阅读说明：本技术 一类方酸类有机小分子空穴传输材料及其应用 (Squaric acid organic small molecule hole transport material and application thereof ) 是由 孔凡太 彭耀乐 孙媛 张近雪 赵春蝶 于 2021-08-06 设计创作，主要内容包括：本发明公开了一类方酸类有机小分子空穴传输材料及其应用,涉及光电材料技术领域,其具有如下结构通式：或本发明提出的方酸类有机小分子空穴传输材料具有较高的空穴迁移率和光电转换效率,可以作为非掺杂空穴传输材料；且该方酸类小分子合成过程简单,原料廉价易得,稳定性好,可以作为钙钛矿太阳电池、有机太阳电池、有机发光二极管、场效应晶体管等光电器件的空穴传输材料。(The invention discloses a squaric acid organic micromolecule hole transport material and application thereof, relating to the technical field of photoelectric materials and having the following structural general formula: or The squarylium organic micromolecule hole transport material provided by the invention has higher hole mobility and photoelectric conversion efficiency, and can be used as a material for preparing a cathode materialA non-doped hole transport material; the squarylium micromolecule has simple synthesis process, cheap and easily obtained raw materials and good stability, and can be used as a hole transport material of photoelectric devices such as perovskite solar cells, organic light emitting diodes, field effect transistors and the like.)

1. The squaric acid organic micromolecule hole transport material is characterized by having a structural general formula shown as a formula (I) or a formula (II):

wherein Ar is selected from substituted or unsubstituted C3-C30 aryl, substituted or unsubstituted C6-C30 aryl and cyclopropenyl;

x is selected from R, OR, SR, SeR, TeR, N (RR '), Si (RR ' R '), P (RR '), B (RR '), CF₃R, R 'and R' are selected from C1-C40 straight chain or branched chain alkyl.

2. The squaric acid-based small organic molecule hole transport material according to claim 1, wherein Ar is selected from the group consisting of cyclopropenyl, benzene, naphthalene, phenanthrene, and,Perylene, benzopyrene, indene, biphenylene, asymmetric indacene, symmetric indacene, acenaphthylene, fluorene, fluoranthene, triphenylene, acenaphthylene, pentacene, tetraphenylene, furan, thiazole, pyrrole, imidazole, thiophene, pyridine, pyrimidine, pyridazine, pyrazine, quinoline, indole, benzofuran, purine, acridine, benzacridine, and substituted derivatives thereof.

3. The application of the squarylium organic small molecule hole transport material as claimed in claim 1 or 2 in photoelectric devices.

4. The application of the squaraine organic small molecule hole transport material in photoelectric devices according to claim 3, wherein the photoelectric devices comprise perovskite solar cells, organic light emitting diodes and field effect transistors.

Technical Field

The invention relates to the technical field of photoelectric materials, in particular to a squarylium organic micromolecule hole transport material and application thereof.

Background

In recent years, with the rapid development of the photovoltaic industry, hole injection/transport materials have attracted extensive attention of researchers in many fields such as materials and physics, and have been successfully applied to optoelectronic devices such as organic-inorganic perovskite solar cells, organic solar cells and organic light emitting diodes.

An ideal hole injection/transport layer generally needs to have several characteristics: the high hole mobility, the HOMO energy level matched with the material of the optical function layer can ensure the effective injection and transmission of holes in each interface, good air and thermal stability, low production cost, good solvent property, good film-forming property and the like.

In organic and inorganic perovskite solar cells, the highest Photoelectric Conversion Efficiency (PCE) of a traditional forward-mounted device structure exceeds 23.3 percent. Due to the limited hole transport capabilities of the perovskite layer itself, hole transport materials have become an integral part of Perovskite Solar Cell (PSCs) devices. Currently, the most commonly used organic small-molecule hole transport material is 2,2,7, 7-tetra [ N, N-bis (4-methoxyphenyl) amino ] -9, 9-spirobifluorene (spiro-OMeTAD), which has many synthesis steps, harsh conditions and complex purification process, resulting in high synthesis cost. In addition, in order to ensure the hole mobility, chemical additives are required to be matched, so that the environmental stability of the device is reduced while the manufacturing cost is increased, and the commercialization of the perovskite solar cell is not facilitated.

