Perovskite solar cell and method of manufacturing the same

Abstract

The application provides a perovskite solar cell and a preparation method thereof. The perovskite solar cell comprises a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer and a second electrode layer which are sequentially stacked, the material of the hole transport layer comprises PTAA and a quinoxaline thienyl polymer or a derivative thereof, and the mass ratio of the two is (2-10):1. The perovskite solar cell provided in the application can effectively improve the surface wettability of the hole transport layer by using the quinoxaline thienyl polymer or the derivative thereof and the PTAA as the material of the hole transport layer, and can greatly reduce the non-uniformity problem of the perovskite thin film generated in the preparation process of the large-area perovskite layer.

Description

Technical Field

[0001] This invention relates to solar cells, and more specifically, to a perovskite solar cell and its fabrication method. Background Technology

[0002] As a third-generation solar cell technology, perovskite solar cells have attracted widespread attention due to their lighter weight, longer exciton diffusion length, solution-processable nature, and low cost, with their photoelectric conversion efficiency exceeding 25%. In perovskite solar cells, the interfacial charge transport layer material between the electrode and the perovskite photoactive layer is crucial for achieving high efficiency and high stability. To date, the most widely used hole transport layer material in nip-structured perovskite solar cells is Spiro-OMeTAD, a metal salt dopant. However, perovskite solar cells using Spiro-OMeTAD as the hole transport layer suffer from significant stability issues.

[0003] Furthermore, due to the weak bonding in organic-inorganic hybrid perovskites and the inherent instability of organic salt compounds, organic cations tend to escape from the perovskite crystals during thermal annealing, leading to an imbalance in the stoichiometry of the perovskite and resulting in numerous defects at the grain boundaries and surface. These defects become charge recombination centers, which are closely related to the photovoltaic performance and stability of the device. Therefore, employing a high-quality hole transport layer is crucial for reducing defects and suppressing charge recombination at the electrode interface of perovskite solar cells.

[0004] The organic polymer PTAA possesses good thermal stability and an amorphous morphology, exhibiting excellent solubility in common organic solvents. It serves as a suitable hole transport layer material in both nip and pin-structured perovskite solar cells. However, it also has some inherent limitations. First, for wide-bandgap perovskite solar cells employing pin structures, especially when used in all-perovskite tandem solar cells, an energy level below -5.7 eV is typically required. PTAA, however, has a relatively high HOMO energy level of approximately -5.1 eV. This significant HOMO energy level difference between perovskite and PTAA leads to substantial voltage drops, thus limiting the open-circuit voltage of wide-bandgap perovskite solar cells. Second, PTAA films exhibit relatively poor surface wettability to perovskite precursor solutions, making the deposition of high-quality wide-bandgap perovskite films difficult. Therefore, improving the wettability and HOMO energy level of PTAA is crucial for achieving efficient and stable wide-bandgap perovskite solar cells.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The main objective of this invention is to provide a perovskite solar cell and its preparation method, in order to solve the problems of relatively high HOMO energy level and poor wettability in existing perovskite solar cells using PTAA as the hole transport layer material.

[0007] To achieve the above objectives, according to one aspect of the present invention, a perovskite solar cell is provided, comprising a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode layer sequentially stacked thereon. The hole transport layer is made of a first polymer and a second polymer, with a mass ratio of (2-10):1. The first polymer is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and the second polymer is a quinoxalothiophene polymer or a derivative thereof, wherein the quinoxalothiophene polymer has the structure shown in formula (I):

[0008]

[0009] Wherein, 0≤x≤1; Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, halogen, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C1-C15 alkoxy, substituted or unsubstituted C1-C15 alkylthio, or substituted or unsubstituted C1-C15 silyl; n represents an integer between 100,000 and 1,000,000; the number average molecular weight of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] is 12,000 to 18,000.

[0010] Furthermore, Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, halogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 alkylthio, or substituted or unsubstituted C1-C10 silyl.

[0011] Furthermore, Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, F, substituted or unsubstituted C1-C4 alkyl, substituted or unsubstituted C1-C4 alkoxy, substituted or unsubstituted C1-C4 alkylthio, or substituted or unsubstituted C1-C4 silyl.

