Organic-inorganic hybrid monolithic assembly and method
阅读说明：本技术 有机-无机混合整体组件和方法 (Organic-inorganic hybrid monolithic assembly and method ) 是由 B·马 C·周 H·林 Y·田 于 2018-10-10 设计创作，主要内容包括：提供可具有期望光致发光量子效率的整体组件。所述整体组件可包括两种或更多种金属卤化物和宽带隙有机网络。所述宽带隙有机网络可包括有机阳离子。所述金属卤化物可设置在所述宽带隙有机网络中。还提供发光复合材料。(An integral assembly is provided that can have a desired photoluminescence quantum efficiency. The monolithic component may include two or more metal halides and a wide bandgap organic network. The wide bandgap organic network may include an organic cation. The metal halide may be disposed in the wide bandgap organic network. Luminescent composites are also provided.)
1. An integral assembly comprising:
two or more metal halides; and
a wide bandgap organic network comprising a plurality of organic cations;
wherein the two or more metal halides are (i) disposed in the wide bandgap organic network and (ii) isolated from each other.
2. The monolithic assembly of claim 1, wherein each of the two or more metal halides is independently selected from the group consisting of: (i) formula MX6Octahedron of (i), (ii) formula M2X9(ii) a dimer of the formula (iii) M3X11Trimer of (iv) formula M4X13Tetramer of (v) formula MX6Triangular prism of (vi) formula MX5A triangular bipyramid of the formula (vii)5Square pyramid of (viii) formula MX4Of formula (ix) and4a seesaw-like body of (1);
wherein M is a metal atom and X is a halide selected from the group consisting of Cl, Br and I.
3. The monolithic assembly of claim 2, wherein M is independently selected from the group consisting of Sn, Pb, Sb, and Mn.
4. The monolithic assembly of claim 2, wherein the two or more metal halides are of the formula MX6M is Sn, and the two or more metal halides have the formula SnX6 4-。
5. The monolithic assembly of claim 2, wherein the two or more metal halides are of the formula MX5M is Sb, and the two or more metal halides have the formula SbX5 2-。
6. The monolithic assembly of claim 2, wherein the two or more metal halides are of the formula MX4M is Sn, and the two or more metal halides have the formula SnX4 2-。
7. The monolithic assembly of claim 2, wherein the two or more metal halides comprise: (i) formula MX4And (ii) a tetrahedron of formula M3X11Wherein M is Pb, and the two or more metal halides each have the formula PbX4 2-And formula PbX11 5-。
8. The unitary assembly of any of claims 1-3, wherein the plurality of organic cations comprises one or more quaternary ammonium cations, one or more tertiary ammonium cations, one or more secondary ammonium cations, one or more primary ammonium cations, or a combination thereof.
9. The monolithic assembly of any of claims 1 to 3, wherein the plurality of organic cations comprises an organic cation selected from the group consisting of:
10. the monolithic assembly of any of claims 1-3, wherein the plurality of organic cations comprises one or more organic cations selected from the group consisting of:
11. according to the claimsThe monolithic assembly of claim 1, wherein (i) the two or more metal halides comprise the formula SnX6 4-(iii) the plurality of organic cations comprises C4N2H14X+And (iii) the monolithic component has the formula:
(C4N2H14X)4SnX6，
wherein X is selected from the group consisting of Cl, Br and I.
12. The monolithic assembly of claim 11, wherein X is Br.
13. The monolithic assembly of claim 12, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of at least 90%.
14. The monolithic assembly of claim 12, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of about 95%.
15. The monolithic assembly of claim 11, wherein X is I.
16. The monolithic assembly of claim 15, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of at least 70%.
17. The monolithic assembly of claim 15, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of about 75%.
18. The monolithic assembly of claim 1, wherein (i) the two or more metal halides comprise the formula SbX5 2-Square pyramids of (ii) the plurality of organic cations comprises C9NH20And (iii) the monolithic component has the formula:
(C9NH20)2SbX5，
wherein X is selected from the group consisting of Cl, Br and I.
19. The monolithic assembly of claim 18, wherein X is Cl.
20. The monolithic assembly of claim 19, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of at least 95%.
21. The monolithic assembly of claim 19, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of about 98%.
22. The monolithic assembly of claim 1, wherein (i) the two or more metal halides comprise the formula SbX5 2-Square pyramids of (ii) the plurality of organic cations comprises Ph4P+And (iii) the monolithic component has the formula:
(Ph4P)2SbX5，
wherein X is selected from the group consisting of Cl, Br and I.
23. The monolithic assembly of claim 22, wherein X is Cl.
24. The monolithic assembly of claim 23, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of at least 80%.
25. The monolithic assembly of claim 23, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of about 87%.
26. The monolithic assembly of claim 1, wherein (i) the two or more metal halides comprise the formula SnX4 2-(iii) the teeterboard-like body of (ii) the plurality of organic cations comprises C9NH20And (iii) the monolithic component has the formula:
(C9NH20)2SnX4，
wherein X is selected from the group consisting of Cl, Br and I.
27. The monolithic assembly of claim 26, wherein X is Br.
28. The monolithic assembly of claim 27, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of at least 40%.
29. The monolithic assembly of claim 27, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of about 46%.
30. The monolithic assembly of claim 1, wherein (i) the two or more metal halides comprise (a) PbX4 2-Tetrahedron and (b) PbX11 5-(iii) the plurality of organic cations comprises C9NH20And (iii) the monolithic component has the formula:
(C9NH20)7(PbX4)Pb3X11，
wherein X is selected from the group consisting of Cl, Br and I.
31. The monolithic assembly of claim 30, wherein X is Cl.
32. The monolithic assembly of claim 31, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of at least 70%.
33. The monolithic assembly of claim 31, wherein the monolithic assembly has a photoluminescence quantum efficiency (PLQE) of about 83%.
34. A luminescent composite, comprising:
a first monolithic component in particulate form;
a second monolithic component in particulate form; and
a matrix material, wherein the first monolithic component and the second monolithic component are dispersed in the matrix material;
wherein the first monolithic component comprises two or more first metal halides and a first wide band gap organic network comprising a plurality of first organic cations, wherein the two or more first metal halides are (i) disposed in the first wide band gap organic network and (ii) isolated from each other; and
wherein the second monolithic component comprises two or more second metal halides and a second wide bandgap organic network comprising a plurality of second organic cations, wherein the two or more second metal halides are (i) disposed in the second wide bandgap organic network and (ii) isolated from each other.
35. The luminescent composite of claim 34, wherein (i) the two or more first metal halides comprise the formula MnX4 2-The tetrahedra of (ii), the plurality of first organic cations comprising Ph4P +, and (iii) the first monolithic component has the formula:
(Ph4P)2MnX4，
wherein X is selected from the group consisting of Cl, Br and I.
36. The luminescent composite of claim 35, wherein X is Br.
37. The luminescent composite of claim 34, wherein (i) the two or more second metal halides comprise the formula SnX6 4-(iii) the plurality of second organic cations comprises C4N2H14X+And (iii) the second monolithic component has the formula:
(C4N2H14X)4SnX6，
wherein X is selected from the group consisting of Cl, Br and I.
38. The luminescent composite of claim 37, wherein X is Br.
39. The light-emitting composite of claim 34, further comprising a third monolithic component in the form of particles, wherein the third monolithic component is dispersed in the host material and comprises two or more third metal halides and a third wide band gap organic network comprising a plurality of third organic cations, wherein the two or more third metal halides are (i) disposed in the third wide band gap organic network and (ii) isolated from each other.
40. The light-emitting composite of claim 39, wherein (i) the two or more third metal halides comprise the formula SbX5 2-Square pyramids of (ii) the plurality of third organic cations comprises Ph4P+And (iii) the third integral component has the formula:
(Ph4P)2SbX5，
wherein X is selected from the group consisting of Cl, Br and I.
41. The light-emitting composite of claim 40, wherein X is Cl.
42. The luminescent composite of claim 34, wherein the host material comprises polydimethylsiloxane.
43. A method of making a monolithic assembly, the method comprising:
providing a precursor solution comprising:
(i) a solvent, a water-soluble organic solvent,
(ii) formula My+XyOne kind of orA plurality of compounds, wherein M is a metal selected from the group consisting of Sb, Pb, Sn and Mn, X is Cl, Br or I, y is the charge of said metal, and
(iii) one or more organic salts; and
contacting the precursor solution with an anti-solvent to form the monolithic assembly.
44. The method of claim 43, wherein the formula My+XyIs present in a molar ratio of the one or more compounds of (a) to the one or more organic salts of from about 1:1.5 to about 1: 2.5.
45. The method of claim 43, wherein the formula My+XyIs about 1:2 to the one or more organic salts.
46. The method of any one of claims 43 to 45, wherein the solvent comprises dimethylformamide.
47. The method of any one of claims 43 to 45, wherein the anti-solvent comprises diethyl ether.
48. A light emitting device comprising:
a light emitting material comprising a first monolithic component, wherein the first monolithic component comprises two or more first metal halides, and a first wide bandgap organic network comprising a plurality of first organic cations, wherein the two or more first metal halides are (i) disposed in the first wide bandgap organic network, and (ii) isolated from each other.
49. The light-emitting device of claim 48, wherein the luminescent material further comprises a second monolithic component, wherein the second monolithic component comprises two or more second metal halides; and a second wide bandgap organic network comprising a plurality of second organic cations, wherein the two or more second metal halides are (i) disposed in the second wide bandgap organic network and (ii) isolated from each other.
50. The light-emitting device of claim 49, wherein the luminescent material further comprises a host material, wherein the first monolithic component and the second monolithic component are dispersed in the host material.
51. The light emitting device of claim 48, wherein the device is a light emitting diode.
Background
Luminescent materials have applications in a variety of technologies, including energy, information, environmental, and medical technologies. Various types of light emitting materials have been developed, including organic and polymeric emitters, transition metal complexes, rare earth doped phosphors, nanocrystals, and organic-inorganic hybrid perovskites.
One possible design of a luminescent material relies on a host-guest concept, where the luminescent substance is doped in an inert host matrix. Benefits of host-guest design may include suspension aggregation-induced self-absorption and self-quenching, and/or allow simple fine-tuning of the emission color.
However, it is difficult to achieve an efficient host-guest system in which the dopant is uniformly distributed in the host matrix, as such systems typically require the selection of appropriate host and dopant materials, precise control of material processing, or a combination thereof.
A crystalline solid is a material whose constituents (such as atoms, molecules or ions) are arranged in an ordered structure, forming a periodic lattice that extends in all directions. The interaction between lattice sites can lead to the formation of a band structure. Thus, the properties of an inorganic crystal may exhibit a strong dependence on its size (particularly on the nanometer scale), and this dependence may be referred to as a quantum size effect. Molecular interactions in organic crystals can result in properties that differ from those of individual molecules.
Luminescent materials with large stokes shifts are useful for a variety of applications from biological imaging to solar fluorescent concentrators, where self-absorption is generally undesirable. Several principles have been identified to guide the possible realization of large stokes shifts for light emitting systems, including Excited State Intramolecular Proton Transfer (ESIPT), excited state intramolecular energy transfer, and/or excited state structural deformation. Metal complexes capable of undergoing structural deformation in an ultrafast excited state may have the potential to produce emissions with large stokes shifts. However, for many systems, a large stokes shift is only available in solution and not in the solid state, since the rigidity of the solid state structure may limit the extent to which the excited state deforms as the emission wavelength red-shifts decreases.
To produce white light, the most common solid state lighting devices include Light Emitting Diodes (LEDs) coated with a single phosphor, such as YAG: Ce3+InGaN blue LED chip (phosphor emitting yellow light). However, these single phosphor coated white leds (wleds) typically emit light with poor color rendering due to spectral discontinuities. UV pumped WLEDs with blue, green and red phosphors can produce higher quality white light, but often suffer from efficiency losses due to re-absorption of the emitted light and self-quenching of the phosphors.
Organic-inorganic metal halide mixtures are a class of crystalline materials that may have unique structures and/or allow tunability of one or more properties. Metal halide polyhedra can form three-dimensional (3D), two-dimensional (2D), one-dimensional (1D), and zero-dimensional (0D) structures surrounded by organic moieties. The reduction in the dimensionality of the inorganic structures can lead to unique properties.
There remains a need for materials (including single crystal materials) that exhibit bulk properties consistent with their individual building blocks or for monolithic assemblies of quantum confined materials that do not have band formation and/or quantum size effects. There is still a need for solid state luminescent materials with a desired stokes shift. There remains a need for methods for making crystalline materials, including methods that are simple, fast, reliable, tunable, or a combination thereof.
Disclosure of Invention
Embodiments of single crystal monolithic assemblies are provided herein, which can include 0D quantum confinement materials. In some embodiments, the overall assembly exhibits a gaussian shape and/or strong stokes shift broadband emission with a photoluminescence quantum efficiency (PLQE) at most close to one. The monolithic component may include individual photosensitive molecular species that exhibit one or more of their inherent properties when in a monolithic material. In some embodiments, the monolithic components herein can have tunable chemical compositions, tunable crystallographic structures, tunable photophysical properties, or combinations thereof.
In one aspect, an integral assembly is provided. In some embodiments, the monolithic component comprises two or more metal halides and a wide band gap organic network comprising a plurality of organic cations. Two or more metal halides may be (i) disposed in a wide bandgap organic network and (ii) isolated from each other.
In some embodiments, the two or more metal halides comprise (i) MX of the formula6Octahedron of (i), (ii) formula M2X9(ii) a dimer of the formula (iii) M3X11Trimer of (iv) formula M4X13Tetramer of (v) formula MX6Triangular prism of (vi) formula MX5A triangular bipyramid of the formula (vii)5Square pyramid of (viii) formula MX4Tetrahedron (ix) formula MX4Or (X) a combination thereof, wherein M is a metal atom and X is a halide.
In another aspect, a method of forming an integral assembly is provided. In some embodiments, the method includes providing a precursor solution, and contacting the precursor solution with an anti-solvent to form a monolithA body assembly. The precursor solution may include (i) a solvent; (ii) formula My+XyWherein M is a metal selected from the group consisting of Sb, Pb, Sn and Mn, X is Cl, Br or I, and y is the charge of the metal; and (iii) one or more organic salts.
In yet another aspect, a luminescent composite is provided. In some embodiments, a luminescent composite includes a first monolithic component, a second monolithic component, and a host material, wherein the first monolithic component and the second monolithic component are dispersed in the host material. The first monolithic component can include two or more first metal halides and a first wide bandgap organic network including a plurality of first organic cations, wherein the two or more first metal halides are (i) disposed in the first wide bandgap organic network and (ii) isolated from each other. The second monolithic component may include two or more second metal halides and a second wide bandgap organic network including a plurality of second organic cations, wherein the two or more second metal halides are (i) disposed in the second wide bandgap organic network and (ii) isolated from each other. In some embodiments, the luminescent composite material comprises a third monolithic component, which may also be dispersed in the matrix material.
