Hole transport material and synthesis method thereof, perovskite solar cell and preparation method thereof

Abstract

The invention discloses a hole transport material and a synthesis method thereof, a perovskite solar cell and a preparation method thereof, and belongs to the technical field of solar cells. In the invention, molecules constructed by alkyl and triphenylamine groups based on the chemical structural general formula of the hole transport material are more beneficial to hole transport, the existence of N atoms is more beneficial to charge transport, and the existence of alkoxy can increase the transport capacity of the molecules, so that the hole transport efficiency is improved. The device stability and photoelectric conversion efficiency of the perovskite solar cell can be improved, and the problems that Spiro-OMeTAD is high in synthesis difficulty and poor in stability after being doped with Li, Co and tributyl phosphate in the prior art are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to hole transport materials and synthesis methods, perovskite solar cells and preparation methods. Background Art

[0002] Perovskite solar cells, as a new generation of photovoltaic materials, are usually made of hole transport material Spiro-OMeTAD.

[0003] However, the difficulty in synthesizing Spiro-OMeTAD leads to a high cost for perovskite solar cells. In addition, after doping Spiro-OMeTAD with Li, Co and tributyl phosphate (TBP), its stability is poor and it is not suitable for large-scale use. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a hole transport material and a synthesis method, a perovskite solar cell and a preparation method, which solve the problems in the prior art that the synthesis of Spiro-OMeTAD is difficult and the stability is poor after doping with Li, Co and tributyl phosphate.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a hole transport material, and the chemical structure of the hole transport material is shown in Formula 1:

[0007]

[0008] In Formula 1, R is an alkyl group, and the number of carbon atoms in the alkyl group is less than or equal to 6.

[0009] Optionally, R is selected from methyl or ethyl.

[0010] In a second aspect, the present invention provides a method for synthesizing a hole transport material, which is used for synthesizing the hole transport material of the first aspect, and the synthesis method comprises the following steps:

[0011] Step 1: Weigh and mix the reaction raw materials to obtain a raw material mixture;

[0012] The reaction raw materials include N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine, 4-X-4'-alkoxy-1,1'-biphenyl, palladium acetate and tri-tert-butylphosphine, and X is Br or I;

[0013] Step 2: Mix the raw material mixture with an organic solvent and react to obtain a hole transport material.

[0014] Optionally, the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to 4-X-4'-alkoxy-1,1'-biphenyl is 1:2.2-2.6; and / or, the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to palladium acetate is 1:0.05-0.1; and / or, the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to tri-tert-butylphosphine is 1:1.2-1.8.

[0015] Optionally, in step 2, the reaction temperature is 110-135° C., and the reaction time is 5-12 h.

[0016] Optionally, the reaction raw materials further include potassium tert-butoxide or sodium tert-butoxide.

[0017] Optionally, the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to potassium tert-butoxide or sodium tert-butoxide is 1:2.2-2.6.

[0018] In a third aspect, the present invention provides a perovskite solar cell comprising a conductive substrate, an electron transport layer, a perovskite light absorbing layer, a hole transport layer and a top electrode stacked in sequence, wherein the hole transport layer comprises the hole transport material provided in the first aspect.

[0019] In a fourth aspect, the present invention provides a method for preparing a perovskite solar cell, which is used for preparing the perovskite solar cell provided in the third aspect, and the preparation method comprises the following steps:

[0020] Step a: providing a conductive substrate;

[0021] Step b: sequentially forming an electron transport layer and a perovskite light absorption layer on the surface of the conductive substrate;

[0022] Step c: coating an organic solution of a hole transport material on the surface of the perovskite light absorbing layer to form a hole transport layer;

[0023] Step d: preparing a top electrode on the surface of the hole transport layer to obtain a perovskite solar cell.

[0024] Optionally, the organic solution of the hole transport material is spin-coated onto the surface of the perovskite light absorption layer by spin coating, the spin coating speed is 2500-3500 rpm, the spin coating time is 25-35 s, the spin coating acceleration is 2500-3500 rpm / s, and the mass volume concentration of the hole transport material in the organic solution of the hole transport material is 48-52 mg / mL.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] A) The hole transport material provided by the present invention can replace the existing Spiro-OMeTAD, and the molecular structure is constructed based on the triphenylamine group. Since triphenylamine is a P-type semiconductor, it is more inclined to holes, which can be conducive to the transmission of holes; the atoms of the N atoms themselves have lone pairs of electrons, which mainly play the role of charge transmission in the molecule, and the introduction of N atoms is more conducive to the transmission of charges; the atoms of the O atoms in the alkoxy group themselves have lone pairs of electrons, which mainly play the role of charge transmission in the molecule, and the introduction of O atoms is also conducive to the transmission of charges. Therefore, the perovskite solar cell prepared by the hole transport material of the present invention has substantially no attenuation in photoelectric conversion efficiency, and has good device stability and photoelectric conversion efficiency.