[0012] Furthermore, the quinoxalothiophene polymer is selected from at least one of PTQ7 to PTQ11:

[0013]

[0014] Furthermore, the hole transport layer is prepared by: mixing and dispersing a quinoxalothiophene polymer or its derivative with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in an organic solvent to obtain a polymer mixed solution; spin-coating the polymer mixed solution onto the surface of the first electrode layer, removing the organic solvent, thus forming the hole transport layer.

[0015] Furthermore, the thickness of the hole transport layer is 30–60 nm.

[0016] Furthermore, the first electrode layer and the second electrode layer are each independently a cathode layer or an anode layer, and the two have different polarities.

[0017] According to a second aspect of the present invention, a method for preparing the above-mentioned perovskite solar cell is also provided. The method includes: step S1, providing a first electrode layer and spin-coating a hole transport layer on the surface of the first electrode layer; step S2, spin-coating a perovskite layer on the surface of the hole transport layer; step S3, evaporating an electron transport layer on the surface of the perovskite layer; and step S4, evaporating a second electrode layer on the surface of the electron transport layer to obtain a perovskite solar cell.

[0018] Further, in step S1, the material of the first electrode layer is ITO, and the first electrode layer includes an ITO substrate layer and strip-shaped ITO disposed on the ITO substrate layer. The thickness of the ITO substrate layer is 1.0 to 1.2 mm, and the thickness of the strip-shaped ITO is 100 to 200 nm.

[0019] Furthermore, the first electrode layer is formed by etching ITO conductive glass; preferably, before spin-coating the hole transport layer, a surface treatment step is included for the first electrode layer, and more preferably, the surface treatment is plasma treatment for 3 to 5 minutes.

[0020] Further, in step S2, the material of the perovskite layer is Cs. 0.2 FA 0.8 Pb(I 0.6 Br 0.4 )3, with a thickness of 500-1000nm.

[0021] Furthermore, the method for preparing the perovskite layer is as follows: Cs 0.2 FA 0.8 Pb(I 0.6 Br 0.4 The solution was coated onto the hole transport layer, and then subjected to antisolvent and annealing treatments to obtain a perovskite layer.

[0022] Further, in step S3, the electron transport layer includes a C60 layer and a SnO2 layer, the thicknesses of the C60 layer and the SnO2 layer being 10–30 nm and 15–25 nm, respectively.

[0023] Furthermore, the electron transport layer is prepared by first depositing C60 onto the surface of the perovskite layer by vacuum evaporation to form a C60 layer, and then depositing SnO2 onto the surface of the C60 layer by vacuum evaporation to form a SnO2 layer, thus obtaining the electron transport layer.

[0024] Further, in step S4, the material of the second electrode layer is Au, and the thickness is 100-120 nm.

[0025] By applying the technical solution of this application, the perovskite solar cell provided by this application, through the use of quinoxalothiophene polymer or its derivatives and PTAA as materials for the hole transport layer, can effectively improve the surface wettability of the hole transport layer and significantly reduce the inhomogeneity problem of the perovskite film during the preparation of large-area perovskite layers. More importantly, it can effectively adjust the HOMO energy level of the hole transport layer, so that it matches the energy level of the wide-bandgap perovskite layer better, ensuring efficient hole extraction and transport, effectively suppressing non-radiative recombination losses at the bulk phase and interface, improving the open-circuit voltage and fill factor of the perovskite solar cell, which is conducive to the large-scale commercial application of perovskite solar cells. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0027] In this application, the term "substituted or unsubstituted" means substituted by one or more substituents selected from the following: deuterium; halogen group; nitrile group; nitro group; hydroxyl group; carbonyl group; ester group; imide group; amino group; phosphine oxide group; alkoxy group; aryloxy group; alkyl thio group; aryl thio group; alkyl sulfonyl group; silyl group; boron group; alkyl group; cycloalkyl group; alkenyl group; or without substituents, or substituted by substituents linked by two or more substituents of the exemplified substituents, or without substituents.