In a further aspect, a light emitting device is provided. In some embodiments, the light emitting device comprises a luminescent material, wherein the luminescent material comprises a first monolithic component. In some embodiments, the luminescent material comprises a second integral component. The first monolithic component and the second monolithic component may be dispersed in a matrix material.
Drawings
Fig. 1 depicts a possible spatial arrangement of an embodiment of the metal halide.
FIG. 2 depicts a structure including being isolated from each other and being represented by C4N2H14Br+Two kinds of SnBr surrounded by ligand6 4-Examples of monolithic components of examples of octahedral species.
FIG. 3 depicts a graph including C9NH20 +Two isolated SbCl surrounded by ligand5 2-An embodiment of a unitary assembly of an embodiment of a quadrangular pyramid matter.
Fig. 4 is a schematic diagram of an embodiment of a perfect host-
Fig. 5 depicts a potential energy diagram of the perfect host-
Fig. 6 depicts powder X-ray diffraction Patterns (PXRD) collected for an example of a powder monolith assembly and simulation results.
FIG. 7 depicts an embodiment of a Sn halide monolithic assembly recorded at 12kHz rotation (rotation sidebands indicated by asterisks) at room temperature119Sn MAS NMR spectrum.
Fig. 8A depicts the measured spectra of two embodiments of Sn halide monolithic assemblies.
FIG. 8B depicts a high resolution Sn spectrum of one embodiment of a material having the formula: (C)4N2H14Br)4SnBr6。
Fig. 9 depicts excitation (dashed line) and emission (solid line) spectra of an embodiment of the monolithic assembly at room temperature.
Fig. 10 depicts absorption (dashed line) and excitation (solid line) spectra of an embodiment of the entire assembly recorded at room temperature.
FIG. 11 depicts (C) at room temperature4N2H14Br)4SnBr6Emission intensity versus excitation power.
Fig. 12 depicts the emission spectrum of an embodiment of the overall assembly at 77K.
Fig. 13 depicts the emission decay of an embodiment of the overall assembly at room temperature (solid line) and 77K (dashed line).
FIG. 14 depicts (C) collected by an integrating sphere4N2H14Br)4SnBr6Reference excitation line and emission spectrum.
FIG. 15A depicts a high power mercury lamp (150 mW/cm)2) The light stability of the embodiment of the monolithic assembly under continuous illumination was performed.
FIG. 15B depicts (C)4N2H14Br)4SnBr6Temperature dependent photoluminescence.
FIG. 16 depicts a configuration graph showing a possible excited state process for an embodiment of an integral assembly.
FIG. 17 depicts BaMgAl10O17:Eu2+And (C)4N2H14Br)4SnBr6Normalized excitation (dashed line) and emission (solid line) spectra of the phosphor.
Fig. 18 depicts the emission spectra of UV pumped LEDs with different blending ratios of blue and yellow phosphors.
Fig. 19 depicts the emission spectra of white LEDs at different drive currents.
FIG. 20 depicts a single SnBr4 2-A bat model of an anionic embodiment.
FIG. 21 depicts (C)9NH20)2SnBr4Excitation and emission spectra of bulk crystal embodiments.
Fig. 22 depicts excitation and emission spectra collected from an embodiment of the monolithic assembly at 77K, room temperature.
FIG. 23 depicts a schematic diagram of the photophysical processes of an embodiment of the integral assembly; the straight and curved arrows represent the optical and relaxation transitions, respectively.
Fig. 24 depicts excitation and emission spectra collected for an embodiment of an integral assembly.
Fig. 25 depicts excitation (dashed lines) and emission (solid lines) of several embodiments of phosphors.
Fig. 26A depicts the emission spectra of an embodiment of a white light emitting diode, simulated white light, and black body radiator at 3000K.
Fig. 26B depicts the emission spectra of an embodiment of a white light emitting diode, simulated white light, and black body radiator at 4000K.
Fig. 26C depicts the emission spectra of an embodiment of a white light emitting diode, simulated white light, and black body radiator at 5000K.
Fig. 26D depicts the emission spectra of an embodiment of a white light emitting diode, simulated white light, and black body radiator at 6000K.
Fig. 27 depicts a comparison of an embodiment of a white light emitting device with a commercially available white light emitting device.
Fig. 28 depicts voltage versus luminance and luminous efficiency for an embodiment of a light emitting device.
Fig. 29 depicts voltage versus current efficiency and luminous efficiency for an embodiment of a light emitting device.
Detailed Description
Provided herein are monolithic assemblies that can include an organic component (e.g., an organic cation) and an inorganic component (e.g., a metal halide).
Without wishing to be bound by any particular theory, it is believed that the use of organic and inorganic components (such as the components disclosed herein) may allow the formation of embodiments of organic-inorganic hybrid monolithic assemblies containing photoactive metal halides, which in some embodiments represent "perfect" host guest systems in which the metal halide is periodically embedded into a wide bandgap organic network through ionic bonds. Due to the lack of band formation or quantum size effects in some embodiments, ionically bonded monolithic assemblies may allow a single photoactive molecular species to exhibit one or more of its inherent properties while in the monolithic material, thereby potentially forming a new generation of high performance light emitting materials for optoelectronic devices.
In some embodiments, highly luminescent, strong stokes shift broadband emission may be exhibited due to excited state structural reorganization of individual metal halides, with the photoluminescence quantum efficiency (PLQE) at most close to one.
In one aspect, an integral assembly is provided. In some embodiments, the monolithic assembly comprises two or more photoactive and/or electroactive species; and wide bandgap organic networks. The wide bandgap organic network can include a plurality of organic cations. Each of the two or more photoactive and/or electroactive species may be (i) disposed in a wide bandgap organic network, and (ii) isolated from each other. In some embodiments, the two or more photoactive and/or electroactive species comprise two or more metal halides.
In some embodiments, the monolithic assembly comprises two or more metal halides, and a wide bandgap organic network comprising a plurality of organic cations, wherein the two or more metal halides are (i) disposed in the wide bandgap organic network and (ii) isolated from each other.
The monolithic component provided herein can be a crystalline material. Accordingly, when an entire assembly is described herein as having a particular formula (e.g., "(C)9NH20)7(PbX4)Pb3Cl11") the formula represents the unit cell of the overall assembly.
As used herein, the phrase "wide bandgap organic network" refers to a network that is capable of eliminating or reducing interactions, band formation, or a combination thereof between two or more metal halides disposed in the network. In some embodiments, the wide bandgap organic network allows the monolithic assembly provided herein to exhibit one or more intrinsic properties of the individual metal halides. In other words, the monolithic assembly herein includes two or more halides and an organic network, and when the two or more halides are disposed in the organic network, the organic network forms a wide bandgap organic network by eliminating or reducing interactions, band formation, or combinations thereof between the two or more metal halides.
Two or more metal halides are "isolated from each other" in the network when (i) the two or more metal halides disposed in the network are not in contact with each other, (ii) a portion of the network is disposed between the two or more metal halides, or (iii) a combination thereof.
Metal halides
The two or more metal halides can have any formula that allows for the formation of an integral assembly provided herein. The two or more metal halides can also have any spatial arrangement that allows for the formation of an integral assembly provided herein. The two or more metal halides may have the same formula, or the two or more metal halides may have two or more different formulas. The two or more metal halides may have the same spatial arrangement, or the two or more metal halides may have two or more different spatial arrangements.
In some embodiments, twoEach of the one or more metal halides is independently selected from the group consisting of: (i) formula MX6Octahedron of (i), (ii) formula M2X9(ii) a dimer of the formula (iii) M3X11Trimer of (iv) formula M4X13Tetramer of (v) formula MX6Triangular prism of (vi) formula MX5A triangular bipyramid of the formula (vii)5Square pyramid of (viii) formula MX4Of formula (ix) and4wherein M is a metal atom, and X is a halide selected from the group consisting of Cl, Br and I.
Fig. 1 depicts examples of possible spatial arrangements of two or more metal halides, including octahedra, dimers, trimers, tetramers, triangular prisms, triangular bipyramids, square pyramids (which may also be referred to as "tetrapyramids"), tetrahedrons, and teeterboards.
The two or more metal halides can generally include any metal atom that allows for the formation of an integral assembly as provided herein. In some embodiments, the metal atoms comprise Sn, Sb, Pb, Mn, or combinations thereof. Thus, in the foregoing embodiments for the formula of two or more metal halides, M may be independently selected from the group consisting of Sn, Pb, Sb, and Mn.
In some embodiments, the two or more metal halides are
Formula MX6M is Sn and the two or more metal halides are of the formula SnX6 4-Wherein X is
Selected from Cl, Br or I. In some embodiments, X is Br, and the two or more metal halides have the formula SnBr6 4-. In some embodiments, X is I, and the two or more metal halides have the formula SnI6 4-. In some embodiments, X is Cl, and the two or more metal halides have the formula SnCl6 4-。
In some embodiments, the two or more metal halides are of the formula MX5M is Sb, and the two or more metal halides have the formula SbX5 2-Which isWherein X is selected from Cl, Br or I. In some embodiments, X is Br, and the two or more metal halides have the formula SbBr5 2-. In some embodiments, X is I, and the two or more metal halides have the formula SbI5 2-. In some embodiments, X is Cl, and the two or more metal halides have the formula SbCl5 2-。
In some embodiments, the two or more metal halides have the formula MX4Wherein M is Sn and the two or more metal halides have the formula SnX4 2-Wherein X is selected from Cl, Br or I. In some embodiments, X is Br, and the two or more metal halides have the formula SnBr4 2-. In some embodiments, X is I, and the two or more metal halides have the formula SnI4 2-. In some embodiments, X is Cl, and the two or more metal halides have the formula SnCl4 2-。
In some embodiments, the two or more metal halides comprise (i) MX of the formula4And (ii) a tetrahedron of formula M3X11Wherein M is Pb, and the two or more metal halides each have the formula PbX4 2-And formula PbX11 5-Wherein X is selected from Cl, Br or I. In some embodiments, X is Cl, and the two or more metal halides have the formula PbCl4 2-And PbCl11 5-. In some embodiments, X is Br, and the two or more metal halides have the formula PbBr4 2-And formula PbBr11 5-. In some embodiments, X is I, and the two or more metal halides have the formula PbI4 2-And formula PbI11 5-。
Organic cation
In general, the plurality of organic cations can include one or more types of organic cations capable of forming a wide bandgap organic network. In some embodiments, the plurality of organic cations includes a single type of organic cation. In some embodiments, the plurality of organic cations includes two or more different types of organic cations.
In some embodiments, the plurality of organic cations comprises one or more quaternary ammonium cations, one or more tertiary ammonium cations, one or more secondary ammonium cations, one or more primary ammonium cations, or a combination thereof.
As used herein, the phrase "quaternary ammonium cation" generally refers to a cation of the formula:
wherein R is1、R2、R3And R4Independently selected from monovalent C1-C20A hydrocarbyl group.
As used herein, the phrase "tertiary ammonium cation" generally refers to a cation of the formula:
wherein R is1、R2And R3Independently selected from monovalent C1-C20A hydrocarbyl group.
As used herein, the phrase "secondary ammonium cation" generally refers to a cation of the formula:
wherein R is1And R2Independently selected from monovalent C1-C20A hydrocarbyl group.
As used herein, the phrase "primary ammonium cation" generally refers to a cation of the formula:
wherein R is1Selected from monovalent C1-C20A hydrocarbyl group.
In some embodimentsThe plurality of organic cations includes cations selected from the group consisting of: n, N, N-trimethyloct-1-ammonium; tetraethyl ammonium; tetrabutylammonium; n, N-dimethylhex-1-aminium; bis (2-ethylhexyl) ammonium; n is a radical of1-methyl ethane-1, 2-diammonium; n is a radical of1,N2-dimethylethane-1, 2-diammonium; n is a radical of1,N1,N2,N2-tetramethylethane-1, 2-diammonium; n is a radical of1,N1-dimethylethane-1, 2-diammonium; n is a radical of1,N1,N2-trimethylethane-1, 2-diammonium; 2, 6-dimethylpyridin-1-ium; 2-amino-4-methylpyridin-1-ium; [4,4' -Bipyridinyl]-1,1' -diimmonium; [4,4' -Bipyridinyl]-1-onium salt
4- (di (pyridin-4-yl) amino) pyridin-1-ium; 1-butyl-1-methylpyrrolidin-1-ium; 3-butyl-1-methyl-1H-imidazol-3-ium; 3- (pyrrolidin-1-yl) propan-1-ammonium; 2- (pyrrolidin-2-yl) ethylamine;
1, 1-dibutylpiperidin-1-ium; 5-azaspiro [4.4] nonan-5-ium; (1r,3r,5s,7s) -1,3,5, 7-tetraazaadamantan-1, 3-diimmonium; 6-azaspiro [5.5] undec-6-ium; 1, 4-diazabicyclo [2.2.2] oct-1-ium; (3s,5s,7s) -1-azaadamantan-1-ium; (3r,5r,7r) -1,3,5, 7-tetraazaadamantan-1-ium; tetraphenylphosphonium, or a combination thereof. These compounds have the following structure:
in some embodiments, the plurality of organic cations includes an organic cation selected from the group consisting of:
in some embodiments, the plurality of organic cations comprises C4N2H14X+、C9NH20 +Or a combination thereof, wherein X is selected from Cl, Br or I.
Integral assembly
In some embodiments, the integral component comprises formula SnX6Two or more halides of formula C4N2H14X+And the overall assembly has the formula:
(C4N2H14X)4SnX6，
wherein X is selected from Cl, Br or I. The two or more metal halides may be octahedral monomers (fig. 1). In some embodiments, the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, at least 90%, or about 95%. In some embodiments, X is Br, and the overall assembly has formula (C)4N2H14Br)4SnBr6. In some embodiments, X is Br and the overall assembly has formula (C)4N2H14Br)4SnBr6And the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, at least 90%, or about 95%. In some embodiments, X is I, and the overall assembly has formula (C)4N2H14I)4SnI6. In some embodiments, X is I and the overall assembly has formula (C)4N2H14I)4SnI6And the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, at least 90%, or about 95%.
In some embodiments, the integral assembly comprises
SbX5Two or more halides of formula C9NH20+ and the overall assembly has the formula:
(C9NH20)2SbX5，
wherein X is selected from Cl, Br or I. The two or more metal halides may be square pyramids (fig. 1). In some casesIn embodiments, the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, at least 90%, at least 95%, or about 98%. In some embodiments, X is Cl and the overall assembly has the formula (C)9NH20)2SbCl5. In some embodiments, X is Cl and the overall assembly has the formula (C)9NH20)2SbCl5And the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, at least 90%, at least 95%, or about 98%. In some embodiments, X is I, and the overall assembly has formula (C)9NH20)2SbI5. In some embodiments, X is I and the overall assembly has formula (C)9NH20)2SbI5And the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, at least 90%, at least 95%, or about 98%.