In organic solar cells, the photovoltaic conversion efficiency has reached 17%. Poly 3, 4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT: PSS) is the most widely used hole transport layer material at present, but the PEDOT: PSS has acidity and can corrode Indium Tin Oxide (ITO) electrode material, thereby reducing the stability of the battery.

Organic Light Emitting Diodes (OLEDs) have been widely used in the field of lighting and display, and have advantages of being light, thin, self-luminous, low power consumption, wide viewing angle, low driving voltage, high color saturation, high contrast, etc., and are gradually replacing conventional liquid crystals and common LEDs, becoming the mainstream display technology adopted in new products of electronic devices such as televisions, computers, smart phones, watches, automobile control panels, etc. Currently, N-biphenyl-4-yl-9, 9-dimethyl-N- [4- (9-phenyl-9H-carbazole-3-yl) phenyl ] -9H-fluorene-2-amine (BCFN) is used as a hole transport material of an organic light emitting diode, and an additive is needed to improve the efficiency of hole injection, so that the problems of the service life reduction and the increase of the power consumption of the organic light emitting diode are caused.

The research of the organic field effect transistor is rapidly developed, and good progress is made in the aspects of solution processability, high mobility, low operating voltage and the like. In the practical application of organic field effect transistors, the design and synthesis of new and high-performance organic semiconductor materials are essential, and hole transport materials with both high mobility and low threshold voltage have been the target of research.

In summary, the presently disclosed organic hole transport materials 2,2,7, 7-tetrakis [ N, N-bis (4-methoxyphenyl) amino ] -9, 9-spirobifluorene (spiro-omatad) and N-biphenyl-4-yl-9, 9-dimethyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl ] -9H-fluoren-2-amine (BCFN) all have the disadvantages of low hole transport efficiency, inability to produce spectral complementarity with the light absorbing layer, and the need for chemical additives. Therefore, the design and synthesis of novel efficient and stable undoped organic hole transport materials become the key point of research and development. The squarylium group-containing molecules are traditional organic dye molecules, and have the characteristics of cheap raw materials, simple synthesis, large light absorption coefficient, high molecular conjugation degree, adjustable band gap in visible light and near infrared regions, capability of being complementary with light absorption layer spectra, flexible structural modification, good photochemical and thermal stability and the like. And the electrons of the squarylium group are highly delocalized on the central ring, which is beneficial to the transmission of hole carriers, so that the squarylium group has unique advantages when being used as a donor center of a hole transport material in a photoelectric material. Most of the squaric acid organic micromolecule hole transport materials disclosed at present are of asymmetric structures, but intermolecular interaction force of asymmetric squaric acid molecules is small, pi-pi stacking is not facilitated to be formed, hole transport is not facilitated, and therefore chemical additives need to be added during use, but the additives can affect device performance. Therefore, the design and synthesis of symmetric, efficient, stable and undoped squarylium organic hole transport materials become important for research and development.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a squaric acid organic micromolecule hole transport material and application thereof, wherein the squaric acid organic micromolecule hole transport material is symmetrical in structure, has higher hole mobility and photoelectric conversion efficiency, and does not need an additive when being used as a hole transport material.

The squaric acid organic micromolecule hole transport material provided by the invention has a structural general formula shown as a formula (I) or a formula (II):

wherein Ar is selected from substituted or unsubstituted C3-C30 aryl, substituted or unsubstituted C6-C30 aryl and cyclopropenyl;

x is selected from R, OR, SR, SeR, TeR, N (RR '), Si (RR ' R '), P (RR '), B (RR '), CF₃R, R 'and R' are selected from C1-C40 straight chain or branched chain alkyl.