[0028] As analyzed in the background section of this application, existing perovskite solar cells using PTAA as the hole transport layer material suffer from several drawbacks. Firstly, the high HOMO energy level leads to significant voltage loss. Secondly, the poor surface wettability of the PTAA-formed hole transport layer on the perovskite precursor solution makes it difficult to deposit high-quality wide-bandgap perovskite thin films. To address these issues, this application provides a perovskite solar cell and its fabrication method.

[0029] In a first typical embodiment of this application, a perovskite solar cell is provided, comprising a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode layer sequentially stacked. The hole transport layer is made of a first polymer and a second polymer, with a mass ratio of (2-10):1. The first polymer is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and the second polymer is a quinoxalothiophene polymer or a derivative thereof, wherein the quinoxalothiophene polymer has the structure shown in formula (I):

[0030]

[0031] Wherein, 0≤x≤1; Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, halogen, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C1-C15 alkoxy, substituted or unsubstituted C1-C15 alkylthio, or substituted or unsubstituted C1-C15 silane; n represents an integer between 100,000 and 1,000,000 (e.g., 100,000, 200,000, 500,000, 800,000, 1,000,000).

[0032] The number average molecular weight of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is 15,000 to 25,000 (15,000, 18,000, 20,000, 22,000, 25,000).

[0033] The perovskite solar cell provided in this application, by employing quinoxalothiophene polymer or its derivatives and PTAA as the hole transport layer materials, effectively improves the surface wettability of the hole transport layer and significantly reduces the inhomogeneity problem of the perovskite film during the fabrication of large-area perovskite layers. More importantly, it can effectively adjust the HOMO energy level of the hole transport layer, enabling it to better match the energy level of the wide-bandgap perovskite layer, ensuring efficient hole extraction and transport, effectively suppressing non-radiative recombination losses at the bulk phase and interface, and improving the open-circuit voltage and fill factor of the perovskite solar cell, which is beneficial for the large-scale commercial application of perovskite solar cells.

[0034] In this application, the first electrode layer and the second electrode layer are each independently a cathode layer or an anode layer, and the two have different polarities. That is, the modified perovskite solar cells that this application seeks to protect include both conventional perovskite solar cells and inverted perovskite solar cells.

[0035] In this application, the mass ratios of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and quinoxalothiophene polymers or their derivatives are, for example, 2:1, 3:1, 4:1, 5:1, 6:1, 8:10, 10:1, or any combination of two values. In particular, when the mass ratio is (2–5):1, the wettability of the hole transport layer formed is superior, and the HOMO energy level is lower.

[0036] To further improve the surface wettability of the hole transport layer and reduce the HOMO energy level, Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 preferably each independently represent any one of H, halogen, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C1-C6 alkylthio, or substituted or unsubstituted C1-C6 silyl. In particular, when Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, halogen, substituted or unsubstituted C1-C4 alkyl, substituted or unsubstituted C1-C4 alkoxy, substituted or unsubstituted C1-C4 alkylthio, or substituted or unsubstituted C1-C4 silyl, the resulting hole transport layer exhibits superior surface wettability and a lower HOMO energy level.

[0037] In some embodiments, when Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent H, F, methyl, ethyl, n-propyl, or isopropyl, the hole transport layer formed by the quinoxalothiophene polymer or its derivatives and PTAA as materials can more effectively improve surface wettability, reduce the HOMO energy level, and thus be more conducive to the preparation of large-area perovskite thin films and improve the open-circuit voltage and fill factor of perovskite solar cells.

[0038] In some specific embodiments, the structure of the quinoxalothiophene polymer is selected from at least one of PTQ7 to PTQ11:

[0039]

[0040] In some embodiments, the hole transport layer is prepared by: mixing and dispersing a quinoxalothiophene polymer or its derivative with poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in an organic solvent to obtain a polymer mixed solution; spin-coating the polymer mixed solution onto the surface of the first electrode layer, removing the organic solvent, and obtaining the hole transport layer.

[0041] The above-mentioned methods for removing organic solvents include, but are not limited to, heating, such as heating at a temperature of 90–110°C.

[0042] In some specific embodiments, the hole transport layer is prepared according to the following steps: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] and quinoxalothiophene polymer or its derivatives are dissolved in chlorobenzene solution at a mass ratio of 3:1, and stirred overnight at 60°C to ensure complete dissolution, resulting in a polymer mixed solution with a mass concentration of 2 mg / mL (mass concentration of solute); the polymer mixed solution is spin-coated onto the surface of the first electrode layer at a spin speed of 4000 rpm for 30–45 s; then transferred to a hot plate at 100°C and annealed for 10 min to obtain the hole transport layer.

