Self-crosslinking compound as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of solar cells, and particularly relates to a self-crosslinking compound and a preparation method and application thereof. The preparation method comprises the following steps: adding tris (4-hydroxyphenyl) amine, p-chloromethyl styrene, a halogenating reagent and inorganic alkali into a solvent, performing reflux reaction for 12-24 hours in an inert atmosphere, and treating reaction liquid to obtain the self-crosslinking compound. The prepared self-crosslinking compound has a plurality of crosslinking sites, a crosslinking reaction can be completed in the perovskite annealing process, and a formed polymer network can effectively prevent moisture permeation and reduce ion migration, so that an efficient and stable perovskite solar cell device is prepared. According to a perovskite device prepared from the self-crosslinking material, 24.53% of photoelectric conversion efficiency, 1.21 V of open-circuit voltage, 25.50 mA cm <-2 > of short-circuit current and 79.19% of fill factor are achieved, and the stability of the device is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to a self-crosslinking compound and a preparation method and application thereof. Background Art

[0002] Solar cells can be divided into three generations according to their development stages and principles. Each generation of cells represents a series of technological advances and innovations. The first generation of solar cells is mainly silicon-based materials: although monocrystalline silicon cells have high conversion efficiency, their cost is relatively high; although polycrystalline silicon is cheaper than monocrystalline silicon, its efficiency is slightly lower. The second generation of solar cells uses multi-compound thin film technology (using materials such as gallium arsenide (GaAs), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe)). Although the efficiency is high, the materials used in its cells are relatively scarce, which limits the further development of the cells. The third generation of solar cells includes perovskite solar cells (PSCs), dye-sensitized solar cells (DSSCs), organic solar cells (OPV), quantum dot solar cells (QDSCs), etc. Among them, perovskite solar cells are considered to be one of the important technical directions that can replace traditional silicon-based solar cells. They have attracted much attention due to their unique material properties, such as high efficiency, low cost, adjustable band gap, and light weight and flexibility. Since the advent of perovskite solar cells, although some progress has been made, there is still room for improvement in efficiency, stability, service life, and sustainability, especially in terms of stability under complex and changing environmental conditions.

[0003] Perovskite films prepared by solution method have a large number of defects, such as grain boundaries, dislocations, vacancies and redox defects, which will reduce the charge transfer efficiency of the film, shorten the carrier lifetime, and lead to decreased device stability. Additive engineering is a means to effectively overcome various defects in the process of preparing perovskite films by solution method. Small molecule additives and polymer additives are two commonly used types of additives. Small molecule additives are small in size and easy to diffuse into the interior of the perovskite film and bind to defect sites. There are many types of small molecule additives, which can be selectively regulated according to different defect types. The price is relatively cheap and easy to mass produce; however, small molecule additives have weak binding force with perovskite films, are easy to fall off, and may decompose at high temperatures, affecting the stability of the film. Polymer additives have strong binding force with perovskite films, which improves the stability of perovskite films; however, polymers have poor solubility, low utilization efficiency, poor diffusivity, and are difficult to enter the interior of the film. They also have poor conductivity, which affects device efficiency. At the same time, they are relatively expensive and have high production costs.

[0004] So far, most of the reported in-situ cross-linked molecules are insulators, and perovskite solar cells with insulating polymers may impair carrier transfer and reduce photovoltaic performance. In addition, due to the in-situ polymerized molecules with a single reaction site, the low-degree linear cross-linked skeleton formed after polymerization is brittle and loose. Therefore, there is an urgent need for a compound that combines the advantages of small molecules and polymer additives, with multiple passivation sites, low cost, good solubility, molecular controllability, and thermal stability after polymerization. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, one of the objects of the present invention is to provide a self-crosslinking compound which has many passivation points, low cost and good solubility, molecular controllability and thermal stability after polymerization.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A self-crosslinking compound, the structure of the self-crosslinking compound is as follows:

[0008]

[0009] A second object of the present invention is to provide a method for preparing a self-crosslinking compound.