Further, Ar is selected from cyclopropenyl, benzene, naphthalene, phenanthrene,Perylene, benzopyrene, indene, biphenylene, asymmetric indacene, symmetric indacene, acenaphthylene, fluorene, fluoranthene, triphenylene, acenaphthylene, pentacene, tetraphenylene, furan, thiazole, pyrrole, imidazole, thiophene, pyridine, pyrimidine, pyridazine, pyrazine, quinoline, indole, benzofuran, purine, acridine, benzacridine, and substituted derivatives thereof.

The invention also discloses application of the squaric acid organic small molecule hole transport material in photoelectric devices.

Preferably, the optoelectronic device comprises a perovskite solar cell, an organic light emitting diode, a field effect transistor.

Has the advantages that: the squaric acid organic micromolecule hole transport material provided by the invention has a symmetrical structure, a central ring is highly delocalized, and the tail end is triphenylamine and a derivative thereof, so that the squaric acid organic micromolecule hole transport material has high hole mobility and photoelectric conversion efficiency, and does not need an additive when being used as a hole transport material; the squarylium micromolecule has the advantages of simple synthesis process, cheap and easily-obtained raw materials, good stability and high hole mobility, and can be used as a hole transport material of photoelectric devices such as perovskite solar cells, organic light emitting diodes and field effect transistors.

Drawings

FIG. 1 is a hydrogen nuclear magnetic spectrum of Compound 3 prepared in example 1 of the present invention;

FIG. 2 is a hydrogen nuclear magnetic spectrum of Compound 5 prepared in example 1 of the present invention;

FIG. 3 is an ultraviolet-visible spectrum of Compound 5 prepared in example 1 of the present invention;

fig. 4 is a schematic view of a formal mesoporous perovskite solar cell in example 3 of the present invention;

FIG. 5 is a J-V curve of an optimized device for the use of compound 5 as a hole transport material in a perovskite solar cell in example 3 of the present invention;

FIG. 6 is a schematic view of an electroluminescent device in example 4 of the present invention;

FIG. 7 is a schematic view of a field effect transistor in embodiment 5 of the present invention;

fig. 8 is a schematic view of an organic solar cell in embodiment 6 of the present invention.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.

Example 1

A preparation method of squaric acid organic micromolecules comprises the following steps:

(1) squaric acid (11.4g) and thionyl chloride (21g) were mixed in a molar ratio of 1: 2.1 adding the mixture into a three-neck flask, adding a catalyst DMF, heating to 50 ℃ for refluxing, and reacting for 12 hours under the condition; then, evaporating to remove thionyl chloride, adding bromobenzene (21g) with the amount of the squaric acid substance being 2 times that of the squarylium, and anhydrous aluminum chloride (8.5g) as a catalyst, heating to 40 ℃, and carrying out reflux reaction for 12 hours; after the reaction is finished, cooling to room temperature, then pouring the reaction liquid into ice water for quenching, and then extracting with dichloromethane; the organic phase obtained by the extraction was dried over anhydrous magnesium sulfate, evaporated under reduced pressure, and recrystallized from anhydrous ethanol to obtain compound 3.

(2) Adding the compound 3, 4-borate-4 ',4' -dimethoxy triphenylamine, alkali liquor and ethanol into a reaction solvent, wherein the molar ratio of the compound 3(0.17g) to the 4-borate-4 ',4' -dimethoxy triphenylamine (0.65g) is 1: 2, under the protection of inert atmosphere and the action of a tetrakis (triphenylphosphine) palladium catalyst (0.02g), refluxing at 80 ℃ to perform Suzuki coupling reaction; and after the reaction is finished, cooling to room temperature, extracting, passing through a column, and recrystallizing to obtain the squaric acid organic micromolecule-compound 5.

