Perovskite cell and preparation method thereof, laminated cell and photovoltaic module

Abstract

The invention provides a perovskite cell, the perovskite cell comprises a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer and an electrode, and the hole transport layer comprises a hole transport material. The hole transport material is a tetrathienopyrrolyl D-pi type organic polymer hole transport material, and the material is a polyvinyl tetrathienopyrrolyl polymer containing different side chain groups Ar. A p orbit occupied by heteroatoms (S, N) is conjugated with a p orbit of an aromatic unit, so that a stronger electron donating characteristic is provided, the stability of molecules is favorably improved, and the problem that the efficiency of a battery is influenced due to poor thermal stability, instability and insufficient HOMO energy level of a hole transport material is solved. The invention also provides a method for preparing the perovskite cell, and a laminated cell and a photovoltaic module comprising the perovskite cell.

Description

Technical Field

[0001] This application relates to the technical field of novel hole transport materials for perovskite solar cells, and mainly relates to a perovskite solar cell, a preparation method thereof, a tandem solar cell, and a photovoltaic module. Background Art

[0002] Perovskite solar cells (PSCs) are devices that use perovskite-type organometallic halide semiconductors as light-absorbing materials to directly convert light energy into electrical energy through the photovoltaic effect. Among them, the inverted structure of PSCs shows great potential in commercial applications. Continuously developing novel hole transport materials is a key factor in fabricating efficient and stable perovskite solar cells. Polymer hole transport materials have great potential in realizing large-area inverted perovskite solar cells due to their excellent film-forming properties, solvent resistance, and low-cost printing technologies. In inverted perovskite solar cells, the hole transport material, as an important transport layer material between the perovskite layer and the transparent electrode, is responsible for hole extraction and transport, blocking electron flow, and directly affects the crystallization and film formation of perovskite, playing a decisive role in improving the performance of the battery and realizing large-area commercial applications.

[0003] Hole transport materials can generally be divided into inorganic hole transport materials and organic hole transport materials. Although inorganic hole transport materials have lower costs and higher hole mobilities, their solvents may dissolve the perovskite layer, resulting in a decrease in device performance and limiting their large-scale use. Common polymer hole transport materials still have some non-negligible defects. For example, the inherent acidity and hygroscopicity of PEDOT:PSS will corrode and accelerate the degradation of perovskite materials, which will affect the stability of inverted PSCs; PTAA has attracted attention due to its high hole mobility and good film-forming properties. However, the cost of PTAA is extremely high, reaching 1980 $ / g, which increases the manufacturing cost of the device. At the same time, the strong hydrophobicity of PTAA may lead to poor interfacial contact with the perovskite layer, affecting the hole extraction and transport efficiency. More importantly, the HOMO energy level of PTAA is relatively shallow, which may limit its effective collection of photo-generated holes in perovskite solar cells, thus affecting the photoelectric conversion efficiency of the battery. In addition to PEDOT:PSS and PTAA, other organic hole transport materials such as Spiro-OMeTAD also generally have poor thermal stability. Under high-temperature conditions, the molecular structures of these materials are prone to change, resulting in a decrease in hole mobility and a decline in battery performance. This lack of thermal stability limits the application of perovskite solar cells in high-temperature environments.

[0004] Therefore, the present application provides a perovskite solar cell, a preparation method thereof, a tandem solar cell, and a photovoltaic module to solve the problem that the performance of the solar cell is affected due to the poor thermal stability, instability, and insufficiently deep HOMO energy level of the hole transport material. Summary of the Invention

[0005] To solve the problem that the efficiency of the solar cell is affected due to the poor thermal stability, instability, and insufficiently deep HOMO energy level of the hole transport material, the present application provides a perovskite solar cell, which includes a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode. The hole transport layer includes a hole transport material, and the structural formula of the hole transport material is any one of the following two:

[0006]

[0007] The present application provides a perovskite solar cell, and the hole transport layer of the cell includes a hole transport material. The hole transport material is a tetrathienopyrrole-based D-π type organic polymer hole transport material, specifically a polyvinyltetrathienopyrrole material. As a multifunctional electron-rich thiophene-fused heterocyclic unit, tetrathienopyrrole (BTP) has a more planar structure and more heteroatoms compared with the commonly used thiophene unit in HTMs. The p orbitals occupied by heteroatoms (S, N) are conjugated with the p orbitals of the aromatic unit, enhancing the π-π stacking of the molecule and providing stronger electron-donating properties. This structural feature not only improves the stability of the molecule but also promotes the effective transport of holes.

[0008] At the same time, the S atom can have a certain interaction with Pb in the perovskite, 2+ which can passivate the interface defects on the perovskite surface. Moreover, the electron-rich N atom in BTP can improve the stability of the organic semiconductor material in the oxidized state, enabling the optoelectronic device to have long-term operating stability, and has been proven to be a successful core unit for constructing high-performance organic HTMs.

[0009] 2PA-BTP is connected by a specific conjugated bridging group to form a D-π-D type structure, where D represents the BTP donor unit. This structure ensures that the material has a high hole mobility and good stability. 4PA-BTP is similar to 2PA-BTP and forms a more complex D-π-D type structure. This structure further enhances the hole transport ability and stability of the material, and may also bring higher photoelectric conversion efficiency. It solves the problem that the efficiency of the solar cell is affected due to the poor thermal stability, instability, and insufficiently deep HOMO energy level of the hole transport material.

[0010] Both 2PA-BTP and 4PA-BTP hole transport materials have good solubility in solvents such as dimethyl sulfoxide, N,N'-dimethylformamide, toluene, chlorobenzene, and dichloromethane; they have a relatively high decomposition temperature, excellent thermal stability, good film-forming properties, good wettability with perovskite precursor solvents, which is helpful for the crystallization and film formation of perovskite. Moreover, they have good mobility, which is beneficial to the extraction and transport of holes, and have a relatively deep HOMO energy level that matches the perovskite.

[0011] 2PA-BTP and 4PA-BTP can be used in inverted quasi-two-dimensional perovskite solar cells without doping any additives and have repeatability, indicating that the compounds described in the present invention have good application prospects.

