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

Abstract

The application discloses a kind of hole transport material and synthesis method, perovskite solar cell and preparation method, belong to solar cell technical field.In the present application, based on the chemical structure general formula of hole transport material: R is alkyl, the molecule more conducive to the transmission of hole that triphenylamine group constructs, the existence of N atom is more conducive to the transmission of charge, the existence of alkoxy can increase the transport capacity of molecule, can improve the device stability and photoelectric conversion efficiency of perovskite solar cell, solve the problem that synthesis difficulty of Spiro-OMeTAD in prior art, after doping Li, Co and tributyl phosphate, poor stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar cells, and particularly relates to a hole transport material and a synthesis method thereof, a perovskite solar cell and a preparation method thereof. BACKGROUND

[0002] As a new generation of photovoltaic material, the perovskite solar cell is usually made of a hole transport material Spiro-OMeTAD.

[0003] However, due to the difficulty in synthesizing Spiro-OMeTAD, the cost of the perovskite solar cell is large; in addition, after Spiro-OMeTAD is doped with Li, Co and tributyl phosphate (TBP), the stability thereof is poor, and it is not suitable for mass use. SUMMARY

[0004] In view of the above analysis, the application aims to provide a hole transport material and a synthesis method thereof, a perovskite solar cell and a preparation method thereof, and solve the problems of the difficulty in synthesizing Spiro-OMeTAD and poor stability after doping Li, Co and tributyl phosphate in the prior art.

[0005] The main purpose of the application is achieved by the following technical solutions.

[0006] In a first aspect, the application 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 a methyl group or an ethyl group.

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

[0011] Step 1: weighing and mixing 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-butyl phosphine, and X is Br or I;

[0013] Step 2: mixing the raw material mixture with an organic solvent to perform a reaction, and obtaining the 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℃, and the reaction time is 5-12h.

[0016] Optionally, the reaction raw material further comprises 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 application provides a perovskite solar cell, comprising a conductive substrate, an electron transport layer, a perovskite light absorption layer, a hole transport layer and a top electrode which are sequentially stacked, and the hole transport layer comprises the hole transport material provided in the first aspect.

[0019] In a fourth aspect, the present application provides a preparation method of a perovskite solar cell, which is used for the preparation of 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 absorption 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 on the surface of the perovskite light absorption layer by spin coating, the spin coating speed is 2500-3500rpm, the spin coating time is 25-35s, the spin coating acceleration is 2500-3500rpm / s, and the mass volume concentration of the hole transport material in the organic solution of the hole transport material is 48-52mg / mL.

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

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

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

[0028] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the structure specifically pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and together with the description serve to explain the principles of the present application.

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

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

[0032] Figure 3 A comparison diagram of the cell performance of the perovskite solar cells prepared by Comparative Example 1 and Example 1.

[0033] Reference signs:

[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 application are described in detail below with reference to the attached drawing figures, wherein the drawing figures form a part of this specification, and wherein the drawing figures together with the description serve to explain the principles of the present application.

[0036] In a first aspect, the present application provides a hole transport material, which is named as N1,N1-bis(4'-alkoxyl-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine in chemistry, and its chemical structure 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 methyl or ethyl in the alkyl group, and preferably is methyl.

[0039] Compared with the prior art, the hole transport material provided by the present application can replace the existing Spiro-OMeTAD, and is constructed based on a triphenylamine group. Since triphenylamine is a P-type semiconductor, it is more inclined to holes, which is conducive to the transmission of holes. The N atom itself has a lone pair of electrons, and mainly plays a role of charge transport in the molecule. The introduction of the N atom is more conducive to the transmission of charges. The O atom in the alkoxy group itself has a lone pair of electrons, and mainly plays a role of charge transport in the molecule. The introduction of the O atom is also conducive to the transmission of charges. Therefore, the perovskite solar cell prepared by using the hole transport material of the present application has basically no decay in photoelectric conversion efficiency, and has good device stability and photoelectric conversion efficiency.

[0040] In a second aspect, the present application provides a synthesis method of a hole transport material, which is used for synthesizing the hole transport material, and comprises the following steps:

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

[0042] Step 2: mixing the raw material mixture with an organic solvent (for example, toluene or xylene) to perform a reaction, so as to obtain the hole transport material.

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

[0044] In order to be able to regulate the yield of the reaction, exemplarily, 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-butyl phosphine is 1:1.2-1.8 (for example, 1:1.5).

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

[0047] Considering that by-products (i.e. hydrogen bromide or hydrogen iodide) will be produced in the above reaction process, in order to be able to consume the by-products and promote the progress of the reaction, the above reaction raw materials further include potassium tert-butoxide or sodium tert-butoxide, so that by adding potassium tert-butoxide or sodium tert-butoxide, it can react with the by-products produced, consume the by-products, and promote the forward progress of the reaction.