In some embodiments, the integral assembly comprises the formula SbX5Two or more halides of formula Ph4P + and the overall assembly has the formula:
(Ph4P)2SbX5，
wherein X is selected from Cl, Br or I. The two or more metal halides may be square pyramids (fig. 1). In some embodiments, the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, or about 87%. In some embodiments, X is Cl, and the overall assembly has the formula (Ph)4P)2SbCl5. In some embodiments, X is Cl and the overall assembly has the formula (Ph)4P)2SbCl5And the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, or about 87%. In some embodiments, X is I, and the overall assembly has the formula (Ph)4P)2SbI5. In some embodiments, X is I and the overall assembly has the formula (Ph)4P)2SbI5And the overall assembly has a PLQE of at least 70%, about 75%, about 80%, at least 80%, about 85%, or about 87%.
In some embodiments, the integral component comprises formula SnX4Of two or more metal halides of the formula C9NH20+ and the overall assembly has the formula:
(C9NH20)2SnX4，
wherein X is selected from Cl, Br or I. The two or more metal halides may have a teeter-totter structure (fig. 1). In some embodiments, the overall assembly has a PLQE of at least 30%, about 35%, at least 40%, about 45%, at least 45%, or about 46%. In some embodiments, X is Br, and the overall assembly has the formula (C)9NH20)2SnBr4. In some embodiments, X is Br and the overall assembly has the formula (C)9NH20)2SnBr4And the overall assembly has a PLQE of at least 30%, about 35%, at least 40%, about 45%, at least 45%, or about 46%. In some embodiments, formula (C)9NH20)2SnBr4Is a lead-free organometallic halide hybrid material having a zero-dimensional (0D) structure in which individual seesaw-like inorganic tin (II) bromide anions (SnBr)4 2-) With organic 1-butyl-1-methylpyrrolidinium cations (C)9NH20 +) And (4) co-crystallizing. In some embodiments, formula (C)9NH20)2SnX4(where X is Cl, Br or I) shows a high-efficiency broadband deep red emission with a peak at about 695nm under photoexcitation, [1 ] of the high-efficiency broadband deep red emission]Stokes shift of about 332nm, [ 2]]Quantum efficiency of about 46%, or [ 3%]Combinations thereof. Without wishing to be bound by any particular theory, it is believed that formula (C) where X is Cl, Br, or I9NH20)2SnX4The photophysical properties of the bulk component of (a) can be attributed, at least in part, to (i) a 0D structure, which can allow the bulk crystal to exhibit SnX alone4 2-Intrinsic properties of the substance, and/or (ii) a teeter-totter structure that can achieve significant excited state structural deformation. In thatIn the excited state, the seesaw-like body structure can be flattened into a tetrahedral structure.
In some embodiments, the monolithic assembly comprises (i) two or more metal halides comprising (a) PbX4 2-Tetrahedron and (b) PbX11 5-Trimer of (ii) C9NH20+ and (iii) the overall assembly has the formula:
(C9NH20)7(PbX4)Pb3X11，
wherein X is selected from the group consisting of Cl, Br and I. In some embodiments, the overall assembly has a PLQE of at least 60%, about 65%, at least 70%, about 75%, about 80%, or about 83%. In some embodiments, X is Cl and the overall assembly has the formula (C)9NH20)7(PbCl4)Pb3Cl11. In some embodiments, X is Br, and the overall assembly has the formula (C)9NH20)7(PbBr4)Pb3Br11. In some embodiments, X is I, and the overall assembly has the formula (C)9NH20)7(PbI4)Pb3I11。
Method of producing a composite material
Methods of forming the integral assembly are also provided. In some embodiments, the method includes providing a precursor solution, and contacting the precursor solution with an anti-solvent to form an integral assembly.
The precursor solution may include (i) a solvent; (ii) formula My+XyWherein M is a metal selected from the group consisting of Sb, Pb, Sn and Mn, X is Cl, Br or I, and y is the charge of the metal; and (iii) one or more organic salts.
In some embodiments, formula My+XyIs present in a molar ratio of the one or more compounds to the one or more organic salts of from about 1:1.5 to about 1: 2.5. In some embodiments, formula My+XyIs about 1:2 to the one or more organic salts.
The solvent used in the methods provided herein can include any liquid capable of dissolving the metal halide and organic salt. In some embodiments, the solvent comprises dimethylformamide. The anti-solvent may be any liquid that promotes crystallization or removal of the entire assembly from the solvent. In some embodiments, the anti-solvent comprises diethyl ether.
The contacting of the precursor solution and the anti-solvent can be achieved by diffusing the anti-solvent into the solution over a specified period of time (e.g., overnight, several hours, etc.). The amount of anti-solvent diffused into the precursor solution should be sufficient to crystallize or remove the entire assembly from the solvent. In some embodiments, a 2:1 volume ratio of the anti-solvent may be diffused into the precursor solution (e.g., 2mL of anti-solvent per 1mL of precursor solution), although other volume ratios may be used, including volume ratios of about 1:1 to about 3: 1.
Contacting the precursor solution and the anti-solvent can be achieved by injecting the anti-solvent into the solution. "injection" contacts the solution with a predetermined amount of anti-solvent in a relatively short period of time (e.g., less than five seconds). The crystal may be grown for several minutes (e.g., 10 minutes) before the crystal is collected.
The methods provided herein can produce monolithic assemblies in yields of about 50% to about 90%.
Luminescent composite material
Also provided herein are luminescent composites. The luminescent composite may comprise a host material in which the monolithic components described herein may be dispersed. The luminescent composite may comprise one type of monolithic component, or the luminescent composite may comprise two or more different types of monolithic components. When two or more different types of monolithic components are included in a luminescent composite, the different types of monolithic components may emit light of different colors, intensities, etc. In some embodiments, the luminescent composite material emits white light.
In some embodiments, a luminescent composite includes a first monolithic component, a second monolithic component, and a host material. The first monolithic component and the second monolithic component may be dispersed in a matrix material. The first monolithic component and the second monolithic component may include different metal halides, different wide bandgap organic networks, or both. In some embodiments, the first monolithic component and the second monolithic component are substantially uniformly dispersed in the matrix material. In some embodiments, the first monolithic component and the second monolithic component are non-uniformly dispersed in the matrix material.
The first and second monolithic components may generally be in any form that allows them to be dispersed in a matrix material. The physical form of the first and second integral components may be the same or different. In some embodiments, the first monolithic component and the second monolithic component are in particulate form (e.g., powder).
Any weight ratio of the first monolithic component to the second monolithic component may be present in the luminescent composite. In some embodiments, the weight ratio of the first unitary assembly to the second unitary assembly is from about 1:10 to about 10:1, although other ratios are also contemplated. The weight ratio may be selected to achieve a desired emission (e.g., color of light, such as white light, etc.).
In some embodiments, the luminescent composite material comprises a third integral component. The third monolithic component may include a metal halide and/or a wide bandgap organic network that is different from the metal halide and/or the wide bandgap organic network of at least one of the first monolithic component and the second monolithic component. Any weight ratio of the first monolithic component to the second monolithic component to the third monolithic component can be used in the luminescent composite.
In some embodiments, the first monolithic component of the light-emitting composite includes two or more first metal halides and a first wide bandgap organic network. In some embodiments, (i) the two or more first metal halides comprise the formula MnX4 2-The tetrahedra of (ii) the plurality of first organic cations of the first wide bandgap organic network comprises Ph4P +, and (iii) the first monolithic component has the formula:
(Ph4P)2MnX4，
wherein X is selected from the group consisting of Cl, Br and I. In some embodiments, X is Br.
In some embodiments, the second monolithic component of the luminescent composite comprises two or more second metal halidesAnd a second wide bandgap organic network. In some embodiments, (i) the two or more second metal halides comprise the formula SnX6 4-(ii) the plurality of second organic cations comprises C4N2H14X+And (iii) the second monolithic component has the formula:
(C4N2H14X)4SnX6，
wherein X is selected from the group consisting of Cl, Br and I. In some embodiments, X is Br.
In some embodiments, a third monolithic component of the light emitting composite includes two or more third metal halides and a third wide bandgap organic network. In some embodiments, (i) the two or more third metal halides comprise the formula SbX5 2-Square pyramids, (ii) a plurality of third organic cations comprising Ph4P+And (iii) the third integral component has the formula:
(Ph4P)2SbX5，
wherein X is selected from the group consisting of Cl, Br and I. In some embodiments, X is Cl.
The matrix material of the luminescent composite may comprise a polymeric matrix. In some embodiments, the host material of the luminescent composite comprises polydimethylsiloxane.
In some embodiments, the concentration of the monolithic component or combination of monolithic components in the matrix material is from about 5mg/mL to about 50mg/mL, from about 10mg/mL to about 40mg/mL, from about 15mg/mL to about 30mg/mL, from about 20mg/mL to about 30mg/mL, or about 25 mg/mL. These concentrations are based on the total weight of one or more monolithic components in the composite. For example, if three different types of monolithic components are present in the luminescent composite, the three different types of monolithic components may be combined into a mixture, and if 25mg of such a mixture is added per mL of matrix material, the concentration would be 25 mg/mL.
Device for measuring the position of a moving object
Light emitting devices are provided herein. In some embodiments, the light emitting device comprises a luminescent material. The luminescent material may comprise one or more integral components. The luminescent material may comprise a first integral component. In some embodiments, the luminescent material comprises a first monolithic component and a second monolithic component. In some embodiments, the luminescent material comprises a first monolithic component, a second monolithic component, and a third monolithic component. The luminescent material may comprise a host material in which one or more integral components are dispersed.
In some embodiments, the light emitting device is a light emitting diode.
As used herein, the phrase "C1-C20Hydrocarbyl "and the like generally refers to an aliphatic, aryl, or arylalkyl group containing 1 to 20 carbon atoms. Examples of aliphatic groups include, but are not limited to, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, alkadienyl, cyclyl, and the like, and include all substituted, unsubstituted, branched, and straight chain analogs or derivatives, having in each
Unless otherwise indicated, the term "substituted" when used to describe a chemical structure or moiety refers to a derivative of said structure or moiety in which one or more of its hydrogen atoms is replaced with a chemical moiety or functional group selected from the group consisting of: such as alcohols, alkoxy, alkanoyloxy, alkoxycarbonyl, alkenyl, alkyl (e.g. methyl, ethyl, propyl, tert-butyl), alkynyl, alkylcarbonyloxy (-OC (O) alkyl), amide (-C (O) NH-alkyl-or-alkylNHC (O) alkyl), tertiary amines (e.g. alkylamino, arylamino, arylalkylamino), aryl, aryloxy, azo, carbamoyl (-NHC (O) O-alkyl-or-OC (O) NH-alkyl), carbamoyl (e.g. CONH)2And CONH-alkyl, CONH-aryl and CONH-arylalkyl), carboxyl, carboxylic acid, cyano, ester, ether (e.g. methoxy, ethoxy), halogen, haloalkyl (e.g. -CCl)3、-CF3、-C(CF3)3) Heteroalkyl, isocyanate, isothiocyanate, nitrile, nitro, phosphodiester, sulfide, sulfonamide (e.g., SO)2NH2、SO2NR' R "), sulfone, sulfonyl (including alkylsulfonyl, arylsulfonyl, and arylalkylsulfonyl), sulfoxide, thiol (e.g., mercapto, thioether), or urea (-NHCONH-alkyl-).
While certain aspects of conventional technology have been discussed to facilitate disclosure of various embodiments, the applicant in no way denies these technical aspects and expects that the present disclosure may encompass one or more of the conventional technical aspects discussed herein.
In the description provided herein, the terms "comprising," is, "" containing, "" has "and" including "are used in an open-ended fashion, and thus should be interpreted to mean" including, but not limited to. When methods and monolithic components are claimed or described as "comprising" various components or steps, the monolithic components and methods may also "consist essentially of or" consist of "the various components or steps, unless otherwise specified.
The terms "a", "an" and "the" are intended to include a plurality of alternatives, such as at least one. For example, unless otherwise specified, the disclosure of "metal halide," "organic cation," "monolith component," and the like is intended to include mixtures or combinations of one or more metal halides, organic cations, monolith components, and the like.
Examples of the invention
The invention is further illustrated by the following examples, which are not to be construed as in any way imposing limitations upon the scope thereof. On the contrary, it is to be clearly understood that resort may be had to various other aspects, embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those of ordinary skill in the art without departing from the spirit of the present invention or the scope of the appended claims. Accordingly, other aspects of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.
Unless otherwise specified, the following materials are used in the examples herein. Tin (II) bromide, tin (II) iodide, tin (II) bromide, antimony trichloride, N' -dimethylethylenediamine (99%), 1-butyl-1-methylpyrrolidinium chloride, gamma-butyrolactone (GBL ≥ 99%), hydrobromic acid (in H)248 wt.% in O), hydroiodic acid (55%) and tetraphenylphosphonium chloride (Ph)4PCl, 98%) was purchased from Sigma Aldrich (Sigma-Aldrich). Dimethylformamide (DMF, 99.8%) and diethyl ether (Et) were purchased2O, anhydrous) for VWR. All reagents and solvents were used without further purification unless otherwise indicated.
It is available from sigma aldrich. Dichloromethane (DCM, 99.9%), dimethylformamide (DMF, 99.8%), toluene (anhydrous, 99.8%) and diethyl ether (stabilized with about 1ppm BHT) were purchased from VWR. Acetone (HPLC grade) was purchased from merck Millipore (EMD Millipore). 1-butyl-1-methylpyrrolidinium bromide (C)9NH20Br, 97.0%) was purchased from delta sigma (TCIAmerica) chemical industries, usa. All reagents and solvents were used without further purification unless otherwise indicated. Spectroscopic grade solvents were used in UV-Vis and photoluminescence spectroscopy measurements.
EXAMPLE 1 preparation of N, N' -dimethylethylene-1, 2-dihaloammonium salt
The N, N '-dimethylethylene-1, 2-dibromide ammonium salt was prepared by adding a solution of hydrobromic acid (2.2 equivalents) to N, N' -dimethylethylenediamine (1 equivalent) in ethanol at 0 ℃. After removal of the solvent and starting reagent in vacuo and then washing with diethyl ether, the organic salt was obtained. The salt is dried and stored in a desiccator until use. The preparation of N, N' -dimethylethylene-1, 2-diiodoammonium salt was followed in a similar manner.
Example 2 solution growth of Single Crystal 0D Sn halide bulk Material
By reaction at N2In a filled glove box, dichloromethane was slowly diffused into tin halide (SnX) at room temperature2X ═ Br or I) and N, N' -dimethylethylene-1, 2-dimethylammonium halide (CH)3NH2 +CH2CH2NH2 +CH3·2X-) In a dimethylformamide precursor solution of (2), a single-crystal bulk material ((C)4N2H14X)4SnX6And X ═ Br or I).
1.(C4N2H14Br)4SnBr6
Specifically, tin (II) bromide and N, N' -dimethylethylene-1, 2-dimethylammonium bromide were mixed in a molar ratio of 1:4 and dissolved in DMF to form a transparent precursor solution. Bulk crystals were prepared by diffusing DCM into DMF solution overnight at room temperature. The large colorless crystals were washed with acetone and dried under reduced pressure.