[0027] B) The method for synthesizing the hole transport material provided by the present invention adopts N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine and 4-X-4'-alkoxy-1,1'-biphenyl as synthetic raw materials. Under the catalysis of the catalytic system, the synthesis of the hole transport material can be achieved in a one-step method. The synthesis is simple and the cost of the synthetic raw materials is low, which helps to reduce the industrialization cost of the later perovskite solar cell production.

[0028] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0030] Figure 1 A diagram showing the synthesis process of the hole transport material provided by the present invention;

[0031] Figure 2 A schematic diagram of the structure of a perovskite solar cell provided by the present invention;

[0032] Figure 3 This is a comparison chart of the cell performance of the perovskite solar cells prepared in Comparative Example 1 and Example 1.

[0033] Reference numerals:

[0034] 1-conductive substrate; 2-electron transport layer; 3-perovskite light absorption layer; 4-hole transport layer; 5-top electrode. DETAILED DESCRIPTION

[0035] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0036] In a first aspect of the present invention, a hole transport material is provided. The chemical name of the hole transport material is N1,N1-bis(4'-alkoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine, and the general chemical structure thereof is shown in Formula 1:

[0037]

[0038] In Formula 1, R is an alkyl group, and the number of carbon atoms in the alkyl group is less than or equal to 6. From the perspective of electron transport, R is selected from a methyl group or an ethyl group in the alkyl group, and is preferably a methyl group.

[0039] Compared with the prior art, the hole transport material provided by the present invention can replace the existing Spiro-OMeTAD, and the molecular structure is constructed based on the triphenylamine group. Since triphenylamine is a P-type semiconductor, it is more inclined to holes, which can be conducive to the transmission of holes; the atoms of the N atoms themselves have lone pairs of electrons, which mainly play the role of charge transmission in the molecule, and the introduction of N atoms is more conducive to the transmission of charges; the atoms of the O atoms in the alkoxy group themselves have lone pairs of electrons, which mainly play the role of charge transmission in the molecule, and the introduction of O atoms is also conducive to the transmission of charges. Therefore, the perovskite solar cell prepared by the hole transport material of the present invention has substantially no attenuation in photoelectric conversion efficiency, and has good device stability and photoelectric conversion efficiency.

[0040] The second aspect of the present invention provides a method for synthesizing a hole transport material, which is used for synthesizing the above-mentioned hole transport material, and the synthesis method comprises the following steps:

[0041] Step 1: Weighing and mixing reaction raw materials to obtain a raw material mixture, the reaction raw materials include N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine, 4-X-4'-alkoxy-1,1'-biphenyl, palladium acetate and tri-tert-butyl phosphine, wherein palladium acetate and tri-tert-butyl phosphine are used as a catalyst system for the reaction, and X is Br or I, that is, 4-bromo-4'-alkoxy-1,1'-biphenyl or 4-iodo-4'-alkoxy-1,1'-biphenyl;

[0042] Step 2: The raw material mixture is mixed with an organic solvent (eg, toluene or xylene) and reacted to obtain a hole transport material.

[0043] Compared with the prior art, the synthesis method of the hole transport material provided by the present invention adopts N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine and 4-X-4'-alkoxy-1,1'-biphenyl as synthesis raw materials. Under the catalysis of the catalytic system, the synthesis of the hole transport material can be achieved in a one-step method. The synthesis is simple and the cost of the synthesis raw materials is low, which helps to reduce the industrialization cost of the later perovskite solar cell production.

[0044] In order to be able to control the reaction yield, illustratively, the molar ratio of various raw materials in the above reaction raw materials is as follows:

[0045] The molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to 4-X-4'-alkoxy-1,1'-biphenyl is 1:2.2-2.6 (for example, 1:2.5), the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to palladium acetate is 1:0.05-0.1 (for example, 1:0.05), and the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to tri-tert-butylphosphine is 1:1.2-1.8 (for example, 1:1.5).