The nmr hydrogen spectrum of compound 3 is:¹h NMR (600MHz, Chloroform-d) δ 7.43(d, J ═ 8.4Hz,8H),7.22(d, J ═ 4.1Hz,1H), 7.22-7.16 (m, 8H); the hydrogen spectrum of nuclear magnetic resonance is shown in FIG. 1.

The nmr hydrogen spectrum of compound 5 is:¹h NMR (600MHz, Chloroform-d) Δ 7.70-7.64 (m,4H), 7.67-7.60 (m,4H), 7.40-7.34 (m,4H), 7.12-7.05 (m,8H), 6.98-6.93 (m,4H), 6.88-6.81 (m,10H),3.80(s, 12H); the hydrogen spectrum of nuclear magnetic resonance is shown in FIG. 2.

The UV-visible absorption spectrum of Compound 5 can be seen in FIG. 3, which is measured by dissolving Compound 5 in dichloromethane with a solution UV-visible absorption of 0.01mg/mL, using a prohibitively UV-visible spectrum gradiometer. The hole mobility of the compound was 2.1X 10^-3cm² V^-1s^-1。

Example 2

In a 100mL three-necked flaskAdding N, N-di (4-methoxyphenyl) - [1, 1' -biphenyl]-4-amine (152.5mg,0.40mmol), squaric acid (61.9mg,0.21mmol), benzene/N-butanol ═ 1: 1 (v/v) (60mL), attached to a water separator, heated under protection of N2 at 80 ℃ and refluxed for 22 h. In the reaction process, the color of the reaction liquid is gradually deepened, and solids are separated out. And after the reaction is finished, cooling to room temperature, extracting, passing through a column, and recrystallizing to obtain the squaric acid organic micromolecule-compound 6. The hole mobility of the compound was 1.9X 10^-3cm² V^-1s^-1。

Experimental example 3

The squaric acid organic micromolecules synthesized in examples 1 and 2, namely compound 5 and compound 6, are respectively used as hole transport materials to be applied to formal perovskite solar cell devices, and the specific structure is FTO/c-TiO₂/m-TiO₂Perovskite/HTM/Au, the structural diagram of which is shown in FIG. 4, a xenon lamp solar simulator is used, and the intensity of a test light source is AM 1.5G (100mW cm)^-2) When the prepared perovskite solar cell is subjected to photovoltaic performance test, the J-V curve of the device is shown in figure 5, and the PCE can reach 19.32% and 19.85% at most.

When the squarylium small molecules are used as the hole transport material of the perovskite solar cell, the device combination mode is not limited to the above embodiment, and other material layers in the device can be the conventional solar cell material type.

Example 4

The squarylium organic micromolecules synthesized in examples 1 and 2, namely compound 5 and compound 6, are respectively used as hole transport materials of electroluminescent devices; fig. 6 is a schematic diagram of an electroluminescent device.

(1) Cleaning a conductive glass ITO substrate: sequentially placing the ITO glass substrate in acetone, isopropanol, cleaning liquid, deionized water and isopropanol for ultrasonic cleaning, removing possible residual stains (such as photoresist and the like) on the surface of the ITO glass substrate and improving interface contact, and after cleaning, placing the ITO glass substrate in a vacuum oven for drying;

(2) placing the ITO in an oxygen plasma etching instrument, and cleaning for twenty minutes by using ozone to thoroughly remove possible residual organic matters on the surface of the ITO glass substrate;

(3) spin-coating compound 5 or compound 6 on ITO to form a hole transport layer (HTM) at 3000 rpm for 20s, and then drying in a vacuum oven at 80 ℃ for 12 hours;

(4) in a glove box in a nitrogen atmosphere, a polymer material poly [9, 9-dioctyl fluorene-co-S, S-dioxo-dibenzothiophene ] (PFSO10) is dissolved in p-xylene to prepare a solution with the concentration of 20mg/mL, a PFSO10 active layer film with the thickness of 40nm is coated on a hole transport layer in a spinning mode, and then heating annealing is carried out for 20 minutes at the temperature of 80 ℃ on a heating table to remove residual solvents and improve the appearance of a luminescent layer film;

