Perovskite solar cell and preparation method thereof

Abstract

The invention provides a perovskite solar cell, and relates to the technical field of solar cells. The transparent conducting layer is arranged on the glass substrate in the first direction; the hole transport material layer is arranged on the side, away from the glass substrate, of the transparent conducting layer in the first direction, the molecular structure of the hole transport material layer comprises a triarylamine core, each aryl group is 3, 4, 5-trimethoxyphenyl, and nitrogen atoms are substituted by-(CH2) 4-PO (OH) 2 groups; the perovskite layer is arranged on the side, away from the glass substrate, of the hole transport material layer in the first direction; the electron transport layer is arranged on one side, far away from the glass substrate, of the perovskite layer along the first direction; the buffer layer is arranged on the side, away from the glass substrate, of the electron transfer layer in the first direction; the metal electrode is arranged on the side, away from the glass substrate, of the buffer layer in the first direction; the antireflection layer is arranged on the side, away from the glass substrate, of the metal electrode in the first direction. The invention also provides a preparation method of the perovskite solar cell.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a perovskite solar cell and its fabrication method. Background Technology

[0002] Perovskite solar cells, as an emerging photovoltaic technology, have attracted widespread attention due to their high photoelectric conversion efficiency, low raw material costs, and excellent solution processing performance. Among various device configurations, inverted (pin) perovskite solar cells demonstrate enormous application potential due to their advantages such as low fabrication temperature, good compatibility with tandem cells, and small current-voltage hysteresis.

[0003] However, the performance and long-term stability of inverted perovskite solar cells heavily depend on the quality of their hole transport layer and the "buried interface" between the perovskite light-absorbing layer and the transparent electrode. Currently widely used conventional hole transport materials, such as Spiro-OMeTAD, have low intrinsic conductivity and require chemical doping with hygroscopic lithium salts (such as Li-TFSI) and organic additives (such as 4-tert-butylpyridine) to achieve satisfactory hole transport capabilities. These dopants, especially lithium salts, are highly hygroscopic, absorbing moisture from the environment and inducing the decomposition of the perovskite layer. They are also prone to migration and aggregation, becoming one of the main degradation pathways for device performance decline and severely limiting the long-term operational stability of the cells.

[0004] To circumvent stability issues caused by dopants, hole transport materials based on self-assembled monolayers have emerged, such as [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz or CEPA). These materials typically contain an anchoring group (such as phosphonic acid or carboxylic acid) that can form a strong chemical bond with the surface of a metal oxide electrode (such as fluorinated tin oxide (FTO) or indium tin oxide (ITO), and a conjugated aromatic unit that provides hole transport functionality. They can form dense, ordered ultrathin layers on the electrode surface, achieving highly efficient hole extraction without the need for any hygroscopic dopants, thus significantly improving device stability.

[0005] Nevertheless, most existing carbazole-based self-assembled monolayer materials possess symmetrical molecular structures. This symmetry limits their self-assembly behavior on electrode surfaces, making it difficult to form perfectly dense and highly ordered monolayers, thus leaving uncovered defect sites at the interface. More importantly, the template effect provided by symmetrical molecules at the interface is limited, and the interaction between their surface chemistry and the three-dimensional perovskite precursor may be less than ideal. This makes it difficult to effectively control nucleation and crystal growth at the bottom interface of the perovskite, easily leading to problems such as pinholes, small grain size, and excessive grain boundaries in the perovskite film, increasing nonradiative recombination losses at the interface. Furthermore, there may be an energy level mismatch between the highest occupied molecular orbital energy level of existing materials and the valence band top of wide-bandgap perovskites, limiting further improvements in hole extraction efficiency and device open-circuit voltage. Summary of the Invention

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a perovskite solar cell and a method for its fabrication.

[0007] A first aspect of the present invention provides a perovskite solar cell, comprising: a glass substrate; a transparent conductive layer disposed on the glass substrate along a first direction; a hole transport material layer disposed along the first direction on the side of the transparent conductive layer away from the glass substrate, the molecular structure of the hole transport material layer comprising a triarylamine core, each aryl group being 3,4,5-trimethoxyphenyl, and nitrogen atoms being substituted by -(CH2)4-PO(OH)2 groups; a perovskite layer disposed along the first direction on the side of the hole transport material layer away from the glass substrate; an electron transport layer disposed along the first direction on the side of the perovskite layer away from the glass substrate; a buffer layer disposed along the first direction on the side of the electron transport layer away from the glass substrate; a metal electrode disposed along the first direction on the side of the buffer layer away from the glass substrate; and an antireflection layer disposed along the first direction on the side of the metal electrode away from the glass substrate.