[0046] Similarly, in order to control the reaction rate, in the above step 2, the reaction temperature is 110-135° C. (eg, 120° C.), and the reaction time is 5-12 h (eg, 8 h).

[0047] Taking into account that by-products (i.e., hydrogen bromide or hydrogen iodide) will be produced during the above reaction, in order to consume the by-products and promote the reaction, the above reaction raw materials also include potassium tert-butoxide or sodium tert-butoxide. In this way, by adding potassium tert-butoxide or sodium tert-butoxide, it can react with the produced by-products, consume the by-products, and promote the forward progress of the reaction.

[0048] In order to increase the yield of the reaction between potassium tert-butoxide or sodium tert-butoxide and the by-product, the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to potassium tert-butoxide or sodium tert-butoxide is 1:

[0049] 2.2~2.6 (for example: 1:2.5).

[0050] A third aspect of the present invention provides a perovskite solar cell, see Figure 2 , comprising a conductive substrate 1, an electron transport layer 2, a perovskite light absorbing layer 3, a hole transport layer 4 and a top electrode 5 stacked in sequence, wherein the raw material for preparing the hole transport layer 4 comprises the hole transport material provided in the first aspect.

[0051] Compared with the prior art, the beneficial effects of the perovskite solar cell provided by the present invention are substantially the same as the beneficial effects of the hole transport material provided by the first aspect of the present invention, and are not described in detail herein.

[0052] A fourth aspect of the present invention provides a method for preparing a perovskite solar cell, comprising the following steps:

[0053] Step a: providing a conductive substrate 1 (for example, a conductive glass substrate);

[0054] Step b: forming an electron transport layer 2 (for example, a SnO2 layer) and a perovskite light absorption layer 3 on the surface of a conductive substrate 1 in sequence;

[0055] Step c: coating an organic solution of a hole transport material on the surface of the perovskite light absorbing layer 3 to form a hole transport layer 4;

[0056] Step d: Prepare a top electrode 5 (for example, an Au electrode with a thickness of 75 to 90 nm) on the surface of the hole transport layer 4 to obtain a perovskite solar cell.

[0057] Compared with the prior art, the beneficial effects of the method for preparing the perovskite solar cell provided by the present invention are substantially the same as the beneficial effects of the perovskite solar cell provided by the second aspect of the present invention, and are not described in detail herein.

[0058] Specifically, the formation methods of the above layers are as follows:

[0059] The method for forming the electron transport layer 2 comprises the following steps:

[0060] Mixing a nano-dispersion liquid of an electron transport material with deionized water and then performing ultrasonic dispersion, wherein the volume ratio of the nano-dispersion liquid to the deionized water is 1:3 to 5 (for example, 1:4), and the ultrasonic dispersion time is 15 to 20 minutes;

[0061] The ultrasonically dispersed solution is spin-coated onto the conductive substrate 1 by spin coating, wherein the spin coating speed is 2800-3000 rpm, the spin coating time is 15-30 s, and the spin coating acceleration is 2500-3200 rpm / s (for example, 3000 rpm / s);

[0062] The conductive substrate 1 spin-coated with the electron transport material is transferred to a heating platform for heating and annealing, and then subjected to ultraviolet ozone treatment to obtain a dense electron transport layer 2, wherein the heating and annealing temperature is 135-160° C. (for example, 150° C.) and the heating and annealing time is 30-40 minutes.

[0063] The method for forming the perovskite light absorbing layer 3 comprises the following steps:

[0064] Mixing the perovskite precursor raw materials and stirring them to obtain a precursor solution, wherein the perovskite precursor raw materials include methylammonium chloride (MACl), lead iodide (PbI2), methyl iodide (FAI) and an organic solvent, wherein the mass ratio of methylammonium chloride, lead iodide and methyl iodide is 3-4:70-72:23-25, and the organic solvent includes N,N-dimethylformamide (DMF) and / or dimethyl sulfoxide (DMSO), preferably, the organic solvent includes N,N-dimethylformamide and dimethyl sulfoxide, and the volume ratio of the two is 5-10:1 (for example, 8:1), the stirring temperature is 20-30°C (for example, 25°C), and the stirring time is 5-12h (for example, 8h);

[0065] Spin coating the precursor solution onto the surface of the electron transport layer 2 by spin coating;

[0066] The conductive substrate 1 spin-coated with the precursor solution is transferred to a heating platform for heating annealing to obtain a perovskite light absorption layer, wherein the heating annealing temperature is 90 to 120° C. (for example, 100° C.) and the heating annealing time is 0.5 to 2 h (for example, 1 h).

