 3D perovskite comprises a mixture of monovalent cations. Thus, in a preferred embodiment, b is greater than 0 and less than 1.
In preferred embodiments of the mixed perovskites of the invention and of the mixtures described above, both b and c are greater than 0 and less than 1. As can be understood from the examples, embodiments wherein b and c are both greater than 0 and less than 1 provide mixed perovskites or mixtures of formula (II) with advantageously higher PLQY and emission spectra that extend deep into the blue region of the visible spectrum. In a preferred aspect of the invention, in particular where b is greater than 0 and less than 1, the emission spectrum of the mixed perovskite or mixture of formula (II) of the invention is extended by at least 450 nm. By "extending at least to 450 nm" is meant that the mixed perovskite or mixture may emit at 450nm and optionally also shorter wavelength emissions.
When b is greater than 0 and less than 1, b is usually 0.01 to 0.99. For example, b may be 0.1 to 0.9. Preferably, b is from 0.2 to 0.8, more preferably from 0.3 to 0.7.
When c is greater than 0 and less than 1, typically c is from 0.01 to 0.99. For example, c may be 0.1 to 0.9. Preferably, c is from 0.2 to 0.8, preferably from 0.3 to 0.7.
In the mixed perovskites of formula (II) of the present invention, a is greater than 0 and less than 1. The size of a is not negligible, so a is typically 0.01 to 0.99. For example, a may be 0.05 to 0.9, preferably 0.05 to 0.5.
In the mixture of the present invention, [ A ] is]2[M][X]4With respect to the amount of the compound of the formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3The ratio of the amounts of the compounds of (a) may vary. However, both components are present in non-negligible amounts. Thus, [ A ]]2[M][X]4And [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Is usually in the range of 1: 99 to 99: 1. For example, [ A ]]2[M][X]4And [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3May be in the range of 5: 95 to 90: 10. Preferably, [ A ]]2[M][X]4And [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3In a molar ratio of from 5: 95 to 50: 50.
The mixed perovskites and mixtures of the invention comprise the formula [ A]2[M][X]4The component (c). [ A ]]Monovalent cations of one or more independent species may be included. These independent species are referred to as a. Thus, [ A ]]2[M][X]4One or more a may be contained. Similarly, [ M ]]May contain one or more metal or metalloid divalent cations, each individually designated as M, and [ X [ ]]May contain one or more halide anions or species X. For example, in [ A ]]2[M][X]4In the case where the component contains both bromide and chloride ions, [ X ]]The composition includes a first X species that is a bromide and a second X species that is a chloride.
[A]Will be considered to be first. [ A ]]Comprising one or more organic monovalent cations. [ A ]]Typically comprising one, two or three species a. When [ A ] is]When more than one species a is included, each species a has a positive charge and may be referred to as a monovalent cation. Preferably, when [ A ]]When more than one species a is included, each species a is an organic monovalent cation. However, A may also be an inorganic substance, such as Cs+。
Typically, [ A ] comprises a single A species.
When the a species is an organic monovalent cation, a is typically an ammonium cation or an iminium cation, each of which may be optionally substituted. For example, each a may be an optionally substituted ammonium cation or an optionally substituted iminium cation.
When the A species is an organic monovalent cation, A is typically selected from C1-10Alkylammonium ion, C2-10Alkenyl ammonium ion, C1-10Alkyl imine ion, C3-10Cycloalkylammonium ion and C3-10Cycloalkyliminium ions, these radicals being optionally substituted by one or more groups selected from amino, C1-6Alkylamino, imino, C1-6Alkyl imino radical、C1-6Alkyl radical, C2-6Alkenyl radical, C3-6Cycloalkyl and C6-12A substituent of an aryl group. In [ A ]]Where more than one substance a is included, typically each substance a is selected from the list.
In some embodiments, where the species a is an organic monovalent cation, a is C optionally substituted with one, two, or three amino or imino groups2-10Alkyl primary ammonium ion. "alkyl primary ammonium ion" refers to an alkyl ammonium cation wherein only one substituent on the quaternary nitrogen atom is other than hydrogen. In typical aspects of this embodiment, each A cation is C optionally substituted with one, two, or three amino or imino groups2-10Alkyl primary ammonium cations.
In a preferred embodiment, when the species a is an organic monovalent cation, it is selected from the group consisting of ethylammonium ion, propylammonium ion, butylammonium ion, pentylammonium ion, hexylammonium ion, heptylammonium ion (septyllammonium), octylammonium ion, benzylammonium ion, phenethylammonium ion, benzylammonium ion, naphthylmethylammonium ion, and guanidinium. In a preferred aspect of this embodiment, each a cation is selected from the group consisting of ethylammonium ion, propylammonium ion, butylammonium ion, pentylammonium ion, hexylammonium ion, heptylammonium ion, octylammonium ion, benzylammonium ion, phenethylammonium ion, benzylammonium ion, naphthylmethylammonium ion, and guanidinium group.
In a particularly preferred embodiment, when the species a is an organic monovalent cation, it is a butylammonium ion. Preferably, each a cation is a butylammonium ion. That is, [ a ] includes a single species of a, which is butylammonium ion, in a particularly preferred embodiment.
As used herein, the term "ammonium ion" refers to an organic cation comprising a quaternary nitrogen. The ammonium cation being of the formula R1R2R3R4N+A cation of (2). R1、R2、R3And R4Is a substituent. R1、R2、R3And R4Each of which is typically independently selected from hydrogen or optionally substituted alkyl, alkenyl, aryl, cycloalkyl, cycloalkenyl and amino; optionally (c) isThe substituent is preferably an amino or imino substituent. In general, R1、R2、R3And R4Each independently selected from hydrogen, and optionally substituted C1-10Alkyl radical, C2-10Alkenyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkenyl radical, C6-12Aryl and C1-6An amino group; where present, the optional substituents are preferably amino groups; particularly preferred is C1-6An amino group. Preferably, R1、R2、R3And R4Each of which is independently selected from hydrogen and unsubstituted C1-10Alkyl radical, C2-10Alkenyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkenyl radical, C6-12Aryl and C1-6An amino group. In a particularly preferred embodiment, R1、R2、R3And R4Independently selected from hydrogen, C1-10Alkyl and C2-10Alkenyl and C1-6An amino group. Further preferably, R1、R2、R3And R4Independently selected from hydrogen, C1-6Alkyl radical, C2-6Alkenyl and C1-6An amino group.
Preferred ammonium cations include C2-10An alkylammonium cation of the formula R1R2R3R4N+Wherein R is1、R2、R3And R4At least one of them is C1-10An alkyl group. For example, R1、R2、R3And R4Is one of C1-10Alkyl, and the other three are hydrogen. For example, preferred ammonium cations include ethylammonium ion, butylammonium ion, pentylammonium ion, and hexylammonium ion.
Preferred ammonium cations also include C2-10An alkenylammonium cation of the formula R1R2R3R4N+Wherein R is1、R2、R3And R4At least one of which is optionally substituted C2-10Alkenyl, preferably unsubstituted C2-10An alkenyl group. For example, R1、R2、R3And R4Is one of C2-10Alkenyl, and the other three are hydrogen. For example, preferred ammonium cations include vinylammonium ions, propenyl ammonium ions, butenyl ammonium ions, pentenyl ammonium ions, and hexenyl ammonium ions.
Preferred ammonium cations further include C3-10A cycloalkylammonium cation of the formula R1R2R3R4N+Wherein R is1、R2、R3And R4At least one of them is C3-10A cycloalkyl group. For example, R1、R2、R3And R4Is one of C3-10Cycloalkyl, and the other three are hydrogen. For example, preferred ammonium cations include cyclopropylammonium, cyclobutylammonium, cyclopentylammonium and cyclohexylammonium.
The term "iminium", as used herein, denotes an imine of formula (R)1R2C＝NR3R4)+Wherein R is1、R2、R3And R4As defined in relation to the ammonium cation. Thus, in a particularly preferred embodiment of the iminium cation, R1、R2、R3And R4Independently selected from hydrogen, C1-10Alkyl radical, C2-10Alkenyl and C1-6An amino group. In another preferred embodiment of the iminium cation, R1、R2、R3And R4Independently selected from hydrogen, C1-6Alkyl radical, C2-6Alkenyl and C1-6An amino group.
Preferred iminium cations include C1-10An alkyl imine cation of the formula (R)1R2C＝NR3R4)+Wherein R is1、R2、R3And R4At least one of them is C1-10An alkyl group. For example, R1、R2、R3And R4Is one of C1-10Alkyl, and the other three are hydrogen. For example, preferred iminium cations include (H)2N＝CH2)+；(H2N＝CHCH3)+；(H2N＝C(CH3)2)+；(H(CH3)N＝CH2)+；(H(CH3)N＝CHCH3)+；(H(CH3)N＝C(CH3)2)+；((CH3)2N＝CH2)+；((CH3)2N＝CHCH3)+；((CH3)2N＝C(CH3)2)+；(H2N＝CHNH2)+；(H2N＝C(CH3)(NH2))+；(H(CH3)N＝CHNH2)+；(H(CH3)N＝C(CH3)(NH2))+；((CH3)2N＝CHNH2)+；((CH3)2N＝C(CH3)(NH2))+. Particularly preferred is (H)2N＝CHNH2)+. Preferred iminium cations also include C2-10An alkenylimine cation of the formula (R)1R2C＝NR3R4)+Wherein R is1、R2、R3And R4At least one of them is C2-10An alkenyl group. For example, R1、R2、R3And R4Is one of C2-10Alkenyl, and the other three are hydrogen.
Further preferred iminium cations include those wherein R is1、R2、R3And R4Is at least one of C1-6Those of amino groups. C1-6Amino is preferably R1Or R2Such that the nitrogen atom of the amino group is directly bonded to the carbon of the imine based substance. Still further preferred iminium cations include those wherein R is1And R2Is at least one of C1-6Amino and wherein R1、R2、R3And R4At least one of the remaining three groups of (A) is C1-10Those of alkyl groups.
Preferred iminium cations further include C3-10A cycloalkylimine cation of the formula (R)1R2C＝NR3R4)+Wherein R is1、R2、R3And R4At least one of them is C3-10A cycloalkyl group. For example, R1、R2、R3And R4Is one of C3-10Cycloalkyl, and the other three are hydrogen.
Now, consider [ M ]. [ M ] includes one or more metal or metalloid divalent cations M. [ M ] may generally comprise one, two or three species of M. When [ M ] includes more than one species of M, each species of M bears a double positive charge and may be referred to as a divalent cation.
Typically, [ M ] comprises a single M species.
Each metal or metalloid divalent cation M may be a divalent cation derived from any metal in groups 1 to 16 of the periodic table. The metal or metalloid cation can be any suitable metal or metalloid divalent cation. Metalloids are generally considered to be the following elements: B. si, Ge, As, Sb, Te and Po.