The yield was about 70%.
C16H56N8SnBr10: analysis calculated value: c, 15.03; h, 4.42; n, 8.77. Measured value: c, 15.31; h, 4.24; n, 8.74.
2.(C4N2H14I)4SnI6
Tin (II) iodide and N, N' -dimethylethylene-1, 2-diammonium iodide were mixed in a molar ratio of 1:4 and dissolved in GBL to form a transparent precursor solution.
Bulk crystals were prepared by diffusing DCM into GBL solution overnight at room temperature. The large red crystals were washed with acetone and dried under reduced pressure.
The yield was about 70%. C16H56N8SnI10: analysis calculated value: c, 10.99; h, 3.23; and N, 6.41. Measured value: c, 11.16; h, 3.23; and N, 6.24.
EXAMPLE 3 solution growth of Single Crystal 0D Sb halide monoliths
By slow diffusion of acetone to a mixture comprising antimony trichloride (SbCl)3) And 1-butyl-1-methylpyrrolidine chloride (C)9NH20 +·Cl-) Is prepared from a dimethylformamide precursor solution of (C)9NH20)2SbCl5。
Specifically, antimony (II) chloride and 1-butyl-1-methylpyrrolidinium chloride were mixed in a molar ratio of 1:2 and dissolved in DMF to form a transparent precursor solution. Bulk crystals were prepared by diffusing acetone into DMF solution overnight at room temperature.
The colorless crystals were washed with acetone and dried under reduced pressure. The yield was about 70%.
C18H40N2SbCl5: analysis calculated value: c, 37.05; h, 6.91; and N, 4.80. Measured value: c, 37.32; h, 6.84; and N, 4.83.
Example 4 characterization
The materials of examples 1-3 were characterized using the following techniques.
1. Single crystal X-ray diffraction (SCXRD)
The crystal structure of the monolithic components of the examples was determined using single crystal X-ray diffraction (SCXRD) which showed a 0D structure in which the individual metal halide ions, SnX, were present6 4-And SbX5 2-Are completely isolated from each other and are each bound by a large organic ligand C4N2H14X+And C9NH20 +And (4) surrounding.
The following table includes single crystal X-ray diffraction data and acquisition parameters. The acquisition that produced the data of the following table was performed at a temperature of about 120K.
a)R1＝Σ║Fo│–│Fc║/Σ│Fo║.b)wR2＝[Σw(Fo 2–Fc 2)2/Σw(Fo 2)2]1/2。
The material of this example (i.e., (C)4N2H14X)4SnX6X ═ Br, I) can be considered as true 0D organometallic halide perovskites. As depicted in fig. 2 and 3, the distance between two metal centers of a wide band gap organic ligand>The complete isolation of the photoactive metal halides at 1nm results in no interaction or band formation between the photoactive metal halides.
FIG. 2 depicts all isolated from each other and by C4N2H14Br+Two kinds of SnBr surrounded by ligand6 4-Octahedral substances.
FIG. 3 depicts a graph formed by C9NH20 +Two SbCl completely isolated and surrounded by ligand5 2-A quadrangular pyramid material.
A space-filling model of the material of this example was prepared and depicted indicating full coverage of the organic ligand to the metal halide alone, indicating a perfect 0D core-shell structure.
Fig. 4 is a schematic diagram of a perfect
The potential energy diagram of the 0D core-shell quantum confinement material or the overall components of a perfect host guest system (fig. 4) of the present example can be described with the schematic diagram of fig. 5. The monolithic material of example 1 may exhibit one or more of the inherent properties of the individual metal halides.
Collection was performed using an Oxford diffraction Xcalibur-2CCD diffractometer with graphite monochromatic Mo K α radiation (C)4N2H14Br)4SnBr6Single crystal x-ray diffraction data of (a). The crystals were mounted in a low temperature loop under Paratone-N oil and cooled to 120K with an Oxford diffractive cryo-jet. Using a 1 frame width, resolution of
The data does not allow for unlimited refinement: all hydrogen is limited to the attached nitrogen or carbon. For F2And refining, wherein anisotropic thermal displacement parameters are used for all non-hydrogen atoms, and isotropic thermal displacement parameters are used for hydrogen in the structure. Analysis by the same method (C)9NH20)2SbCl5The crystal structure of (1). Using heavy oil will (C)4N2H14I)4SnI6Is arranged on a nylon ring. The samples were kept at 100K for data collection. The data were collected on a Bruker SMART APEX II diffractometer using a detector distance of 6 cm.
The number of frames taken with a frame acquisition time of 20 or 30 seconds using a 0.3 degree omega scan was 2400. Integration was performed using the program SAINT, which is part of the Bruker program suite. Absorption correction was performed using SADABS. XPREP is used to obtain an indication of the space group, and the structure is usually resolved by direct methods and refined by SHELXTL. The non-hydrogen atoms are anisotropically refined. VESTA was used as crystal structure visualization software for images presented in the manuscript.
2. Powder X-ray diffraction (PXRD)
Powder X-ray diffraction (PXRD) patterns of the ball-milled crystalline powders were collected and showed identical features to the simulated pattern of SCXRD (fig. 6), indicating that the as-synthesized monolithic assembly had a uniform crystalline structure.
PXRD analysis was performed on a Panalytical X 'PERT Pro powder X-ray diffractometer using copper X-ray tube (standard) radiation at 40kV and 40mA and an X' Celerator RTMS detector. The diffraction pattern was scanned at room temperature in 0.02 steps over an angular range of 5-50 degrees (2 θ). Simulated powder plots were calculated by Mercury software using the Crystallization Information File (CIF) from single crystal x-ray experiments.
Sn Nuclear Magnetic Resonance (NMR)
Elemental analysis also confirmed the purity and uniformity of the overall assembly of this example. To further verify the structure, composition and presence of only Sn (ii) in the Sn-based material, solid state was performed119Sn nuclear magnetic resonance spectroscopy (NMR) (fig. 7) and X-ray photoelectron spectroscopy (XPS) (fig. 8A and 8B).
FIG. 7 depicts a Sn halide monolithic assembly recorded at room temperature with 12kHz rotation119Sn MAS nuclear magnetic resonance spectroscopy. The rotating sidebands are indicated by asterisks.
119Sn-MAS nuclear magnetic resonance spectroscopy was recorded on a Bruker Advance III high definition spectrometer equipped with a 4mm MAS probe, operating at 186.5MHz with the sample rotated at 12kHz, high power proton decoupling, 30s cyclic delay, and typically 2048 scans. SnO2Used as a secondary reference at-604.3 ppm.
X-ray photoelectron spectroscopy (XPS)
Fig. 8A and 8B depict X-ray photoelectron spectroscopy (XPS) of the Sn halide monolithic assembly of the present example. Fig. 8A depicts measured spectra of Sn halide monolithic assemblies of two embodiments, and fig. 8B depicts a high resolution Sn spectrum of one embodiment of a material having the formula: (C)4N2H14Br)4SnBr6。
XPS measurements were performed using PHI 5000Versa Probe II from ULVACPHI, Inc. XPS was recorded with a monochromatic Al K α source using 93.9 fluence and 0.8 ev/step recordingThe spectrum is measured. High resolution spectra were recorded using 11.75 pass energy and 0.1/eV steps. C1s binding energy pair (C) at 286.2ev was used4N2H14Br)4SnBr6C-N ═ bonds in (a) assign high resolution spectral binding energies. Then, the bonding energy of Sn 3d5 is found to be 487.0eV, and SnBr is found2The binding energy of Sn (II) in (1) corresponds to that of (II).
As explained in the following paragraphs, the photophysical properties of the overall assembly were characterized using UV-Vis absorption spectra and steady state and time resolved emission spectra. Table 1 summarizes the main photophysical properties.
TABLE 1 photophysical properties of the monolithic assemblies at room temperature and 77K
λExcitationIs the maximum excitation wavelength; lambda [ alpha ]LaunchingIs the maximum emission wavelength, Φ is the photoluminescence quantum efficiency; tau isAverageIs the photoluminescent lifetime; the value in parentheses is 77K.
Images of the entire assembly of this example were taken under ambient light and UV lamp illumination (365 nm). Under UV irradiation, (C) is observed4N2H14Br)4SnBr6、(C4N2H14I)4SnI6And (C)9NH20)2SbCl5High luminescent yellow, red and orange emission, excitation spectrum and emission spectrum as depicted in fig. 9. Fig. 9 depicts excitation (dashed line) and emission (solid line) spectra of the entire assembly at room temperature.
In addition to the scattering of the low energy regions, the absorption spectra of these bulk components match well with their excitation spectra (fig. 10). Fig. 10 depicts the absorption (dashed line) and excitation (solid line) spectra of the entire assembly of this example recorded at room temperature.
When in SnX6 4-When Br is replaced with I in the octahedron, the excitation maximum shifts from 355nm to 410nm, which is consistent with the weaker ligand field effect of I on Br. The emission of these monolithic components shows a significant stokes shift (>200nm) and full half-peakWidth (FWHM) ((>100nm) similar to that observed in rare earth doped phosphors with localized excited states.
To verify that these emissions represent an inherent property of the monolithic assembly of the present example, the relationship between emission intensity and excitation power at room temperature was measured. As shown in fig. 11, from (C)4N2H14Br)4SnBr6Exhibits an intensity of up to 500W/cm for a broad band yellow emission2Indicating that the emission is not caused by a permanent defect. The emission of these materials became narrower at 77K (fig. 12), which may be due to the reduction of the hot-fill vibrational state at low temperatures.
FIG. 11 depicts (C) at room temperature4N2H14Br)4SnBr6Emission intensity versus excitation power. Fig. 12 depicts the emission spectrum at 77K of the overall assembly of this example.
Fig. 13 depicts the broadband emission decay curves of these entire assemblies at room temperature and 77K. In particular, fig. 13 depicts the emission decay of the overall assembly of the present example at room temperature (solid line) and 77K (dashed line). Attenuation curve indication (C)4N2H14Br)4SnBr6Has a lifetime of about 2.2. mu.s, (C)4N2H14I)4SnI6Has a lifetime of about 1.1. mu.s, (C)9NH20)2SbCl5The lifetime of (2) is about 4.2. mu.s. Similar decay behavior observed at room temperature and 77K indicates that there is little change in the nature of the radiative and non-radiative processes.
At room temperature, the monolithic component of this example has an extremely high PLQE: for (C)4N2H14Br)4SnBr695. + -. 5% for (C)4N2H14I)4SnI675. + -. 4% for (C)9NH20)2SbCl598. + -. 2% (FIG. 14).
FIG. 14 depicts (C) collected by an integrating sphere4N2H14Br)4SnBr6Reference excitation line and emission spectrum. PLQE is calculated by:ηQE＝IS/(ER-ES)。
under the irradiation of a continuous high-power mercury lamp (150 mW/cm)2) The monolithic assembly of this example also showed great stability (fig. 15A), and higher thermal stability (fig. 15B).
FIG. 15A depicts a high power mercury lamp (150 mW/cm)2) Under continuous illumination the light stability of the integral assembly of this example.
FIG. 15B depicts (C)4N2H14Br)4SnBr6Temperature dependent photoluminescence.
Broadband radiation at large stokes shifts indicates that the emission is not from a direct excited state, but from other lower energy excited states. At least in some cases, since these monolithic components appear to be perfect host-guest systems, where the luminescent molecular species are periodically embedded in an inert matrix, without intermolecular interactions or band formation, the emission of the monolithic material is likely to come from the metal halide molecular species SnX alone6 4-And SbX5 2-。
The recombination of molecular excited state structures can explain the large Stokes shift of various luminescent materials, including tin bromide complex [ NEt ] in solution4]SnBr3. Thus, the excited state process of these integral components can be depicted in the configuration diagram of fig. 16. Fig. 16 depicts the mechanism of excited state structural reorganization: the straight and curved arrows represent the optical and relaxation transitions, respectively.
Upon absorption of a photon, the metal halide is excited to a high-energy excited state and then undergoes structural reorganization of an ultrafast excited state to form a low-energy excited state, thereby generating intense stokes shift broadband photoluminescence. On the other hand, similar below-gap broadband Emission is observed in corrugated 2D and 1D metal halide Perovskites due to exciton self-trapping (see, e.g., Dohner, e.r.; Jaffe, a.; Bradshaw, l.r.; karunadas, h.i., "Intrinsic White-Light Emission from Layered Hybrid Perovskites"; journal of the american chemical society (J Am Chem Soc): 2014,136(38), 13154-.
For metal halides, the formation of local self-trapping excited states depends on the dimensionality of the crystal system, which can make self-trapping of excitons easier. Thus, a 0D system with the strongest quantum confinement may favor the formation of self-trapping excited states. Thus, (C)4N2H14Br)4SnBr6Yellow emission and SnBr at low temperature (12K)2The self-trapping 2.2ev emission of the crystal is very similar (Yamasaki, Y.; Ohno, N., orthogonal SnBr)2Self-trapped exciton (Self-trapped exitons inporthorombic SnBr) in (1)2)). Journal of International modern Physics B (International Journal of modern Physics B) 2001,15(28-30), 4009-.
Unlike corrugated 2D and 1D perovskites, which emit from free and self-trapped excited states at room temperature due to band formation caused by the linkage and structural distortion of metal halide octahedra, Sn-based 0D perovskites (C)4N2H14X)4SnX6Only by indirect recombination excited state emission, no band is formed. Thus, the monolithic assembly of the present example relates the classical "exciton self-trapping" solid-state theory to the molecular photophysical term of "excited state structural reorganization" because the building units of metal halides can be considered as "lattice sites" or "molecular species". It should be noted that the plausible 0D perovskite (C) present in this example4N2H14X)4SnX6Similar compounds (e.g. Cs) as previously reported4PbBr6And Cs2SnI6) There is a fundamental difference that it has little quantum confinement to the individual metal halide octahedra and exhibits emission in the direct excited state.
The ability to exhibit high PLQE in the solid state makes the rare earth-rich lead-free material of this example promising as a light emitter for various applications. Unlike most conventional emitters, such as organic emitters and colloidal quantum dots, which require doping to prevent aggregation and self-quenching in the solid state, the monolithic component of this example is, at least in some embodiments, a perfect host-guest system in itself.
Strong stokes shift broadband emission without self-absorption may be of particular interest in applications of down-converted white LEDs and solar fluorescent concentrators. To demonstrate the application of these materials as phosphors, a down-conversion LED was fabricated by optically pumping a Polydimethylsiloxane (PDMS) film with a commercially available UV LED (340nm) that was optically pumped with ball-milled yellow luminescence (C)4N2H14Br)4SnBr6And commercial blue-emitting europium-doped barium magnesium aluminate (BaMgAl)10O17:Eu2+) And (4) mixing.