[0043] In other embodiments, the thickness of the hole transport layer is 100-120 nm (e.g., 100 nm, 105 nm, 110 nm, 115 nm, 120 nm).

[0044] In a second typical embodiment of this application, a method for fabricating a perovskite solar cell is provided. The method includes: step S1, providing a first electrode layer and spin-coating a hole transport layer on the surface of the first electrode layer; step S2, spin-coating a perovskite layer on the surface of the hole transport layer; step S3, evaporating an electron transport layer on the surface of the perovskite layer; and step S4, evaporating a second electrode layer on the surface of the electron transport layer to obtain a perovskite solar cell.

[0045] The perovskite solar cell preparation method provided in this application uses spin coating to prepare the hole transport layer and the perovskite layer, and evaporation to prepare the electron transport layer and the second electrode layer. The process is simple, easy to operate, and more suitable for large-scale production, thereby reducing the preparation cost.

[0046] [Preparation of the first electrode layer]

[0047] In some embodiments, in step S1, the material of the first electrode layer is ITO (indium tin oxide), which is formed by etching ITO conductive glass. Specifically, the method involves etching the surface of the ITO conductive glass into strips to obtain the first electrode layer.

[0048] In some specific embodiments, the first electrode layer includes an ITO glass substrate layer and strip-shaped ITO disposed on the substrate layer, wherein the thickness of the ITO glass substrate layer is 1.0 to 1.2 mm, and the thickness of the strip-shaped ITO is 100 to 200 nm.

[0049] To improve the bonding stability between the first electrode layer and the hole transport layer, it is preferable to include a surface treatment step on the first electron layer before sputtering the hole transport layer. This improves the surface wettability and work function of the conductive layer, thereby enhancing the photoelectric performance and long-term stability of the perovskite solar cell. More preferably, this surface treatment is a plasma treatment, which further improves the efficiency of the surface treatment. The plasma treatment time is, for example, 3–5 minutes.

[0050] To remove impurities adhering to the surface of the first electrode layer, it is preferable to sequentially use glass cleaner (commercially available), deionized water, acetone, and isopropanol for ultrasonic cleaning for 15-20 minutes each, then dry it with a nitrogen gun, and finally place it in a vacuum plasma machine for plasma treatment.

[0051] [Preparation of the hole transport layer]

[0052] The fabrication of the hole transport layer has been described previously and will not be repeated here.

[0053] [Preparation of perovskite precursors]

[0054] In some embodiments, the perovskite layer is prepared by coating a perovskite precursor solution onto a passivation layer, followed by antisolvent treatment and annealing to obtain the perovskite layer.

[0055] In this application, the solute of the perovskite precursor solution is a perovskite precursor with the structural formula ABX3, wherein A is a monovalent cation, including but not limited to any one of potassium, cesium, rubidium, methylamino, or formamidinium monovalent cations, or a mixture of two or more monovalent cations; B is a divalent cation, including but not limited to any one of lead, tin, or germanium divalent cations, or a mixture of two or more divalent cations; X' is a monovalent anion, including but not limited to any one of halogens or halogen-like monovalent anions, such as chlorine, bromine, or iodide ions, and halogen-like elements such as thiocyanate, formate, or tetrafluoroborate. The solvent of the perovskite precursor solution is an organic solvent, including but not limited to chlorobenzene.

[0056] In some specific embodiments, the perovskite precursor is preferably Cs. 0.2 FA 0.8 Pb(I 0.6 Br 0.4 )3, and in the perovskite precursor solution, Cs 0.2 FA 0.8 Pb(I 0.6 Br 0.4The molar concentration of 3 is 1–2 mmol / mL. For example, the perovskite precursor solution is prepared according to the following steps: 0.24 mmol of CsI, 0.96 mmol of FAI, 0.48 mmol of PbI2, 0.72 mmol of PbBr2, and 0.015 mmol of Pb(SCN)2 are dissolved in 1 mL of a mixed solvent of DMF and DMSO (DMF to DMSO volume ratio 3:1), and stirred overnight at 60 °C to obtain the perovskite precursor solution.