[0012] This application also provides a method for preparing a perovskite solar cell for preparing the above-mentioned perovskite solar cell, which includes the following steps: sequentially laminating the hole transport layer, perovskite absorption layer, electron transport layer, and electrode on the transparent conductive substrate. Among them, the preparation step of the hole transport layer includes coating the above-mentioned hole transport material configured as a solution onto the transparent conductive substrate, and the preparation method of the hole transport material includes the following steps:

[0013] S1: After dissolving the first raw material in dry THF, degas the mixture and rinse it with N2, stir at 0 °C for 10 - 15 min, then dissolve NBS in THF and add it dropwise to the reaction solution, continue the reaction at 0 °C for 3 - 5 hours, quench the reaction with deionized water, extract and dry with DCM, and distill under reduced pressure. After purification by chromatography, the first product is obtained, and the structural formula of the first raw material is:

[0014]

[0015] S2: Mix the first product, tetrabutylammonium bromide, KOH, and the second raw material, react at 65 - 70 °C for 12 - 24 h, then extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the second product after purification;

[0016] S3: React the second product with triethyl phosphite at 140 - 150 °C for 12 - 16 h, then extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the third product after purification;

[0017] S4: Put the third product, thiophene-2,5-diboronic acid bis(pinacol) ester, tetrakis(triphenylphosphine)palladium, and potassium carbonate into a solvent and mix them, react at 80 - 90 °C for 8 - 16 h. The solvent is toluene, ethanol, and water, and the volume ratio of toluene, ethanol, and water is 2:1:1. After the reaction, extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the fourth product after purification and drying;

[0018] S5: Dissolve the fourth product in 1,4-dioxane, add trimethylsilyl bromide dropwise at 25 °C, then stir overnight. After removing the solvent, dissolve the obtained solid powder in methanol, add deionized water dropwise, stir and react until the mixture becomes opaque, and then stir for 10 - 16 hours. After filtration, washing and purification, the hole transport material is obtained.

[0019] Optionally, the molar ratio of the first raw material to NBS in S1 is 1:(2.2 - 3).

[0020] Optionally, the molar ratio of the first product, tetrabutylammonium bromide, KOH, and the second raw material in S2 is 1:

[0021] (0.1 - 0.2):(5 - 10):(50 - 200).

[0022] Optionally, the molar ratio of the second product to triethyl phosphite in S3 is 1:(25 - 50).

[0023] Optionally, the molar ratio of the third product, thiophene-2,5-diboronic acid bis(pinacol) ester, tetrakis(triphenylphosphine)palladium, and potassium carbonate in S4 is 1:(2.2 - 3):(0.01 - 0.1):(4 - 10).

[0024] Optionally, the molar ratio of the fourth product to trimethylsilyl bromide in S5 is 1:(8 - 15).

[0025] This application also provides a tandem cell, including: a top cell, which is the above-mentioned perovskite cell; a crystalline silicon bottom cell, which is located on the side of the transparent conductive substrate of the perovskite cell away from the electrode.

[0026] This application also provides a photovoltaic module, including: a plurality of the above-mentioned tandem cells; a connecting component, which is used to connect adjacent tandem cells; a glue film, which covers the surface of the tandem cells; a cover plate, which is located on the surface of the glue film away from the tandem cells.

[0027] The present application provides a perovskite solar cell, which includes a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode. The hole transport layer includes a hole transport material. The hole transport material is a tetrathienopyrrole-based D-π type organic polymer hole transport material, and this type of material is a polyvinyltetrathienopyrrole polymer containing different side chain groups Ar. The p orbitals occupied by heteroatoms (S, N) are conjugated with the p orbitals of the aromatic units, providing stronger electron-donating properties, which helps to improve the stability of the molecule and solves the problem that the efficiency of the solar cell is affected due to the poor thermal stability, instability, and insufficiently deep HOMO energy level of the hole transport material. The present application also provides a method for preparing the above-mentioned perovskite solar cell, as well as a tandem solar cell and a photovoltaic module including the above-mentioned perovskite solar cell. Description of the Drawings

[0028] To more clearly illustrate the technical solutions of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0029] Figure 1 Schematic diagram of the battery structure provided by the embodiment of the present application;

[0030] Figure 2 1H NMR spectrum of 2PA-BTP;

[0031] Figure 3 1H NMR spectrum of 4PA-BTP;

[0032] Figure 4 Schematic diagram of the process for preparing the hole transport material;

[0033] Figure 5 Schematic diagram of the synthesis route of 2PA-BTP;

[0034] Figure 6 Schematic diagram of the synthesis route of 4PA-BTP;

[0035] Figure 7 Short-circuit current density - open-circuit voltage curve. Detailed Description of the Embodiments

[0036] The embodiments will be described in detail below, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following examples do not represent all embodiments consistent with the present application. They are merely examples of systems and methods consistent with some aspects of the present application detailed in the claims.

[0037] To solve the problem that the efficiency of the battery is affected due to the poor thermal stability, instability, and insufficiently deep HOMO energy level of the hole transport material, the present application provides a perovskite battery. The perovskite battery includes a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode. The transparent conductive substrate is ITO glass, and the electrode includes chromium and gold. The structure of the perovskite battery is as shown in Figure 1 shown. The hole transport layer includes a hole transport material, and the structural formula of the hole transport material is any one of the following two:

[0038]

[0039] Figure 2 is the 1H NMR spectrum of 2PA-BTP, Figure 3 is the 1H NMR spectrum of 4PA-BTP.

[0040] The present application provides a perovskite battery. The hole transport layer of the perovskite battery includes a hole transport material. The hole transport material is a tetrathienopyrrole-based D-π type organic polymer hole transport material, specifically a polyvinyltetrathienopyrrole material. As a multifunctional electron-rich thiophene-fused heterocyclic unit, tetrathienopyrrole BTP has a more planar structure and more heteroatoms compared with the commonly used thiophene unit in HTMs. The p orbitals occupied by heteroatoms (S, N) are conjugated with the p orbitals of the aromatic unit, enhancing the π-π stacking of the molecule and providing stronger electron-donating properties. This structural feature not only improves the stability of the molecule but also promotes the effective transport of holes.

[0041] At the same time, the S atom can have a certain interaction with Pb in the perovskite 2+ and can passivate the interface defects on the surface of the perovskite. Moreover, the electron-rich N atom in BTP can improve the stability of the organic semiconductor material in the oxidized state, enabling the optoelectronic device to have long-term operational stability and has been proven to be a successful core unit for constructing high-performance organic HTMs.

[0042] 2PA-BTP is connected through a specific conjugated bridging group to form a D-π-D type structure, where D represents the BTP donor unit. This structure ensures that the material has high hole mobility and good stability. 4PA-BTP is similar to 2PA-BTP and forms a more complex D-π-D type structure. This structure further enhances the hole transport ability and stability of the material and may bring higher photoelectric conversion efficiency. It solves the problem that the efficiency of the battery is affected due to the poor thermal stability, instability, and insufficiently deep HOMO energy level of the hole transport material.