[0010] The second object of the present invention is achieved by adopting the following technical solution:

[0011] The preparation method of the self-crosslinking compound comprises the following steps: adding tris(4-hydroxyphenyl)amine, p-chloromethylstyrene, a halogenating agent and an inorganic base into a solvent, performing a reflux reaction for 12 to 24 hours under an inert atmosphere, and treating the reaction solution to obtain a self-crosslinking compound.

[0012] Furthermore, the molar ratio of tris(4-hydroxyphenyl)amine, p-chloromethylstyrene, halogenating agent and inorganic base is 1:(3.0-3.5):(0.3-0.4):(5.8-6.5).

[0013] Furthermore, the halogenation agent is one of tetrabutylammonium bromide and tetrabutylammonium iodide; the inorganic base is one of potassium hydroxide and sodium tert-butoxide; and the solvent is toluene.

[0014] Furthermore, the preparation method of tri(4-hydroxyphenyl)amine comprises the following steps: adding tri(4-methoxyphenyl)amine and boron tribromide to dichloromethane under low temperature conditions, reacting at room temperature for 11 to 15 hours under an inert atmosphere, and treating the reaction solution to obtain tri(4-hydroxyphenyl)amine.

[0015] Furthermore, the molar ratio of tri(4-methoxyphenyl)amine to boron tribromide is 1:(3.3-3.6).

[0016] Furthermore, the preparation method of tri(4-methoxyphenyl)amine comprises the following steps: adding iodoanisole, bis(4-methoxyphenyl)amine, potassium tert-butoxide, tri-tert-butylphosphine tetrafluoroborate, and tridibenzylideneacetone dipalladium to toluene, reacting at 90-110° C. in an inert atmosphere for 12-16 hours, and treating the reaction solution to obtain tri(4-methoxyphenyl)amine.

[0017] Furthermore, the molar ratio of the bis(4-methoxyphenyl)amine, iodoanisole, potassium tert-butoxide, tri-tert-butylphosphine tetrafluoroborate, and trisdibenzylideneacetone dipalladium is 1:(1.1-1.5):(3.0-3.5):(0.1-0.3):(0.3-0.6).

[0018] A third object of the present invention is to provide an application of a self-crosslinking compound.

[0019] The third object of the present invention is achieved by adopting the following technical solution:

[0020] The self-crosslinking compound is used to prepare a perovskite film or a perovskite solar cell.

[0021] A fourth object of the present invention is to provide a perovskite solar cell.

[0022] The fourth object of the present invention is achieved by adopting the following technical solution:

[0023] The perovskite solar cell comprises a transparent conductive oxide layer, an electron transport layer, a perovskite layer, a hole transport layer and an electrode, and the perovskite layer is prepared from a perovskite precursor solution to which the self-crosslinking compound is added.

[0024] Furthermore, the concentration of the self-crosslinking compound in the perovskite precursor solution is 0.5 g / L.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The self-crosslinking compound prepared by the present invention has multiple crosslinking sites, which can complete the crosslinking reaction during the perovskite annealing process. The formed polymer network can effectively prevent water penetration and reduce ion migration, thereby preparing an efficient and stable perovskite solar cell device. The perovskite device prepared by the self-crosslinking material of the present invention achieved a photoelectric conversion efficiency of 24.53%, an open circuit voltage of 1.21V, and a current of 25.50mA cm -2 The short-circuit current and fill factor of 79.19% are achieved, and the stability of the device is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the synthesis of the self-crosslinking compound of the present invention;

[0028] Figure 2 The hydrogen nuclear magnetic spectrum of tri(4-methoxyphenyl)amine prepared by the present invention 1 H NMR spectrum;

[0029] Figure 3 The NMR carbon spectrum of tri(4-methoxyphenyl)amine prepared by the present invention 13 C NMR spectrum;

[0030] Figure 4 The hydrogen nuclear magnetic spectrum of tris(4-hydroxyphenyl)amine prepared by the present invention 1 H NMR spectrum;

[0031] Figure 5 The NMR carbon spectrum of tris(4-hydroxyphenyl)amine prepared by the present invention 13 C NMR spectrum;