[0057] In some specific embodiments, the perovskite layer is prepared by spin-coating a perovskite precursor solution onto a passivation layer, first at 500 rpm for 2 seconds, then at 4000 rpm for 60 seconds, and in the last 25 seconds, spin-coating 500 μL of diethyl ether onto the perovskite wet film, and then transferring it to a hot plate at 100°C for annealing for 10 minutes.

[0058] [Preparation of the electron transport layer]

[0059] In some embodiments, in step S4, the method for preparing the electron transport layer includes: firstly, depositing C60 on the surface of the perovskite layer by vacuum evaporation to form a C60 layer, and then depositing SnO2 on the surface of the C60 layer by vacuum evaporation to form a SnO2 layer, thereby obtaining the electron transport layer.

[0060] The aforementioned C60 can be a fullerene or its derivative. Its spherical structure endows it with a high electron mobility, which can significantly accelerate electron transport efficiency. When SnO2 is deposited on it, charge transport is effectively conducted, greatly reducing recombination loss.

[0061] In some specific embodiments, the electron transport layer is prepared according to the following steps: transferring the perovskite layer to a vacuum evaporation machine, at 5 × 10⁻⁶ m³ / s. -4 A 20 nm thick C60 layer was deposited under low pressure below Pa, and then the sample was transferred to an ALD instrument to deposit a 20 nm SnO2 layer to obtain the electron transport layer.

[0062] [Preparation of the second electrode layer]

[0063] The material of the second electrode layer is metal. In some embodiments, the material of the second electrode layer is Au. The second electrode is prepared by depositing Au on the surface of the electron transport layer by vacuum evaporation to form an electron electrode layer.

[0064] In some specific embodiments, the electron transport layer is prepared according to the following steps: an Au electrode layer (second electrode layer) is vacuum-deposited on the surface of the electron transport layer. The specific process conditions for vacuum deposition are: at 5 × 10⁻⁶... -4 At low pressures below Pa The film was deposited at a high rate, with a thickness of 100 nm, and the effective area of ​​the battery was 1.02 cm². 2 .

[0065] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0066] Example 1

[0067] This embodiment provides an inverted perovskite solar cell, which includes a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode layer stacked sequentially from bottom to top. The first electrode layer includes a 1.1 mm thick ITO transparent conductive glass substrate and 140 nm thick strip-shaped ITO disposed on the substrate. The hole transport layer is made of PTAA (number average molecular weight 12000) and PTQ10 (degree of polymerization n 200000) in a 3:1 mass ratio, and has a thickness of 40 nm. The perovskite layer is made of Cs. 0.2 FA 0.8 Pb(I 0.6 Br 0.4 )3, with a thickness of 700nm; the electron transport layer has a thickness of 40nm, including a 20nm C60 layer and a 20nm SnO2 layer; the second electrode layer is made of Au and has a thickness of 100nm.

[0068] The solar cell was prepared according to the following steps:

[0069] (1) The transparent conductive glass with striped ITO etched on its surface was cleaned in sequence with glass cleaner, deionized water, acetone and isopropanol under ultrasonic conditions, with each ultrasonic treatment lasting 15 minutes. The cleaned ITO glass was dried with a nitrogen gun and then placed in a vacuum plasma machine for 3 minutes to optimize the surface wettability and work function of ITO, thus obtaining the first electrode layer.

[0070] (2) Preparation of hole transport layer: PTAA and PTQ10 were dissolved in chlorobenzene solution at a mass ratio of 3:1 and stirred overnight at 60°C to ensure complete dissolution, resulting in a polymer mixed solution with a mass concentration of 2 mg / mL (mass concentration of solute); the polymer mixed solution was spin-coated onto the surface of the first electrode layer at a spin speed of 4000 rpm for 30-45 s; then transferred to a hot plate at 100°C and annealed for 10 min to obtain the hole transport layer.