[0067] In order to improve the spin coating efficiency and quality, the spin coating of the precursor solution includes three stages (i.e., the first spin coating, the second spin coating and the third spin coating) performed in sequence, wherein the spin coating speed, spin coating time and spin coating acceleration of the second spin coating and the third spin coating are all greater than those of the first spin coating.

[0068] Exemplarily, the first spin coating has a spin coating speed of 900-1050 rpm (e.g., 1000 rpm), a spin coating time of 8-12 s (e.g., 10 s), and a spin coating acceleration of 900-1050 rpm / s (e.g., 1000 rpm / s); the second spin coating has a spin coating speed of 4500-5500 rpm (e.g., 5000 rpm), a spin coating time of 15-25 s (e.g., 20 s), and a spin coating acceleration of 4500-5500 rpm (e.g., 5000 rpm); during the third spin coating, 120 μL of anti-solvent ethyl acetate is slowly added dropwise, and the third spin coating has a spin coating speed of 4500-5500 rpm (e.g., 5000 rpm), a spin coating time of 8-12 s (e.g., 10 s), and a spin coating acceleration of 4500-5500 rpm (e.g., 5000 rpm).

[0069] The method for forming the hole transport layer 4 comprises the following steps:

[0070] An organic solvent solution of N1,N1-bis(4'-alkoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-alkoxyphenyl)benzene-1,4-diamine (PhN-MeO) is spin-coated onto the surface of the perovskite light absorption layer to obtain a hole transport layer 4, wherein the mass volume concentration of the organic solvent solution of N1,N1-bis(4'-alkoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-alkoxyphenyl)benzene-1,4-diamine (PhN-MeO) is 48-52 mg / mL (e.g., 50 mg / mL), the spin coating speed is 2500-3500 rpm (e.g., 3000 rpm), the spin coating time is 25-35 s (e.g., 30 s), and the spin coating acceleration is 2500-3500 rpm / s (e.g., 3000 rpm / s).

[0071] It can be understood that the above step c also includes a step of synthesizing hole transport materials. For the synthesis of hole transport materials, the synthesis method of hole transport materials provided in the second aspect of the present invention can be adopted, which will not be described in detail here.

[0072] In order to ensure the cleanliness of the conductive substrate 1, the following steps are further included between step a and step b:

[0073] The conductive substrate 1 is sequentially subjected to water cleaning, water cleaning, organic solvent (e.g., acetone) cleaning, drying and ultraviolet ozone treatment (UVO), wherein the cleaning water comprises a cleaning liquid and water (e.g., deionized water), the volume ratio of the cleaning liquid to the water is 1:40 to 60 (e.g., 1:50), the organic solvent is acetone, the drying is nitrogen purge drying, and the treatment time of the ultraviolet ozone cleaning is 20 to 30 minutes.

[0074] Example 1

[0075] This embodiment uses N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine as a hole transport material to prepare a perovskite solar cell, which specifically includes the following steps:

[0076] Step A: providing a conductive glass substrate;

[0077] Step B: the conductive glass substrate is cleaned in sequence with a glass cleaning solution, deionized water and acetone in a volume ratio of 1:50, and after cleaning, the conductive glass substrate is blown dry with dry nitrogen, and after drying, the conductive glass substrate is cleaned with ultraviolet ozone for 20 minutes;

[0078] Step C: Mix the SnO2 nano-dispersion liquid with deionized water (volume ratio of 1:4), ultrasonically disperse for 18 minutes, and spin-coat the ultrasonically dispersed solution onto a conductive glass substrate by spin coating at a speed of 3000 rpm, a time of 30 seconds, and an acceleration of 3000 rpm / s. After the spin coating is completed, the conductive glass substrate is transferred to a heating table, heated and annealed at 150°C for 30 minutes, and then subjected to ultraviolet ozone treatment for 25 minutes to obtain a dense SnO2 electron transport layer;

[0079] Step D: 33.47 mg MACl, 705.75 mg PbI2 and 240.94 mg FAI were dissolved in 1 mL DMF and DMSO mixed solvent (volume ratio of 8:1), and stirred at 25 °C for 8 h to obtain a precursor solution;