An ultraviolet light emitting diode (340nm) was selected in consideration of excitation of yellow and blue phosphors in the ultraviolet region (fig. 17). FIG. 17 depicts BaMgAl10O17:Eu2+And (C)4N2H14Br)4SnBr6Normalized excitation (dashed line) and emission (solid line) spectra of the phosphor.
Images of PDMS films doped with blue and yellow phosphors at different weight ratios were collected under ambient light and uv lamp illumination. The captured image included images of blue phosphor, yellow phosphor and their mixture at different weight ratios (1:2, 1:1 and 2:1) embedded in PDMS under ambient light and hand-held uv lamp illumination (365 nm). Fig. 18 depicts the emission spectra of UV pumped LEDs, and the CIE color coordinates and Correlated Color Temperature (CCT) were collected and evaluated.
Fig. 18 depicts the emission spectra of UV pumped LEDs with different mixing ratios between the blue and yellow phosphors.
By controlling the mixing ratio of the two phosphors, a range of white light from "cold" to "warm" is achieved. A suitable white emission with CIE coordinates (0.35, 0.39), CCT 4946k, and Color Rendering Index (CRI) 70 was obtained for a blue/yellow weight ratio of 1:1.
As shown in fig. 19, excellent color stability was observed in the white light emitting diode at different operating currents. This can be attributed to little energy transfer from the blue phosphor to the yellow phosphor because there is minimal overlap between the excitation of the yellow phosphor and the emission of the blue phosphor. White LEDs also appeared very well in air during preliminary testingHigh stability, almost no variation in luminance and color (at the same operating power, the device is at about 400cd/m2Continuously lighting for six hours or more). Fig. 19 depicts the emission spectra of white LEDs at different drive currents.
5. Absorption spectroscopy measurements
The absorption spectrum of the whole assembly was measured at room temperature by simultaneous scanning in an integrating sphere, which was incorporated in a fluorescence spectrometer (FLS980, Edinburgh Instruments) while maintaining a 1nm separation between the excitation and emission monochromators.
6. Excitation spectroscopy measurement
The excitation spectra of the entire assembly were measured at room temperature on an FLS980 fluorescence spectrometer (edinburg instruments) monitored at the maximum emission spectrum.
7. Photoluminescence steady state study
The steady state photoluminescence spectra of the entire assembly were obtained on an FLS980 fluorescence spectrometer at room temperature and 77K (cooling the sample with liquid nitrogen).
8. Temperature dependent photoluminescence
Temperature dependent photoluminescence spectra were measured on a Varian Cary Eclipse fluorescence spectrometer with a Water 4Position Multicell Holder attachment (Water 4Position Multicell Holder Access) connected to a Julabo F12-EC refrigeration/heating circulator filled with a glycol-Water mixture (3: 2). 0D (C)4N2H14Br)4SnBr6The photoluminescent intensity of the bulk crystal increases even slightly with increasing temperature (recovery with decreasing temperature), which may be due to the refractive index change of the bulk crystal sample (absorption increases with increasing temperature).
9. Photoluminescence quantum efficiency (PLQE)
For photoluminescence quantum efficiency measurements, the sample was excited by light output from a built-in 450W Xe lamp with a single grating (1800l/mm, 250nm blaze) Czerny-Turner monochromator and a 5nm bandwidth slit. The emission of the sample was passed through a single grating (1800l/mm, 500nm blaze) Czerny-Turner monochromator (Bandwidth)5nm) and detected by a Peltier cooled Hamamatsu R928 photomultiplier tube the absolute quantum efficiency was obtained using an integrating sphere in an FLS980 fluorescence spectrometer PLQE from equation ηQE＝IS/(ER-ES) Calculation of wherein ISRepresenting the luminescence emission spectrum of the sample, ERIs the spectrum of the excitation light from the empty integrating sphere (without sample), ESIs an excitation spectrum for exciting the sample. The control sample rhodamine 101 and the blue phosphor BaMgAl were measured by this method10O17:Eu2+The PLQE of the product is 98 percent and 93 percent respectively, which are close to the values reported in the literature. PLQE was verified using a Hamamatsu-C9920 system equipped with a xenon lamp, a calibrated integrating sphere and a Photon Multichannel Analyzer (PMA) model C10027. Taking into account the measurement of indirect PL provides the same result within the error bars.
10. Time resolved photoluminescence
Time-correlated single photon counting was performed with a Horiba-JY-Fluoromax-4 fluorometer and time resolved emission data were collected at room temperature and 77K (cooling the sample with liquid nitrogen). The sample was excited with a 295nm pulsed diode laser. Emission counts were monitored at 530 nm. The average lifetime is obtained by multi-exponential fitting.
11. Photoluminescence intensity dependence of excitation power density
PL intensity and power studies were performed on an edinburg instruments PL980-KS transient absorption spectrometer using a continuous Nd: YAG laser (Surelite-EX) pumped continuous optical parametric oscillator (Horizon II OPO) to provide 360nm5ns pulses at 1 Hz. The profile of the pump light is carefully defined by collimating the laser pulses through an aperture of 5mm in diameter. The pulse intensity was monitored by a power meter (Ophir PE10BF-C) and the reflection from the beam splitter was detected. The same power meter placed at the sample location was used to calibrate the power meter and neutral density filter. The power density of the pump is reduced to the required power range using a neutral density filter and an external power attenuator. Detection consisted of an Andor enhanced CCD (1024x 256 element) camera, acquiring spectra from 287nm to 868nm, with gate-optimized PL acquisition (typically a 30 to 50ns gate starting immediately after a 5ns laser pulse depending on PL lifetime). An average of 100 acquisitions at each power level was made and each laser pulse was monitored to determine the average intensity. PL intensity was measured at the maximum of the PL emission curve.
12. Photostability study of materials
For testing the light stability, a 100W 20V mercury short arc lamp was used as a continuous irradiation light source. The irradiation intensity was calibrated to 150mW/cm2. The emission was measured periodically on a HORIBA iHR320 fluorescence spectrometer equipped with a HORIBA Synapse CCD detection system.
13. Thermogravimetric analysis (TGA)
Thermogravimetric analysis (TGA) showed that the tin-based monolithic component did not decompose until 200 ℃. This high stability in air may be attributed to the unique core-shell structure, where the photosensitive metal halide is well protected by the organic shell.
TGA was performed using a thermal Analyzer company (TA Instruments) Q50 TGA system. At 100mL min-1Under nitrogen flow, at 5 ℃ for min-1The rate of heating the sample from room temperature (about 22 ℃) to 800 ℃.
14. Ultraviolet pumping LED
Blue (BaMgAl)10O17:Eu2+) And yellow ((C)4N2H14)4SnBr10) The phosphor was mixed with Sylgard 184 Polydimethylsiloxane (PDMS) encapsulant and then placed into a Polytetrafluoroethylene (PTFE) mold to control shape and thickness. The entire mold was heated in an oven at 100 ℃ for 40 minutes to cure the PDMS. The phosphor doped PDMS film was then connected to a 0.33mW window with 340nmUV pumped LEDs are formed on the UV LEDs (THERLABS). The LEDs were driven by a Keithly2400 source meter and the emission spectra were recorded on a marine Optics (Ocean Optics) USB4000 micro fiber optic spectrometer. For device stability testing, the white LEDs were continuously powered by Keithley 2400 at a steady current power and a luminance of about 400cd/m2. Emission spectra were recorded periodically using a USB4000 micro fiber optic spectrometer from the ocean optics company.
Example 5- (C)9NH20)2SnBr4Growth of bulk crystals
In this example, a crystalline organic tin bromide mixture ((C)9NH20)2SnBr4) In which isolated tin bromide ions (SnBr)4 2-) Is an organic ligand (C)9NH20 +) Surrounding to form a solid 0D structure.
SnBr4 2-Ions have a unique, rarely reported, see J.A. Bellow, D.Fang, N.Kovacevic, P.D. Martin, J.Shearer, G.A. Cisneros, S.Grosysman, J.Eur.Chem.Eur.J.2013, 19, 12225-. In this example, the organometallic halide mixture achieves a strong Stokes shift broadband deep red emission with a peak of about 695nm (full Width half Max (FWHM)146nm, photoluminescence quantum efficiency (PLQE) of about 46%).
The large stokes shift of 332nm (1.63ev) is one of the highest values reported so far for solid state luminescent materials, and a high PLQE is also an excellent value for deep red luminescent materials. The unique photophysical properties of this material can be attributed to SnBr4 2-The deformation of the excited state structure from a seesaw-like body to a flat tetrahedron is confirmed by the DFT calculation described in the examples below.
SnBr2(2.0mmol) and C9NH20Br (4.0mmol) was dissolved in 5ml DMF solution and then filtered to form a clear precursor solution. After adding 5mL of acetone, the resulting solution was sealed and left to stand for about 24 hours to obtain pale yellow single crystals. (C)9NH20)2SnBr4The crystals were washed with acetone and dried under reduced pressure. The yield was about 31%. All procedures are in N2In a filled glove box to prevent oxidation of Sn (II) to Sn (IV). C18H40N2SnBr4: analysis calculated value: c, 29.91; h, 5.58; and N, 3.88. Measured value: c, 30.07; h, 5.60; and N, 3.88.
FIG. 20 depicts a single SnBr of the present example4 2-Anionic bat model.
Example 6- (C)9NH20)2SnBr4Characterization of bulk crystals
1. Single crystal X-ray diffraction (SCXRD)
(C) of example 5 by Single Crystal X-ray diffraction (SCXRD)9NH20)2SnBr4The crystal structure of (1). The material adopts a monoclinic space group C2/C, wherein SnBr4 2-Anion quilt C9NH20 +The cations surround, thereby forming a 0D structure at the molecular level. The data show individual SnBr4 2-Between anions by C9NH20 +The cations are completely separated, and the nearest Sn-Sn distance isDue to the large spatial separation, SnBr4 2-Intermolecular coupling between anions should be negligible. Isolated SnBr4 2-The structure of the anion is shown in figure 1. The ions adopt a seesaw-shaped body structure with four-coordinate Sn (II) centers. The axial Br1-Sn-Br1 angle was 178.9 °, while the Br2-Sn-Br2 and Br1-Sn-Br2 angles were approximately 90 °. The length of the equatorial and axial Sn-Br bonds (respectivelyAnd 2.96) are significantly shorter than those with 0D [ (C) which are present in organotin bromides4N2H14Br)4SnBr6
2. Powder X-ray diffraction (PXRD)
The overall purity of the prepared crystalline material was confirmed by powder X-ray diffraction (XRD). PXRD analysis was performed on a Panalytical X 'PERT Pro powder X-ray diffractometer using copper X-ray tube (standard) radiation at 40kV and 40mA and an X' Celerator RTMS detector. The diffraction pattern was scanned at room temperature in 0.02 steps over an angular range of 5-50 degrees (2 θ). Simulated powder plots were calculated by Mercury software using the Crystallization Information File (CIF) from single crystal x-ray experiments.
3. Thermogravimetric analysis (TGA)
The stability and composition of the crystals were further verified by thermogravimetric analysis (TGA) and elemental analysis. TGA was performed using a thermal analyzer Q50 TGA system. Under 40mL min-1 argon flow, at 5 ℃ min-1The rate of heating the sample from room temperature (about 22 ℃) to 800 ℃.
Example 7- (C)9NH20)2SnBr4Photophysical properties of bulk crystals
Example 5 (C)9NH20)2SnBr4The whole crystal appeared pale yellow under ambient light and exhibited bright red emission when irradiated with a UV lamp (365 nm).
Using steady state UV-visible absorption spectrum, emission spectrum and time resolved emission spectrum for crystal (C)9NH20)2SnBr4The detailed photophysical properties of (a). Fig. 21 shows an emission spectrum and an excitation spectrum.
1. Absorption spectroscopy measurements
Measurement at room temperature (C) was carried out by simultaneous scanning in an integrating sphere of a fluorescence spectrometer (FLS980, Edinburgh instruments Co.)9NH20)2SnBr4Absorption spectra of the crystals while maintaining a 1nm separation between the excitation and emission monochromators. The absorption spectrum is consistent with the excitation spectrum, but scattering occurs in the low energy region due to sample crystallization. Broad red photoluminescence (FWHM 146nm, 0.38eV) extensionTo the near infrared region. Stokes shift (332nm, 1.63ev) is significantly greater than yellow luminescence 0D (C)4N2H14Br)4SnBr6(215nm, 1.31 ev). This is believed to be the maximum stokes shift reported to date for organometallic halide mixtures, and is also one of the maximum shifts for any single crystal light emitting system.
2. Excitation spectroscopy measurement
Measured on an FLS980 fluorescence spectrometer (Edinburgh instruments) at room temperature, monitored by the maximum emission spectrum (C)9NH20)2SnBr4Excitation spectrum of bulk crystal.
The PLQE of the bulk crystal was determined to be 46. + -. 1% at room temperature, which is also high for deep red emitting materials PLQE is calculated from ηQE＝IS/(ER-ES). The international commission on illumination (CIE) chromaticity coordinates for this red emission were calculated to be (0.63, 0.36), close to the "ideal red" coordinates (0.67, 0.33) defined by the National Television Systems Committee (NTSC). The luminescence decay curve at room temperature shows a longer mono-exponential lifetime (□ ═ 6.51 μ s), which is consistent with phosphorescence.
3. Photoluminescence steady state study
Measurement with FLS980 fluorescence spectrometer at room temperature (C)9NH20)2SnBr4Steady state photoluminescence spectrum of the bulk crystal.
4. Photoluminescence quantum efficiency (PLQE)
PLQE was obtained using a Hamamatsu C9920 system equipped with a xenon lamp, a calibrated integrating sphere and a Photon Multichannel Analyzer (PMA) type C10027, PLQE calculated from ηQE＝IS/(ER-ES) In which ISRepresenting the luminescence emission spectrum of the sample, ERIs the spectrum of the excitation light from the empty integrating sphere (without sample), ESIs an excitation spectrum for exciting the sample.
5. Time resolved photoluminescence
Time resolved emission data were collected at room temperature using an FLS980 fluorescence spectrometer. The dynamics of emission decay were monitored using the time-dependent single photon counting capability of FLS980 (1024 channels, 200 μ s window) and data acquisition of 10000 counts. Excitation is provided by an Edinburgh EPL-360 picosecond pulsed diode laser. The average lifetime is obtained by a single exponential fit.
6. Photostability study
For testing the light stability, a 100W 20V mercury short arc lamp was used as a continuous irradiation light source. The irradiation intensity was calibrated to 150mW/cm2. Photoluminescence was measured at periodic intervals on a HORIBA iHR320 fluorescence spectrometer equipped with a HORIBA Synapse CCD detection system.
The crystals were irradiated by a continuous high-power mercury lamp (150 mW/cm)2) Has light stability and high heat stability.
Example 8 calculation method
In a solid state luminescent material having a 0D structure, one possible cause of such a large stokes shift may be structural deformation of an excited state. The mixed SnBr can be deeply understood through the calculation of Density Functional Theory (DFT)4 2-The mechanism of photophysical basis of (1). Calculated (C)9NH20)2SnBr4The band structure of (a) shows a flat band, indicating that the electronic states are highly localized.