[0071] (3) Preparation of perovskite layer:

[0072] (3.1) Preparation of perovskite precursor solution with a mass concentration of 1.5 mmol / mL: 0.24 mmol of CsI, 0.96 mmol of FAI, 0.48 mmol of PbI2, 0.72 mmol of PbBr2 and 0.015 mmol of Pb(SCN)2 were dissolved in 1 mL of a mixed solvent of DMF and DMSO (the volume ratio of DMF to DMSO was 3:1), and stirred overnight at 60 °C to obtain perovskite precursor solution.

[0073] (3.2) Take 70 μL of perovskite precursor solution and spin-coat it onto the surface of the hole transport layer. First spin-coat at 500 rpm for 2 s, then spin-coat at 4000 rpm for 60 s. In the last 25 s, spin-coat 500 μL of diethyl ether onto the perovskite wet film. Then transfer it to a hot stage at 100 °C and anneal for 10 minutes to obtain the perovskite layer.

[0074] (4) Preparation of the electron transport layer: The sample prepared above was transferred to a vacuum evaporation machine and deposited at 5 × 10⁻⁶ ℃. -4 A 20 nm thick C60 layer was deposited on the surface of the perovskite layer under a low pressure below Pa. The sample was then transferred to an ALD (atomic layer deposition) machine to deposit a 20 nm thick SnO2 layer, thus obtaining an electron transport layer.

[0075] (5) Preparation of the second electrode layer: On the surface of the electron transport layer prepared above, a 100 nm thick Au layer is obtained by vacuum evaporation to obtain the second electrode layer. The specific process parameters are: at 5 × 10 -4 At low pressures below Pa The perovskite solar cell was deposited at a high rate, resulting in an inverse perovskite solar cell with an effective area of ​​1.02 cm². 2 .

[0076] Example 2

[0077] The difference between this embodiment and Embodiment 1 is that PTQ10 is replaced with PTQ7, which has a polymerization degree n of 200,000, in the hole transport layer material.

[0078] Example 3

[0079] The difference between this embodiment and Embodiment 1 is that PTQ10 is replaced with PTQ8, which has a polymerization degree n of 180000, in the hole transport layer material.

[0080] Example 4

[0081] The difference between this embodiment and Embodiment 1 is that PTQ10 is replaced with PTQ9, which has a polymerization degree n of 300,000, in the hole transport layer material.

[0082] Example 5

[0083] The difference between this embodiment and Embodiment 1 is that PTQ10 is replaced with PTQ11 with a polymerization degree n of 390000 in the hole transport layer material.

[0084] Example 6

[0085] The difference between this embodiment and Embodiment 1 is that, in the hole transport layer material, the number average molecular weight of PTAA is 15,000, and the degree of polymerization n of PTQ10 is 100,000.

[0086] Example 7

[0087] The difference between this embodiment and Embodiment 1 is that the number-average molecular weight of PTAA in the hole transport layer is 18,000, and the degree of polymerization n of PTQ10 is 1,000,000.

[0088] Example 8

[0089] The difference between this embodiment and Embodiment 1 is that the mass ratio of PTAA to PTQ10 in the hole transport layer material is 2:1.

[0090] Example 9

[0091] The difference between this embodiment and Embodiment 1 is that the mass ratio of PTAA to PTQ10 in the hole transport layer material is 10:1.

[0092] Comparative Example 1

[0093] The difference between this comparative example and Example 1 is that the hole transport layer is made of PTAA and PTQ10 is not added.

[0094] The hole transport layer was prepared as follows: PTAA was dissolved in chlorobenzene solution and stirred overnight at 60°C to ensure complete dissolution, resulting in a PTAA chlorobenzene solution with a mass concentration of 2 mg / mL. The PTAA chlorobenzene solution was then spin-coated onto the surface of strip-shaped ITO at a spin speed of 4000 rpm for 30–45 s. The solution was then transferred to a hot plate at 100°C and annealed for 10 minutes to obtain the hole transport layer.

[0095] Comparative Example 2

[0096] The difference between this comparative example and Example 1 is that the hole transport layer is made of PTQ10 and PTAA is not added.