[0032] Figure 6 The NMR hydrogen spectrum of the self-crosslinking compound prepared by the present invention is 1 H NMR spectrum;

[0033] Figure 7 The NMR carbon spectrum of the self-crosslinking compound prepared by the present invention 13 C NMR spectrum;

[0034] Figure 8 This is a schematic diagram of the structure of a perovskite solar cell prepared in Example 4 of the present invention;

[0035] Fig. 9 A schematic diagram of an electrostatic potential distribution diagram and a frontier molecular orbital result diagram of a self-crosslinking compound prepared in the present invention;

[0036] Fig.10 A schematic diagram of the differential scanning calorimeter results of the self-crosslinking compound prepared in the present invention;

[0037] Fig.11 Fourier transform infrared (FTIR) spectra of the self-crosslinking compound prepared in the present invention before and after crosslinking;

[0038] Fig.12 A schematic diagram of the transmission electron microscopy results of the perovskite device FTO / TPA-VB / Au prepared in Example 4 of the present invention;

[0039] Fig.13 This is a current density-voltage (JV) characteristic curve of the perovskite solar cell prepared in Example 4 of the present invention;

[0040] Fig.14 This is the electrochemical impedance spectroscopy (EIS) of the perovskite solar cell prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0041] Below, in conjunction with the accompanying drawings and specific embodiments, the present invention is further described. It should be noted that, under the premise of no conflict, the embodiments described below or the technical features can be arbitrarily combined to form new embodiments. The specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0042] Example 1

[0043] A method for preparing a self-crosslinking compound, such as Figure 1 As shown, the following steps are included:

[0044] (1) In a dry 100 mL Schlenk bottle, p-iodoanisole (2.8 g, 11.9 mmol), bis(4-methoxyphenyl)amine (2.5 g, 10.9 mmol), potassium tert-butoxide (t-BuOK, 3.67 g, 32.7 mmol), tri-tert-butylphosphine tetrafluoroborate (0.32 g, 1.09 mmol) and trisdibenzylideneacetone dipalladium (Pd2(dba)3, 0.3 g, 0.327 mmol) were dissolved in 30 mL of toluene, and the reaction was heated to 90°C under an argon atmosphere for 12 hours. After the reaction was completed, 20 mL of ice water was added to the reaction mixture to quench it, and the reaction solution was extracted with dichloromethane. The organic phases were combined and dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:14) to purify and concentrate to obtain 3.0 g of tris(4-methoxyphenyl)amine (yield 83%).

[0045] Tris(4-methoxyphenyl)amine 1 H NMR results are as follows Figure 2 As shown, 1 H NMR (400MHz, DMSO-d6) δ6.86–6.76(m,12H),3.70–3.62(m,9H).

[0046] Tris(4-methoxyphenyl)amine 13 C NMR results are as follows Figure 3 As shown, 13 C NMR (101MHz, DMSO-d6) δ155.14, 141.90, 124.98, 115.26, 55.73.

[0047] MS of tri(4-methoxyphenyl)amine: m / z (%) [M + ]calcd for C 21 H 21NO3:335.152; found:336.155.

[0048] (2) At -84°C, tri(4-methoxyphenyl)amine (1.5 g, 4.45 mmol) was added to a 100 mL dry round-bottom flask and dissolved with 20 mL of dichloromethane. After complete dissolution, 15 mL of boron tribromide (1 M dichloromethane solution) was slowly added. The reaction mixture was stirred for 1 hour, then the temperature was raised to room temperature and stirred for 11 hours. 10 mL of deionized water was added to the reaction mixture, and the mixture was stirred for 1 hour. The reaction mixture was extracted with ethyl acetate. The combined organic phases were dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:2). After purification and concentration, 1.3 g of tri(4-hydroxyphenyl)amine (yield 97%) was obtained.

[0049] Tris(4-hydroxyphenyl)amine 1 H NMR results are as follows Figure 4 As shown, 1 H NMR (400MHz, DMSO-d6) δ9.05 (s, 3H), 6.68 (dt, J = 8.0, 4.0 Hz, 6H), 6.59 (dt, J = 8.0, 4.0 Hz, 6H).