(5) in a vacuum evaporation chamber, an electron transport material 1,3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene (TPBI) with the thickness of 40nm is evaporated on an active layer film, a layer of cesium fluoride (CsF) with the thickness of 1.0nm is evaporated, and a layer of ultra-pure aluminum cathode (Al) with the thickness of 90nm is evaporated, wherein lithium fluoride and aluminum layers are subjected to vacuum deposition through a mask plate.

The OLED devices were tested for current efficiency, luminance, current density as a function of voltage by a Keithley 2602 digital source meter and a calibrated luminance meter. The maximum luminous brightness and current efficiency of the hole transport material compound 5 applied to the device are 3274cd m^-2And 5.31cd A^-1. The maximum luminous brightness and current efficiency of the hole transport material compound 6 applied to the device are 5827cd m^-2And 6.23cd A^-1。

Example 5

The squarylium organic small molecule compound 5 and compound 6 synthesized in examples 1 and 2 were used as hole transport materials for field effect transistors, respectively; fig. 7 is a schematic view of a field effect transistor.

(1) Using a silicon wafer with the thickness of 1mm as a grid electrode (Substrate), and preparing SiO with the thickness of 300nm on the grid electrode layer by a thermal oxidation growth method₂As an insulating layer (Gate), and then an Octadecyltrichlorosilane (OTS) monomolecular layer was prepared on the insulating layer by a vapor phase method(about 2nm) is an insulation modifying layer (Dielectric layer).

(2) And (2) evaporating a compound 5 or a compound 6 on the insulating modification layer in the step (1) by using a vacuum evaporation method to form a semiconductor film (Organic semiconductor), wherein the thicknesses of the semiconductor film are 40nm and 45nm respectively.

(3) Gold of 40nm was evaporated on the semiconductor film as a Source (Source) and a Drain (Drain).

The devices were tested by Keithley 2602 digital source table. The devices using compounds 5 and 6 had a lower threshold voltage of about-10V and both had a higher on-off ratio of 10, respectively⁷～10⁸And 10⁶～10⁷。

Example 6

The squarylium organic micromolecules synthesized in examples 1 and 2, namely compound 5 and compound 6, are respectively used as hole transport materials of organic solar cells; fig. 8 is a schematic view of an organic solar cell.

(1) Cleaning a conductive glass ITO substrate: sequentially placing the ITO glass substrate in acetone, isopropanol, cleaning liquid, deionized water and isopropanol for ultrasonic cleaning, removing possible residual stains (such as photoresist and the like) on the surface of the ITO glass substrate and improving interface contact, and after cleaning, placing the ITO glass substrate in a vacuum oven for drying;

(2) placing the ITO in an oxygen plasma etching instrument, and cleaning for twenty minutes by using ozone to thoroughly remove possible residual organic matters on the surface of the ITO glass substrate;

(3) spin-coating a hole transport material, namely compound 5 or compound 6 (2500rpm, 30s and 30nm) on the surface of the transparent conductive cathode ITO to form a hole transport layer (HTM);

(4) an optically Active layer (Active layer) is spin-coated on the hole transport layer.

(5) Selecting a methanol solution of PDINO with the concentration of 1mg/mL, and spin-coating on the photoactive layer for 35s at 3500rpm to form an electron transport layer.

(6) And evaporating an Al electrode as a cathode by adopting a vacuum evaporation method.

The intensity of the light source was measured to be AM 1.5G (100mW cm) using a xenon lamp solar simulator^-2) Paired systemThe prepared organic solar cell is subjected to photovoltaic performance test, the PCE of the hole transport material 5 applied to the organic solar cell is 8.6%, and the PCE of the hole transport material 6 applied to the organic solar cell is 10.1%.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.