Typically, each M cation is selected from Ca2+、Sr2+、Cd2+、Cu2+、Ni2+、Mn2+、Fe2+、Co2+、Pd2+、Ge2+、Sn2+、Pb2+、Yb2+And Eu2+. Preferably, the or each metal or metalloid cation M is Cu2+、Pb2 +、Ge2+Or Sn2+. Typically, the or each metal or metalloid cation M is selected from Pb2+Or Sn2+Particularly preferred is Pb2+. Thus, in a preferred embodiment, [ M ] is]From Pb2+And (4) forming.
About [ X ]]，[X]Comprising one or more halide anions X. In general [ X ]]Comprising one, two or three halide ions X. The halide ions X are each selected from F-、Cl-、Br-And I-Preferably Cl-Or Br-. Therefore, the temperature of the molten metal is controlled,in some embodiments, [ X ]]Including the first halide being Cl-And the second halide ion is Br-。
However, usually, [ X ]]Including a single halide X. Thus, in a preferred embodiment of the mixed perovskite or mixture of the invention, [ X ] is]From Cl-Or Br-Consists of a single X anion.
Thus, in a preferred embodiment of the mixed perovskite or mixture of formula (II) of the present invention:
each a is an ammonium ion or iminium cation as defined herein;
each M is selected from Cu2+、Pb2+、Ge2+Or Sn2+(ii) a And is
Each X is selected from Cl-Or Br-.
In a first preferred aspect of this embodiment, in the mixed perovskite of formula (II), a, b and c are each 0.01 to 0.99. In a second preferred aspect of this embodiment, in the mixture of the invention, b and c are 0.01 to 0.99, and [ A]2[M][X]4And [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3In a molar ratio of 1: 99 to 99: 1.
In a further preferred embodiment of the mixed perovskite of formula (II) of the present invention or of the above-mentioned mixtures:
[A]comprising one, two or three substances A, wherein each A is of the formula R1R2R3R4N+Ammonium cation of the formula (R)1R2C＝NR3R4)+In which R is1、R2、R3And R4Each of which is independently selected from hydrogen and unsubstituted C1-10Alkyl radical, C2-10Alkenyl radical, C3-10Cycloalkyl radical, C3-10Cycloalkenyl radical, C6-12Aryl and C1-6An amino group;
[M]comprises one or two of Cu2+And Pb2+The M substance of (1); and is
[X]Comprises one or two of Cl-Or Br-The substance X of (1).
In a first preferred aspect of this embodiment, in the mixed perovskite of formula (II), a is 0.01 to 0.9, and b and c are each 0.1 to 0.9. In a second preferred aspect of this embodiment, in the mixture of the invention, b and c are 0.1 to 0.9, and [ A]2[M][X]4And [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3In a molar ratio of 1: 99 to 90: 10.
In a further preferred embodiment of the mixed perovskite or mixture of formula (II) of the present invention:
[A] comprising one, two or three species A, wherein each species A is selected from the group consisting of ethylammonium ion, propylammonium ion, butylammonium ion, pentylammonium ion, hexylammonium ion, heptylammonium ion, octylammonium ion, benzylammonium ion, phenylethylammonium ion, benzylammonium ion, naphthylmethylammonium ion and guanidinium;
[M]comprising a M species, i.e. Pb2+(ii) a And is
[X]Comprises one or two of Cl-Or Br-The substance X of (1).
In a first preferred aspect of this embodiment, in the mixed perovskite of formula (II), a is from 0.05 to 0.5, and b and c are each from 0.2 to 0.8. In a second preferred aspect of this embodiment, in the mixture of the invention, b and c are 0.2 to 0.8, and [ A]2[M][X]4And [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3In a molar ratio of from 5: 95 to 50: 50.
Photoactive material
The present invention further provides a photoactive material comprising a perovskite of formula (I) as defined herein and/or a mixed perovskite of formula (II) as defined herein and/or a mixture as defined herein.
As used herein, the term "photoactive material" refers to a material that can absorb and/or emit photons. The photoactive material may perform one or more of the following:
(i) photons are absorbed which can then generate free charge carriers such as electrons and holes. These materials are referred to as light absorbing materials.
(ii) Absorb photons having energies above their band gap and re-emit photons at the energy of the band gap (these materials are referred to as light emitting materials); one type of light emitting material is a luminescent material, which refers to a material that emits light upon absorption of a photon, i.e., a phosphorescent material or a fluorescent material.
(iii) Accepting charges, i.e., electrons and holes, which can then recombine and emit light.
Thus, photoactive materials are examples of semiconductor materials. As used herein, a semiconductor or semiconductor material refers to a material having an electrical conductivity of an order between that of a conductor and an insulator. The semiconductor may have a bandgap of 0.5 to 3.5eV, for example 0.5 to 2.5eV or 1.0 to 2.0eV (when measured at 300K).
The photoactive materials of the present invention are generally capable of absorbing and/or emitting photons in the visible region of the spectrum, particularly in the blue region of the visible spectrum. For example, the photoactive materials of the present invention can generally absorb and/or emit at least one photon having a wavelength of 500nm or less, e.g., 495nm or less. In a preferred embodiment, the compounds of the invention have a peak emission wavelength in the range from 450nm to 500nm, preferably from 455nm to 495nm, particularly preferably from 460nm to 490 nm. However, photoactive materials that can absorb and emit photons do not typically exhibit peak absorption and peak emission at exactly the same wavelength.
Peak absorption refers to the wavelength at which the photoactive material most efficiently absorbs photons, and peak emission refers to the wavelength at which the photoactive material most efficiently emits photons. Typically, the peak emission of the photoactive material is 500nm or less, for example 495nm or less. In a preferred embodiment, the compounds of the invention have a peak emission wavelength in the range from 450nm to 500nm, preferably from 455nm to 495nm, particularly preferably from 460nm to 490 nm.
The photoactive material can comprise greater than or equal to 5 wt% of the compounds of the present invention. Typically, at least 50 wt% of the photoactive material consists of one or more of the compounds of formula (I) and/or compounds of formula (II) and/or mixtures as defined herein. The photoactive material can comprise additional components described herein, such as a scaffold material, a matrix material, or a coating. Typically, however, the photoactive material comprises greater than or equal to 80 wt% of a compound of the invention as defined herein. Preferably, the photoactive material comprises greater than or equal to 95 wt% of a compound of the invention as defined herein, for example greater than or equal to 99 wt% of a compound of the invention as defined herein. The photoactive material may consist of or consist essentially of a compound of the invention as defined herein.
Photoactive materials are typically solids.
There is no particular limitation on the physical form of the compounds of the present invention within the photoactive material. When present, the compounds of the present invention may be in powder form or crystalline form.
When the compound of the present invention is present in a crystalline form, the compound may be crystalline or polycrystalline. A crystalline compound is a compound having an extended 3D crystal structure. The crystalline compound is generally in the form of crystals, or in the case of a polycrystalline compound, in the form of crystallites (i.e., a plurality of crystals having a particle size of 1 μm or less). Typically the crystals together form a layer. The crystals of the crystalline material may be of any size. When the crystals of the compound of the present invention are in a crystalline form (non-polycrystalline form), the smallest dimension thereof is usually not less than 1nm, and the largest dimension thereof is not more than 100 micrometers (μm). When crystals have a size in the range of 1nm to 1000nm in one or more dimensions, they may be described as nanocrystals.
Thus, in one aspect, the photoactive material of the present invention comprises or consists of at least one compound of the present invention in powder form. In another aspect of the invention, the photoactive material comprises or consists of at least one compound of the invention in crystalline form (e.g., a polymorph or nanocrystal).
Typically, photoactive materials comprise one or more compounds of the present invention in crystalline form, which may be crystalline or polycrystalline. For example, the photoactive material may comprise a plurality of crystallites of one or more compounds of the present invention. In a preferred embodiment, the present invention provides a photoactive material comprising a compound of formula (I) and/or a compound of formula (II) that is a crystalline or polycrystalline compound.
The photoactive material is typically a light emitting material or a light absorbing material. The light emitting material is a material that can emit light, typically visible light, particularly blue light (e.g., light having a wavelength of about 450nm to 500nm, preferably about 455nm to 495nm, more preferably about 460nm to 490 nm). The light absorbing material is a material that can absorb light, typically visible light, particularly blue light (e.g., light having a wavelength of about 450nm to 500nm, preferably about 455nm to 495nm, more preferably about 460nm to 490 nm).
The photoactive material can be in any form. Typically, the photoactive material is in the form of a layer. The photoactive material in the form of a layer is typically at least 1nm thick. The layer of photoactive material may be as thick as 10mm, for example in the case where the layer is intended as a free-standing component of a device. Typically, the layer of photoactive material is 2nm to 1mm thick, more typically 5nm to 5 μm thick.
A layer of photoactive material comprises one or more compounds of the present invention within the layer. The amount of the compound of the invention in the layer may depend on other components in the layer, such as any coating on the crystals of the compound of the invention; or the matrix or scaffold material. In some embodiments, the photoactive material may consist essentially of a layer of one or more compounds of the present invention, i.e. a layer of one or more of a compound of formula (I), a compound of formula (II) or a mixture as defined herein. For example, a photoactive material may be composed entirely of one or more compounds of the invention, e.g., composed of a single compound of the invention. More typically, however, the photoactive material may comprise at least 50 wt% of a compound of the present invention, for example at least 70 wt%, 80 wt% or 80 wt% of a compound of the present invention. In some embodiments, a photoactive material can comprise at least 95 wt% of a compound of the present invention. Typically, a layer of photoactive material according to the present invention comprises up to 99.9 wt% of a compound of the present invention.
The photoactive material may include multiple layers. Some or all of these layers may comprise a compound of the present invention.
When the photoactive material is in the form of a layer, the compounds of the present invention may be uniformly or non-uniformly distributed throughout the layer. For example, the photoactive material can comprise a coating consisting essentially of or consisting only of the compound of the present invention and on the compound of the present invention. Alternatively or additionally, the photoactive material may comprise a substrate having one or more compounds of the present invention thereon (e.g., in powder form or crystalline form). In other embodiments, the photoactive material may consist of only layers of one or more compounds of the present invention (e.g., in powder or crystalline form).
In some embodiments, a photoactive material may comprise one or more compounds of the present invention in the form of a thin film. The thin film typically comprises a polycrystalline material disposed on a substrate.
The photoactive materials of the present invention may comprise one or more compounds of the present invention and one or more layers of each of the surface layers or coatings.
In some embodiments, for example, a photoactive material of the present invention can comprise one or more compounds of the present invention and a passivating agent. The phlegmatising agent is described in published application WO 2015/092397, the entire content of which is incorporated herein by reference. In these embodiments, the photoactive material comprises a crystalline or polycrystalline material according to the present invention, and a passivating agent. Passivating agents are organic substances that can form halogen bonds or chalcogen-metal bonds with under-coordinated portions of the metal halide perovskite structure, thereby allowing the formation of self-assembled layers on the crystal or crystallite surfaces of the compounds of the present invention.