[0043] In some embodiments, the present application further provides a method for preparing a perovskite solar cell for preparing the above-mentioned perovskite solar cell, including the following steps: sequentially stacking a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode on a transparent conductive substrate. Among them, the preparation step of the hole transport layer includes coating the above-mentioned hole transport material on the transparent conductive substrate after configuring it into a solution. The preparation method of the hole transport material includes the following steps:

[0044] S1: After dissolving the first raw material in dry THF, degas the mixture and rinse it with N2, stir at 0 °C for 10 - 15 min, then dissolve NBS in THF and add it dropwise to the reaction solution, continue the reaction at 0 °C for 3 - 5 hours, quench the reaction with ionic water, extract and dry with DCM, and distill under reduced pressure. After purification by chromatography, the first product is obtained. The structural formula of the first raw material is:

[0045]

[0046] S2: Mix the first product, tetrabutylammonium bromide, KOH with the second raw material, react at 65 - 70 °C for 12 - 24 h, then extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the second product after purification. The second raw material is 1,2-dibromoethane or 1,4-dibromobutane;

[0047] S3: React the second product with triethyl phosphite at 140 - 150 °C for 12 - 16 h, then extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the third product after purification;

[0048] S4: Mix the third product with thiophene-2,5-diboronic acid bis(pinacol) ester, tetrakis(triphenylphosphine)palladium, and potassium carbonate in a solvent and react at 80 - 90 °C for 8 - 16 h. The solvent is toluene, ethanol, and water, and the volume ratio of toluene, ethanol, and water is 2:1:1. After the reaction, extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the fourth product after purification and drying;

[0049] S5: Dissolve the fourth product in 1,4-dioxane, add trimethylbromosilane dropwise at 25 °C, then stir overnight. After removing the solvent, dissolve the obtained solid powder in methanol, add deionized water dropwise, stir and react until the mixture becomes opaque, then stir for 10 - 16 hours. After filtration, washing, and purification, the hole transport material is obtained.

[0050] Specifically, the flowchart of the preparation method of the hole transport material is as Figure 4 , and the prepared products include 2PA-BTP and 4PA-BTP. The specific synthesis steps are as follows:

[0051] Reaction step a: Weigh raw material I and add it into a 500 mL three-necked flask. Then add 30 mL of dry THF. After degassing the mixture, rinse it with N2 gas and stir at 0 °C for 10 - 15 min. Then dissolve NBS in THF and add it dropwise into the mixture, and continue the reaction at 0 °C for 3 - 5 hours. Quench the reaction with 50 mL of deionized water, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, distill under reduced pressure, and finally purify it by column chromatography to obtain monomer I. The molar ratio of raw material I to NBS is 1:(2.2 - 3).

[0052] Reaction step b: Under the protection of inert gas, dissolve monomer I, tetrabutylammonium bromide, and KOH in raw material II (or raw material II') for a substitution reaction. The reaction temperature is 65 - 70 °C and the reaction time is 12 - 24 h. After the reaction is completed, quench the reaction with water, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, distill under reduced pressure, separate and purify the crude product with a silica gel chromatography column, and dry it under vacuum to obtain monomer II (or monomer II'). The molar ratio of monomer I, tetrabutylammonium bromide, KOH, and raw material II (or raw material II') is 1:(0.1 - 0.2):(5 - 10):(50 - 200).

[0053] Reaction step c: Under the protection of inert gas, react monomer II (or monomer II') with triethyl phosphite. The reaction temperature is 140 - 160 °C and the reaction time is 12 - 16 h. Cool to room temperature, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, distill under reduced pressure, and obtain the crude product monomer III (or monomer III'). The molar ratio of monomer II (or monomer II') to triethyl phosphite is 1:(25 - 50).

[0054] Reaction step d: Under the protection of inert gas, put monomer III (or monomer III'), 2,5 - diboronic acid dipinacol ester of thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate into a solvent. The solvent is toluene, ethanol, and water (volume ratio 2:1:1). The reaction temperature is 80 - 90 °C and the reaction time is 6 - 16 h. Cool to room temperature, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, distill under reduced pressure, separate and purify the crude product with a silica gel chromatography column, and dry it under vacuum to obtain monomer IV (or monomer IV'). The molar ratio of monomer III (or monomer III'), 2,5 - diboronic acid dipinacol ester of thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:(2.2 - 3):(0.01 - 0.1):(4 - 10).

[0055] Reaction step e: Under the protection of an inert gas, dissolve monomer Ⅳ (or monomer Ⅳ') in 1,4-dioxane at 25 °C, add trimethylbromosilane dropwise, and then stir overnight. Remove the solvent using a rotary evaporator to obtain a solid powder. Dissolve the solid powder in methanol at room temperature, and then dropwise add deionized water until the mixture becomes opaque, and then stir for 10 - 16 hours. The crude product is collected by filtration and washed with deionized water. The crude product is dissolved in THF and reprecipitated in propane, and then filtered to obtain the final compound material 2PA-BTP or 4PA-BTP. The molar ratio of monomer Ⅳ (or monomer Ⅳ') to trimethylbromosilane is 1:(8 - 15).

[0056] In some embodiments, the method for preparing a perovskite solar cell comprises the following steps:

[0057] (1) Cleaning: Ultrasonically clean the ITO glass substrate with deionized water, acetone, and ethanol in sequence for 15 - 20 minutes, then use an N2 gas gun to blow dry the solvent remaining on the ITO surface, then perform oxygen plasma treatment for 10 - 15 minutes, and subsequently transfer the ITO glass substrate to a nitrogen glove box.

[0058] (2) Preparation of the hole transport layer: Weigh 3 - 15 mg of the above-mentioned tetrathienopyrrole-based D-π type organic polymer hole transport material and completely dissolve it in 1 mL of chlorobenzene solution. Take an appropriate amount of the solution and uniformly drop it onto the ITO glass substrate, spin-coat at 4000 - 5000 rpm for 20 - 30 seconds, and then anneal at 90 - 110 °C for 10 minutes to obtain the ITO / hole transport layer substrate.

[0059] (3) Preparation of the perovskite layer: Cool the obtained ITO / hole transport layer substrate to room temperature, preheat it at 130 - 140 °C for 3 - 5 minutes, take 50 μl of the perovskite solution and spread it evenly on the ITO / hole transport layer substrate, spin-coat at 3000 - 5000 rpm for 20 - 30 seconds, and then anneal at 90 - 100 °C for 10 minutes to obtain the ITO / hole transport layer / perovskite substrate. The perovskite solution is prepared by mixing 3-bromo-benzylammonium iodide or 3-chlorobenzylammonium iodide, methylammonium chloride, and lead iodide in a certain molar ratio in DMF and DMSO.

[0060] (4) Preparation of the electron transport layer: Cool the obtained ITO / hole transport layer / perovskite substrate to room temperature, prepare a solution of PC61BM at 15 mg / mL, then take 40 μl of the PC61BM solution and spread it evenly on the ITO / hole transport layer / perovskite substrate, spin-coat at 1000 rpm for 30 - 50 seconds to obtain the ITO / hole transport layer / perovskite layer / electron transport layer substrate.

[0061] (5) Preparation of the electrode: Place the above-mentioned substrate in a vacuum evaporation chamber, and deposit Cr (6 nm) and Au (80 nm) on the PC61BM layer respectively to obtain the required inverted quasi-two-dimensional perovskite solar cell.