[0008] In the above scheme, the hole transport material layer is an amine derivative with the molecular structure N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl); wherein, the -(CH2)4-PO(OH)2 phosphonic acid group located on the nitrogen atom acts on the surface of the transparent conductive layer through chemical adsorption and forms a self-assembled monolayer; the 3,4,5-trimethoxyphenyl substituents located on both sides of the nitrogen atom extend from the molecular body in the direction toward the perovskite layer and act as templates to guide the directional crystallization of the perovskite film.

[0009] In the above scheme, the highest occupied molecular orbital (HOMO) energy level of the hole transport material layer ranges from -5.2 eV to -5.6 eV, which matches the valence band top energy level of the perovskite layer.

[0010] In the above scheme, the material structure of the perovskite layer is ABX3, where A represents methylammonium ion, formamidinium ion, cesium ion or a mixture thereof, B represents lead or tin, and X represents iodide ion, bromide ion, chloride ion or a mixture thereof; the band gap of the perovskite layer ranges from 1.60 eV to 1.75 eV.

[0011] In the above-described scheme, the perovskite solar cell includes at least one of the following: the transparent conductive layer is made of fluorine-doped tin oxide and indium tin oxide; the electron transport layer is made of C... 60 and C 60 The derivatives; the buffer layer material includes 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; the metal electrode material includes silver, copper and gold; the antireflective layer material includes lithium fluoride.

[0012] In the above scheme, the perovskite solar cell includes at least one of the following: the hole transport material layer has a thickness ranging from 1 nm to 5 nm; the perovskite layer has a thickness ranging from 400 nm to 800 nm; the electron transport layer has a thickness ranging from 18 nm to 25 nm; the buffer layer has a thickness ranging from 4 nm to 8 nm; the metal electrode has a thickness ranging from 50 nm to 200 nm; the antireflection layer has a thickness ranging from 1 nm to 5 nm; and the transparent conductive layer has a thickness ranging from 100 nm to 200 nm.

[0013] A second aspect of the present invention provides a method for fabricating a perovskite solar cell, comprising: providing a glass substrate and depositing a transparent conductive layer on the glass substrate by sputtering; depositing a hole transport material layer on the transparent conductive layer, wherein the hole transport material layer is a amine derivative with the molecular structure N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl), the molecular structure of the hole transport material layer containing a triarylamine core, each aryl group being 3,4,5-trimethoxyphenyl, and the nitrogen atom being replaced by a -(CH2)4-PO(OH)2 group; depositing a perovskite layer on the hole transport material layer; and sequentially depositing an electron transport layer, a buffer layer, a metal electrode, and an antireflection layer on the perovskite layer by vacuum thermal evaporation.

[0014] The above scheme also includes the preparation of a hole transport material layer. The method for preparing the hole transport material layer includes: placing 3,6-dibromo-9H-carbazole and 3,4,5-trimethoxyphenylboronic acid in a tetrahydrofuran solvent in the presence of a palladium catalyst, a ligand, and a base to complete the reaction at a first temperature and a first time to obtain 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole; and placing 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole and 1,4-dibromobutane in a toluene solvent in the presence of a phase transfer catalyst and a base to complete the reaction at a second temperature and a second time to obtain N-(4-bromobutyl) -3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole; N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole reacts with triethyl phosphite at a third temperature under nitrogen protection to generate diethyl[4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl]phosphonate; diethyl[4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl]phosphonate is placed with trimethylbromosilane in dichloromethane solvent to complete the removal of the ethyl protecting group at a second temperature and a third time, obtaining the hole transport material layer.

[0015] In the above scheme, depositing a hole transport material layer on the transparent conductive layer includes: dissolving an N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl)amine derivative in an anhydrous organic solvent to prepare a target solution with a concentration range of 0.5 mg / mL to 5 mg / mL, and coating the target solution onto the transparent conductive layer by spin coating; annealing the target solution coated on the transparent conductive layer to allow the phosphonic acid groups (-(CH2)4-PO(OH)2) to chemically adsorb onto the metal oxide on the surface of the transparent conductive layer, forming a self-assembled monolayer.

[0016] In the above scheme, depositing a perovskite layer on a hole transport material layer includes: coating a perovskite precursor solution onto the hole transport material layer using a solution method; and annealing the perovskite precursor solution coated on the hole transport material layer to form a perovskite polycrystalline thin film with a thickness ranging from 400 nm to 800 nm.