For example, as can be seen from the calculated density of states (DOS), the band around the band gap around 0eV and 4eV is limited to SnBr4 2-Within the substance. The flatness of these bands may indicate SnBr4 2-Intermolecular coupling between substances is negligible or no electron bands are formed therebetween. Thus, each SnBr4 2-The anion can function as an effective luminescence center by trapping excitons and undergoing efficient radiative recombination.
Four times the degenerate band at 0eV is formed by four equivalents SnBr in the unit cell4 2-The Highest Occupied Molecular Orbital (HOMO) composition of the anion, as shown by DOS, has mixed characteristics of Br-4p and Sn-5s, and a partial charge density. The twelve bands around 4eV consist of eight lower bands and four higher bands. 8 lower bands consisting of 4 SnBr4 2-Anion(s)Derived from Sn-5p Dangling Bonds (DB) perpendicular to the Br-Sn-Br axis of the seesaw-like structure. The higher four bands were obtained from the Sn-5p orbitals oriented along the Br-Sn-Br axis.
SnBr4 2-The teeter-totter structure of (a) may be stabilized by a non-bonded Sn 5s lone pair that is polarized by two near-equatorial Br2 ions due to coulomb repulsion forces. Vertical excitation generation at SnBr4 2-Spin singlet excitons on the species.
The electrons are boosted to two Sn-5p DBs. The coulombic repulsion of the electrons in Sn-5 pDB pushes the Sn-5s lone pair towards the two equatorial Br2 ions, which in turn repel each other, thus destabilizing the see-saw structure.
Thus, the calculated Br2-Sn-Br2 angle increased from 94.1 to 151.6. Meanwhile, the linear Br1-Sn-Br1 axis in the seesaw-like body structure was bent, and the calculated Br1-Sn-Br1 angle was changed from 178.8 to 151.2. The calculated bond length for the axial Sn-Br1 bond is also from
Partial density of electrons in spin triplet excitons and hole wave function were evaluated. The electron state is a pi-type inversion orbital between Sn-5p and Br-4p, and the hole state is a sigma-type inversion orbital between Sn-5s and Br-4 p. The bandgap at the point Perew-Burke-Ernzerhof (PBE) is 3.65eV, which is considered to be an underestimate due to the bandgap error of the well-known semi-local exchange correlation function. The non-local mixing function PBE0 calculated to increase the band gap to 5.27 eV. MeterCalculated to (C)9NH20)2SnBr4The photoexcitation energy (at the PBE0 level) of the mid-spin singlet exciton is 4.01eV, which is greater than the experimentally observed excitation peak at 3.42 eV. The calculated emission energy of the spin triplet excitons is 1.55eV, less than the measured emission peak of 1.78 eV. Given the challenges faced in excitation state calculation using DFT, the numerical difference between the calculated and measured excitation and emission energies is quite small. Nevertheless, it is believed that the apparent excited state structural deformation found in the calculations at least partially accounts for the large stokes shift observed experimentally.
The calculations are based on the Density Functional Theory (DFT) performed in VASP code (G.Kresse, J.Furthhm muller, 1996,6,15-50, Computational Materials Science).
The kinetic energy cutoff for the plane wave reference is 262 eV. The projector-enhanced wave method is used to describe the interaction between ions and electrons (g.kresse, d.joubert, physical Review b 1999,59, 1758).
(C) is calculated using Perew-Burke-Ernzerhof (PBE) cross-correlation function9NH20)2SnBr4The band structure and density of states (DOS) of (J.P.Perew, K.Burke, M.Ernzerhof, Physical review letters 1996,77,3865), while the light excitation and emission energies were calculated using a hybrid PBE0 function (J.P.Perew, M.Emzerhof, K.Burke, Journal of Chemical Physics 1996,105,9982-9985), with 25% of non-local Fock exchanges. (inclusion of a portion of the Fock exchange significantly improves the description of band gap energy and charge localization in the insulator (M. -H.Du, S.B.Zhang, physical review B2009, 80; bJ.B.Varley, A.Janotti, C.Franchini, C.G.Van de Walle, physical review B2012, 85, 081109).
Previous PBE0 calculations provided insight into the structural and electronic properties of self-trapping and dopant-bound excitons in halides (k. biswas, m.h.du, physical reviews B. 2012,86, 7; bm.h.du, journal of Materials Chemistry c (journal of Materials Chemistry c) 2014,2, 4784. 4791; cm.h.du, journal of the electrochemical society of solid science and technology (ECS j. solid State sci. technol.) 2016,5, R3007-R3018).
The total energy difference between the excited state and the ground state was calculated using PBE0 optimized ground state and excited state structures, respectively, according to Frank-Condon (Frank-Condon) principle, to obtain photoexcitation and emission energies. While optimizing the atomic position, the lattice parameters were fixed on the experimentally measured values until the force on each atom was less than
EXAMPLE 7 blue light emitting monolithic Assembly
Preparing a single crystal monolithic assembly of metal halide clusters having the formula (C)9NH20)7(PbCl4)Pb3Cl11Wherein the lead chloride tetrahedron (PbCl)4 2-) Sharing lead chloride trimer (Pb) with molten surface3Cl11 5-) With an organic cation (C)9NH20 +) Co-crystallizing to form 0D structure on molecular level.
Due to Pb3Cl11 5-Is wide band gap PbCl4 2-And C9NH20 +Partial complete isolation of Pb3Cl11 5-There is no interaction or band formation between clusters, which makes the bulk crystal exhibit Pb3Cl11 5-The inherent nature of the cluster. This lead chloride mixture achieves high luminescent blue emission with PLQE over 80% due to the formation of local excitons in the molecular cluster.
(C) of the present example was grown at a high yield of about 70% using a simple wet chemical method9NH20)7(PbCl4)Pb3Cl11And (3) single crystal. The method comprises slowly diffusing acetone, a non-soluble solvent, into a solution containing lead chloride (PbCl) at room temperature2) And 1-butyl-1-methylpyrrolidinium chloride (C)9NH20Cl) acetonitrile (CH)3CN) precursor solution.
Single crystal X-ray diffraction (SCXRD) was used to determine the crystal structure of the hybrid material employing triclinic space group P-1.
The crystal structure shows a perfect 0D structure at the molecular level. The crystal structure comprises metal halide, PbCl alone4 2-Tetrahedron and Pb3Cl11 5-Clusters, which are completely isolated from each other and are surrounded by large organic cations C9NH20 +And (4) surrounding.
Organic liquid CH is also present in the single crystal assembly3CN molecule, considering that the single crystal growth process includes CH3The use of CN, which is not surprising.
By PbCl4 2-And C9NH20 +Complete separation of Pb3Cl11 5-And two Pb3Cl11 5-The closest distance between the anions is greater than 1 nm. This separation eliminates or reduces Pb3Cl11 5-Interaction between the moieties. Such a perfect 0D structure at the molecular level may cause the bulk crystal to exhibit the intrinsic properties of the individual lead chloride clusters.
It should be noted that PbCl4 2-The tetrahedra, which has a large band gap (about 4.22eV), can be considered an insertion structure scaffold that does not affect photophysical properties in the visible range of the single crystal. The composition of the prepared single crystal was further confirmed by elemental analysis.
Of this example (C)9NH20)7(PbCl4)Pb3Cl11·CH3The CN single crystal is colorless and transparent under ambient light, which indicates that there is little absorption in the visible region, and has a wide band gap. Under the irradiation of ultraviolet rays (365nm), the crystal emits bright blue light.
As shown in fig. 22, an emission spectrum and an excitation spectrum were recorded. At room temperature, the blue emission peaked at 470nm with a large Stokes shift at 122nm (0.925ev) and a full width at half maximum (FWHM) of 84 nm.
Such strong stokes shift broadband emission may be typical for 0D organometallic halide mixtures due to the formation of highly localized excitons. However, PLQE of such blue-emitting organometallic halide mixtures reaches a significant level of 83 ± 1%, which is the highest value reported to date for single crystal blue emitters.
The molecular level 0D structure of this organometallic halide mixture indicates that the bright blue emission is from a single metal halide species, or PbCl4 2-Tetrahedron or Pb3Cl11 5-Clusters, or both. Far below PbCl considering about 3.56eV excitation4 2-Tetrahedral bandgap (about 4.22eV), PbCl4 2-The tetrahedron is less likely to emit blue light. In contrast, blue light is likely to be derived from Pb3Cl11 5-The cluster is emitted.
The chromaticity coordinates of the international commission on illumination (CIE) indicate that the blue emission has a value of (0.14, 0.19). The luminous attenuation of the blue emitter at room temperature was calculated and indicated by a single exponential fit to have a lifetime of about 418 ns. This is consistent with the results observed in other 0D organometallic halide mixtures, with the emission of excitons residing in a single metal halide species.
At 77K, the emission spectrum narrowed and shifted slightly to the high energy region (fig. 22), which is likely due to a decrease in the vibrational state of the hot fill at low temperatures, and the emission lifetime increased to about 12.4 μ s by single exponential fitting. The decay lifetime at room temperature is hundreds of nanoseconds and at 77K microseconds, indicating that these emissions have phosphorescent properties. The following table summarizes the main photophysical properties of the overall assembly of the example.
(C9NH20)7(PbCl4)Pb3Cl11·CH3Summary of photophysical properties of CN Single crystals
The strong stokes shift broadband emission with microsecond decay lifetime indicates that the hybrid material in this example behaves more like a single molecule than inorganic semiconductor or 3D metal halide perovskites, which typically exhibit narrow emission with small stokes shifts and decay lifetimes of a few nanoseconds.
Without wishing to be bound by any particular theory, metal halide clusters consisting of a very small number of atoms may exhibit molecular transitions due to insufficient state density to incorporate the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) into the valence and conduction bands that occur in inorganic semiconductors and 3D perovskites.
Thus, the photophysical process of the hybrid material of this example can be described as shown in fig. 23. Under the excitation of ultraviolet light, only Pb exists3Cl11 5-The clusters are excited to a high energy excited state, which is from a singlet state (S) due to heavy atom effects1) To the triplet state (T)1) Ultrafast structural reorganization and intersystem crossing (ISC) occur. The radiation decay from the lowest triplet state produces highly efficient blue phosphorescence with large stokes shifts.
To ensure co-crystallized CH3CN molecules have little influence on photophysical properties, and are used for removing CH3The material was characterized after CN molecules. By placing fresh single crystals under vacuum overnight, CH can be successfully removed3CN molecule, which has been passed1HNMR spectra confirmed.
After overnight drying, a small peak at about 2.08ppm disappeared, indicating CH3The CN molecules have been removed from the bulk crystal. CH was further confirmed by TGA measurements3And (4) removing CN molecules. For fresh crystals, the weight was significantly reduced by 1.7% at around 85 ℃ due to CH3Loss of CN molecules, while no such weight loss was observed in the dried samples.
In this example, lead (II) chloride (0.25mmol) and 1-butyl-1-methylpyrrolidinium chloride (1mmol) were mixed in a molar ratio of 1:4 and dissolved in acetonitrile to form a clear solution. Bulk crystals were prepared by diffusing acetone into acetonitrile solution overnight at room temperature. The large colorless crystals were washed with acetone and dried under reduced pressure. All procedures are in N2In a filled glove box. The calculated yield was about 70%. C63H140N7Pb4Cl15: analysis calculated value: c, 32.11; h, 5.99; and N, 4.16. Measured value: c, 32.19; h, 6.02; and N, 4.18.
Single crystal x-ray diffraction data for lead chloride hepta (1-butyl-1-methylpyridine) acetonitrile was collected using a Xcalibur-2CCD single crystal diffractometer with irradiation of graphite monochromatic Mo K α the crystal was mounted in a cryogenic loop under Paratone-N oil and nitrogen was cooled to 105K using an oxford diffractive cryo-ejector using a 1 frame width with a resolution of 1 ° resolutionData are acquired for a ω scan (equivalent to 2 θ ≈ 60.262 °). CrysAlisPro software Using Oxford diffraction1Recording, indexing and correcting absorption, followed by use of crystals2Performing structure determination and refinement by using Superflip3The crystal structure is resolved. The data does not allow for unlimited refinement: all hydrogens are geometrically constrained by their associated carbons, and in some cases, the bond length within the 1-butyl-1-methyl-pyridinium molecule is constrained by its physically reasonable length. For F2A refinement is performed. The anisotropic thermal displacement parameters of all inorganic clusters and most of the related molecular ligands were refined. And refining the isotropic thermal displacement parameters of all the components. CIF has been stored in CCDC (1836729). VESTA was used as crystal structure visualization software for images presented in the manuscript.
PXRD analysis was performed on a Panalytical X 'PERT Pro powder X-ray diffractometer using copper X-ray tube (standard) radiation at 40kV and 40mA and an X' Celerator RTMS detector. The bulk crystals were carefully ground to a powder and then encapsulated using 3511Kapton film. The diffraction pattern was scanned at room temperature in 0.02 steps over an angular range of 5-50 degrees (2 θ). The simulated morphology of the powder was calculated using the Crystal Information File (CIF) obtained from the SCXRD experiment using Mercury software.
The absorption spectra of the metal halide clusters were measured by simultaneous scanning in an integrating sphere incorporated into a fluorescence spectrometer (FLS980, edinburg instruments) at room temperature, while maintaining a 1nm separation between the excitation and emission monochromators.
The excitation spectra of the metal halide clusters were measured on an FLS980 fluorescence spectrometer (edinburg instruments) under maximum emission spectroscopy monitoring at room temperature and 77K (sample cooled with liquid nitrogen).
Steady state photoluminescence spectra of the metal halide clusters were obtained on an FLS980 fluorescence spectrometer at room temperature and 77K (sample cooled with liquid nitrogen).
PLQE was obtained using a Hamamatsu Quantauus-QY spectrometer (model C11347-11) equipped with a xenon lamp, an integrating sphere sample chamber and a CCD detector PLQE was calculated from ηQE＝IS/(ER-ES) In which ISRepresenting the luminescence emission spectrum of the sample, ERIs the spectrum of the excitation light from the empty integrating sphere (without sample), ESIs an excitation spectrum for exciting the sample.
Time resolved emission data were collected at room temperature using an FLS980 fluorescence spectrometer. The dynamics of emission decay were monitored using the time-dependent single photon counting capability of FLS980 (1024 channels, 10 μ s window) and data acquisition of 10000 counts. Excitation is provided by an Edinburgh EPL-360 picosecond pulsed diode laser. Long-lived measurements at 77K (1024 channels; 800 μ s window) were acquired using Xe flash lamps as excitation source. The average lifetime is obtained by a single exponential fit.
TGA was performed using a thermal analyzer Q600 SDT system. At 40 mL/min-1At 5 ℃ for min under the argon flow-1The rate of heating the sample from room temperature (about 22 ℃) to 800 ℃.
Example 8 monolith materials comprising tetraphenylphosphonium and antimony chloride salts
In this example, tetraphenylphosphonium cation (Ph)4P+) For assembling 0D organic antimony chloride (Ph)4P)2SbCl5And (3) single crystal.