[0080] Step E: Spin coating the precursor solution onto the surface of the electron transport layer three times by spin coating. After the spin coating is completed, the conductive glass substrate is placed on a hot plate at 100° C. for annealing for 1 hour, and the perovskite light absorption layer is obtained after cooling. The first spin coating is performed at a rotation speed of 1000 rpm, a time of 10 s, and an acceleration of 1000 rpm / s. The second spin coating is performed at a rotation speed of 5000 rpm, a time of 20 s, and an acceleration of 5000 rpm / s. The third spin coating is performed at a rotation speed of 5000 rpm, a time of 10 s, and an acceleration of 5000 rpm / s. During the third spin coating, 120 μL of anti-solvent ethyl acetate is slowly added;

[0081] Step F: 1 g of N1,N1-bis(4-methoxyphenyl)benzene-1,4-diamine, 2.04 g of 4-bromo-4'-methoxy-1,1'-biphenyl (2.5 equivalents), 25 mg of palladium acetate (0.1 equivalents), 948 mg of tri-tert-butylphosphine (1.5 equivalents) and 875 mg of potassium tert-butoxide (2.5 equivalents) were mixed, 60 mL of toluene solvent was added, and the mixture was reacted at 120° C. for 8 h to obtain 1.45 g of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine;

[0082] Step G: Weigh 50 mg of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine and dissolve it in 1 mL of chlorobenzene to prepare a solution with a concentration of 50 mg / mL;

[0083] Step H: Spin-coat the solution obtained in step G onto the surface of the perovskite light-absorbing layer 3 to obtain the hole transport layer 4 at a speed of 3000 rpm, a time of 30 s, and an acceleration of 3000 rpm / s;

[0084] Step I: Evaporate the top electrode 5 on the hole transport layer 4 to obtain a metal Au electrode with a thickness of 81 nm, thereby completing the preparation of the perovskite solar cell.

[0085] Example 2

[0086] This embodiment uses N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine as a hole transport material to prepare a perovskite solar cell, which specifically includes the following steps:

[0087] Step A: providing a conductive glass substrate;

[0088] Step B: the conductive glass substrate is cleaned in sequence with a glass cleaning solution, deionized water and acetone in a volume ratio of 1:42, and after cleaning, the conductive glass substrate is blown dry with dry nitrogen, and after drying, the conductive glass substrate is cleaned with ultraviolet ozone for 30 minutes;

[0089] Step C: Mix the SnO2 nanodispersion liquid with deionized water (volume ratio of 1:3), ultrasonically disperse for 20 minutes, and spin-coat the ultrasonically dispersed solution onto a conductive glass substrate by spin coating at a speed of 2800 rpm, a time of 20 seconds, and an acceleration of 2600 rpm / s. After the spin coating is completed, transfer the conductive glass substrate to a heating table, heat anneal at 135°C for 40 minutes, and then perform ultraviolet ozone treatment for 28 minutes to obtain a dense SnO2 electron transport layer;

[0090] Step D: 38.52 mg MACl, 714.33 mg PbI2 and 235.61 mg FAI were dissolved in 1 mL DMF and DMSO mixed solvent (volume ratio of 10:1), stirred at 30 °C for 6 h to obtain a precursor solution;

[0091] Step E: Spin coating the precursor solution onto the surface of the electron transport layer three times by spin coating. After the spin coating is completed, the conductive glass substrate is placed on a hot plate at 120° C. for annealing for 0.5 h, and the perovskite light absorption layer is obtained after cooling. The first spin coating is performed at a rotation speed of 900 rpm, a time of 12 s, and an acceleration of 900 rpm / s. The second spin coating is performed at a rotation speed of 4500 rpm, a time of 25 s, and an acceleration of 4500 rpm / s. The third spin coating is performed at a rotation speed of 4500 rpm, a time of 12 s, and an acceleration of 4500 rpm / s. During the third spin coating, 110 μL of anti-solvent ethyl acetate is slowly added;

[0092] Step F: 1 g of N1,N1-bis(4-methoxyphenyl)benzene-1,4-diamine, 1.80 g of 4-bromo-4'-methoxy-1,1'-biphenyl (2.2 equivalents), 20 mg of palladium acetate (0.08 equivalents), 758.4 mg of tri-tert-butylphosphine (1.2 equivalents) and 770 mg of potassium tert-butoxide (2.2 equivalents) were mixed, 60 mL of toluene solvent was added, and the mixture was reacted at 110° C. for 12 h to obtain 1.37 g of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine;

[0093] Step G: Weigh 48 mg of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine and dissolve it in 1 mL of chlorobenzene to prepare a solution with a concentration of 48 mg / mL;

[0094] Step H: Spin-coat the solution obtained in step G onto the surface of the perovskite light-absorbing layer 3 to obtain the hole transport layer 4 at a speed of 2500 rpm, a time of 35 s, and an acceleration of 2500 rpm / s;

[0095] Step I: Evaporate the top electrode 5 on the hole transport layer 4 to obtain a 75nm metal Au electrode, thereby completing the preparation of the perovskite solar cell.