[0062] Example 1:

[0063] The synthetic route of 2PA-BTP is as Figure 5 shown. The specific steps for synthesizing the first 2PA-BTP are as follows:

[0064] Synthesis of Compound 2: Add Compound 1 (10.8 mmol), copper(I) iodide (10.8 mmol), DMEDA (12.96 mmol), and potassium carbonate (37.81 mmol) to freshly distilled toluene (40 mL) and deionized water (0.1 mL). After degassing the mixture, flush it with nitrogen, and then add benzamide (12.96 mmol). The reaction is refluxed at 110 °C for 2 days. Cool to room temperature, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, distill under reduced pressure, and finally purify it by column chromatography (PE:DCM = 6:1) to obtain Compound 2 with a yield of 49%.

[0065] Synthesis of Compound 3: Weigh Compound 2 (3 mmol) and add it to a 500 mL three-necked flask. Then add 30 mL of dry THF. After degassing the mixture, flush it with N2 gas and stir at 0 °C for 10 min. Then dissolve NBS in THF (20 mL) and add it dropwise to the mixture. Continue the reaction at 0 °C for 3 hours. Quench the reaction with 50 mL of deionized water, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, distill under reduced pressure, and finally purify it by column chromatography (PE:DCM = 6:1) to obtain solid Compound 3 with a yield of 90%. Among them, the molar ratio of Compound 2 to NBS is 1:2.2.

[0066] Synthesis of Compound 4: Add Compound 3 (2.72 mmol) to a 100 mL two-necked flask. Dissolve tetrabutylammonium bromide in dibromoethane and then dropwise add 50% aqueous potassium hydroxide solution. Heat the mixture to 65 °C and then stir overnight for 12 h. Quench the reaction with water, extract with dichloromethane, combine and dry the organic layer with anhydrous magnesium sulfate, and then remove the organic solvent with a rotary evaporator to obtain the crude product. Use silica gel column chromatography with an eluent of petroleum ether / dichloromethane = 10 / 1 for further purification to obtain Compound 4 (yield 81%). Among them, the molar ratio of Compound 3, tetrabutylammonium bromide, KOH, and dibromoethane is 1:0.1:5:50.

[0067] Synthesis of Compound 5: Add Compound 4 (2.4 mmol) and triethyl phosphite into a 100 mL two-necked flask. Then heat the mixture to 160 °C and stir overnight under a nitrogen atmosphere for 12 h. Then remove the organic solvent using a rotary evaporator to obtain crude Compound 5 with a yield of 83%. The molar ratio of Compound 4 to triethyl phosphite is 1:25.

[0068] Synthesis of Compound 6: Add Compound 5 (1 mmol), 2,5-bis(pinacolato)diboron thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate into a 100 mL two-necked flask. The solvent is toluene, ethanol, and water (in a ratio of 2:1:1). React at 85 °C for 6 h. Cool to room temperature, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, and distill under reduced pressure. Finally, purify by column chromatography (PE:DCM = 4:1) to obtain Compound 6 with a yield of 60%. The molar ratio of Compound 5, 2,5-bis(pinacolato)diboron thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:2.2:0.01:4.

[0069] Synthesis of 2PA-BTP: Add Compound 6 into a 100 mL two-necked flask in anhydrous 1,4-dioxane (10 mL) at room temperature. Dropwise add trimethylsilyl bromide (20 mmol), and then stir overnight. Remove 1,4-dioxane using a rotary evaporator to obtain a solid powder. Dissolve the solid powder in methanol (10 mL) at room temperature, and then dropwise add deionized water until the mixture becomes opaque, and stir for another 12 h. Collect the crude product by filtration and wash with deionized water. Dissolve the crude product in THF (5 mL) and reprecipitate in acetone (20 mL), and filter to obtain the final product, the first 2PA-BTP (yield 53%). The molar ratio of Compound 6 to trimethylsilyl bromide is 1:8.

[0070] Example 2:

[0071] The steps for synthesizing the second 2PA-BTP are basically the same as those in Example 1, and the differences from Example 1 are as follows:

[0072] In the step of preparing Compound 3, the molar ratio of Compound 2 to NBS is 1:3. After flushing with N2 gas, stir at 0 °C for 15 min, then dissolve NBS in THF (20 mL) and add it dropwise into the mixture, and continue to react at 0 °C for 5 h. Obtain solid Compound 3 with a yield of 91%.

[0073] In the step of preparing Compound 4, the molar ratio of Compound 3, tetrabutylammonium bromide, KOH, and dibromoethane is 1:0.2:10:200. Heat the mixture to 70 °C and then stir overnight for 24 h. Obtain Compound 4 with a yield of 83%.

[0074] In the step of preparing Compound 5, the molar ratio of Compound 4 to triethyl phosphite is 1:50. The mixture is heated to 140 °C and stirred overnight under a nitrogen atmosphere for 16 h. Compound 5 is obtained with a yield of 85%.

[0075] In the step of preparing Compound 6, the molar ratio of Compound 5, 2,5-bis(pinacolborane)thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:3:0.1:10. The reaction is carried out at 80 °C for 16 hours. Compound 6 is obtained with a yield of 65%.

[0076] In the step of preparing 2PA-BTP, the molar ratio of Compound 6 to trimethylsilyl bromide is 1:15. The mixture is stirred for 10 hours. The second 2PA-BTP is obtained with a yield of 55%.

[0077] Example 3:

[0078] The step of synthesizing the third 2PA-BTP is basically the same as the preparation method in Example 1, and the difference from Example 1 is as follows:

[0079] In the step of preparing Compound 3, the molar ratio of Compound 2 to NBS is 1:2.5. After flushing with N2 gas, the mixture is stirred at 0 °C for 13 min, then NBS is dissolved in THF (20 mL) and added dropwise to the mixture, and the reaction continues at 0 °C for 4 hours. Solid Compound 3 is obtained with a yield of 87%.

[0080] In the step of preparing Compound 4, the molar ratio of Compound 3, tetrabutylammonium bromide, KOH, and 1,2-dibromoethane is 1:0.15:7:65. The mixture is heated to 67 °C and then stirred overnight for 18 h. Compound 4 is obtained with a yield of 80%.

[0081] In the step of preparing Compound 5, the molar ratio of Compound 4 to triethyl phosphite is 1:35. The mixture is heated to 160 °C and stirred overnight under a nitrogen atmosphere for 14 h. Compound 5 is obtained with a yield of 86%.

[0082] In the step of preparing Compound 6, the molar ratio of Compound 5, 2,5-bis(pinacolborane)thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:2.5:0.05:7. The reaction is carried out at 90 °C for 12 hours. Compound 6 is obtained with a yield of 62%.