Exemplary passivating agents are pyrrolidine, piperidine, morpholine, 2H-pyrrole, 2-pyrroline, 3-pyrroline, pyrrolopyridine, naphthalene, anthracene, phenanthrene, pyrene, fluoranthene, thiophene, 3-hexylthiophene or tetrahydrothiophene and iodopentafluorobenzene. Thus, in one embodiment, the photoactive material comprises one or more compounds of the invention in crystalline form and a passivating agent selected from one or more of pyrrolidine, piperidine, morpholine, 2H-pyrrole, 2-pyrroline, 3-pyrroline, pyrrolopyridine, naphthalene, anthracene, phenanthrene, pyrene, fluoranthene, thiophene, 3-hexylthiophene or tetrahydrothiophene, and iodopentafluorobenzene. Passivating agents are typically present on or at the surface of crystalline materials and thus may be described as surface substances.
In some embodiments, the photoactive material may include a coating. In general, the coating may be a protective coating that protects the material of the present invention in the photoactive material from environmental factors such as moisture and oxygen.
The coating is compatible with any physical form of the compound of the present invention. For example, the powder may be deposited onto or into a coating. Similarly, crystals of the compounds of the invention may be coated or deposited individually within a coating. The coating may be present as a layer on the polycrystalline material or may coat the polycrystalline material.
Suitable coatings include transparent polymers such as Polyethylene (PE), poly (methyl methacrylate) (PMMA), Polystyrene (PS), Polycarbonate (PC), polyvinyl chloride (PVC), poly (vinylidene fluoride) (PVDF), Polyurea (PU), polyvinyl alcohol (PVA), Cellulose Acetate (CA), acrylonitrile-butadiene-styrene (ABS), Polyimide (PEI), and polydimethylsiloxane. Preferred polymers are polyethylene or Polymethylmethacrylate (PMMA). Other suitable coatings include silicones (silicones).
In a particularly preferred embodiment, the coating comprises oxide or metal or metalloid cations. Preferably, the coating comprises an oxide of a metal or metalloid cation, the oxide having a band gap above 4 eV. In a particularly preferred embodiment, the coating comprises an oxide of one or more of Al, Si, Zr, Ga, Mg, Y, Ti, Ni and Zn, preferably an oxide of Al or Si, most preferably an oxide of Al.
In a preferred aspect of the invention, the photoactive materials of the invention comprise crystalline or polycrystalline compounds of the invention, including a coating on all or part of the crystalline or polycrystalline material. Particularly preferably, the coating comprises alumina and/or silica; particularly preferably comprises aluminum oxide (Al)2O3)。
The photoactive material can include a plurality of coating layers. The coating comprising the photoactive material may or may not be in direct contact with the compound of the present invention.
In some embodiments, the photoactive materials of the present invention comprise a host material. That is, the photoactive materials of the present invention may comprise one or more compounds of the present invention as well as a host material.
When the photoactive material of the present invention comprises a host material, the photoactive material typically comprises particles of one or more compounds of the present invention suspended in one or more host materials. "particle" refers to a powder or crystal (e.g., nanocrystal) of a compound of the invention. Preferably, where the photoactive material comprises a host material, the photoactive material comprises nanocrystals of one or more compounds of the present invention suspended in the host material.
Suitable matrix materials are described in WO 2017/017441, the entire content of which is incorporated herein by reference. The matrix material is any suitable material in which a plurality of nanoparticles may be suspended. The matrix material is typically a solid. The host material is typically non-reactive in that it does not chemically react with the nanoparticles or any other portion of the light emitting device (e.g., the metal component). The host material is typically highly transparent to most of the light in the visible spectrum.
The matrix material may be an inorganic material or an organic material. The matrix material is generally stable at temperatures up to 150 ℃ or up to 100 ℃. Typically, the matrix material comprises a polymeric matrix material.
A polymer matrix material is a matrix material comprising a polymer. The polymer matrix material typically comprises a polymer as follows: polyolefins (for example polyethylene, polypropylene, polybutylene, polymethyl methacrylate or polystyrene), polyesters (for example polyethylene terephthalate, polyhydroxybutyrate or polyethylene adipate), polyurethanes, polycarbonates, polyimides, polyamides (for example polyamide 6 or polyamide 66) or epoxy resins. Preferably, the polymer matrix material comprises a polymer selected from polymethylmethacrylate, polystyrene, polyurethane, polycarbonate, polyimide, polyamide or epoxy.
The inorganic matrix material is typically an inorganic oxide, such as a metal oxide. Examples of inorganic matrix materials include ZnO, NiO and SnO2。
In some embodiments, the host material is a semiconductor material. Examples of suitable semiconducting matrix materials include polyvinylcarbazole, polyfluorene derivatives, and CBP (4,4 '-bis (N-carbazolyl) -1,1' -biphenyl).
Thus, in some embodiments, a photoactive material comprises nanoparticles of one or more compounds of the present invention and a host material selected from the group consisting of: polymethyl methacrylate, polystyrene, polyurethane, polycarbonate, polyimide, polyamide, epoxy resin, ZnO, NiO and SnO2Polyvinylcarbazole, polyfluorene derivatives and CBP (4,4 '-bis (N-carbazolyl) -1,1' -biphenyl).
When the photoactive material comprises a host material, the photoactive material typically comprises up to 50 wt% of the host material. For example, photoactive materials typically contain up to 40 wt%, up to 30 wt%, or up to 20 wt% of a host material. In these embodiments, the photoactive material typically comprises at least 50 wt% of the compounds of the present invention.
When the photoactive material comprises a host material, the photoactive material is typically present in the form of a layer. The thickness of the layer is typically from 100nm to 4mm, for example from 1 μm to 1000 μm or from 50 μm to 500 μm. In some cases, the layer may have a thickness of 1 to 4mm, for example if a free-standing layer is to be built up.
In some embodiments, the photoactive material comprises a scaffold material. The scaffold material is typically a solid material. The scaffold material is typically a solid support on which one or more compounds of the invention are distributed.
In some embodiments, a photoactive material of the present invention comprises a porous scaffold and one or more compounds of the present invention. Typically, the porous scaffold material is contacted with the one or more compounds of the invention. Suitable examples of porous scaffold materials are described in WO 2013/171518, the entire content of which is incorporated herein by reference.
Typically, the compounds of the invention are disposed on the surface of a scaffold material. Typically, where the scaffold is a porous scaffold, the compound of the invention is disposed on the surface of the porous scaffold material such that the compound of the invention is supported on the surface of the pores within the scaffold. In such embodiments, the compound of the invention is distributed on one or more of the inner surfaces of the scaffold material, and thus the compound of the invention can be said to be distributed within the scaffold material. In this case, the compounds of the invention generally act as light-absorbing photosensitive materials as well as charge transport materials. Photoactive materials comprising a compound of the invention and a scaffold material (e.g., a porous scaffold material) can advantageously rapidly transport charge carriers through the photoactive material.
The scaffold material is typically a dielectric scaffold material or an n-type scaffold material. Preferably, the scaffold material is a porous dielectric scaffold material or a porous n-type scaffold material.
"dielectric material" refers to an insulating material. The dielectric support material can include a material having a band gap greater than or equal to 3.6eV or greater than or equal to 4 eV. The dielectric support material is typically a dielectric oxide. The dielectric support material typically comprises one or more oxides of aluminum, germanium, zirconium, silicon, yttrium, or ytterbium. However, the dielectric support material may comprise one or more of Polymethylmethacrylate (PMMA), polystyrene, polycarbonate or polyimide. The dielectric support material may preferably be selected from aluminosilicates, zirconia, alumina and silica, e.g. alumina (Al)2O3)。
The n-type scaffold may be selected from any of the n-type materials described herein, such as titanium dioxide (TiO)2). "n-type material" refers to an electron transport material.
Suitable n-type materials are typically inorganic materials. Suitable n-type inorganic materials may be selected from the group consisting of metal oxides, metal sulfides, metal selenides, metal tellurides, perovskites, amorphous silicon, n-type group IV semiconductors, n-type group III-V semiconductors, n-type group II-VI semiconductors, n-type group I-VII semiconductors, n-type group IV-VI semiconductors, n-type group V-VI semiconductors, and n-type group II-V semiconductor semiconductors, any of which may be doped or undoped. More typically, the amount of the liquid to be used,the n-type material is selected from the group consisting of metal oxides, metal sulfides, metal selenides, and metal tellurides. The n-type material may comprise an inorganic material selected from oxides of the following metals, or oxides of a mixture of two or more of said metals: titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, or cadmium. For example, the n-type material may comprise TiO2、SnO2、ZnO、Nb2O5、Ta2O5、WO3、W2O5、In2O3、Ga2O3、Nd2O3PbO or CdO. Other suitable n-type materials that may be employed include sulfides of cadmium, tin, copper or zinc, including sulfides of mixtures of two or more of the metals. For example, the sulfide may be FeS2CdS, ZnS or Cu2ZnSnS4. The n-type material may comprise, for example, selenides of cadmium, zinc, indium or gallium, or selenides of mixtures of two or more of the metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of two or more of said metals. For example, the selenide may be Cu (In, Ga) Se2. Typically, the telluride is cadmium, zinc, cadmium or tin telluride. For example, the telluride may be CdTe. The n-type material may, for example, comprise an inorganic material selected from: oxides of titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, cadmium, or mixtures of two or more of said metals; sulfides of cadmium, tin, copper, zinc, or mixtures of two or more of said metals; selenides of cadmium, zinc, indium, gallium, or selenides of mixtures of two or more of said metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of two or more of said metals. Examples of other semiconductors as suitable n-type materials include group IV compound semiconductors, for example if they are n-doped; amorphous silicon; group III-V semiconductors (e.g., gallium arsenide); II-VI semiconductors (e.g., cadmium selenide); group I-VII semiconductors (e.g., cuprous chloride); group IV-VI semiconductors (e.g., lead selenide); group V-VI semiconductors (e.g., bismuth telluride) and group II-V semiconductors (e.g., arsenic)Cadmium sulfide). Typically, the n-type material comprises TiO2。。
Thus, in some embodiments, a photoactive material of the present invention may comprise a compound of the present invention and a porous scaffold material, preferably wherein the dielectric scaffold material is selected from one or more of alumina, silica and titania.
Where the photoactive material comprises a scaffold material, the photoactive material is typically present in the form of a layer. Typically, the layer has a thickness of 100nm to 1000nm, for example the layer may have a thickness of 400nm to 800 nm. Typically, the layer has a thickness of 400nm to 700 nm.
The photoactive material layers of the present invention may be free of open porosity. The layer of photoactive material may comprise a layer of a compound of the present invention that is free of open porosity. Alternatively, the layer of photoactive material may be porous, or the layer of photoactive material may be deposited on a porous scaffold as described herein.