[0097] The hole transport layer was prepared as follows: PTQ10 was dissolved in chlorobenzene solution and stirred overnight at 60°C to ensure complete dissolution, resulting in a 2 mg / mL PTQ10 chlorobenzene solution. The PTQ10 chlorobenzene solution was then spin-coated onto the surface of strip-shaped ITO at 4000 rpm for 30–45 s. The layer was then transferred to a hot plate at 100°C and annealed for 10 minutes to obtain the hole transport layer.

[0098] Comparative Example 3

[0099] The difference between this comparative example and Example 1 is that the degree of polymerization n of PTQ10 in the hole transport layer is 50000.

[0100] Comparative Example 4

[0101] The difference between this comparative example and Example 1 is that the degree of polymerization n of PTQ10 in the hole transport layer is 2,000,000.

[0102] Comparative Example 5

[0103] The difference between this comparative example and Example 1 is that the mass ratio of PTAA to PTQ10 in the hole transport layer material is 15:1.

[0104] Comparative Example 6

[0105] The difference between this comparative example and Example 1 is that the mass ratio of PTAA to PTQ10 in the hole transport layer material is 1:1.

[0106] Comparative Example 7

[0107] The difference between this comparative example and Example 1 is that, in the hole transport layer material, PTQ10 is replaced with a polymer having the following structure and a degree of polymerization n of 200,000:

[0108]

[0109] Experimental Example 1

[0110] The inverted perovskite solar cells provided in the examples and comparative examples were subjected to spectral distribution AM1.5G and illumination intensity of 100mW / cm². 2 The photoelectric performance of the solar cell was measured using an Oriel 300W solar simulator as the light source. The effective area of ​​the solar cell was 1.02 cm². 2 The JV curve was obtained by measuring with a Keithly 2400 digital source meter, and the photoelectric performance test parameters were then obtained. The results are shown in Table 1 below.

[0111] Table 1

[0112]

[0113]

[0114] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0115] Compared to the perovskite solar cell in Comparative Example 1 that only used PTAA as the hole transport layer, the perovskite solar cell provided in this application, by using a blend of quinoxalothiophene polymer or its derivatives and PTAA as the hole transport layer material, exhibits higher open-circuit voltage, short-circuit current density, and fill factor. This is mainly because the measures adopted in this invention can effectively improve the surface wettability of the hole transport layer, significantly reducing the perovskite film inhomogeneity problem generated during the fabrication of large-area perovskite layers. More importantly, it can effectively adjust the HOMO energy level of the hole transport layer, enabling it to better match the energy level of the wide-bandgap perovskite layer, ensuring efficient hole extraction and transport, and effectively suppressing non-radiative recombination losses at the bulk phase and interface.

[0116] Furthermore, after 1000 hours of continuous illumination, the perovskite solar cell in Comparative Example 1, which only used PTAA as the hole transport layer, retained only about 15% of its initial efficiency. In contrast, the embodiment using the claims of this invention maintained more than 90% of its initial efficiency after 1000 hours of continuous illumination. This is mainly because the quinoxalothiophene polymer or its derivative molecules in this application have passivation groups that can passivate multiple perovskite defects simultaneously, significantly reducing grain boundary defects and effectively improving the stability of the device during operation. As can be seen from Comparative Examples 2-6, even when the proportion and degree of polymerization of PTQ10 introduced into PTAA exceed the scope of the claims of this invention, it can still maintain about 60% of the initial efficiency after 1000 hours of continuous illumination. In contrast, in Comparative Example 7, after introducing the compound FTAZ (which does not conform to the structural formula of the quinoxalothiophene polymer or its derivatives) outside the scope of the claims of this invention into PTAA, it almost lost its photoelectric properties after 1000 hours of continuous illumination. This further proves the superiority of introducing the quinoxalothiophene polymer or its derivatives into PTAA as a hole transport layer. The implementation of this invention is conducive to the large-scale commercialization of perovskite solar cells.

[0117] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A perovskite solar cell, characterized in that, The perovskite solar cell comprises a first electrode layer, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode layer stacked sequentially. The hole transport layer is made of a first polymer and a second polymer, with a mass ratio of (2~10):

1. The first polymer is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and the second polymer is a quinoxalothiophene polymer or a derivative thereof, wherein the quinoxalothiophene polymer has the structure shown in formula (I): Equation (I) Where 0 ≤ x ≤ 1; Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, halogen, substituted or unsubstituted C1-C15 alkyl, substituted or unsubstituted C1-C15 alkoxy, substituted or unsubstituted C1-C15 alkylthio, or substituted or unsubstituted C1-C15 silyl. n represents an integer between 100,000 and 1,000,000; The number-average molecular weight of the poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] is 12,000 to 18,000.