[0083] In the step of preparing 2PA-BTP, the molar ratio of Compound 6 to trimethylsilyl bromide is 1:9. The mixture is stirred for 16 hours. The third 2PA-BTP is obtained with a yield of 51%.

[0084] Comparative Example 1:

[0085] The steps for synthesizing Comparative 2PA-BTP are basically the same as the preparation method in Example 1, and the differences from Example 1 are as follows:

[0086] In the step of preparing Compound 3, the molar ratio of Compound 2 to NBS is 1:5. After flushing with N2 gas, it is stirred at 0 °C for 10 min, then NBS is dissolved in THF (20 mL) and added dropwise to the mixture, and the reaction continues at 0 °C for 3 hours. Solid Compound 3 is obtained with a yield of 75%.

[0087] In the step of preparing Compound 4, the molar ratio of Compound 3, tetrabutylammonium bromide, KOH, and 1,2-dibromoethane is 1:0.5:15:20. The mixture is heated to 50 °C and then stirred overnight for 10 h. Compound 4 is obtained with a yield of 63%.

[0088] In the step of preparing Compound 5, the molar ratio of Compound 4 to triethyl phosphite is 1:20. The mixture is heated to 160 °C and stirred overnight under a nitrogen atmosphere for 16 h. Compound 5 is obtained with a yield of 73%.

[0089] In the step of preparing Compound 6, the molar ratio of Compound 5, 2,5-bis(pinacolborane)thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:5:0.01:2, and the reaction is carried out at 85 °C for 6 hours. Compound 6 is obtained with a yield of 50%.

[0090] In the step of preparing 2PA-BTP, the molar ratio of Compound 6 to trimethylsilyl bromide is 1:5, and it is stirred for 12 hours. Comparative 2PA-BTP is obtained with a yield of 35%.

[0091] Example 4:

[0092] The synthesis route of 4PA-BTP is as Figure 6 shown, and the specific steps for synthesizing the first 4PA-BTP are as follows:

[0093] Synthesis of Compound 2: Compound 1 (10.8 mmol), copper(I) iodide (10.8 mmol), DMEDA (12.96 mmol), and potassium carbonate (37.81 mmol) are added to freshly distilled toluene (40 mL) and deionized water (0.1 mL). After the mixture is degassed, it is flushed with nitrogen, and then benzamide (12.96 mmol) is added. The reaction refluxes at 110 °C for 2 days. It is cooled to room temperature, the mixture is extracted with DCM, the organic phase is dried over anhydrous Mg2SO4, filtered, distilled under reduced pressure, and finally purified by column chromatography (PE:DCM = 6:1) to obtain Compound 2 with a yield of 49%.

[0094] Synthesis of Compound 3: Weigh Compound 2 (3 mmol) and add it to a 500 mL three-necked flask. Then add 30 mL of dry THF. After degassing the mixture, rinse it with N2 gas and stir at 0 °C for 10 min. Then dissolve NBS in THF (20 mL) and add it dropwise to the mixture. Continue the reaction at 0 °C for 3 h. Quench the reaction with 50 mL of deionized water, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, and distill under reduced pressure. Finally, purify it by column chromatography (PE:DCM = 6:1) to obtain solid Compound 3 with a yield of 90%. Among them, the molar ratio of Compound 2 to NBS is 1:2.2.

[0095] Synthesis of Compound 7: Add Compound 3 (2.72 mmol) to a 100 mL two-necked flask. Dissolve tetrabutylammonium bromide in dibromobutane and then add 50% aqueous potassium hydroxide dropwise. Heat the mixture to 65 °C and then stir overnight for 12 h. Quench the reaction with water, extract with dichloromethane, combine and dry the organic layer with anhydrous magnesium sulfate, and then remove the organic solvent with a rotary evaporator to obtain the crude product. Further purify it by silica gel column chromatography with an eluent of petroleum ether / dichloromethane = 10 / 1 to obtain Compound 7 (yield 83%). Among them, the molar ratio of Compound 3, tetrabutylammonium bromide, KOH, and dibromobutane is 1:0.1:5:50.

[0096] Synthesis of Compound 8: Add Compound 7 (2.4 mmol) and triethyl phosphite to a 100 mL two-necked flask. Then heat the mixture to 140 °C and stir overnight under a nitrogen atmosphere for 12 h. Then remove the organic solvent with a rotary evaporator to obtain crude Compound 8 (2.1 mmol) with a yield of 89%. Among them, the molar ratio of Compound 7 to triethyl phosphite is 1:25.

[0097] Synthesis of Compound 9: Add Compound 8 (1 mmol), 2,5-bis(pinacolato)diboron thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate to a 100 mL two-necked flask. The solvent is toluene, ethanol, and water (in a ratio of 2:1:1). React at 80 °C for 6 h. Cool to room temperature, extract the mixture with DCM, dry the organic phase with anhydrous Mg2SO4, filter, and distill under reduced pressure. Finally, purify it by column chromatography (PE:DCM = 4:1) to obtain Compound 9 with a yield of 64%. Among them, the molar ratio of Compound 8, 2,5-bis(pinacolato)diboron thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:2.2:0.01:4.

[0098] Synthesis of 4PA-BTP: Add compound 9 to a 100 mL two-necked flask in anhydrous 1,4-dioxane (10 mL) at room temperature. Dropwise add trimethylsilyl bromide (20 mmol), and then stir overnight. Remove 1,4-dioxane using a rotary evaporator to obtain a solid powder. Dissolve the solid powder in methanol (10 mL) at room temperature, and then dropwise add deionized water until the mixture becomes opaque. Stir for another 10 hours. The crude product is collected by filtration and washed with deionized water. The crude product is dissolved in THF (5 mL) and reprecipitated in acetone (20 mL). Filter to obtain the final product as the first 4PA-BTP (yield 55%). The molar ratio of compound 9 to trimethylsilyl bromide is 1:8.

[0099] Example Five:

[0100] The steps for synthesizing the second 4PA-BTP are basically the same as the preparation method in Example Four. The differences from Example Four are as follows:

[0101] In the step of preparing compound 3, the molar ratio of compound 2 to NBS is 1:3. After flushing with N2 gas, stir at 0 °C for 15 min. Then dissolve NBS in THF (20 mL) and add it dropwise to the mixture. Continue the reaction at 0 °C for 5 hours. Obtain solid compound 3 with a yield of 92%.

[0102] In the step of preparing compound 7, the molar ratio of compound 3, tetrabutylammonium bromide, KOH, and 1,2-dibromobutane is 1:0.2:10:200. Heat the mixture to 70 °C and then stir overnight for 24 h. Obtain compound 7 with a yield of 81%.

[0103] In the step of preparing compound 8, the molar ratio of compound 7 to triethyl phosphite is 1:50. Heat the mixture to 160 °C and stir overnight under a nitrogen atmosphere for 16 h. Obtain compound 8 with a yield of 88%.