[0050] Tris(4-hydroxyphenyl)amine 13 C NMR results are as follows Figure 5 As shown, 13 C NMR (101MHz, DMSO-d6) δ152.94,140.92,124.97,116.37.

[0051] MS of tri(4-hydroxyphenyl)amine: m / z(%) [M+]calcd for C 18 H 15 NO3:293.105; found:294.109.

[0052] (3) In a 150 ml dry round-bottom flask, tris(4-hydroxyphenyl)amine (1 g, 3.4 mmol), p-chloromethylstyrene (1.6 g, 10.5 mmol), and tetrabutylammonium bromide (0.34 g, 1.05 mmol) were dissolved in 30 mL of toluene. Subsequently, 10 mL of 2M potassium hydroxide aqueous solution was slowly added, and the reaction was stirred at room temperature for 12 hours; 20 mL of ice water was added to the reaction to quench the reaction, and the reaction solution was extracted with ethyl acetate. The organic layers were combined and dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:20), and concentrated to obtain 1.8 g of self-crosslinking compound (yield 82%).

[0053] Self-crosslinking compounds 1H NMR results are as follows Figure 6 As shown, 1 H NMR (400MHz, DMSO-d6) δ7.49–7.43(m,6H),7.37(d,J=8.2Hz,6H),6.89(dt,J=12.0,4.0Hz,6H),6.83(dt,J=12.0, 4.0Hz, 6H), 6.71 (dd, J=16.0, 12.0Hz, 3H), 5.81 (dd, J=16.0, 1.2Hz, 3H), 5.23 (dd, J=8.0, 4.0Hz, 3H), 4.99 (s, 6H).

[0054] Self-crosslinking compounds 13 C NMR results are as follows Figure 7 Shown 13 C NMR (101MHz, DMSO-d6) δ154.26,141.98,137.41,137.18,136.83,128.48,126.72,124.98,116.18,114.98,69.69.

[0055] MS of self-crosslinked compounds: m / z (%) [M + ]calcd for C45H39NO3:641.293; found:642.294.

[0056] This embodiment also provides a self-crosslinking compound obtained by the above preparation method.

[0057] Example 2

[0058] A synthesis of a self-crosslinking compound comprises the following steps:

[0059] (1) In a dry 100 mL Schlenk bottle, p-iodoanisole (13 mmol), bis(4-methoxyphenyl)amine (10.9-12 mmol), potassium tert-butoxide (35 mmol), tri-tert-butylphosphine tetrafluoroborate (2.35 mmol) and tris(dibenzylideneacetone dipalladium) (0.47 mmol) were dissolved in 30 mL of toluene, and the reaction was heated to 90° C. under an argon atmosphere for 14 hours. After the reaction was completed, 20 mL of ice water was added to the reaction mixture to quench it, and the reaction solution was extracted with dichloromethane. The organic phases were combined and dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:14) to purify and concentrate to obtain tris(4-methoxyphenyl)amine. 1 H NMR, 13 The results shown by C NMR and MS were consistent with those of Example 1.

[0060] (2) At -84°C, tri(4-methoxyphenyl)amine (4.45 mmol) was added to a 100 mL dry round-bottom flask and dissolved with 20 mL of dichloromethane. After complete dissolution, 15 mL of boron tribromide (1 M dichloromethane solution) was slowly added, and the reaction was stirred for 1 hour, then the temperature was raised to room temperature and stirred for 13 hours. 10 mL of deionized water was added to the reaction solution, and the reaction solution was extracted with ethyl acetate after stirring for 1 hour. The combined organic phases were dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:2) to purify and concentrate to obtain tri(4-hydroxyphenyl)amine. 1 H NMR, 13 The results shown by CNMR and MS are consistent with those of Example 1.