2. The perovskite solar cell according to claim 1, characterized in that, Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, halogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 alkylthio, or substituted or unsubstituted C1-C10 silyl.

3. The perovskite solar cell according to claim 1, characterized in that, Y, Z, R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent any one of H, F, substituted or unsubstituted C1-C4 alkyl, substituted or unsubstituted C1-C4 alkoxy, substituted or unsubstituted C1-C4 alkylthio, or substituted or unsubstituted C1-C4 silyl.

4. The perovskite solar cell according to claim 1, characterized in that, The quinoxalothiophene polymer is selected from at least one of PTQ7 to PTQ11: .

5. The perovskite solar cell according to any one of claims 1 to 4, characterized in that, The hole transport layer is prepared by: mixing and dispersing the quinoxaline thiophene polymer or its derivative and the poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in an organic solvent to obtain a polymer mixed solution; spin-coating the polymer mixed solution onto the surface of the first electrode layer, removing the organic solvent, and obtaining the hole transport layer.

6. The perovskite solar cell according to claim 5, characterized in that, The thickness of the hole transport layer is 30~60nm; And / or, the first electrode layer and the second electrode layer are each independently a cathode layer or an anode layer, and the two have different polarities.

7. A method for preparing a perovskite solar cell according to any one of claims 1 to 6, characterized in that, The preparation method includes: Step S1: Provide the first electrode layer, and spin-coat the hole transport layer on the surface of the first electrode layer; Step S2: Spin-coating the perovskite layer onto the surface of the hole transport layer; Step S3: The electron transport layer is prepared by vapor deposition on the surface of the perovskite layer; Step S4: The second electrode layer is deposited on the surface of the electron transport layer to obtain the perovskite solar cell.

8. The preparation method according to claim 7, characterized in that, In step S1, the material of the first electrode layer is ITO, and the first electrode layer includes an ITO substrate layer and strip-shaped ITO disposed on the ITO substrate layer. The thickness of the ITO substrate layer is 1.0~1.2mm, and the thickness of the strip-shaped ITO is 100~200nm.

9. The preparation method according to claim 8, characterized in that, The first electrode layer is formed by etching ITO conductive glass.

10. The preparation method according to claim 8, characterized in that, Before sputtering the hole transport layer, the method further includes a step of surface treatment of the first electrode layer.

11. The preparation method according to claim 10, characterized in that, The surface treatment is a plasma treatment, which takes 3 to 5 minutes.

12. The preparation method according to claim 7, characterized in that, In step S2, the material of the perovskite layer is Cs. 0.2 FA 0.8 Pb(I 0.6 Br 0.4 )3, with a thickness of 500~1000nm.

13. The preparation method according to claim 12, characterized in that, The perovskite layer is prepared by: using Cs 0.2 FA 0.8 Pb(I 0.6 Br 0.4 The solution was coated onto the hole transport layer, and then subjected to antisolvent and annealing treatments to obtain the perovskite layer.

14. The preparation method according to claim 7, characterized in that, In step S3, the electron transport layer includes a C60 layer and a SnO2 layer, the thicknesses of the C60 layer and the SnO2 layer being 10~30nm and 15~25nm, respectively.

15. The preparation method according to claim 14, characterized in that, The electron transport layer is prepared by first depositing C60 on the surface of the perovskite layer by vacuum evaporation to form a C60 layer, and then depositing SnO2 on the surface of the C60 layer by vacuum evaporation to form a SnO2 layer, thereby obtaining the electron transport layer.

16. The preparation method according to any one of claims 7 to 15, characterized in that, In step S4, the material of the second electrode layer is Au, and the thickness is 100~120nm.

17. The preparation method according to claim 16, characterized in that, The second electrode is prepared by depositing Au onto the surface of the electron transport layer by vacuum evaporation to form the second electrode layer.

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