[0104] In the step of preparing compound 9, the molar ratio of compound 8, 2,5-bis(pinacolato)diboron, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:3:0.1:10. React at 90 °C for 16 hours. Obtain compound 9 with a yield of 66%.

[0105] In the step of preparing 4PA-BTP, the molar ratio of compound 9 to trimethylsilyl bromide is 1:15. Stir for 16 hours. Obtain the second 4PA-BTP with a yield of 57%.

[0106] Example Six:

[0107] The steps for synthesizing the third 4PA-BTP are basically the same as the preparation method in Example Four. The differences from Example Four are as follows:

[0108] In the step of preparing Compound 3, the molar ratio of Compound 2 to NBS is 1:2.5. After flushing with N2 gas, the mixture is stirred at 0 °C for 13 min, then NBS is dissolved in THF (20 mL) and added dropwise to the mixture, and the reaction continues at 0 °C for 4 h. Compound 3 solid is obtained with a yield of 89%.

[0109] In the step of preparing Compound 7, the molar ratio of Compound 3, tetrabutylammonium bromide, KOH, and 1,4-dibromobutane is 1:0.15:7:80. The mixture is heated to 68 °C and then stirred overnight for 24 h. Compound 7 is obtained with a yield of 81%.

[0110] In the step of preparing Compound 8, the molar ratio of Compound 7 to triethyl phosphite is 1:34. The mixture is heated to 150 °C and stirred overnight under a nitrogen atmosphere for 14 h. Compound 8 is obtained with a yield of 88%.

[0111] In the step of preparing Compound 9, the molar ratio of Compound 8, 2,5-bis(pinacolato)diboron, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:2.7:0.05:7. The reaction is carried out at 85 °C for 8 h. Compound 9 is obtained with a yield of 61%.

[0112] In the step of preparing 4PA-BTP, the molar ratio of Compound 9 to trimethylsilyl bromide is 1:12, and the mixture is stirred for 12 h. The third 4PA-BTP is obtained with a yield of 53%.

[0113] Comparative Example 2:

[0114] The steps for synthesizing the comparative 4PA-BTP are basically the same as the preparation method in Example 4, and the differences from Example 4 are as follows:

[0115] In the step of preparing Compound 3, the molar ratio of Compound 2 to NBS is 1:5. After flushing with N2 gas, the mixture is stirred at 0 °C for 20 min, then NBS is dissolved in THF (20 mL) and added dropwise to the mixture, and the reaction continues at 0 °C for 2 h. Compound 3 solid is obtained with a yield of 80%.

[0116] In the step of preparing Compound 7, the molar ratio of Compound 3, tetrabutylammonium bromide, KOH, and 1,4-dibromobutane is 1:0.5:2:40. The mixture is heated to 80 °C and then stirred overnight for 18 h. Compound 7 is obtained with a yield of 75%.

[0117] In the step of preparing Compound 8, the molar ratio of Compound 7 to triethyl phosphite is 1:20. The mixture is heated to 160 °C and stirred overnight under a nitrogen atmosphere for 14 h. Compound 8 is obtained with a yield of 80%.

[0118] In the step of preparing Compound 9, the molar ratio of Compound 8, 2,5-bis(pinacolborane)thiophene, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:4:0.2:3, and the reaction is carried out at 85 °C for 6 hours. Compound 9 is obtained with a yield of 50%.

[0119] In the step of preparing 4PA-BTP, the molar ratio of Compound 9 and trimethylsilyl bromide is 1:7, and the mixture is stirred for 12 hours. Comparative 4PA-BTP is obtained with a yield of 40%.

[0120] The thermal stabilities of 2PA-BTP and 4PA-BTP were evaluated. Using a thermogravimetric analyzer, the first 2PA-BTP, the second 2PA-BTP, the third 2PA-BTP, comparative 2PA-BTP, the first 4PA-BTP, the second 4PA-BTP, the third 4PA-BTP, and comparative 4PA-BTP were subjected to thermogravimetric analysis. N2 was selected as the program protection gas, the purge flow rate was set at 20 cm3 / min, the starting temperature was set at 25 °C, and the heating rate was 10 °C / min.

[0121] The thermal decomposition temperature of comparative 2PA-BTP is 221 °C, and the thermal decomposition temperature of comparative 4PA-BTP is 202 °C. The measured curves were analyzed, and the average thermal decomposition temperatures of the first 2PA-BTP, the second 2PA-BTP, and the third 2PA-BTP; the average thermal decomposition temperatures of the first 4PA-BTP, the second 4PA-BTP, and the third 4PA-BTP were calculated. The average thermal decomposition temperatures of the products 2PA-BTP and 4PA-BTP are shown in Table 1. (Td, 5% weight loss)

[0122] Table 1 Thermal decomposition temperatures of 2PA-BTP and 4PA-BTP

[0123]

[0124] Both 2PA-BTP and 4PA-BTP have excellent thermal stabilities. Among them, the thermal stabilities of comparative 2PA-BTP and comparative 4PA-BTP are significantly worse than those of the first 2PA-BTP, the second 2PA-BTP, the third 2PA-BTP, the first 4PA-BTP, the second 4PA-BTP, and the third 4PA-BTP; the Td value of 2PA-BTP is 298 °C, indicating its good thermal stability and its ability to maintain structural integrity under the high-temperature preparation or working conditions of battery devices. Compared with 4PA-BTP (Td = 259 °C), the thermal decomposition temperature of 2PA-BTP is increased by 39 °C, indicating that its molecular structure (such as conjugation degree, substituent steric hindrance) is more conducive to thermal stability and is suitable as a hole transport layer material for high-efficiency perovskite batteries.

[0125] Example Seven

[0126] Preparation of Perovskite Solar Cell I:

[0127] (1) Cleaning: The ITO glass substrate was ultrasonically cleaned with deionized water, acetone, and ethanol in sequence for 15 minutes, and then the residual solvent on the ITO surface was blown dry using an N2 gas gun. Subsequently, it was subjected to oxygen plasma treatment for 10 minutes, and then the ITO glass substrate was transferred to a nitrogen glove box.

[0128] (2) Preparation of the hole transport layer: 3 mg of the first 2PA - BTP was weighed and completely dissolved in 1 mL of chlorobenzene solution. An appropriate amount of the solution was evenly dropped onto the ITO glass substrate and spin - coated at 4000 rpm for 20 seconds, and then annealed at 90 °C for 10 minutes to obtain the ITO / hole transport layer substrate.

[0129] (3) Preparation of the perovskite layer: The obtained ITO / hole transport layer substrate was cooled to room temperature, pre - heated at 130 °C for 3 minutes, 50 μl of perovskite solution was spread over the ITO / hole transport layer substrate, spin - coated at 3000 rpm for 20 seconds, and then annealed at 90 °C for 10 minutes to obtain the ITO / hole transport layer / perovskite substrate. The perovskite solution was prepared by mixing 3 - bromo - benzylammonium iodide, methylammonium chloride, and lead iodide in DMF and DMSO.