[0061] (3) In a 150 ml dry round-bottom flask, tris(4-hydroxyphenyl)amine (3.4 mmol), p-chloromethylstyrene (13.6 mmol), and tetrabutylammonium bromide (1.36 mmol) were dissolved in 30 ml toluene. Then, 11 ml of 2 M potassium hydroxide aqueous solution was slowly added, and the reaction was stirred at room temperature for 12 to 18 hours; 20 ml of ice water was added to the reaction to quench the reaction, and the reaction solution was extracted with ethyl acetate. The organic layers were combined and dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:20), and concentrated to obtain a self-crosslinking compound. 1 H NMR, 13 The results shown by C NMR and MS were consistent with those of Example 1.

[0062] This embodiment also provides a self-crosslinking compound obtained by the above preparation method.

[0063] Example 3

[0064] A synthesis of a self-crosslinking compound comprises the following steps:

[0065] (1) In a dry 100 mL Schlenk bottle, p-iodoanisole (16 mmol), bis(4-methoxyphenyl)amine (10.9 mmol), potassium tert-butoxide (38 mmol), tri-tert-butylphosphine tetrafluoroborate (3.27 mmol) and tris(dibenzylideneacetone dipalladium) (0.654 mmol) were dissolved in 30 mL of toluene, and the reaction was heated to 90° C. under an argon atmosphere for 16 hours. After the reaction was completed, 20 mL of ice water was added to the reaction mixture to quench it, and the reaction solution was extracted with dichloromethane. The organic phases were combined and dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:14) to purify and concentrate to obtain tris(4-methoxyphenyl)amine. 1 H NMR, 13The results shown by C NMR and MS were consistent with those of Example 1.

[0066] (2) At -84°C, tri(4-methoxyphenyl)amine (4.45 mmol) was added to a 100 mL dry round-bottom flask and dissolved with 20 mL of dichloromethane. After complete dissolution, 16 mL of boron tribromide (1 M dichloromethane solution) was slowly added, and the reaction was stirred for 1 hour, then the temperature was raised to room temperature and stirred for 15 hours. 10 mL of deionized water was added to the reaction solution, and the reaction solution was extracted with ethyl acetate after stirring for 1 hour. The combined organic phases were dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:2) to purify and concentrate to obtain tri(4-hydroxyphenyl)amine. 1 H NMR, 13 The results shown by CNMR and MS are consistent with those of Example 1.

[0067] (3) In a 150 ml dry round-bottom flask, tri(4-hydroxyphenyl)amine (3.4 mmol), p-chloromethylstyrene (12 mmol), and tetrabutylammonium iodide (1.2 mmol) were dissolved in 30 mL of toluene. Subsequently, 10 mL of 2 M potassium hydroxide aqueous solution was slowly added, and the reaction was stirred at room temperature for 24 hours; 20 mL of ice water was added to the reaction to quench the reaction, and the reaction solution was extracted with ethyl acetate. The organic layers were combined and dried over anhydrous sodium sulfate and separated by column chromatography (eluent, the volume ratio of ethyl acetate to petroleum ether was 1:20), and concentrated to obtain a self-crosslinking compound. 1 H NMR, 13 The results shown by C NMR and MS were consistent with those of Example 1.

[0068] This embodiment also provides a self-crosslinking compound obtained by the above preparation method.

[0069] Example 4

[0070] A perovskite solar cell having a structure as follows Figure 8 As shown, from the bottom layer to the top layer, it includes: a transparent conductive oxide layer, an electron transport layer, a perovskite layer, a hole transport layer and an electrode. The perovskite layer is prepared from a perovskite precursor solution to which the self-crosslinking compound prepared in Example 1 is added. The amount of the self-crosslinking compound added to the perovskite precursor solution is 0.5 g / mL.

[0071] The perovskite precursor solution of the present invention uses a mixed solvent of DMF:DMSO=8:1. The perovskite precursor solution of the present invention can use a precursor solution well known to those skilled in the art without any special requirements.

[0072] Comparative Example 1

[0073] A perovskite solar cell, which is different from Example 4 in that the self-crosslinking compound prepared in Example 1 is not added to the perovskite layer.