Two feasible synthetic routes were established to prepare (Ph) in high yield4P)2SbCl5Single crystal: one through a slow solvent interdiffusion process, and the other involving rapid growth of metastable products followed by spontaneous transformation to form thermodynamically stable products.
1.(Ph4P)2SbCl5Growth of bulk crystals by anti-solvent vapor diffusion
0.82mmol of SbCl3And 1.64mmol Ph4PCl was mixed in a 1:2 molar ratio and dissolved in 3ml dmf to form a transparent precursor solution. By mixing 2ml of Et at room temperature2O was diffused overnight into 1ml DMF solution to prepare bulk crystals. With Et2The large, light-colored crystals were washed with O and dried under reduced pressure. The calculated yield was about 65%. C48H40P2SbCl5: analysis calculated value: c, 58.96; h, 4.12; cl, 18.13. Measured value: c, 58.86; h, 4.30; cl, 17.99.
2.(Ph4P)2SbCl5Fast crystal growth method of bulk crystal
At room temperature, by adding 0.4ml of Et2O was initiated by injection into 0.5ml of the prepared DMF solution (Ph)4P)2SbCl5And (5) growing crystals. After 10 minutes, the crystal growth process was stopped by removing the mother liquor. With Et2O washed the crystals and dried under reduced pressure. The calculated yield was about 60%.
Metastable and stable (Ph) prepared by different methods of this example4P)2SbCl5The photophysical properties of (A) are fully characterized. It is believed that the metastable product containing solvent molecules showed yellow luminescence peaking at 605nm, while the stable product had red emission peaking at 648nm with nearly uniform PLQE.
In N2In a filled glove box, the anti-solvent diethyl ether was dispersed to antimony chloride (SbCl) at room temperature3) And tetraphenylphospholyl chloride (Ph)4PCl) overnight in Dimethylformamide (DMF) precursor solution to give (Ph)4P)2SbCl5The yield of the light yellow single crystal of (1) was 65%. Ion structure was determined using single crystal X-ray diffraction (SCXRD) and employing triclinic space group P-1, with a single SbCl5 2-Tetrahedron Ph with large cones4P+The cations are surrounded.
In the structure, a plurality of Ph4P+Cation-coated SbCl5 2-An anion. (Ph)4P)2SbCl5Middle SbCl5 2-The bonding distance between the middle Sb atom and the top Cl atom is
Meanwhile, the bond length between Sb atom and other four Cl atoms is all in
Entirety (Ph)4P)2SbCl5The crystal showed bright red luminescence under irradiation of ultraviolet light (365 nm). Further characterization (Ph)4P)2SbCl5Photophysical properties of the sample. (Ph)4P)2SbCl5The excitation spectrum of (2) was 375nm at the maximum (FIG. 24). Full width at half maximum (FWHM) of broadband red emission with a peak at 648nm was 136nm (FIG. 24), and the characteristic phosphorescence lifetime was 4.57 +. + -0.09μs。(Ph4P)2SbCl5Is lower than (C)9NH20)2SbCl5Luminous energy (λ) ofMaximum of590nm), stokes shift 273nm (1.41 eV). The larger Stokes shift indicates (Ph)4P)2SbCl5Ratio in excited state (C)9NH20)2SbCl5Undergo greater structural deformation. For red luminescent materials, the photoluminescence efficiency (PLQE 87 ± 2%) of the bulk crystal is rather high. Thermogravimetric analysis showed that (Ph)4P)2SbCl5The crystals also showed high thermal stability, were not degraded until 300 ℃ and were irradiated in a continuous high-power mercury lamp (150 mW/cm)2) The composition has excellent light stability.
Density Functional Theory (DFT) calculations were performed to further elucidate (Ph)4P)2SbCl5The photophysical properties of (a). (Ph)4P)2SbCl5The calculated electronic structure of (1) shows SbCl5Derived valence band and Ph4P-derived conduction band. The strong hybridization between the occupied Sb-5s orbital and the Cl-3p orbital pointing to the Sb ion produces the anti-bond orbitals of Sb-5s and Cl-3p, which are higher in energy than the other Cl-3p orbitals.
This results in a highest valence band, which is separated from the remaining valence bands. Due to the long Sn-Sn distance, the band is hardly dispersed. Conduction band mainly composed of Ph4The reverse bond pi states on the cation of the P molecule. The empty Sb-5p band is located at Ph4Within the P-dominated conduction band. Although the Sb-5p level is higher than the lowest conduction band of the ground state, excited electrons tend to localize to SbCl due to strong Coulomb bonding between electrons and holes5。
Testing two types of excitons, one located in SbCl5(EX1) and the other is of the charge transfer type (EX2) with holes in SbCl5Cluster, electrons located in adjacent Ph4And (3) a P molecule. The table below compares the energy of the spin triplet and spin singlet EX1 and
The most stable exciton is located in SbCl5EX1, the partial charge density profile of the electron and the hole wave function of the exciton are plotted. The calculated emission energy of spin triplet EX1 was 1.91eV, which is in close agreement with the experimentally measured emission peak at 1.91eV (648 nm). The emission of spin triplet excitons is also consistent with the observed emission lifetimes, on the order of microseconds. The calculated excitation energy was 3.68eV, within the experimentally measured excitation band, and the calculated stokes shift was 1.77 eV.
Such a large stokes shift may be due to structural reorganization of the excited state, which lowers the exciton energy by 0.96eV, at least to some extent. Exciton relaxation involving SbCl4Shortening of four Sb-Cl bonds in the plane and lengthening of Sb-Cl bonds perpendicular to the four shortened bonds. The significant elongation of the perpendicular Sb-Cl bond during exciton relaxation may be explained (Ph4P)2SbCl5And (C)9NH20)2SbCl5The vertical Sb — Cl bond lengths in the ground state of these were 2.20A and 2.38A, respectively, for the different stokes shifts observed in (a). Since the Stokes shift is caused by the structural distortion of the excited state, (Ph)4P)2SbCl5Stokes shift ratio (C)9NH20)2SbCl5The stokes shift of (a) is large, probably due to the larger distortion of the excited state caused by the short Sb-Cl bond.
In this example, (Ph)4P)2SbCl5Is prepared in the process of accelerating the growth of crystal. By injecting a fixed amount of diethyl ether directly into the DMF precursor solution at room temperature, the lamellar crystals quickly grow out of solution within a few minutes. With the increase of the amount of ether, the crystallization rate of the plate-like crystals was increased and the crystal size was decreased. Interestingly, crystals produced by this rapid growth method exhibited a yellow emission peak around 600nm after ultraviolet excitation (365 nm). In-situ photoluminescence measurements show that the spectral line shape is unchanged and the broadband emission intensity is increased during the crystal growth process.
These yellow luminescent crystals were collected and stored in N2Filled withAfter the glovebox, their emission was found to gradually change from yellow (λ)Maximum of600nm) to red (λ)Maximum of648 nm). It should be noted that the optical properties of the fast-growing, fully-converted crystals are almost identical to those of crystals prepared by the slow vapor diffusion method. The PLQE of the fast-growing transformed crystals was higher, up to 99. + -. 1%, probably due to fewer defects in these crystals.
The unique optical properties of crystals prepared by slow and fast processes indicate that the metastable phase is likely to be a kinetically favored product formed during the latter growth process, which subsequently undergoes a structural transition to a thermodynamically stable phase. To verify this hypothesis, a spin cast DMF precursor solution was used for preparation (Ph)4P)2SbCl5Film then on N2Heat treatment was carried out in the filled glove box.
The cast film showed a yellow emission, exactly the same as the fast growing crystals in solution, turning to a red emission after heat treatment, indicating a transition from a kinetically favored product to a thermodynamically stable product. PXRD was used to characterize the structural differences between the two phases.
The PXRD pattern of the film showed that over time the 8 ° and 11.1 ° peaks disappeared, while the 9.8 ° peak increased, confirming the formation of a thermodynamically stable product. Thus, the fast growth process forms kinetically favored metastable products, while the slow diffusion process produces thermodynamically stable products.
Since the influence of the solvent on the electron spectra of molecules in solution is well documented, it is reasonable to speculate that the change in emission may be due to the removal of solvent molecules from the crystals and films. During rapid crystal growth, polar liquid molecules (i.e., DMF) can react with Ph4P + and SbCl5 2-Co-crystallizing to form a metastable structure1The H NMR spectrum confirms that the structure is transformed into a thermodynamically stable phase in the absence of solvent molecules. By the heat treatment, the structure transformation process can be accelerated. TGA measurements of fresh metastable crystals and transformed metastable crystals show that at about 100 ℃ the weight of the metastable crystals is significantThis is a significant drop, which corresponds to the removal of the DMF molecules. In contrast, the converted crystals had almost no weight loss, and the crystals prepared by the slow diffusion method were stable up to 300 ℃.
In this example, an Oxford diffractive Xcaliibur-2 CCD diffractometer with graphitic monochromatic Mo K α radiation was used for acquisition (Ph4P)2SbCl5Single crystal X-ray diffraction data of (a). The crystals were mounted in a low temperature loop under Paratone-N oil and cooled to 150K with an Oxford diffractive cryo-jet. Using a 1 frame width, resolution of
PXRD analysis was performed on a Panalytical X 'PERT Pro powder X-ray diffractometer using copper X-ray tube (standard) radiation at 40kV and 40mA and an X' Celerator RTMS detector. The diffraction pattern was scanned at room temperature in 0.02 steps over an angular range of 5-50 degrees (2 θ). The morphology of the simulated powder was calculated using the crystallography information file obtained from the SCXRD experiment using Mercury software.
TGA was performed using the thermal analyzer SDT Q600 system. At 100 mL/min-1At 10 ℃ per minute in an argon flow of-1The rate of heating the sample from room temperature (about 22 ℃) to 800 ℃.
Measurement of ((Ph) was carried out at room temperature by simultaneous scanning in an integrating sphere of a fluorescence spectrometer (FLS980, Edinburgh instruments Co.)4P)2SbCl5Absorption spectrum of crystal while exciting monochromatic colorThe instrument and the emission monochromator were kept at a 1nm separation.
Measured on an FLS980 fluorescence spectrometer (Edinburgh instruments) at room temperature under maximum emission spectroscopy (Ph)4P)2SbCl5Excitation spectrum of the crystal.
Solid state (Ph) was obtained at room temperature with FLS980 fluorescence spectrometer4P)2SbCl5Steady state photoluminescence spectrum of the crystal.
PLQE was obtained using a Hamamatsu C9920 system equipped with a xenon lamp, a calibrated integrating sphere and a Photon Multichannel Analyzer (PMA) type C10027, PLQE calculated from ηQE＝IS/(ER-ES) In which ISRepresenting the luminescence emission spectrum of the sample, ERIs the spectrum of the excitation light from the empty integrating sphere (without sample), ESIs an excitation spectrum for exciting the sample. The PLQE values measured by the method are respectively-98% and 93% by taking rhodamine 101 and a blue light phosphor BaMgAl10O17: Eu2+ as a comparison, and are close to the values reported in the literature.
Time resolved emission data were collected at room temperature using an FLS980 fluorescence spectrometer. The dynamics of emission decay were monitored using the time-dependent single photon counting capability of FLS980 (1024 channels) and data acquisition of 10000 counts. Excitation is provided by an Edinburgh EPL-360 picosecond pulsed diode laser. The average lifetime is obtained by a single exponential fit.
For testing the light stability, a 100W 20V mercury short arc lamp was used as a continuous irradiation light source. The irradiation intensity was calibrated to 150mW/cm2. Photoluminescence was measured at periodic intervals on a HORIBA Synapse CCD detection system equipped HORIBAiHR320 fluorescence spectrometer.
All calculations are based on the Density Functional Theory (DFT) implemented in the VASP code. The kinetic energy cutoff for the plane wave reference is 400 eV. The interaction of ions and electrons is described by a projected enhanced wave method. (Ph) calculated using Perew-Burke-Ernzerhof (PBE) cross-correlation function4P)2SbCl5While exciton excitation energy and emission energy were calculated using a hybrid PBE0 function with 25% non-local Fock exchange. Joining partFractional Fock switching can significantly improve the bandgap energy and the description of charge localization in the insulator. While optimizing the atomic position, the lattice parameters were fixed on the experimentally measured values until the force on each atom was less than
The calculation includes a formula unit (Ph)4P)2SbCl5The primitive unit of (1). Analysis by X-ray diffraction of SbCl5 2-The two top Cl sites in the anion each occupy 50% of the occupancy. Since partial occupancy could not be modeled, the Cl ions were fixed in a top position during the calculation. To evaluate the effect of immobilizing apical Cl sites, experiments were performed using three larger supercells, which doubled in size from the original cells along the crystallographic directions of a, b and c. Selecting each SbCl5 2-The apical Cl site occupied in the anion and the adjacent SbCl5 2-The occupied top Cl sites in the anion are different. The test results show that the average in-plane Sb-Cl bond length and the perpendicular Sb-Cl bond length in the large cell are almost the same as in the original cell. Difference is less than
Example 9 white light emitting diode
In this example, a "quasi-solar" White Light Emitting Diode (WLED) based on a zero-dimensional organometallic halide mixture was prepared.
Specifically, a series of UV-pumped WLEDs were prepared, in which BaMgAl was present10O17:Eu2+(BAM:Eu2+) Used as blue phosphor, the following 0D organometallic halide mixture- (Ph)4P)2MnBr4、(C4N2H14Br)4SnBr6And (Ph)4P)2SbCl5Respectively as green, yellow and red phosphors.
The WLED of this example produces a full spectrum white light approximating a halogen or incandescent lamp and natural lighting, with an extremely high CRI of up to 99, excellent deep red color rendering, R9 of up to 99 and excellent color quality rating (CQS) values.
By controlling the phosphor mixing ratio in this example, white light emission with different Correlated Color Temperatures (CCT) in the range of 3000K to 6000K is exhibited, which imitates sunlight at different times of the day. The thermal and current stability of CCT and commission internationale de l' eclairage (CIE) chromaticity coordinates were also investigated.
(C4N2H14Br)4SnBr6(i.e. by C)4N2H14Br+Cation-surrounded SnBr6 4-Octahedron) and (Ph)4P)2SbCl5(i.e. by Ph4P+SbCl surrounded by cations5 2-Cone) was synthesized according to the previously reported procedure (Zhou, c.k. et al, chemical science 2018,9(3), 586-; and Zhou, c.k. et al, materials chemistry (chem.mater.) 2018,30(7), 2374-.
(Ph4P)2MnBr4(i.e. by Ph4P+Cation-surrounded MnBr4 2-Tetrahedral) crystal by improved method, by using (C)2H5)2Diffusion of O into Ph4PBr and
Crystal structure analysis shows that the 0D organometallic halide mixture is different from its higher dimensional mixture in that the photosensitive polyhedra are completely isolated by large wide band gap organic cations, thereby suppressing the formation of electron bands between the luminescent centers.