[0130] (4) Preparation of the electron transport layer: The obtained ITO / hole transport layer / perovskite substrate was cooled to room temperature, PC61BM was configured into a 15 mg / mL solution, and then 40 μl of the PC61BM solution was spread over the ITO / hole transport layer / perovskite substrate and spin - coated at 1000 rpm for 30 seconds to obtain the ITO / hole transport layer / perovskite layer / electron transport layer substrate.

[0131] (5) Preparation of the electrode: The above - mentioned substrate was placed in a vacuum evaporation chamber, and Cr (6 nm) and Au (80 nm) were respectively evaporated onto the PC61BM layer to obtain Perovskite Solar Cell I.

[0132] Example VIII:

[0133] Preparation of Perovskite Solar Cell II. The steps for preparing Perovskite Solar Cell II are basically the same as those in Example VII, and the differences from Example VII are as follows:

[0134] In (1), the ITO glass substrate was ultrasonically cleaned for 20 minutes and subjected to oxygen plasma treatment for 15 minutes.

[0135] In (2), 15 mg of the second 2PA - BTP was weighed, spin - coated at 5000 rpm for 30 seconds, and annealed at 110 °C for 10 minutes.

[0136] In (3), preheat at 140 °C for 5 minutes, take 50 μl of perovskite solution to cover the ITO / hole transport layer substrate, spin-coat at 5000 rpm for 30 seconds, and then anneal at 100 °C for 10 minutes.

[0137] In (4), spin-coat at 1000 rpm for 50 seconds.

[0138] Example Nine:

[0139] Prepare perovskite solar cell three. The preparation steps of perovskite solar cell three are basically the same as those of Example Seven. The difference from Example Seven is as follows:

[0140] In (1), ultrasonically clean the ITO glass sheet for 17 minutes and perform oxygen plasma treatment for 13 minutes.

[0141] In (2), weigh 12 mg of the third 2PA-BTP, spin-coat at 4500 rpm for 27 seconds, and anneal at 100 °C for 10 minutes.

[0142] In (3), preheat at 135 °C for 4 minutes, take 50 μl of perovskite solution to cover the ITO / hole transport layer substrate, spin-coat at 3500 rpm for 25 seconds, and then anneal at 97 °C for 10 minutes.

[0143] In (4), spin-coat at 1000 rpm for 35 seconds.

[0144] Comparative Example Three:

[0145] Prepare comparative perovskite solar cell one. The preparation steps of comparative perovskite solar cell one are basically the same as those of Example Nine. The difference is that the hole transport material in step (2) is replaced with comparative 2PA-BTP to obtain comparative perovskite solar cell one.

[0146] Example Ten:

[0147] Replace the hole transport material in step (2) of the method in Example Seven with the first 4PA-BTP to obtain perovskite solar cell four.

[0148] Example Eleven:

[0149] Replace the hole transport material in step (2) of the method in Example Seven with the second 4PA-BTP to obtain perovskite solar cell five.

[0150] Example Twelve:

[0151] Replace the hole transport material in step (2) of the method in Example Seven with the third 4PA-BTP to obtain perovskite solar cell six.

[0152] Comparative Example Four:

[0153] Replace the hole transport material in step (2) of Example 7 with Comparative 4PA-BTP to prepare Comparative Perovskite Cell II.

[0154] Under the illumination condition of AM 1.5G, at a speed of 0.02V s -1 The performance of Perovskite Cell I - Perovskite Cell VI, Comparative Perovskite Cell I and Comparative Perovskite Cell II were measured by forward and reverse scans. The detailed photovoltaic indexes open circuit voltage (Vo c ), short circuit current density (Js c ), fill factor (FF) and power conversion efficiency (PCE) are shown in Table 2. The short circuit current density - open circuit voltage curves of the best devices among them are as Figure 7 shown, which are Cell I and Cell V respectively.

[0155] Table 2 Test results of the performance of each cell

[0156] Battery Photovoltaic conversion efficiency / % External circuit voltage / / V <![CDATA[Short-circuit current / mA·cm 2 > Fill factor / % Perovskite solar cell one 19.00 1.21 20.77 75.82 Perovskite solar cell two 18.80 1.20 20.60 75.50 Perovskite solar cell three 18.90 1.21 20.70 75.70 Comparative perovskite solar cell one 12.00 1.05 16.00 68.00 Perovskite solar cell four 18.70 1.20 20.50 75.30 Perovskite solar cell five 20.24 1.21 20.98 79.69 Perovskite solar cell six 19.00 1.21 20.75 76.00 Comparative perovskite solar cell two 11.50 1.00 15.50 67.00

[0157] According to the above experimental results, the two tetrathienopyrrole-based D-π type organic polymer hole transport materials (2PA-BTP and 4PA-BTP) provided by this application both exhibit excellent performance. The perovskite cells (Perovskite Cell I, Perovskite Cell II, Perovskite Cell III, Perovskite Cell IV, Perovskite Cell V and Perovskite Cell VI) prepared with the hole transport materials provided by this application all exhibit good optoelectronic performance. The power conversion efficiencies of these cells are all between 18.70% and 20.24%, the open circuit voltage is between 1.20V and 1.21V, the short circuit current density is between 20.50mA·cm 2 to 20.98mA·cm 2 and the fill factor is between 75.30% and 79.69%.

[0158] The optoelectronic performance of Comparative Perovskite Cell I and Comparative Perovskite Cell II prepared with comparative materials (Comparative 2PA-BTP and Comparative 4PA-BTP) is significantly worse. The power conversion efficiency of Comparative Perovskite Cell I is 12.00%, and the power conversion efficiency of Comparative Perovskite Cell II is even as low as 11.50%. This shows that the hole transport materials provided by this application have significant advantages in improving the performance of perovskite cells.

[0159] Relatively speaking, the power conversion efficiency of 2PA-BTP is slightly better than that of 4PA-BTP. Specifically, in terms of power conversion efficiency, Cell V using 2PA-BTP as the hole transport layer reaches the highest power conversion efficiency of 20.24%.

[0160] The present application also provides a tandem cell, comprising: a top cell, which is the above-mentioned perovskite cell; a crystalline silicon bottom cell, which is located on the side of the transparent conductive substrate of the perovskite cell away from the electrode.

[0161] Tandem cells usually stack two or more different types of solar cells (such as perovskite cells and crystalline silicon cells) to utilize their respective absorption advantages in different spectral ranges, thereby improving the photoelectric conversion efficiency of the entire photovoltaic system.