[0096] Example 3

[0097] This embodiment uses N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine as a hole transport material to prepare a perovskite solar cell, which specifically includes the following steps:

[0098] Step A: providing a conductive glass substrate;

[0099] Step B: the conductive glass substrate is cleaned in sequence with a glass cleaning solution, deionized water and acetone in a volume ratio of 1:60, and after cleaning, the conductive glass substrate is blown dry with dry nitrogen, and after drying, the conductive glass substrate is cleaned with ultraviolet ozone for 25 minutes;

[0100] Step C: Mix the SnO2 nano-dispersion liquid with deionized water (volume ratio of 1:5), ultrasonically disperse for 15 minutes, and spin-coat the ultrasonically dispersed solution onto a conductive glass substrate by spin coating at a speed of 2950 rpm, a time of 15 seconds, and an acceleration of 3200 rpm / s. After the spin coating is completed, the conductive glass substrate is transferred to a heating table, heated and annealed at 155°C for 35 minutes, and then subjected to ultraviolet ozone treatment for 30 minutes to obtain a dense SnO2 electron transport layer;

[0101] Step D: 32.32 mg MACl, 718.56 mg PbI2 and 24.88 mg FAI were dissolved in 1 mL DMF and DMSO mixed solvent (volume ratio of 6:1), and stirred at 20 °C for 12 h to obtain a precursor solution;

[0102] Step E: The precursor solution is spin-coated onto the surface of the electron transport layer three times by spin coating. After the spin coating is completed, the conductive glass substrate is placed on a hot plate at 90° C. for annealing for 2 hours, and the perovskite light absorption layer is obtained after cooling. The first spin coating is performed at a rotation speed of 1050 rpm, a time of 8 seconds, and an acceleration of 1050 rpm / s. The second spin coating is performed at a rotation speed of 5500 rpm, a time of 15 seconds, and an acceleration of 5500 rpm / s. The third spin coating is performed at a rotation speed of 5500 rpm, a time of 8 seconds, and an acceleration of 5500 rpm / s. During the third spin coating, 125 μL of anti-solvent ethyl acetate is slowly added;

[0103] Step F: 1 g of N1,N1-bis(4-methoxyphenyl)benzene-1,4-diamine, 2.12 g of 4-bromo-4'-methoxy-1,1'-biphenyl (2.6 equivalents), 15 mg of palladium acetate (0.06 equivalents), 1137.6 mg of tri-tert-butylphosphine (1.8 equivalents) and 910 mg of sodium tert-butoxide (2.6 equivalents) were mixed, 60 mL of toluene solvent was added, and the mixture was reacted at 135° C. for 6 h to obtain 1.52 g of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine;

[0104] Step G: Weigh 52 mg of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine and dissolve it in 1 mL of chlorobenzene to prepare a solution with a concentration of 52 mg / mL;

[0105] Step H: Spin-coat the solution obtained in step G onto the surface of the perovskite light-absorbing layer 3 to obtain the hole transport layer 4 at a speed of 3500 rpm, a time of 25 s, and an acceleration of 3500 rpm / s;

[0106] Step I: Evaporate the top electrode 5 on the hole transport layer 4 to obtain a 88nm metal Au electrode, thereby completing the preparation of the perovskite solar cell.