[0048] In order to be able to improve the reaction yield of potassium tert-butoxide or sodium tert-butoxide with the by-products, 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] The third aspect of the present application provides a perovskite solar cell, referring to Figure 2 , comprising a conductive substrate 1, an electron transport layer 2, a perovskite light absorption layer 3, a hole transport layer 4 and a top electrode 5 which are sequentially laminated, wherein the preparation raw material of the hole transport layer 4 comprises the hole transport material provided by the first aspect.

[0051] Compared with the prior art, the perovskite solar cell provided by the present application has basically the same beneficial effects as the hole transport material provided by the first aspect of the present application, which will not be described here.

[0052] In a fourth aspect, the present application 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: sequentially forming an electron transport layer 2 (for example, a SnO2 layer) and a perovskite light-absorbing layer 3 on the surface of the conductive substrate 1;

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

[0057] Compared with the prior art, the method for preparing a perovskite solar cell provided by the present application has basically the same beneficial effects as the perovskite solar cell provided by the second aspect of the present application, which will not be described here.

[0058] Specifically, the formation method of each layer is as follows:

[0059] For the formation method of the electron transport layer 2, comprising the following steps:

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

[0061] The solution after ultrasonic dispersion is spin-coated on 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] After the conductive substrate 1 coated with the electron transport material is transferred to a heating table for heating annealing and then ultraviolet ozone treatment, a dense electron transport layer 2 is obtained, wherein the heating annealing temperature is 135-160℃ (for example, 150℃), and the heating annealing time is 30-40 min.

[0063] For the formation method of the perovskite light-absorbing layer 3, comprising the following steps:

[0064] The perovskite precursor raw materials are mixed and stirred to obtain a precursor solution, wherein the composition of the perovskite precursor raw materials includes methylammonium chloride (MACI), 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 composition of the organic solvent includes N, N-dimethylformamide (DMF) and / or dimethyl sulfoxide (DMSO), preferably the composition of 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] The precursor solution is spin-coated onto the surface of the electron transport layer 2 by spin coating;

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

[0067] In order to improve the spin coating efficiency and quality, the spin coating of the precursor solution includes three stages (i.e., first spin coating, second spin coating, and third spin coating) 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 spin coating speed of the first spin coating is 900-1050rpm (for example, 1000rpm), the spin coating time is 8-12s (for example, 10s), and the spin coating acceleration is 900-1050rpm / s (for example, 1000rpm / s); the spin coating speed of the second spin coating is 4500-5500rpm (for example, 5000rpm), the spin coating time is 15-25s (for example, 20s), and the spin coating acceleration is 4500-5500rpm (for example, 5000rpm); 120μL of anti-solvent ethyl acetate is slowly added during the third spin coating process, and the spin coating speed of the third spin coating is 4500-5500rpm (for example, 5000rpm), the spin coating time is 8-12s (for example, 10s), and the spin coating acceleration is 4500-5500rpm (for example, 5000rpm).

[0069] For the formation method of the hole transport layer 4, the following steps are included:

[0070] 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 spin-coated onto the surface of the perovskite light-absorbing layer to obtain the 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 (for example, 50 mg / mL), the spin-coating speed is 2500-3500 rpm (for example, 3000 rpm), the spin-coating time is 25-35 s (for example, 30 s), and the spin-coating acceleration is 2500-3500 rpm / s (for example, 3000 rpm / s).

[0071] It can be understood that the above step c also includes a step of synthesizing the hole transport material before the step c. For the synthesis of the hole transport material, the synthesis method of the hole transport material provided in the second aspect of the present application can be used, and details are not described herein.

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

[0073] The conductive substrate 1 is sequentially subjected to water cleaning, water cleaning, organic solvent (for example, acetone) cleaning, drying, and ultraviolet ozone treatment (UVO), wherein the composition of the cleaning water includes a cleaning solution and water (for example, deionized water), the volume ratio of the cleaning solution to water is 1:40-60 (for example, 1:50), the organic solvent is acetone, the drying is nitrogen blowing drying, and the treatment time of the ultraviolet ozone cleaning is 20-30 min.