[0162] A crystalline silicon bottom cell refers to a solar cell that uses crystalline silicon as the substrate material. Crystalline silicon includes single-crystalline silicon and polycrystalline silicon, which are one of the most commonly used materials in solar cells. Crystalline silicon bottom cells have high photoelectric conversion efficiency, good stability, and long service life. Different technical routes and structures (such as PERC, TOPCon, HJT, etc.) can be implemented on the crystalline silicon substrate to meet different application requirements. The PERC cell is fully called "emitter and rear passivated cell". The PERC cell improves the light absorption and electron collection efficiency at the back of the cell by introducing a silicon oxide film at the back of the cell, thereby improving the photoelectric conversion efficiency of the cell. The TOPCon cell is fully called "tunnel oxide passivated contact cell", which is a solar cell using tunnel oxide passivated contact. It reduces surface defects by adding an oxide layer, improves electron lifetime and carrier collection efficiency, and also has good stability and long service life. The HJT cell is fully called "intrinsic thin-film heterojunction cell", which is a solar cell using a heterostructure and an extremely thin intrinsic layer. The HJT cell combines the advantages of traditional silicon-based solar cells and organic thin-film solar cells, has high conversion efficiency, low temperature coefficient, and long life. It adopts a design that reduces the cell thickness and multi-layer structure, and can provide more stable power output in high-temperature and low-light environments.

[0163] When sunlight irradiates the tandem cell, the perovskite cell first absorbs short-wavelength photons and generates photo-generated carriers (electrons and holes), and then these carriers are collected on the electrodes of the top cell through the electron transport layer and the hole transport layer respectively. At the same time, the crystalline silicon cell absorbs long-wavelength photons and generates corresponding photo-generated carriers, and these carriers are also collected on the electrodes of the bottom cell

[0164] In some embodiments, the tandem cell further includes a top cell and an amorphous silicon bottom cell.

[0165] The present application also provides a photovoltaic module, comprising: a plurality of the above-mentioned tandem cells; a connecting member, which is used to connect adjacent tandem cells; a glue film, which covers the surface of the tandem cells; and a cover plate, which is located on the surface of the glue film away from the tandem cells.

[0166] The present application provides a perovskite solar cell, which includes a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode. The hole transport layer includes a hole transport material. The hole transport material is a tetrathienopyrrole-based D-π type organic polymer hole transport material, and this type of material is a polyvinyltetrathienopyrrole polymer containing different side chain groups Ar. The p orbitals occupied by heteroatoms (S, N) are conjugated with the p orbitals of the aromatic unit, providing stronger electron-donating properties, which helps to improve the stability of the molecule and solves the problem that the efficiency of the battery is affected due to the poor thermal stability, instability, and insufficiently deep HOMO energy level of the hole transport material. The present application also provides a method for preparing the above perovskite solar cell, as well as a tandem solar cell and a photovoltaic module including the above perovskite solar cell.

[0167] For the similar parts among the embodiments provided in the present application, reference can be made to each other. The specific embodiments provided above are only several examples under the general concept of the present application and do not constitute a limitation on the protection scope of the present application. For those skilled in the art, any other embodiments extended based on the solution of the present application without creative efforts belong to the protection scope of the present application.

Claims

1. A perovskite solar cell, characterized in that, The perovskite solar cell includes a transparent conductive substrate, a hole transport layer, a perovskite absorption layer, an electron transport layer, and an electrode. The hole transport layer includes a hole transport material, and the structural formula of the hole transport material is any one of the following I and II:

2. A method for preparing a perovskite solar cell, which is used to prepare the perovskite solar cell according to claim 1, characterized in that, Comprising the following steps: The hole transport layer, the perovskite absorption layer, the electron transport layer, and the electrode are sequentially stacked on the transparent conductive substrate. Among them, the preparation step of the hole transport layer includes coating the hole transport material as described in claim 1 on the transparent conductive substrate after configuring it into a solution. The preparation method of the hole transport material includes the following steps: S1: After dissolving the first raw material in dry THF, degassing the mixture and flushing it with N2, stirring at 0 °C for 10 - 15 min, then dissolving NBS in THF and adding it dropwise to the reaction solution, continuing the reaction at 0 °C for 3 - 5 hours, quenching the reaction with ionic water, extracting and drying with DCM, and distilling under reduced pressure. After purification by chromatography, the first product is obtained. The structural formula of the first raw material is: S2: Mix the first product, tetrabutylammonium bromide, KOH, and the second raw material, react at 65 - 70 °C for 12 - 24 h, then extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the second product after purification; S3: React the second product with triethyl phosphite at 140 - 150 °C for 12 - 16 h, then extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the third product after purification; S4: Put the third product, thiophene-2,5-diboronic acid bis(pinacol) ester, tetrakis(triphenylphosphine)palladium, and potassium carbonate into a solvent and mix them, react at 80 - 90 °C for 8 - 16 h. The solvent is toluene, ethanol, and water, and the volume ratio of toluene, ethanol, and water is 2:1:

1. After the reaction, extract the mixture with DCM, dry the organic phase, filter, distill under reduced pressure, and obtain the fourth product after purification and drying; S5: Dissolve the fourth product in 1,4-dioxane, dropwise add trimethylbromosilane at 25 °C, then stir overnight. After removing the solvent, dissolve the obtained solid powder in methanol, dropwise add deionized water, stir and react until the mixture becomes opaque, then stir for 10 - 16 hours. After filtration, washing, and purification, the hole transport material is obtained.

3. The preparation method of the perovskite battery according to claim 2, wherein, In S1, the molar ratio of the first raw material to NBS is 1:(2.2 - 3).

4. The preparation method of the perovskite battery according to claim 2, wherein, In S2, the second raw material is 1,2-dibromoethane or 1,4-dibromobutane.

5. The preparation method of the perovskite battery according to claim 2, wherein, In S2, the molar ratio of the first product, tetrabutylammonium bromide, KOH, and the second raw material is 1:(0.1 - 0.2):(5 - 10):(50 - 200).

6. The preparation method of the perovskite battery according to claim 2, wherein, In S3, the molar ratio of the second product to triethyl phosphite is 1:(25 - 50).

7. The preparation method of the perovskite battery according to claim 2, wherein In S4, the molar ratio of the third product, thiophene-2,5-diboronic acid bis(pinacol) ester, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:(2.2 - 3):(0.01 - 0.1):(4 - 10).

8. The preparation method of the perovskite battery according to claim 2, wherein In S5, the molar ratio of the fourth product to trimethylbromosilane is 1:(8 - 15).

9. A stacked battery, characterized in that, Including: a top cell, wherein the top cell is the perovskite cell described in claim 1; a crystalline silicon bottom cell, which is located on the side of the transparent conductive substrate of the perovskite cell away from the electrode.

10. A photovoltaic module, characterized in that, comprising: a plurality of stacked cells as described in claim 9; connecting components, which are used to connect adjacent stacked cells; a glue film, which covers the surface of the stacked cells; a cover plate, which is located on the surface of the glue film away from the stacked cells.

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