Method for generating blue light
The invention further provides a method of producing blue light, the method comprising inducing a perovskite of formula (I) and/or a mixed perovskite and/or mixture of formula (II) and/or a photoactive material as described herein to produce blue light.
Accordingly, the present invention provides a method of producing blue light, the method comprising inducing a perovskite of formula (I) to emit blue light
[RbxCs(1-x)][Pb][BryCl(1-y)]3 (I)
Wherein x is greater than 0 and less than 1 and y is greater than 0 and less than 1. Typically, blue light emitted in this way has a wavelength of less than 500nm, for example from about 450nm to 495nm, preferably from about 455nm to 495nm, more preferably from about 460nm to 490nm, more preferably from 460nm to 485nm, most preferably from 465nm to 480 nm. For example, blue light emitted in this way has a peak emission wavelength, e.g., peak photoluminescent emission wavelength, of less than 500nm, e.g., from about 450nm to 495nm, preferably from about 455nm to 495nm, more preferably from about 460nm to 490nm, more preferably from 460nm to 485nm, most preferably from 465nm to 480 nm.
In the method of inducing blue emission of the perovskite of formula (I), x is generally 0.1 to 0.9, and y is 0.1 to 0.9. For example, x and y can each be 0.2 to 0.8 or 0.3 to 0.7. In a preferred embodiment, x is from 0.35 to 0.65 and y is from 0.4 to 0.6. For example, x is 0.35 to 0.45 and y is 0.4 to 0.6 or 0.45 to 0.55.
Similarly, the present invention provides a method of producing blue light comprising inducing a mixed perovskite of formula (II) to emit blue light
{[A]2[M][X]4}a{[RbbCs(1-b)][Pb][BrcCl(1-c)]3}1-a (II)
Wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
a is greater than 0 and less than 1;
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
Typically, in processes involving induction of blue light emission from a mixed perovskite of formula (II), the blue light has a wavelength of less than 500 nm. For example, blue light may have a wavelength of about 450 to 495nm, preferably 460 to 495nm, more preferably 465 to 490nm, for example 470 to 490nm or 475 to 490 nm. The mixed perovskite of formula (II) may be particularly useful for emitting light having a peak emission wavelength (e.g. a photoluminescence peak emission wavelength) of less than 500nm, preferably from 450nm to 495nm, preferably from 460nm to 495nm, more preferably from 465nm to 490 nm; such as 470nm to 490nm or 475nm to 490 nm.
Similarly, the present invention provides a method of producing blue light, the method comprising inducing a mixture comprising:
(a) formula [ A ]]2[M][X]4The compound of (a) to (b),
wherein
[A] Comprises one or more A cations, wherein the A cation is an organic univalent cation;
[ M ] comprises one or more M cations, which are metal or metalloid divalent cations;
[ X ] comprises one or more X anions which are halide anions;
and
(b) formula [ Rb ]bCs(1-b)][Pb][BrcCl(1-c)]3Of (a) a compound
Wherein
b is a number of 0 to 1,
c is 0 to 1, and
at least one of b and c is greater than 0 and less than 1.
Typically, in the method involving inducing the mixture to emit blue light, the blue light has a wavelength of less than 500 nm. For example, blue light may have a wavelength of about 450 to 495nm, preferably 460 to 495nm, more preferably 465 to 490nm, for example 470 to 490nm or 475 to 490 nm. The mixture is particularly useful for emission peak emission wavelengths (e.g. photoluminescence peak emission wavelengths) of less than 500nm, preferably 450nm to 495nm, preferably 460nm to 495nm, more preferably 465nm to 490 nm; such as 470nm to 490nm or 475nm to 490 nm.
There is no particular limitation on the means by which the compounds of the present invention can be induced to emit blue light in the above-described method. Methods by which these materials can be induced to emit light are well known to those skilled in the art. For example, the method may comprise irradiating a compound of the invention with electromagnetic radiation, for example radiation having a wavelength of less than 450 nm. Examples of suitable electromagnetic radiation that may be used to irradiate the compounds of the present invention to induce blue light emission include UV light and/or X-rays.
Other means by which the compounds of the invention can be induced to emit blue light include electrical means. For example, the compounds of the present invention can be induced to emit blue light by applying a potential difference or voltage to the compounds of the present invention, and/or by passing a charge through the compounds of the present invention.
Optoelectronic device
The present invention further provides an optoelectronic device comprising a photoactive material as defined herein. Accordingly, the present invention provides optoelectronic devices comprising one or more compounds of the present invention, i.e. a perovskite of formula (I) and/or a mixed perovskite and/or mixture of formula (II) as defined herein.
As used herein, the term "optoelectronic device" refers to a device that emits, controls, detects, or emits light. Typically, the light is visible light, preferably blue light (i.e., light having a wavelength of about 450nm to 495nm, preferably about 455nm to 490nm, more preferably about 460nm to 485 nm). Optoelectronic devices of the present invention comprise photoactive materials of the present invention, and thus are capable of achieving one or more of the following:
(i) absorb photons, which can then generate free charge carriers, such as electrons and holes;
(ii) absorbing photons having energies above their band gaps and re-emitting photons at the band gap energies; and
(iii) accepting charges, including electrons and holes, which can then recombine and emit light.
In a preferred embodiment, the present invention provides an optoelectronic device which is a photovoltaic device comprising a photoactive material as defined herein. By "photovoltaic device" is meant herein a device capable of converting electrical energy into light, in particular visible light, and preferably blue light (i.e. light having a wavelength of about 450 to 495nm, preferably about 455 to 490nm, more preferably about 460 to 485 nm).
In another preferred embodiment, the present invention provides an optoelectronic device which is a light emitting device comprising a photoactive material as defined herein. The light emitting device may be a light emitting diode. The light emitting device of the present invention is generally capable of emitting visible light, preferably blue light (i.e., light having a wavelength of about 450nm to 495nm, preferably about 455nm to 490nm, more preferably about 460nm to 485 nm).
In some preferred embodiments, optoelectronic devices of the present invention comprise a photoactive material, wherein the photoactive material is disposed in a layer. The layer of photoactive material is defined herein. Typically, the layer of photoactive material has a thickness of at least 2 nm. However, in some embodiments, when the layer is intended to be free-standing, the layer may be very thick (e.g., up to 10mm thick, more typically up to 5mm thick).
In some embodiments, an optoelectronic device of the present invention comprises a layer of photoactive material that is a thin photosensitive layer, e.g., having a thickness of 5nm to 50 nm.
In devices in which the layer of photoactive material forms a planar heterojunction with an n-type region or a p-type region, the layer of photoactive material may have a thickness of at least 1nm, such as at least 10nm or at least 50nm, or such as a thickness greater than or equal to 100 nm. Preferably, the layer of photoactive material has a thickness of from 100nm to 700nm, for example from 200nm to 500 nm. As used herein, the term "planar heterojunction" refers to a surface defining a junction between a semiconductor material and an n-type or p-type region that is substantially planar and has a low roughness, e.g., a root mean square roughness of less than 20nm over an area of 25nm x 25nm, e.g., a root mean square roughness of less than 10nm over an area of 25nm x 25nm, or less than 5 nm.
Photoactive materials are commonly used as photoactive components (e.g., light absorbing components or light emitting components) in optoelectronic devices. In other embodiments, the semiconductor material may form a layer of a p-type or n-type semiconductor in an optoelectronic device (e.g., a solar cell or LED).
In general, an optoelectronic device (which may be a light emitting device or a photovoltaic device) of the present invention comprises:
(a) an n-type region comprising at least one n-type layer;
(b) a p-type region comprising at least one p-type layer; and disposed between the n-type region and the p-type region:
(c) a layer of photoactive material.
Preferred examples of optoelectronic devices of the present invention, which may be light emitting devices or photovoltaic devices, include Light Emitting Diodes (LEDs), photodiodes, solar cells, photodetectors or photosensors; particularly preferred are LEDs, photodiodes or solar cells.
For example, an optoelectronic device may include:
an n-type region comprising at least one n-type layer;
a p-type region comprising at least one p-type layer; and disposed between the n-type region and the p-type region:
the layer of photoactive material, a layer comprising (or consisting essentially of) a crystalline compound of the invention (e.g., a crystalline compound or mixture of formula (I) or formula (II) as defined herein).
The n-type region includes at least one n-type layer. The n-type region typically includes one or two n-type layers. Each layer may be porous or dense. The dense layer is typically a layer of open porosity (e.g., absent any mesopores or macropores). The p-type region includes at least one p-type layer. The p-type region typically includes one or two p-type layers. Each layer may be porous or dense. The dense layer is typically a layer without open porosity. The n-type and p-type materials in these layers may be as further defined herein.
In some cases, an optoelectronic device includes the layer of photoactive material without open porosity. The photoactive material layer of the layer without open porosity is typically a crystalline layer without open porosity of a perovskite or mixed perovskite or mixture according to the invention. Thus, the layer of photoactive material can comprise greater than or equal to 95 volume percent of one or more compounds of the present invention (and thus less than 5 volume percent of the void-free volume). A layer without open porosity is a layer that does not typically include macropores or mesopores.
The layer of photoactive material typically forms a planar heterojunction with either the n-type region or the p-type region. The layer of photoactive material typically forms a first planar heterojunction with the n-type region and a second planar heterojunction with the p-type region. This forms a planar heterojunction device. As used herein, the term "planar heterojunction" refers to a junction (junction) between two regions, wherein one region does not penetrate into the other region. This does not require that the junction be completely smooth, only that one region not substantially penetrate into the pores of the other region.
Thin film devices are typically formed when a layer of photoactive material forms a planar heterojunction with both the p-type and n-type regions. The thickness of the layer of photoactive material can be greater than or equal to 50 nm.
In some embodiments, it is desirable to have a porous scaffold material, wherein the porous scaffold is as defined herein. The scaffold material can assist in the transport of charge from the photoactive material to adjacent regions. The scaffold material may also or alternatively help form a layer of photoactive material during device construction. Accordingly, in some embodiments, an optoelectronic device comprises:
an n-type region comprising at least one n-type layer;
a p-type region comprising at least one p-type layer; and a layer of photoactive material disposed between the n-type region and the p-type region comprising:
(i) a porous scaffold material; and
(ii) a compound of the invention in contact with a scaffold material.
The architecture of such devices is described in more detail in WO 2014/045021, the entire content of which is incorporated herein by reference.
The layer of photoactive material comprising the porous support material and the compound of the invention may form a sensitized layer of photoactive material. Thus, the optoelectronic device may be a sensitized device.
Further details regarding the architecture of optoelectronic devices such as solar cells and suitable materials therefor are described in published application WO 2017/037448, the entire content of which is incorporated herein by reference. The compounds of the present invention may be used in place of the semiconductor materials therein.