This arrangement enables the 0D organometallic halide mixture of this example to exhibit the intrinsic properties of individual metal halide polyhedra in bulk crystals with nearly uniform PLQE. Moreover, such materials are observed to have broad emission and large stokes shifts due to the reorganization of the excited state structure of the molecule. In addition, the organic cation also acts as a shell for the photosensitive metal halide core, providing stability to moisture and oxidizing agents.
Eu blue light emission BAM using steady state photoluminescence and UV-Vis absorption Spectroscopy2+Green light emission (Ph)4P)2MnBr4Yellow light emission (C)4N2H14Br)4SnBr6And red light emission (Ph)4P)2SbCl5The photophysical properties of these four phosphors were characterized. The results are summarized in the following table.
Summary of photophysical properties of the phosphors
As shown in FIG. 25, the 0D organometallic halide mixtures generally exhibit broad emission for (Ph)4P)2MnBr4、(C4N2H14Br)4SnBr6And (Ph)4P)2SbCl5The calculated full widths at half maximum (FWHM) were 48nm (0.22eV), 108nm (0.43eV) and 118nm (0.36eV), respectively. These broad-band emissions have significant advantages over the narrow emissions of quantum dots and typical 3D metal halide perovskites to achieve full spectrum white light emission. Further, as shown in fig. 25, the excitation spectra of all four phosphors peaked at a similarly short wavelength between 330nm and 370 nm. The absorption spectrum of three of the four phosphors never exceeded the visible range of 400 nm.
Due to Mn (II) ions4T1Energy splitting of the excited state, only (Ph)4P)2MnBr4Three distinct absorption peaks are shown at 300nm, 350nm and 460 nm. However, the absorption coefficient at 460nm is small, and thus blue light is emittedResorption is negligible. For BAM Eu2+、(Ph4P)2MnBr4、(C4N2H14Br)4SnBr6And (Ph)4P)2SbCl5The calculated Stokes shifts were 115nm (0.84eV), 52nm (0.27eV), 205nm (1.28eV) and 283nm (1.56eV), respectively. These large stokes shifts are very helpful in fabricating WLEDs, with little loss of efficiency in reabsorption of emitted light. Commercial blue phosphor BAM Eu2+And 0D organometallic halide mixed crystal (Ph)4P)2MnBr4、(C4N2H14Br)4SnBr6And (Ph)4P)2SbCl5The PLQEs of (A) are respectively as high as 93%, 97%, 95% and 87% (Zhou, C.K., et al, chemical sciences 2018,9(3), 586-. These results indicate that the 0D organometallic halide mixtures have broad radiance, strong ultraviolet excitation, large stokes shift and high PLQE, are suitable for high color rendering, full spectrum ultraviolet pumped high efficiency WLEDs, and negligible reabsorption losses.
To manufacture the optically pumped WLED of the present example, a method of embedding a phosphor in a polymeric matrix to prepare a phosphor-polymer composite was investigated. A typical process involves grinding a single crystal phosphor into a fine powder, encapsulating the ground phosphor in an inert polymer matrix, and then attaching the phosphor-polymer composite to a commercial UV-LED. Two methods of reducing the single crystal to powder were explored: hand milling and planetary ball milling were performed with a mortar and pestle. Although a particle size of about 300nm was obtained by planetary ball milling, PLQE was significantly reduced compared to single crystals. This is probably due to the increased oxidation and moisture adsorption resulting from the larger surface area to volume ratio of the milled powder. For (C)4N2H14Br)4SnBr6The largest PLQE reduction was observed, most probably due to Sn2+Oxidized to Sn4+. Despite the creation of larger scalesThe particles were small, but the hand-milled phosphor still retained reasonable PLQE, and thus was used in phosphor-polymer composite preparation and device fabrication. Silicone and epoxy resins are the most widely used polymeric matrices for phosphor encapsulation. EI-1184 Polydimethylsiloxane (PDMS) is used as an inert polymer matrix due to its transparency in the uv-visible spectrum, inertness, and stability under various operating conditions. However, other materials such as Sylgard-184PDMS and epoxy EPO-TEK 305 may be used. Under the irradiation of ambient light and ultraviolet light, the phosphorus-doped PDMS polymer composite material is researched. Colorless phosphor-polymer composites under ambient light are consistent with little absorption of these phosphors in the visible region. However, the intense photoluminescence of the complex under UV irradiation matches that of a single crystal.
In this example, color mixing simulations were performed in order to produce white light of optimal color rendering and tunable CCT. This is achieved by first fabricating monochromatic LEDs and then combining the spectra to produce ultra-high color rendering white light. Color rendering values, CRI and CQS were optimized for four different CCT values of 3000K, 4000K, 5000K and 6000K using Osram-Sylvania color calculator software. These CCT values are chosen because they represent a typical range of color temperatures in solid state lighting applications, from warm white for residential lighting (3000K) to cold white for commercial and industrial sites (6000K). The simulation results are shown in the following table, and the results show that ultra-high color rendering ratio, CRI and CQS are achievable in the range of 98-99.
Simulating photometric results of white light
However, of the 14 recommended reflectance test color samples, only the first 8 CRIs (R1-R8) were used to calculate the general CRI (R1-R8)a) The value is obtained. Ignoring the value of R9, the number of colors representing deep red may result in a high RaWhite light, while the color development of the deep red region is not accurate. Commercial WLEDs are typically limited to R9 values below 30, and there are few reports of high R9 values. However, simulations yielded R9 values as high as 99. Such asColor values of degree are rarely reported in the literature. The color development is relatively insensitive to changes in CCT. This indicates that WLEDs based on these phosphors can be used for high color rendering applications in any field, whether residential or industrial. In contrast, based on YAG to Ce3+The most typical commercial white LEDs of phosphors exhibit poor color rendering at lower CCTs, Ra70, and little flexibility in CCT adjustment (mckitrick, j, et al, journal of the american society for ceramics (j.am.ceramic. soc.), 2014,97(5), 1327-.
The simulation results show that: BAM Eu2+:(Ph4P)2MnBr4:(C4N2H14Br)4SnBr6:(Ph4P)2SbCl5At a weight ratio of 1:2.7:3.6:9, 1:3:4.5:3.5, 1:3.3:4:3 and 1:2.5:3:2, respectively, to produce 3000k, 4000k, 5000k and 6000k CCT white light, respectively. The phosphors were then mixed according to the simulation results and encapsulated in PDMS to produce a white light emitting phosphor-polymer composite.
WLED was prepared by attaching these phosphor layers directly to an Opulent 365nm uv led. The emission spectra of the devices were collected using a Keithley 2400 source meter and a marine optics USB4000 spectrometer at a forward bias current of 20 mA. The photometric values summarized in the table below were calculated from the emission spectra using the Osram-Sylvania color calculator software.
Prototype device photometric characterization results
These experimental results confirm the ultra-high color rendering achievable, such as RaCQS and R9 values. Furthermore, this color rendering is maintained in widely varying CCTs, making these devices useful for a variety of solid state lighting applications. The experimental results were compared with the spectra of simulated and blackbody radiators at the corresponding color temperaturesThere is similarity in shape and width as shown in fig. 26A, 26B, 26C, 26D.
Thus, the color rendering properties of the white light emission from the devices of the present examples are at least partially due to their exceptional similarity to the emission of a black body radiator. The calculated CIE coordinates of these devices also almost agree with the planckian locus, again demonstrating that the device in this example simulates the emission of a black body radiator. When CCT is 4028k, R of 4000k equipmentaCQS and R9 were 99.
FIG. 27 depicts the 4000k device of this example with a YAG: Ce based3+CRI comparison between commercial WLEDs. It is believed to have such a high RaCQS and R9 and WLEDs for such precise CCT control and tunability have not been reported.
The thermal stability of the phosphor was investigated using a spectrophotometer equipped with a temperature controller. The result was to take from the forward direction, first increasing the temperature to 80 ℃ in 20 ℃ steps, and then from the reverse direction, decreasing the temperature back to 20 ℃ in 20 ℃ steps. Except that (C)4N2H14Br)4SnBr6In addition, the results show a similar trend, i.e. a slight decrease in the photoluminescence intensity with increasing temperature.
Record (Ph)4P)2SbCl5The highest intensity loss at 80 ℃ which retains about 62% of the room temperature photoluminescence intensity. In addition, a slight blue shift of the emission peak was also observed. This may be due to temperature induced stretching of the bonds, resulting in a lower stokes shift than observed at room temperature. Commercial blue phosphor BAM Eu2+And green luminescence (Ph)4P)2MnBr490% and 92% of their initial room temperature photoluminescence intensity were retained, respectively. When the temperature exceeds 500 ℃, BAM is Eu2+Significant oxidative thermal degradation of the phosphors occurs (Bizarri, G., et al, J.Lumin.). 2005,113(3-4), 199-. However, (C)4N2H14Br)4SnBr6The emission intensity of (a) increases with increasing temperature. This abnormality may be due to increased absorption at higher temperatures (Zhou, C.K., et al, chemical sciences 2018,9(3), 5)86-593). The measurement in the opposite direction shows that the photoluminescence intensity of all phosphors in this example is well recovered.
The stability of white light emission under forward bias current variation was also investigated. The emission of the test device was recorded in 1mA steps with a forward bias current range of 10mA to 20 mA. The results of this experiment show that there is no significant change in the shape of the spectrum. CRI (R) of a devicea) From 94 at 10mA to 96 at 20 mA. A slight change in the CIE coordinates was also observed, from 10mA (0.3264, 0.3395) to 20mA (0.3354, 0.3506).
However, as the current increases, the irradiance increases linearly, but has no significant effect on the photometric characteristics of the white light produced. The color stability of the phosphor layer under thermal strain was also tested due to the heat generated by the pump LED. A batch of devices was made and aged at 85 ℃ for 24, 48, 72 and 96 hours in ambient air. Since commercial blue phosphors have thermally stable emission, the white light emission of these layers is normalized by the blue peak intensity at 450 nm. After 96 hours in an oven at 85 ℃, the CIE chromaticity coordinates were shifted from (0.3254, 0.3448) to (0.3195, 0.3423) before aging. Maximum coordinate offset is-0.0059, well at Δ+0.01 (Schubert, E.F., et al, Science 2005,308(5726), 1274-8).
The efficiencies of WLED models of 5217K CCT, 99cri (ra), and 96R9 were studied. The device was operated using a Keithley 2400 source meter with a forward bias current of up to 105 mA. The resulting optical power and photocurrent were measured using a Newport 818-UV photodetector and a Newport multifunction optical meter.
To eliminate the effect of the pump UV-LEDs on photocurrent, an Edmund Optics (Edmund Optics) deep dyed polyethylene terephthalate (PET) UV filter was used. Only forward emissions are acquired during this measurement. As shown in FIG. 28, up to 1935cd m was obtained-2Sum of luminance values of up to 9.73lm W-1The light emission efficiency of (1). In addition, further calculations showed an External Quantum Efficiency (EQE) of 5.7% and a current efficiency of 9cd a-1As shown in fig. 29.
However, due to the strong waveguiding effect, forward emission accounts for only about one-fourth of the total outcoupled optical power. Therefore, measuring light efficiency in one integrating sphere may yield up to 40lm W-1The value of (c).
In this example, it has been demonstrated that a series of 0D organometallic halide mixtures are mixed with the commercially available blue phosphor BAM Eu2+Together for making a full spectrum WLED with a near perfect CRI value of a solar-like light. The 0D organometallic halide mixture of this example is made of rare earth rich elements and has a variety of properties desirable as a down-converting phosphor, including simple synthesis, nearly uniform PLQE, broadband emission, and large stokes shift.
In this example, the following materials were used: tin (II) bromide (SnBr)2) Antimony (III) chloride (SbCl)399.95%), manganese (II) bromide (MnBr)298%), tetraphenylphosphonium chloride (Ph)4PCl, 98%), tetraphenylphosphonium bromide (Ph)4PBr, 97%), N, N' -dimethylethylenediamine (C)4N2H1499%), hydrobromic acid (H)248wt in O. %) was purchased from sigma aldrich. Dichloromethane (DCM, 99.9%), dimethylformamide (DMF, 99.8%) and diethyl ether ((C)2H5)2O, anhydrous) from VWR. Acetone (HPLC grade) was purchased from merckmicrobile. All reagents and solvents were used without further purification unless otherwise indicated.
Solution growth of 0D metal halide monolith: yellow luminescence (C) was prepared according to the reported method (Zhou, CK. et al, Chemicals 2018,9(3),586-4N2H14Br)4SnBr6Crystals by diffusion of DCM to SnBr2And C4N2H14Br2Overnight. Following the reported procedure, by reacting (C)2H5)2Diffusion of O to SbCl3And Ph4Preparation of Red-emitting (Ph) in DMF solution of PCl overnight4P)2SbCl5Crystals (Zhou, C.K., et al, materials chemistry 2018,30(7), 2374-. Following a revised procedure, by heating at room temperatureMixing 12ml (C)2H5)2O diffusion to 2mmol Ph4PBr and 1mmol MnBr2Overnight in 4ml DMF to prepare a green light emitting (Ph)4P)2MnBr4Crystals (Xu, l, et al, advanced materials 2017,29(10), 5). With (C)2H5)2The crystals were washed and dried under reduced pressure.
Production of white LED: the white spectrum was simulated and optimized using an Osram-Sylvania LED color calculator. The single crystal phosphor was hand ground with a mortar and pestle. This was then mixed in proportion with a two-component Polydimethylsiloxane (PDMS) EI-1184 (available from Dow-Corning) at a concentration of 25mg ml-1. The mixture gel was placed in a Polytetrafluoroethylene (PTFE) mold and cured at 100 ℃ for 30 minutes under ambient atmosphere. The phosphor layer was then attached to an Opule America LST1-01G01-UV 01-00365 nm UV-LED.
And (3) characterization: the steady state emission and excitation of the phosphor was collected using a Horiba JY Fluoromax-4 fluorometer. Temperature dependent photoluminescence spectra were measured on a Varian Cary Eclipse fluorescence spectrometer with a water 4-position multi-cell holder attachment connected to a juebo F12-EC refrigeration/heating circulator filled with a glycol-water mixture (3: 2). Photoluminescence quantum efficiency (PLQE) of the phosphor and phosphorus polymer composite was determined using a Hamamatsu Quantaurus-QY absolute PL quantum yield spectrometer at an excitation wavelength of 365 nm. The white led electroluminescence spectra, current dependence and thermal stability were measured on a marine optics USB4000 micro fiber optic spectrometer in conjunction with a Keithley 2400 source table. Efficiency measurements were made using a Keithley 2400 source table, a Newport 818-UV photodetector and a Newport multifunction optical gauge. During the efficiency measurements, an eintermate optically deep dyed polyethylene terephthalate (PET) ultraviolet filter was used to eliminate the effect on the photocurrent generated by the UV-LED.
- 上一篇：一种医用注射器针头装配设备
- 下一篇：地板用触感改善剂