[0074] Test Example 1

[0075] The electrostatic distribution and frontier molecular orbital calculation results of the self-crosslinking compound prepared in Example 1 are as follows: Fig. 9 As shown. Structurally, the self-crosslinking compound prepared by the present invention has a triphenylamine core, an interaction group and a crosslinking group. The triphenylamine core can adjust the energy level so that the energy level of the perovskite is more matched with the energy level of the hole transport layer; the interaction group of the molecule is an ether group, and the lone pair of electrons of the ether bond can interact with the perovskite; the vinyl group can complete crosslinking during the annealing process of the perovskite; therefore, the molecule with multiple crosslinking sites prepared by the present invention has a higher degree of crosslinking in the spatial dimension, and can form a polymer network to wrap the perovskite film, thereby passivating the defects of the perovskite and protecting the perovskite.

[0076] Depend on Fig. 9 The electrostatic potential distribution of the molecule shows that the electrons at the oxygen atom are denser and can more easily interact with the uncoordinated Pb in the perovskite. 2+ In addition, the frontier molecular orbital theory calculation results show that the highest occupied molecular orbital (HOMO) of the two cross-linked molecules is mainly distributed near the triphenylamine core, while the lowest unoccupied molecular orbital is mainly distributed near styrene, which will form a strong intramolecular charge transfer within the molecule, which is beneficial to the molecular transport of holes, and the energy level of the material is more matched with that of perovskite and Spiro-OMeTAD, which is more conducive to the transport of holes and reduces the charge loss at the interface.

[0077] Test Example 2

[0078] The self-crosslinking compound prepared in Example 1 was thermodynamically tested using a differential scanning calorimeter. Fig.10 The sample box used in the test is an aluminum crucible, the reference sample is a different aluminum crucible from the same batch, the heating rate is 10℃ / min, and the cooling rate is 20℃ / min.

[0079] Depend on Fig.10 It can be seen that the melting point of the material is 71°C and the cross-linking temperature is 110°C, indicating that the self-cross-linking compound prepared by the present invention can undergo self-cross-linking at 110°C.

[0080] Test Example 3

[0081] Fourier transform infrared spectroscopy (FTIR) was used to test the self-crosslinking compound prepared in Example 1 before and after heating. The self-crosslinking compound prepared in Example 1 was dissolved in ethyl acetate and spin-coated on a glass slide at 3000r for FTIR testing. Another self-crosslinking compound prepared in Example 1 was dissolved in ethyl acetate and spin-coated on a glass slide at 3000r and heated on a hot stage at 100°C for 1h for FTIR testing. The results are shown in FIG. Fig.11 shown.

[0082] Depend on Fig.11 It can be seen that the self-crosslinked compound after heating is located at 1608 cm -1 The stretching vibration peak of C=C disappears, which indicates that the self-crosslinking compound prepared in the present invention is completely crosslinked after annealing.

[0083] Test Example 4

[0084] In order to verify that the self-crosslinking compound prepared by the present invention forms a polymer in the process of preparing the perovskite device, this test example is characterized by transmission electron microscopy, and the sample preparation process is as follows: the self-crosslinking compound is dissolved in the perovskite precursor solution at a concentration of 0.5g / mL, the perovskite is spin-coated onto the FTO surface, and then annealed at 100°C for 1 hour. The perovskite powder sample is scraped off the FTO surface and dispersed in n-octane solvent, ultrasonicated for 10s, and then 15μL of solvent is drawn with a pipette and dropped on the copper mesh. Finally, the excess solvent is vacuum dried to obtain a sample for transmission electron microscopy characterization. The transmission electron microscope picture is as follows Fig.12 shown.

[0085] Depend on Fig.12 It can be seen that the characterized sample has perovskite grains with clear lattice stripes, and amorphous polymer phases are observed at the edges of these grains, proving that the self-crosslinking small molecule compound of the present invention forms a polymer during the process of preparing perovskite devices.