In some embodiments, an optoelectronic device comprises:
an n-type region comprising at least one n-type layer;
a p-type region comprising at least one p-type layer; and the following layers disposed between the n-type region and the p-type region:
(i) a first layer comprising a porous scaffold material and said compound of the invention; and
(ii) a capping layer disposed on the first layer, the capping layer being a layer of the compound of the invention free of open porosity,
wherein the compound of the invention in the capping layer is in contact with the compound of the invention in the first layer.
The first layer comprises said porous scaffold material and said compound of the invention disposed on the surface of the scaffold material. As used herein, the term "scaffold material" refers to a material whose function includes acting as a physical support for another material. In the present example, the scaffold material acts as a support for the compound of the invention present in the first layer. The compounds of the invention are disposed on or supported on the surface of a scaffold material. Porous scaffold materials typically have an open porous structure. Thus, the "surface" of a porous scaffold material herein generally refers to the surface of the pores within the scaffold material. Thus, the compound of the invention in the first layer is typically disposed on the surface of pores within the scaffold material.
In some embodiments, the scaffold material is porous and the compound of the invention in the first layer is disposed in the pores of the scaffold material. The scaffold material typically has an effective porosity of at least 50%. For example, the effective porosity may be about 70%. In one embodiment, the effective porosity is at least 60%, such as at least 70%.
Typically, the compound of the invention (or photoactive material) in the first layer is in contact with one of the p-type region and the n-type region, and the compound of the invention in the capping layer is in contact with the other of the p-type region and the n-type region. The compounds of the invention in the capping layer typically form a planar heterojunction with either the p-type region or the n-type region.
In one embodiment, the compound of the invention in the capping layer is in contact with the p-type region and the compound of the invention in the first layer is in contact with the n-type region. In another embodiment, the compound of the invention in the capping layer is in contact with the n-type region and the compound of the invention in the first layer is in contact with the p-type region (e.g., in an inverted device).
In one embodiment, the compound of the invention in the capping layer is in contact with the p-type region and the compound of the invention in the first layer is in contact with the n-type region. Typically, in this embodiment, the scaffold material is an electron transporting scaffold material or a dielectric scaffold material. Typically, the compound of the invention in the capping layer forms a planar heterojunction with the p-type region.
However, in another embodiment, the compound of the invention in the capping layer is in contact with the n-type region and the compound of the invention in the first layer is in contact with the p-type region. Typically, in this embodiment, the scaffold material is a hole transporting scaffold material or a dielectric scaffold material. Typically, the compound of the invention in the capping layer forms a planar heterojunction with the n-type region.
The thickness of the capping layer is typically greater than the thickness of the first layer. Thus, most of the photoactivity (e.g., light absorption or light emission) typically occurs in the capping layer. The thickness of the capping layer is typically 10nm to 100 μm. More typically, the capping layer has a thickness of 10nm to 10 μm. Preferably, the capping layer has a thickness of 50nm to 1000nm, or for example 100nm to 700 nm. The capping layer may have a thickness greater than or equal to 100 nm. On the other hand, the thickness of the first layer is usually 5nm to 1000 nm. More typically, it is from 5nm to 500nm, or for example from 30nm to 200 nm.
The n-type region is typically an n-type layer. Alternatively, the n-type region may include an n-type layer and an n-type exciton blocking layer. Such an n-type exciton blocking layer is typically disposed between the n-type layer and the layer comprising the compounds of the present invention. The n-type region may have a thickness of 50nm to 1000 nm. For example, the n-type region may have a thickness of 50nm to 500nm or 100nm to 500 nm.
Preferably, the n-type region comprises a dense layer of n-type semiconductor. The n-type region may further comprise a porous layer of an n-type semiconductor, which may be a porous scaffold material as described above (wherein the porous scaffold material is an electron transport material).
The n-type region in the opto-electronic device of the present invention comprises one or more n-type layers. Typically, the n-type region is an n-type layer, i.e., a single n-type layer. However, in other embodiments, the n-type region may include an n-type layer and an n-type exciton blocking layer. In the case of using an n-type exciton blocking layer, the n-type exciton blocking layer is typically disposed between the n-type layer and the layer comprising the compound of the present invention.
The exciton blocking layer is a material having a wider band gap than the compound of the present invention, but whose conduction band or valence band closely matches that of the compound of the present invention. If the conduction band (or lowest unoccupied molecular orbital level) of the exciton blocking layer is closely aligned with the conduction band of the compounds of the present invention, electrons can pass from the compounds of the present invention into and through the exciton blocking layer, or through the exciton blocking layer and into the compounds of the present invention, which we refer to as an n-type exciton blocking layer. An example of this is bathocuproine, described in P.Peamans, A.Yakimov, and S.R.Forrest, "Small molecular weight organic thin-film photo detectors and solar cells" J.Appl.Phys.93,3693(2001) and Masaya Hirad, and Chihaya Adachi, "Small molecular organic photo cells with organic coating layer and interface for improved device performance" Appl.Phyt.99, 153302(2011) }.
An n-type layer is a layer of electron transporting (i.e., n-type) material. The n-type material may, for example, be a single n-type compound or elemental material, which may be undoped or doped with one or more doping elements.
The n-type layer employed in the opto-electronic device of the present invention may comprise inorganic or organic n-type materials.
Suitable inorganic n-type materials may be selected from the following: metal oxides, metal sulfides, metal selenides, metal tellurides, perovskites, amorphous silicon, n-type group IV semiconductors, n-type group III-V semiconductors, n-type group II-VI semiconductors, n-type group I-VII semiconductors, n-type group IV-VI semiconductors, n-type group V-VI semiconductors, and n-type group II-V semiconductors, any of which may be doped or undoped.
The n-type material may be selected from the following: metal oxides, metal sulfides, metal selenides, metal tellurides, perovskites, amorphous silicon, n-type group IV semiconductors, n-type group III-V semiconductors, n-type group II-VI semiconductors, n-type group I-VII semiconductors, n-type group IV-VI semiconductors, n-type group V-VI semiconductors, and n-type group II-V semiconductors, any of which may be doped or undoped.
More typically, the n-type material is selected from the group consisting of metal oxides, metal sulfides, metal selenides, and metal tellurides.
Thus, the n-type layer may comprise an inorganic material selected from oxides of the following metals, or oxides of mixtures of two or more of said metals: titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, or cadmium. For example, the n-type layer may comprise TiO2、SnO2、ZnO、Nb2O5、Ta2O5、WO3、W2O5、In2O3、Ga2O3、Nd2O3PbO or CdO.
Other suitable n-type materials that may be used include sulfides of cadmium, tin, copper or zinc, including sulfides of mixtures of two or more of the metals. For example, the sulfide may be FeS2CdS, ZnS, SnS, BiS, SbS or Cu2ZnSnS4。
The n-type layer may, for example, comprise a selenide of cadmium, zinc, indium or gallium, or a selenide of a mixture of two or more of the metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of two or more of said metals. For example, the selenide may be Cu (In, Ga) Se2. Typically, the telluride is cadmium, zinc, cadmium or tin telluride. For example, the telluride may be CdTe.
The n-type layer may, for example, comprise an inorganic material selected from: oxides of titanium, tin, zinc, niobium, tantalum, tungsten, indium, gallium, neodymium, palladium, cadmium, or mixtures of two or more of said metals; sulfides of cadmium, tin, copper, zinc, or mixtures of two or more of said metals; selenides of cadmium, zinc, indium, gallium, or selenides of mixtures of two or more of said metals; or a telluride of cadmium, zinc, cadmium or tin, or a telluride of a mixture of two or more of said metals.
Examples of other semiconductors as suitable n-type materials include, for example, group IV elemental or compound semiconductors if they are n-doped; amorphous silicon; group III-V semiconductors (e.g., gallium arsenide); II-VI semiconductors (e.g., cadmium selenide); group I-VII semiconductors (e.g., cuprous chloride); group IV-VI semiconductors (e.g., lead selenide); group V-VI semiconductors (e.g., bismuth telluride); and group II-V semiconductors (e.g., cadmium arsenide).
Typically, the n-type layer comprises TiO2。
When the n-type layer is an inorganic material, e.g. TiO2Or any of the other materials listed above, it may be a dense layer of the inorganic material. Preferably, the n-type layer is TiO2The dense layer of (1).
Other n-type materials, including organic and polymeric electron transport materials and electrolytes, may also be used. Suitable examples include, but are not limited to, fullerenes or fullerene derivatives (e.g., C)60Or phenyl-C61-butyric acid methyl ester (PCBM)); an organic electron transport material comprising perylene or a derivative thereof; or poly { [ N, N0-bis (2-octyldodecyl) -naphthalene-1, 4,5, 8-bis (dicarboximide) -2, 6-diyl]-alt-5, 50- (2, 20-bithiophene) } (P (NDI2 OD-T2)).
The p-type region is typically a p-type layer. The p-type region may alternatively include a p-type layer and a p-type exciton blocking layer. Such a p-type exciton blocking layer is typically disposed between a p-type layer and a layer comprising the compounds of the present invention. The p-type region may have a thickness of 50nm to 1000 nm. For example, the p-type region may have a thickness of 50nm to 500nm or 100nm to 500 nm.
The p-type region in the opto-electronic device of the present invention comprises one or more p-type layers. Typically, the p-type region is a p-type layer, i.e., a single p-type layer. However, in other embodiments, the p-type region may include a p-type layer and a p-type exciton blocking layer. In the case of using a p-type exciton blocking layer, the p-type exciton blocking layer is typically disposed between the p-type layer and the layer comprising the compound of the present invention. If the valence band (or highest occupied molecular orbital energy level) of the exciton blocking layer closely conforms to the valence band of the compounds of the present invention, holes may enter from the compounds of the present invention through the exciton blocking layer or pass through the exciton blocking layer and into the compounds of the present invention, which we refer to as a p-type exciton blocking layer. An example of this is tris [4- (5-phenylthiophen-2-yl) phenyl ] amine, described in Masaya Hirade, and Chihaya Adachi, "Small molecular organic photonic cells with an experimental coating layer at interface for improved device performance," applied. Phys. Lett.99,153302 (2011).
The p-type layer is a layer of hole transporting (i.e., p-type) material. The p-type material may be a single p-type compound or elemental material, or a mixture of two or more p-type compounds or elemental materials, which may be undoped or may be doped with one or more doping elements.
The p-type layer employed in the opto-electronic device of the present invention may comprise inorganic or organic p-type materials. Typically, the p-type region includes an organic p-type material layer.