[0074] Example 1

[0075] In this embodiment, N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine is used as the 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: sequentially cleaning the conductive glass substrate with a glass cleaning solution with a volume ratio of 1:50, deionized water, and acetone, and then drying the conductive glass substrate with dry nitrogen, and then cleaning the conductive glass substrate with ultraviolet ozone for 20 min;

[0078] Step C: SnO2 nanodispersion was mixed with deionized water (volume ratio of 1:4) and ultrasonically dispersed for 18 min. The ultrasonically dispersed solution was spin-coated onto a conductive glass substrate at a speed of 3000 rpm for 30 s with an acceleration of 3000 rpm / s. After spin coating, the conductive glass substrate was transferred to a heating table and annealed at 150°C for 30 min, followed by ultraviolet ozone treatment for 25 min to obtain a dense SnO2 electron transport layer;

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

[0080] Step E: The precursor solution was spin-coated onto the surface of the electron transport layer in three times by spin coating. After spin coating, the conductive glass substrate was placed on a hot table at 100°C and annealed for 1 h. After cooling, a perovskite light absorption layer was obtained. The first spin coating was performed at a speed of 1000 rpm for 10 s with an acceleration of 1000 rpm / s, the second spin coating was performed at a speed of 5000 rpm for 20 s with an acceleration of 5000 rpm / s, and the third spin coating was performed at a speed of 5000 rpm for 10 s with an acceleration of 5000 rpm / s. During the third spin coating, 120 μL of anti-solvent ethyl acetate was 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 equivalent), 948 mg of tri-tert-butyl phosphine (1.5 equivalents) and 875 mg of potassium tert-butoxide (2.5 equivalents) were mixed, 60 mL of solvent toluene 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: 50 mg of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine was dissolved in 1 mL of chlorobenzene to prepare a solution with a concentration of 50 mg / mL;

[0083] Step H: The solution obtained in step G was spin-coated onto the surface of the perovskite light absorption layer 3 by spin coating to obtain a hole transport layer 4 at a speed of 3000 rpm for 30 s with an acceleration of 3000 rpm / s;

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

[0085] Example 2

[0086] In this example, N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4- methoxyphenyl)benzene-1,4-diamine is used 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: sequentially using a volume ratio of 1:42 glass cleaning solution aqueous solution, deionized water and acetone to clean the conductive glass substrate, and then using dry nitrogen to dry the conductive glass substrate after cleaning, and then using ultraviolet ozone to clean the conductive glass substrate for 30 min after drying;

[0089] Step C: mixing SnO2 nanodispersion liquid with deionized water (volume ratio of 1:3), ultrasonic dispersion for 20 min, and using spin coating to spin coat the ultrasonic dispersion solution onto the conductive glass substrate, the rotation speed is 2800 rpm, the time is 20 s, and the acceleration is 2600 rpm / s, after spin coating, the conductive glass substrate is transferred to a heating table, and after heating annealing at 135℃ for 40 min, ultraviolet ozone treatment is performed for 28 min to obtain a dense SnO2 electron transport layer;

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

[0091] Step E: using spin coating to spin coat the precursor solution onto the surface of the electron transport layer three times, and after spin coating, the conductive glass substrate is placed on a hot table at 120℃ for 0.5h, and after cooling, a perovskite light absorbing layer is obtained, wherein the first spin coating: the rotation speed is 900 rpm, the time is 12 s, and the acceleration is 900 rpm / s, the second spin coating: the rotation speed is 4500 rpm, the time is 25 s, and the acceleration is 4500 rpm / s, the third spin coating: the rotation speed is 4500 rpm, the time is 12 s, and the acceleration is 4500 rpm / s, and 110 μL of anti-solvent ethyl acetate is slowly added during the third spin coating;

[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 eq), 20 mg of palladium acetate (0.08 eq), 758.4 mg of tri-tert-butylphosphine (1.2 eq), and 770 mg of potassium tert-butoxide (2.2 eq) were mixed, 60 mL of solvent toluene was added, and the reaction was carried out 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: 48 mg of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine was weighed and dissolved in 1 mL of chlorobenzene to prepare a solution with a concentration of 48 mg / mL;

[0094] Step H: The solution obtained in Step G was spin-coated onto the surface of the perovskite light-absorbing layer 3 by spin coating at a speed of 2500 rpm for 35 s with an acceleration of 2500 rpm / s to obtain a hole transport layer 4;

[0095] Step I: A top electrode 5 was evaporated on the hole transport layer 4 to obtain a 75 nm metal Au electrode, and the preparation of the perovskite solar cell was completed.

[0096] Example 3

[0097] In this example, N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine was used as a hole transport material to prepare a perovskite solar cell, which specifically included the following steps:

[0098] Step A: A conductive glass substrate was provided;

[0099] Step B: The conductive glass substrate was sequentially cleaned with a glass cleaning solution, deionized water, and acetone in a volume ratio of 1:60, and then dried with dry nitrogen after cleaning. The conductive glass substrate was cleaned with ultraviolet ozone for 25 min after drying;

[0100] Step C: SnO2 nanodispersion was mixed with deionized water (volume ratio of 1:5) and ultrasonically dispersed for 15 min. The ultrasonically dispersed solution was spin-coated onto the conductive glass substrate using spin coating at a speed of 2950 rpm for 15 s with an acceleration of 3200 rpm / s. After spin coating, the conductive glass substrate was transferred to a heating stage and annealed at 155°C for 35 min, followed by ultraviolet ozone treatment for 30 min to obtain a dense SnO2 electron transport layer;