[0086] Test Example 5

[0087] In the AM 1.5G standard light solar simulator, the simulated solar illuminance is 100mW cm -2 Under the conditions of, the current density-voltage (JV) characteristic curves of the perovskite solar cells prepared in Example 4 and Comparative Example 1 were tested, as shown in detail. Fig.13 shown.

[0088] Depend on Fig.13 It can be seen that the photoelectric conversion efficiency and open circuit voltage V OC , short-circuit current Jsc, and fill factor FF are 22.38%, 1.16V, and 25.13mA cm -2 , 76.34% and 24.53%, 1.21V, 25.50mAcm-2 , 79.19%.

[0089] Test Example 6

[0090] The electrochemical impedance spectroscopy (EIS) of the perovskite solar cells of Example 4 and Comparative Example 1 was performed. Fig.14 shown.

[0091] Depend on Fig.14 It can be seen that the transmission resistance Rct of the device in comparative example 1 is 97.40Ω, and the transmission resistance Rct of the device in embodiment 4 is reduced to 52.34Ω; the composite resistance Rrec of the device in comparative example 1 is 518.86KΩ, and the composite resistance Rrec of the device in embodiment 4 is increased to 1004.7KΩ.

[0092] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A self-crosslinking compound, characterized in that The structure of the self-crosslinking compound is as follows:

2. A method for preparing the self-crosslinking compound according to claim 1, characterized in that: The following steps are involved: Tris(4-hydroxyphenyl)amine, p-chloromethylstyrene, a halogenating agent and an inorganic base are added to a solvent, and the mixture is refluxed for 12 to 24 hours under an inert atmosphere. The reaction solution is treated to obtain a self-crosslinking compound.

3. The method for preparing the self-crosslinking compound according to claim 2, characterized in that: The molar ratio of tris(4-hydroxyphenyl)amine, p-chloromethylstyrene, halogenating agent and inorganic base is 1:(3.0-3.5):(0.3-0.4):(5.8-6.5).

4. The method for preparing the self-crosslinking compound according to claim 2, characterized in that: The halogenating agent is one of tetrabutylammonium bromide and tetrabutylammonium iodide; the inorganic base is one of potassium hydroxide and sodium hydroxide; and the solvent is toluene.

5. The method for preparing the self-crosslinking compound according to claim 2, characterized in that: The preparation method of tri(4-hydroxyphenyl)amine comprises the following steps: adding tri(4-methoxyphenyl)amine and boron tribromide into dichloromethane under low temperature conditions, reacting at room temperature for 11 to 15 hours under an inert atmosphere, and treating the reaction solution to obtain tri(4-hydroxyphenyl)amine.

6. The method for preparing the self-crosslinking compound according to claim 5, characterized in that: The molar ratio of tri(4-methoxyphenyl)amine to boron tribromide is 1:(3.3-3.6).

7. The method for preparing the self-crosslinking compound according to claim 5, characterized in that: The preparation method of tri(4-methoxyphenyl)amine comprises the following steps: adding p-iodoanisole, bis(4-methoxyphenyl)amine, potassium tert-butoxide, tri-tert-butylphosphine tetrafluoroborate and trisdibenzylideneacetone dipalladium into toluene, reacting at 90-110° C. in an inert atmosphere for 12-16 hours, and treating the reaction solution to obtain tri(4-methoxyphenyl)amine.

8. The method for preparing the self-crosslinking compound according to claim 7, characterized in that: The molar ratio of the bis(4-methoxyphenyl)amine, p-iodoanisole, potassium tert-butoxide, tri-tert-butylphosphine tetrafluoroborate and trisdibenzylideneacetone dipalladium is 1:(1.1-1.5):(3.0-3.5):(0.1-0.3):(0.3-0.6).

9. The use of the self-crosslinking compound according to claim 1, characterized in that: The invention is applied to the preparation of perovskite thin films and / or perovskite solar cells.

10. A perovskite solar cell, characterized in that: The invention comprises a transparent conductive oxide layer, an electron transport layer, a perovskite layer, a hole transport layer and an electrode, wherein the perovskite layer is prepared from a perovskite precursor solution to which the self-crosslinking compound according to claim 1 is added.

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