Suitable p-type materials may be selected from polymers or molecular hole transporters. For example, the P-type layer used in the opto-electronic device of the present invention may comprise spiro-OMeTAD (2, 2', 7, 7' -tetrakis- (N, N-di-P-methoxyaniline) 9,9 '-spirobifluorene), P3HT (poly (3-hexylthiophene)), PCPDTBT (poly [2,1, 3-benzothiadiazole-4, 7-diyl [4, 4-bis (2-ethylhexyl) -4H-cyclopenta [2,1-b:3,4-b' ] bithiophene-2, 6-diyl ] ]), PVK (poly (N-vinylcarbazole)), HTM-TFSI (1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide), Li-TFSI (lithium bis (trifluoromethylsulfonyl) imide) or tBP (tert-butylpyridine). The p-type region may include carbon nanotubes. Typically, the P-type material is selected from spiro-OMeTAD, P3HT, PCPDTBT and PVK. Preferably, the p-type layer employed in the optoelectronic device of the present invention comprises a spiro-OMeTAD.
The P-type layer may, for example, comprise spiro-OMeTAD (2, 2', 7, 7' -tetrakis- (N, N-di-P-methoxyaniline) 9,9 '-spirobifluorene), P3HT (poly (3-hexylthiophene)), PCPDTBT (poly [2,1, 3-benzothiadiazole-4, 7-diyl [4, 4-bis (2-ethylhexyl) -4H-cyclopenta [2,1-b:3,4-b' ] bithiophene-2, 6-diyl ] ]) or PVK (poly (N-vinylcarbazole)).
Suitable p-type materials also include molecular, polymeric, and copolymeric hole transporters. The P-type material may be, for example, a molecular hole transport material, a polymer or copolymer including one or more of the following moieties: thienyl, phenylalkenyl, dithiazolyl, benzothiazolyl, diketopyrrolopyrrolyl, ethoxydithiophenyl, amino, triphenylamino, carbazolyl, ethylenedioxythienyl, dioxythienyl or fluorenyl. Thus, the p-type layer employed in the opto-electronic device of the present invention may, for example, comprise any of the molecular hole transport materials, polymers or copolymers described above.
Suitable p-type materials also include m-MTDATA (4,4',4 "-tris (methylphenylphenylamino) triphenylamine), MeOTPD (N, N ' - -tetrakis (4-methoxyphenyl) -benzidine), BP2T (5,5' -bis (biphenyl-4-yl) -2,2' -bithiophene), Di-NPB (N, N ' -bis- [ (1-naphthyl) -N, N ' -diphenyl ] -1,1' -biphenyl) -4, 4' -diamine), α -NPB (N, N ' -bis (naphthalen-1-yl) -N, N ' -biphenyl-benzidine), TNATA (4,4',4" -tris- (N- (naphthalen-2-yl) -N-aniline) triphenylamine), BPAPF (9, 9-bis [4- (N, N-bis-biphenyl-4-yl-amino) phenyl ] -9H-fluorene), spiro-NPB (N2, N7-di-1-naphthyl-N2, N7-diphenyl-9, 9' -spirobis [ 9H-fluorene ] -2, 7-diamine), 4P-TPD (4, 4-bis- (N, N-diphenylamino) -tetraphenyl), PEDOT: PSS and spiro-OMeTAD.
The p-type layer may be doped with, for example, t-butylpyridine and LiTFSI. The p-type layer may be doped to increase the hole density. For example, NOBF can be used4The p-type layer is doped with (nitrosonium tetrafluoroborate) to increase the hole density.
In other embodiments, the p-type layer may include an inorganic hole transporter. For example, the p-type layer may include an inorganic hole transporter including an oxide of nickel, vanadium, copper, or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS; a perovskite; amorphous silicon; p-type group IV semiconductors, P-type group III-V semiconductors, P-type group II-VI semiconductors, P-type group I-VII semiconductors, P-type group IV-VI semiconductors, P-type group V-VI semiconductors, and P-type group II-V semiconductors, which inorganic materials may be doped or undoped. The p-type layer may be a dense layer of the inorganic hole transport agent.
For example, the p-type layer may include an inorganic hole transporter containing: oxides of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS; a perovskite; amorphous silicon; p-type group IV semiconductors, P-type group III-V semiconductors, P-type group II-VI semiconductors, P-type group I-VII semiconductors, P-type group IV-VI semiconductors, P-type group V-VI semiconductors, and P-type group II-V semiconductors, which inorganic materials may be doped or undoped. The p-type layer may beFor example, including a compound selected from the group consisting of CuI, CuBr, CuSCN, Cu2O, CuO and CIS. The p-type layer may be a dense layer of the inorganic hole transporter.
Typically, the p-type layer includes a polymer or molecular hole transporter, and the n-type layer includes an inorganic n-type material. The p-type polymer or molecular hole transporter may be any suitable polymer or molecular hole transporter, such as any of those listed above. Likewise, the inorganic n-type material can be any suitable n-type inorganic, such as any of those listed above. In one embodiment, for example, the p-type layer comprises spiro-OMeTAD and the n-type layer comprises TiO2. Generally, in this embodiment, TiO is included2The n-type layer of (2) is TiO2The dense layer of (1).
In other embodiments, both the n-type layer and the p-type layer comprise an inorganic material. Thus, the n-type layer may comprise an inorganic n-type material and the p-type layer may comprise an inorganic p-type material. The inorganic p-type material may be any suitable p-type inorganic, such as any of those listed above. Likewise, the inorganic n-type material can be any suitable n-type inorganic, such as any of those listed above.
In other embodiments, the p-type layer includes an inorganic p-type material (i.e., an inorganic hole transporter) and the n-type layer includes a polymer or molecular hole transporter. The inorganic p-type material may be any suitable p-type inorganic, such as any of those listed above. Likewise, the n-type polymer or molecular hole transporter can be any suitable n-type polymer or molecular hole transporter, such as any of those listed above.
For example, the p-type layer may comprise an inorganic hole-transporter and the N-type layer may comprise an electron-transporting material, wherein the electron-transporting material comprises a fullerene or fullerene derivative, an electrolyte, or an organic electron-transporting material, preferably wherein the organic electron-transporting material comprises perylene or a derivative thereof, or poly { [ N, N0-bis (2-octyldodecyl) -naphthalene-1, 4,5, 8-bis (dicarboximide) -2, 6-diyl]-alt-5, 50- (2, 20-bithiophene) } (P (NDI2 OD-T2)). Inorganic hole transporters may, for example, include:oxides of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS; a perovskite; amorphous silicon; p-type group IV semiconductors, P-type group III-V semiconductors, P-type group II-VI semiconductors, P-type group I-VII semiconductors, P-type group IV-VI semiconductors, P-type group V-VI semiconductors, and P-type group II-V semiconductors, which inorganic materials may be doped or undoped. More typically, the inorganic hole transporter comprises an oxide of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS; p-type group IV semiconductors, P-type group III-V semiconductors, P-type group II-VI semiconductors, P-type group I-VII semiconductors, P-type group IV-VI semiconductors, P-type group V-VI semiconductors, and P-type group II-V semiconductors, which inorganic materials may be doped or undoped. Thus, the inorganic hole transporter may comprise an oxide of nickel, vanadium, copper or molybdenum; CuI, CuBr, CuSCN, Cu2O, CuO or CIS.
Optoelectronic devices typically further comprise one or more first electrodes and one or more second electrodes. The one or more first electrodes are typically in contact with the n-type region, if such a region is present. One or more second electrodes are typically in contact with the p-type region, if such a region is present. Typically, the one or more first electrodes are in contact with the n-type region and the one or more second electrodes are in contact with the p-type region; or the one or more first electrodes are in contact with the p-type region and the one or more second electrodes are in contact with the n-type region.
The first and second electrodes may comprise any suitable conductive material. The first electrode typically comprises a transparent conductive oxide. The second electrode typically comprises one or more metals. Typically, the first electrode typically comprises a transparent conductive oxide and the second electrode typically comprises one or more metals.
The transparent conductive oxide may be as defined above and is typically FTO, ITO or AZO, typically ITO. The metal may be any metal. Typically, the second electrode comprises a metal selected from silver, gold, copper, aluminium, platinum, palladium or tungsten. The electrodes may form a single layer or may be patterned.
An optoelectronic device (e.g. a light emitting device or a photovoltaic device such as a sensitized solar cell) according to the present invention may comprise the following layers in the following order:
I. one or more first electrodes as defined herein;
a dense n-type layer, optionally as defined herein;
a porous layer of an n-type material as defined herein;
a layer of the compound of the invention (e.g. as a sensitizer);
v. a p-type region as defined herein;
optionally another dense p-type layer as defined herein; and
one or more second electrodes as defined herein.
The optoelectronic device according to the invention (which may be a light emitting device or a photovoltaic device) may comprise the following layers in the following order:
I. one or more first electrodes as defined herein;
an n-type region comprising at least one n-type layer as defined herein;
a layer of photoactive material comprising a compound of the invention as defined herein;
a p-type region as defined herein comprising at least one p-type layer; and
v. one or more second electrodes as defined herein.
The optoelectronic device according to the invention (which may be a light emitting device or a photovoltaic device) may comprise the following layers in the following order:
I. one or more first electrodes comprising a transparent conductive oxide, preferably FTO;
an n-type region comprising at least one n-type layer as defined herein;
a layer of a compound of the invention as defined herein;
a p-type region as defined herein comprising at least one p-type layer; and
v. one or more second electrodes comprising a metal, preferably silver and gold.
A photovoltaic device according to the present invention, which may be a light emitting device or a photovoltaic device (e.g. an inverted device), may comprise the following layers in the following order:
I. one or more second electrodes as defined herein;
an n-type region comprising at least one n-type layer as defined herein;
a layer of a compound of the invention as defined herein;
a p-type region as defined herein comprising at least one p-type layer; and
v. one or more first electrodes as defined herein.
A photovoltaic device according to the present invention, which may be a light emitting device or a photovoltaic device (e.g. a sensitized solar cell), may comprise the following layers in the following order:
I. one or more second electrodes comprising a metal;
an n-type region as defined herein comprising at least one mesoporous n-type layer;
a sensitising layer of a compound of the invention as defined herein;
a p-type region as defined herein comprising at least one p-type layer; and
v. one or more first electrodes comprising a transparent conductive oxide.
The one or more first electrodes may have a thickness of 100nm to 700nm, for example 100nm to 400 nm. The one or more second electrodes may have a thickness of 10nm to 500nm, for example 50nm to 200nm or 10nm to 50 nm. The n-type region may have a thickness of 50nm to 500 nm. The p-type region may have a thickness of 50nm to 500 nm.
In other embodiments, the photoactive material functions as a phosphor in an optoelectronic device. In such embodiments, the optoelectronic device generally comprises a light source and a photoactive material as defined herein. The photoactive material may comprise a compound of the present invention in crystalline or powder form. Typically, the photoactive material comprises a compound of the invention in powder form or in nanocrystalline form. Also typically, the photoactive material comprises a host material as defined herein.
By "acting as a phosphor" is meant that the photoactive material functions by absorbing light of a first wavelength and subsequently re-emitting light of a different, greater wavelength.