[0101] Step D: 32.32 mg of MACl, 718.56 mg of PbI2and 24.88 mg of FAI were dissolved in 1 mL of 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 was spin-coated onto the surface of the electron transport layer in three times by spin coating, and after spin coating, the conductive glass substrate was placed on a hot stage at 90°C and annealed for 2 h, and after cooling, a perovskite light absorption layer was obtained, wherein the first spin coating: the rotation speed was 1050 rpm, the time was 8 s, and the acceleration was 1050 rpm / s, the second spin coating: the rotation speed was 5500 rpm, the time was 15 s, and the acceleration was 5500 rpm / s, the third spin coating: the rotation speed was 5500 rpm, the time was 8 s, and the acceleration was 5500 rpm / s, and 125 μL of anti-solvent ethyl acetate was slowly added during the third spin coating;

[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 times the equivalent), 15 mg of palladium acetate (0.06 times the equivalent), 1137.6 mg of tri-tert-butyl phosphine (1.8 times the equivalent) and 910 mg of sodium tert-butoxide (2.6 times the equivalent) were mixed, 60 mL of solvent toluene was added, and 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: 52 mg of N1,N1-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-N4,N4-bis(4-methoxyphenyl)benzene-1,4-diamine was weighed and dissolved in 1 mL of chlorobenzene to prepare a solution with a concentration of 52 mg / mL;

[0105] Step H: The solution obtained in step G was spin-coated onto the surface of the perovskite light absorption layer 3 by spin coating to obtain a hole transport layer 4, the speed was 3500 rpm, the time was 25 s, and the acceleration was 3500 rpm / s;

[0106] Step I: A top electrode 5 was evaporated on the hole transport layer 4 to obtain a 88 nm metal Au electrode, and the preparation of the perovskite solar cell was completed.

[0107] Comparative Example 1

[0108] This comparative example used a similar preparation method as Example 1, and Spiro-OMeTAD was used as a hole transport material to prepare a perovskite solar cell, the difference being that steps G to 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, and 72.3 mg of Spiro-OMeTAD was dissolved in 1 mL of chlorobenzene to obtain a 72.3 mg / mL Spiro-OMeTAD solution;

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

[0111] Step H: The mixed solution obtained in Step G was spin-coated onto the surface of the perovskite light-absorbing layer 3 by spin coating to obtain a hole transport layer 4, at a speed of 3000 rpm for 30 s, with 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 the perovskite solar cell, and the steps are not prior art.

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

[0114] Table 1 Photovoltaic parameters of the perovskite solar cells prepared in Examples 1-3 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 of Comparative Example 1 (Spiro-OMeTAD).

[0117] From Table 1, it can be seen that the photovoltaic parameters of the perovskite solar cells prepared in Examples 1-3 of the present application are all significantly improved compared to Comparative Example 1.

[0118] The above description is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed in the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application.​

Claims

1. A hole transport material, characterized in that, The general chemical structural formula 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 described 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)phenyl-1,4-diamine, 4-X-4'-alkoxy-1,1'-biphenyl, palladium acetate and tri-tert-butylphosphine, where X is Br or I; Step 2: The raw material mixture is mixed with an organic solvent and then reacted to obtain a hole transport material.

4. The method for synthesizing hole transport materials according to claim 3, characterized in that, The molar ratio of N1,N1-bis(4-alkoxyphenyl)phenyl-1,4-diamine to 4-X-4'-alkoxy-1,1'-biphenyl is 1:2.2 to 2.6; And / or, the molar ratio of N1,N1-bis(4-alkoxyphenyl)phenyl-1,4-diamine to palladium acetate is 1:0.05 to 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 to 1.

8.

5. The method for synthesizing hole transport materials according to claim 3, characterized in that, In step 2, the reaction temperature is 110–135°C and the reaction time is 5–12 h.

6. The method for synthesizing hole transport materials 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 hole transport materials 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 to 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 sequentially, characterized in that, The hole transport layer comprises the hole transport material as described in claim 1 or 2.

9. A method for fabricating a perovskite solar cell, characterized in that, The method for preparing the perovskite solar cell as described in claim 8 includes the following steps: Step a: Provide a conductive substrate; Step b: An electron transport layer and a perovskite light-absorbing layer are sequentially formed on the surface of the conductive substrate; Step c: Coat the surface of the perovskite light-absorbing layer with an organic solution of hole transport material to form a hole transport layer; Step d: Prepare 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 hole transport material was spin-coated onto the surface of the perovskite light absorption layer using a spin-coating method. The spin-coating speed was 2500-3500 rpm, the spin-coating time was 25-35 s, the spin-coating acceleration was 2500-3500 rpm / s, and the mass-volume concentration of hole transport material in the organic solution was 48-52 mg / mL.

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