[0107] Comparative Example 1

[0108] This comparative example adopts a preparation method similar to that of Example 1, using Spiro-OMeTAD as a hole transport material to prepare a perovskite solar cell, except that from step G to step F:

[0109] Step F: 520 mg of Li-TFSI was dissolved in 1 mL of acetonitrile solution to obtain a Li-TFSI solution, 300 mg of Co-TFSI was dissolved in 1 mL of acetonitrile solution to obtain a Co-TFSI solution, 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene, and the mixture was stirred to obtain a 72.3 mg / mL Spiro-OMeTAD solution;

[0110] Step G: 18 μL of Li-TFSI solution and 29 μL of Co-TFSI solution were added to the Spiro-OMeTAD solution and stirred at room temperature for 30 min to obtain a mixed solution;

[0111] Step H: Spin-coat the mixed solution obtained in step G onto the surface of the perovskite light-absorbing layer 3 to obtain the hole transport layer 4 at a speed of 3000 rpm, a time of 30 s, and an acceleration of 3000 rpm / s.

[0112] It should be noted that Comparative Example 1 is only to better reflect the influence of different hole transport materials on the performance of perovskite solar cell, and its steps are not prior art.

[0113] The perovskite solar cells prepared in Example 1 and Comparative Example 1 were tested for cell performance. Figure 3 The photovoltaic parameters of the perovskite solar cells prepared in Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0114] Table 1 Photovoltaic parameters of perovskite solar cells prepared in Examples 1 to 3 and Comparative Example 1

[0115]

[0116] from Figure 3 It can be seen that the cell performance of the perovskite solar cell prepared in Example 1 (PhN-MeO) is significantly better than that in Comparative Example 1 (Spiro-OMeTAD).

[0117] It can be seen from Table 1 that, compared with Comparative Document 1, the photovoltaic parameters of the perovskite solar cells prepared in Examples 1 to 3 of the present invention are significantly improved.

[0118] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A hole transport material, characterized in that: The chemical structure of the hole transport material is shown in Formula 1: In Formula 1, R is an alkyl group, and the number of carbon atoms in the alkyl group is less than or equal to 6.

2. The hole transport material according to claim 1, characterized in that R is selected from methyl or ethyl.

3. A method for synthesizing a hole transport material, characterized in that: For the synthesis of the hole transport material as claimed in claim 1 or 2, the synthesis method comprises the following steps: Step 1: Weigh and mix the reaction raw materials to obtain a raw material mixture; The reaction raw materials include N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine, 4-X-4'-alkoxy-1,1'-biphenyl, palladium acetate and tri-tert-butylphosphine, and X is Br or I; Step 2: Mix the raw material mixture with an organic solvent and react to obtain a hole transport material.

4. The method for synthesizing a hole transport material according to claim 3, characterized in that: The molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to 4-X-4'-alkoxy-1,1'-biphenyl is 1:2.2-2.6; and / or, the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to palladium acetate is 1:0.05-0.1; And / or, the molar ratio of N1,N1-bis(4-alkoxyphenyl)benzene-1,4-diamine to tri-tert-butylphosphine is 1:1.2-1.

8.

5. The method for synthesizing a hole transport material according to claim 3, characterized in that: In the step 2, the reaction temperature is 110-135° C., and the reaction time is 5-12 hours.

6. The method for synthesizing a hole transport material according to claim 3, characterized in that: The reaction raw materials also include potassium tert-butoxide or sodium tert-butoxide.

7. The method for synthesizing a hole transport material according to claim 6, characterized in that: The molar ratio of N1, N1-bis(4-alkoxyphenyl)benzene-1, 4-diamine to potassium tert-butoxide or sodium tert-butoxide is 1:2.2-2.

6.

8. A perovskite solar cell, comprising a conductive substrate, an electron transport layer, a perovskite light absorbing layer, a hole transport layer and a top electrode stacked in sequence, characterized in that: The hole transport layer comprises the hole transport material according to claim 1 or 2.

9. A method for preparing a perovskite solar cell, characterized in that: For the preparation of the perovskite solar cell according to claim 8, the preparation method comprises the following steps: Step a: providing a conductive substrate; Step b: forming an electron transport layer and a perovskite light absorption layer in sequence on the surface of the conductive substrate; Step c: coating an organic solution of a hole transport material on the surface of the perovskite light absorbing layer to form a hole transport layer; Step d: preparing a top electrode on the surface of the hole transport layer to obtain the perovskite solar cell.

10. The method for preparing a perovskite solar cell according to claim 9, characterized in that: The organic solution of the hole transport material is spin-coated onto the surface of the perovskite light absorption layer by spin coating, the spin coating speed is 2500-3500 rpm, the spin coating time is 25-35 s, the spin coating acceleration is 2500-3500 rpm / s, and the mass volume concentration of the hole transport material in the organic solution of the hole transport material is 48-52 mg / mL.

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