The light source is typically a white light source, a blue light source or a UV light source. That is, the light source is typically a source of electromagnetic radiation emitting at wavelengths below 500nm, more typically below 480 nm. For example, the light source typically emits electromagnetic radiation having a wavelength of 400 to 480 nm.
Examples of optoelectronic devices in which the photoactive material functions as a phosphor include light emitting devices, such as display screens, e.g., LED display screens; and a solid state lighting device. Such devices represent another aspect of the present invention.
Use of photoactive materials
In another aspect, the present invention provides the use of a compound of the invention and a photoactive material of the invention comprising said compound.
In a first embodiment, the present invention provides the use of a photoactive material as defined herein as a photo-emitter, preferably as a photo-emitter emitting light in the wavelength range 450nm to 500nm, preferably 450nm to 495nm, more preferably 455nm to 495nm, even more preferably 460nm to 490 nm.
Where the photoactive material described herein comprises a perovskite of formula (I), the photoactive material is typically used to emit light at a wavelength of from about 450nm to 495nm, preferably from about 455nm to 495nm, more preferably from about 460nm to 490nm, more preferably from 460nm to 485nm, most preferably from 465nm to 480 nm. In this case, the photoactive material may be particularly useful for emitting light having a peak emission wavelength (e.g., a peak photoluminescent emission wavelength) of about 450nm to 495nm, preferably about 455nm to 495nm, more preferably about 460nm to 490nm, more preferably 460nm to 485nm, and most preferably 465nm to 480 nm.
Where the photoactive material described herein comprises a mixed perovskite of formula (II) or mixtures thereof, the photoactive material is typically used to emit light at a wavelength of from about 450nm to 495nm, preferably from 460nm to 495nm, more preferably from 465nm to 490nm, for example from 470nm to 490nm or from 475nm to 490 nm. In this case, the photoactive material may be particularly useful for emitting a peak emission wavelength (e.g. a photoluminescence peak emission wavelength) of 450nm to 495nm, preferably 460nm to 495nm, more preferably 465nm to 490 nm; such as 470nm to 490nm or 475nm to 490 nm.
In a second embodiment, the present invention provides the use of a photoactive material as defined herein in the manufacture of an optoelectronic device, preferably wherein the optoelectronic device emits light in the wavelength range from 450nm to 500nm, more preferably from 455nm to 495nm, further preferably from 460nm to 490 nm.
In a third embodiment, the present invention provides the use of a photoactive material as defined herein as a phosphor. For example, the present invention provides the use of a photoactive material as defined herein in the manufacture of a screen, in particular an LED screen or a solid state lighting device.
In a fourth embodiment, the present invention further provides the use of an optoelectronic device as defined herein in a method of producing light, preferably in a method of producing light in the wavelength range 450nm to 500nm, more preferably 455nm to 495nm, even more preferably 460nm to 490 nm. For example, the present invention provides a method of generating light, the method comprising illuminating a photoactive material as defined herein with a light source; thereby producing an emission of light from the photoactive material in the wavelength range of 450nm to 500nm, more preferably 455nm to 495nm, and even more preferably 460nm to 490 nm.
Manufacturing method
The compounds, photoactive materials, and optoelectronic devices of the present invention can be fabricated using techniques well known in the art. Specific examples of such processes are described in, for example, WO 2017/037448, WO 2017/017441 and WO 2015/092397, which may be considered part of the present invention, the entire contents of which are incorporated herein by reference.
For example, the compounds of the present invention may be produced by vapor deposition. Such methods comprise first generating a vapor by vaporizing a compound of the invention or a plurality of precursor compounds capable of producing a compound of the invention. In this step, the compound of the invention or the plurality of precursor compounds is typically transferred to a vaporization chamber, which is subsequently evacuated. The compound of the invention or the plurality of precursor compounds is then typically heated to produce the resulting vapor.
By "precursor compound capable of producing a compound of the invention" is meant a reactant that, when contacted under suitable conditions, such as at a suitable temperature, for example 300K, in vapor or dissolved form, will produce a compound of the invention.
The resulting vapor is then exposed to a surface and thereby deposited on the surface. The surface may for example be an optoelectronic device, a substrate (such as a glass substrate) or a surface on or in a holder. Thereby producing a solid layer of the compound of the invention on the surface. If precursor compounds are used, they may react in situ while generating the compounds of the invention on the surface.
Typically, vapor deposition is continued until a layer of the compound of the invention is formed having a desired thickness, for example, a thickness of 1nm to 100 μm, or more typically 2nm to 10 μm.
The compounds of the invention produced by the above-described vapor deposition processes may or may not be subjected to additional processing steps to produce the photoactive materials of the invention.
In another exemplary method, the compounds of the invention may be produced by solution processing. Such methods generally include:
(i) placing one or more solutions comprising one or more solvents and a compound of the invention or a plurality of precursor compounds capable of producing a compound of the invention on a surface; and
(ii) removing the one or more solvents to produce the compound of the invention on the surface.
The one or more solvents may be any suitable solvent. Typically, the one or more solvents are selected from polar solvents. Examples of the polar solvent include water, alcohol solvents (such as methanol, ethanol, n-propanol, isopropanol, and n-butanol), ether solvents (such as dimethyl ether, diethyl ether, and tetrahydrofuran), ester solvents (such as ethyl acetate), carboxylic acid solvents (such as formic acid and glycolic acid), ketone solvents (such as acetone), amide solvents (such as dimethylformamide and diethylformamide), amine solvents (such as triethylamine), nitrile solvents (such as acetonitrile), sulfoxide solvents (dimethylsulfoxide), and halogenated solvents (such as dichloromethane, chloroform, and chlorobenzene). The one or more solvents may be selected from polar aprotic solvents. Examples of protic nonpolar solvents include Dimethylformamide (DMF), acetonitrile, and dimethyl sulfoxide (DMSO).
Typically, step (i) of placing one or more solvents on the surface and step (ii) of removing the solvents comprises spin coating or slot die coating one or more solvents onto the surface to produce a layer of a compound of the invention on the surface. The coating may be carried out in an inert atmosphere, for example under nitrogen, or may be carried out in air. Spin coating is typically carried out at speeds of 1000rpm to 3000 rpm. The spin coating is usually carried out for 30 seconds to 2 minutes.
The solution is typically produced by dissolving a powder of the compound of the invention or a powder of the precursor compound in one or more polar solvents.
The steps of placing the solution or solutions on the surface and removing the solvent or solvents are carried out until a layer of the compound of the invention having the desired thickness is produced, for example a thickness of 1nm to 100 μm, typically 2nm to 10 μm.
Removing the one or more solvents typically includes heating or evaporating the one or more solvents. The surface, solvent or first region may be heated at a temperature of 40 ℃ to 100 ℃ for a period of 5 minutes to 2 hours to remove the one or more solvents.
The compounds of the present invention produced by the above exemplary solution processing methods may be subjected to further processing steps or without further processing steps to produce the photoactive materials of the present invention.
In a first preferred method, a precursor compound capable of producing a compound of the invention is contacted in the solution or gas phase in the presence of an oxide precursor and water. Water generally only needs to be present in very small amounts, e.g. in trace amounts, and may for example depend on atmospheric humidity. The oxide precursor is a mixture ofOne or more compounds or class of compounds of element Z capable of reacting with water to produce one or more oxides of element Z, wherein the oxide has a band gap of at least 3 eV. An exemplary oxide precursor is of the formula ZRnA compound of (1); wherein n is an integer from 1 to 6, and each R is independently selected from optionally substituted C1-10Alkyl radical, C2-10Alkenyl radical, C3-10Cycloalkyl radical, C1-10Alkoxy radical, C2-10Alkenyloxy, hydride and halide; preferably unsubstituted or substituted C1-10Alkyl radical, C2-10Alkenyl radical, C3-10Cycloalkyl radical, C1-10Alkoxy radical, C2-10Alkenyloxy, hydride and halide. In particular, exemplary oxide precursors are of the formula ZRnWherein n is an integer from 2 to 4, and each R is independently selected from unsubstituted C1-6Alkyl and C1-6An alkoxy group; preferably, R is methyl and n is 3.
In another preferred method, the compounds of the invention may be produced by contacting an aqueous solution with an organic solution and forming a precipitate upon contacting the aqueous organic solution. The aqueous solution comprises the various a cations present in the compounds of the present invention, as well as an aqueous solvent. For example, where the compound of the invention is a perovskite of formula (I), the aqueous solution comprises Cs+And Rb+. In case the compound is a mixture or a mixed perovskite of formula (II), the aqueous solvent comprises Cs+And Rb+And if not [ A ]]Of the further cation present in (a). The organic solution contains Pb2+And in case the compound is a mixture or a mixed perovskite of formula (II), the organic solution further comprises [ M]Any M cation present in (a). Preferably, a thin film of the compound of the present invention obtained by this method may be formed from the precipitate. The film is formed by: optionally washing the precipitate; dissolving the precipitate in an organic solvent to form a film-forming solution and dispersing the film-forming solution on a substrate; and removing the organic solvent. Alternatively, the film may be formed by: optionally washing the precipitate; evaporating the precipitate; and make gas flowThe precipitated precipitate is placed on a substrate.
The photoactive materials of the present invention can be directly produced by the above-described process. For example, the compounds of the invention may be deposited directly with the matrix material (as described in WO 2017/017441), or deposited on a support or on a part of an optoelectronic device, such that no further processing is required.
However, the photoactive material may be subjected to further processing steps. For example, in a further processing step, a coating may be provided on the compound of the invention (typically on the crystalline compound of the invention). Examples of such coatings are protective coatings, such as metal oxide coatings, e.g. alumina coatings. Silica coatings and aluminosilicate coatings are also contemplated. Such coatings may be produced by, for example, vapor deposition.
In some embodiments, in a further processing step, the method of producing a photoactive material further comprises providing a surface species on the crystals or crystallites of the compounds of the present invention. An example of a surface substance is an organic passivating agent. A method for depositing a passivating agent on a perovskite is described in WO 2015/092397 (the entire content of which is incorporated herein by reference).
With respect to the production of electronic devices, photoactive materials are typically produced in situ. That is, the production of the photoactive material of the present invention is generally a step in the production of optoelectronic devices. For example, where the device is a thin film device, the photoactive material of the present invention is generated in situ on another layer of the device. However, in some embodiments, a method for producing an optoelectronic device comprises the step of incorporating a photoactive material according to the present invention into the device.
Examples
1. Material
CsBr(99.9％)、CsCl(99.9％)、RbBr(99.9％)、RbCl(99.9％)、PbBr2(≥98％)、PbCl2
(≥98％)、PbI2(. gtoreq.98%), HBr acid (48 wt% in water), N-Dimethylformamide (DMF), anhydrous dimethyl sulfoxide (DMSO), chlorobenzene (anhydrous 99.8%), toluene (anhydrous 99.8%) and methyl acetate (anhydrous 99.5%) were purchased fromSigma-Ardrich. CsI (99.9%) was purchased from Alfa-Aesar. Ethyl ammonium bromide (EABr), butyl ammonium bromide (BABr) and phenethyl ammonium bromide (PEABr) were synthesized by the following methods.
1.3M amine and 30mL ethanol (99.5% anhydrous) were mixed and stirred in a 250mL three-necked flask under ice-water bath conditions. Then, 10mL of aqueous HBr solution was slowly added to the mixture. The mixture was stirred at 0 ℃ with an ice-water bath for 30 to 60 minutes. The reaction solution was evaporated by a rotary evaporator at 55 to 60 ℃ to remove the solvent, and a white precipitate was formed. The white precipitate was then washed with diethyl ether and collected by vacuum filtration, and this step was repeated 3 times. After filtration, the obtained amine bromide was collected as a white powder and dried in a vacuum oven at 60 ℃ overnight. Thereafter, the amine bromide was dissolved in ethanol and ether to make a supersaturated solution. The solution was placed in a refrigerator overnight. The white precipitate was then washed with diethyl ether and collected by vacuum filtration, and this step was repeated 3 times. After filtration, the obtained amine bromide was collected as a white powder and dried in a vacuum oven at 60 ℃ overnight.
2、CsPb(Br1-xClx)3Preparation of precursor solution
By mixing CsBr and CsCl with PbBr at different molar ratios2And PbCl2To prepare CsPb (Br)1-xClx)3. The molar ratio of Cs to Pb was maintained at 2: 1. The halide salt was dissolved in a mixed solvent of DMF and DMSO at a volume ratio of 1: 9 to obtain a perovskite solution having a desired composition and a lead halide concentration of 0.1M, and the solution was mixed with a magnetic stirring bar at 40 ℃ for 30 minutes or more. The solution was filtered through a PTFE filter (pore size 0.45 μm).
3、Cs1-xRbxPb(Br1-xClx)3Preparation of precursor solution
By adding CsPb (Br)1-xClx)3And RbPb (Br)1-xClx)3Preparation of Cs by mixing precursor solutions1-xRbxPb(Br1- xClx)3. By mixing different molar ratios as described in (2)CsBr and CsCl with different molar ratios of PbBr2And PbCl2While maintaining a Cs: Pb molar ratio of 2: 1 to produce CsPb (Br)1-xClx)3. By combining different molar ratios of RbBr and RbCl with different molar ratios of PbBr2And PbCl2Combining while maintaining the molar ratio of Rb to Pb at 2: 1 to produce RbPb (Br)1-xClx)3. The halide salt was dissolved in a mixed solvent of DMF and DMSO at a volume ratio of 1: 9 to obtain a perovskite solution having a desired composition and a lead halide concentration of 0.1M. The solution was mixed with a magnetic stir bar at 40 ℃ for more than 30 minutes. The solution was filtered through a PTFE filter (pore size 0.45 μm).
4、(“A”)2PbX4Preparation of Mixed precursor solution
By reacting "A" Br with PbBr2Or PbCl2Combined while maintaining a 2: 1 molar ratio of "A" to Pb ("A")2PbX4A precursor solution. The solvent is a mixed solvent of DMF and DMSO with the volume ratio of 1: 9. A perovskite solution having the desired molar composition and a lead halide concentration of 0.1M is thus obtained. The solution was mixed with a magnetic stir bar at 40 ℃ for more than 30 minutes. The solution was filtered through a PTFE filter (pore size 0.45 μm).
By changing presence ('A')2PbX4The relative amounts of precursor solution and perovskite precursor solution to prepare a perovskite precursor solution comprising the same ("A")2PbX4Precursor compounds and perovskite precursor solutions.
5. Preparation of films
The perovskite precursor solution was coated on the glass substrate by spin coating at 3000rpm (acceleration 500rpm) for 50 seconds under a normal laboratory atmosphere (18 ℃ to 20 ℃, humidity 40% to 60%), and then the perovskite film was annealed at 100 ℃ for 5 minutes under the same dry atmosphere.
In an alternative solvent quenching method, each substrate was spin coated with 80 μ L of the precursor solution, the spin coating process was terminated after 10s of 30s spinning at 3000rpm (acceleration 500rpm), and the spun substrate was then quenched with 200 μ L of anti-solvent. Thereafter, the perovskite thin film was annealed at 100 ℃ for 5 minutes in the same dry atmosphere.
All film samples were coated with poly (methyl methacrylate) (PMMA, 20mg/mL in chlorobenzene) to protect against atmospheric moisture.
6. Characterization of
The UV-Vis absorption spectra were measured by a commercial spectrophotometer (Varian Cary 300UV-Vis, USA). Photoluminescence (PL) spectra were recorded on a commercial spectrofluorometer (Horiba, fluorologue) using an excitation wavelength of 365nm and a slit width of 3 mm. The photoluminescence quantum yield (PLQY) values were determined by illuminating the sample in an integrating sphere (Oriel Instruments 70682NS) with a 405nm CW laser (RLTMDL-405, Roithner Lasertechnik GmbH) and collecting the laser light scatter and PL using a fiber-coupled detector (Ocean Optics mayapor). PLQY calculations were performed using existing techniques. The laser intensity was adjusted using an optical density filter.
7. Results
The above methods were used to prepare and characterize various compounds of the invention as well as various comparative materials. The results of these experiments are shown in the figures and in the following table.
Table 1 summarizes the results for various CsPb (Br) prepared according to the invention1-xClx)3Photoluminescent properties of the thin film. In particular, it can be seen that the photoluminescence quantum yield PLQY decreases as the amount of chloride ions present decreases. The relevant emission spectra are shown in fig. 1(b), and the absorption spectra are shown in fig. 1 (a). "PL peak position" means the wavelength at which the peak of the photoluminescence spectrum is found. This is also referred to as the photoluminescence peak emission wavelength.
TABLE 1
Table 2 provides the results of the reaction of CPb (Br)0.5Cl0.5)3With different concentrations (top) (BA)2PbBr4And (bottom) (BA)2PbBr2Cl2Summary of photoluminescence properties of the perovskite thin film formed by mixing. BA represents butylammonium cation. The relevant emission spectra are shown in fig. 2(b) and 2(d), and the absorption spectra are shown in fig. 2(a) and 2 (c). A dramatic increase in PLQY is observed as the emission wavelength is shifted into the blue region of the spectrum.
TABLE 2
Table 3 summarizes Cs according to the present invention1-xRbxPb(Br0.5Cl0.5)3Photoluminescent properties of the thin film. Good PLQY is observed even when the emission spectrum is shifted to the blue region of the spectrum. The corresponding absorption and emission spectra are shown in fig. 3.
TABLE 3
Table 4 summarizes the results in the Presence and absence (BA)2PbBr4In the case of (2), Cs0.6Rb0.4Pb(Br0.5Cl0.5)3Photoluminescent properties of the thin film. The associated absorption and emission spectra are shown in fig. 4. Attention should be paid particularly to FIG. 4(b), which shows that although the PL peak position is at 480nm, strong emission occurs in the far blue region, even at 450 nm.
TABLE 4
Table 5 summarizes the results of the antisolvent quenching method ((BA)2PbBr4)0.1(Cs0.6Rb0.4Pb(Br0.5Cl0.5)3)0.9The photoluminescent properties of the films and provide data for each different solvent. The corresponding data emission spectra are shown in fig. 5. It can be seen that good PLQY is observed even with different preparation methods, and the substance emits in the blue region.
TABLE 5
Table 6 summarizes Cs for comparison purposes1-xRbxPbBr3Photoluminescent properties of the thin film. The absorption spectrum and emission spectrum of these substances are shown in FIG. 6. Clearly, these substances emit at wavelengths much greater than 500nm, i.e., in the green region of the visible spectrum.
TABLE 6
Table 7 summarizes (CsPbBr) for comparison purposes3)1-x((BA)2PbBr4)xPhotoluminescent properties of the thin film. The absorption spectrum and emission spectrum of these substances are shown in FIG. 7. These do not reach below 500nm despite the blue shift of the peak, and these materials clearly emit in the green region of the visible spectrum.
TABLE 7
For comparison, Cs is shown in FIG. 81-xRbxPb(I0.45Br0.55)3Steady state photoluminescence spectra of various thin films of a substance. It is clear that these substances emit well above 500nm, and indeed in the red region of the visible spectrum. Moreover, the addition of a small amount of rubidium actually red-shifts the emission peak further.
FIG. 9 shows [ A ]]2[M][X]4The effect of different A cations in the substance on the photoluminescence properties of the compounds of formula (II) and mixtures according to the invention. In the absence of [ A]2[M][X]4In the case of (2), a large amount of photoluminescence was observed (the peak area was large and almost completely below 500 nm). However, when [ A ] is added]2[M][X]4The amount of photoluminescence increases significantly with materials, especially when the a cation is phenethylamine or butylamine. This is observed as the area under the peak becomes quite large. Thus, containing [ A]2[M][X]4The emission properties of the compounds and mixtures of (a) are greatly improved.
FIG. 10 shows (Cs)0.6Rb0.4)Pb(Br0.5Cl0.5)3Photoluminescence peak positions of exposure to ultraviolet light (365nm) for a period of up to 60 minutes. In the case of exposure to ultraviolet light for this period of time, for (Cs)0.6Rb0.4)Pb(Br0.5Cl0.5)3No significant peak shift was observed. Also, although the data is not shown in fig. 10, the compound was also exposed to UV light for a period of time exceeding 60 minutes. Again, no significant shift in the photoluminescence peak position was observed during this period. Thus, it was shown that the photoluminescence spectrum of the compound of formula (I) is highly stable and not prone to red-shifting.
Fig. 11 shows the effect of increasing x above zero in the mixed perovskite of formula (II). The figure provides ((BA)2Pb(Br2Cl2)4)0.33(CsPbBr3)0.67And ((BA)2Pb(Br2Cl2)4)0.33(Cs0.4Rb0.6PbBr3)0.67The Steady State Photoluminescence (SSPL) spectrum (right axis) and the absorption spectrum (left axis) of the thin film. It can be clearly seen that as the Rb content increases above zero, the photoluminescence peak position shifts to higher energies (blue shift). In contrast, mixed perovskites containing only Cs have a higher peak photoluminescence emission wavelength, indicated in the figure by the dashed arrow pointing to the right. Similarly, in ((BA)2Pb(Br2Cl2)4)0.33(Cs0.4Rb0.6PbBr3)0.67A significant blue shift of the band edge was observed in the absorption spectrum of (a). This is indicated in the figure by the solid arrow pointing to the right. Furthermore, the features between 370nm and 430nm indicate the formation of lead halide octahedral sheets with variable layer thickness (multiple "n" values in the low-dimensional perovskite structure).
TABLE 8
Table 8 summarizes the photoluminescence spectral characteristics of fig. 11. It is clear that the introduction of Rb into the structure causes a large increase in PLQY and produces a blue shift. This is very unusual.
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