[0017] In the above scheme, an electron transport layer, a buffer layer, a metal electrode, and an antireflection layer are sequentially deposited using a vacuum thermal evaporation method, including: depositing a C layer with a thickness ranging from 18 nm to 25 nm at an evaporation rate of 0.1 Å / s to 0.3 Å / s. 60As an electron transport layer; 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with a thickness ranging from 4 nm to 8 nm was deposited at an evaporation rate of 0.1 Å / s to 0.3 Å / s as a buffer layer; a metal electrode with a thickness ranging from 50 nm to 200 nm was deposited at an evaporation rate of 2 Å / s to 3 Å / s; and lithium fluoride with a thickness ranging from 1 nm to 5 nm was deposited as an antireflection layer.

[0018] The technical solution of this invention provides a perovskite solar cell and its preparation method. A hole transport material with carbazole as the core framework is designed and synthesized. The 3 and 6 positions of this framework are substituted with electron-rich 3,4,5-trimethoxyphenyl groups, and the 9 position is functionalized via a 4-phosphonic acid butyl side chain (i.e., -(CH2)4-PO(OH)2). This molecular structure has an asymmetric substitution mode and a phosphonic acid anchoring group, and has at least the following beneficial effects:

[0019] (1) The phosphonic acid groups at the end of the material can form a strong chemical adsorption with the surface of transparent conductive oxides (such as FTO or ITO), constructing a dense and stable self-assembled monolayer. This not only enhances the adhesion and stability of the interface, but also enables the hole transport layer to work without relying on any hygroscopic dopants, fundamentally solving the problem of device performance degradation caused by the moisture absorption and migration of additives in traditional doped hole transport layers (such as Spiro-OMeTAD), and significantly improving the long-term operational stability of the battery.

[0020] (2) The upwardly extending 3,4,5-trimethoxyphenyl forms an electron-rich and methoxy-dipolar-rich interface, which can significantly improve the compatibility with the perovskite precursor and serve as an effective nucleation template to guide the perovskite layer to crystallize in a uniform and directional manner, thereby forming a high-quality perovskite film with larger grains and lower defect density at the buried interface, effectively suppressing non-radiative recombination.

[0021] (3) The molecular design gives it a deep highest occupied molecular orbital energy level (-5.2 eV to -5.6 eV), which can achieve excellent energy level matching with the valence band top of common perovskite light-absorbing layers. This reduces the hole transport barrier, realizes efficient hole extraction and collection, and helps the device obtain a higher open-circuit voltage, thereby improving the photoelectric conversion efficiency. Attached Figure Description

[0022] Figure 1 A schematic diagram of a perovskite solar cell according to an embodiment of the present invention is shown.

[0023] Figure 2 A flowchart illustrating a method for fabricating a perovskite solar cell according to an embodiment of the present invention is shown schematically.

[0024] Figure 3 A flowchart illustrating a method for preparing a hole transport material layer according to an embodiment of the present invention is shown schematically.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1-Glass substrate; 2-Transparent conductive layer; 3-Hole transport material layer; 4-Perovskite layer; 5-Electron transport layer; 6-Buffer layer; 7-Metal electrode; 8-Antireflection layer. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0028] Figure 1 A schematic diagram of a perovskite solar cell according to an embodiment of the present invention is shown.

[0029] In embodiments of the present invention, such as Figure 1 As shown, the perovskite solar cell includes a glass substrate 1; a transparent conductive layer 2 disposed on the glass substrate 1 along a first direction X1; a hole transport material layer 3 disposed along the first direction X1 on the side of the transparent conductive layer 2 away from the glass substrate 1; a perovskite layer 4 disposed along the first direction X1 on the side of the hole transport material layer 3 away from the glass substrate 1; an electron transport layer 5 disposed along the first direction X1 on the side of the perovskite layer 4 away from the glass substrate 1; a buffer layer 6 disposed along the first direction X1 on the side of the electron transport layer 5 away from the glass substrate 1; a metal electrode 7 disposed along the first direction X1 on the side of the buffer layer 6 away from the glass substrate 1; and an antireflection layer 8 disposed along the first direction X1 on the side of the metal electrode 7 away from the glass substrate 1.

[0030] The following is a detailed description of each structural layer of the perovskite solar cell described above.

[0031] In embodiments of the present invention, the material of the transparent conductive layer 2 includes fluorine-doped tin oxide and indium tin oxide, for example, it can be at least one of fluorine-doped tin oxide and indium tin oxide. The thickness of the transparent conductive layer 2 ranges from 100 nm to 200 nm.

[0032] In an embodiment of the present invention, the molecular structure of the hole transport material layer 3 comprises a triarylamine core, each aryl group being 3,4,5-trimethoxyphenyl, and the nitrogen atom being replaced by a -(CH2)4-PO(OH)2 group.

[0033] Specifically, the hole transport material layer 3 is made of an amine derivative with the molecular structure N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl). The -(CH2)4-PO(OH)2 phosphonic acid group on the nitrogen atom acts on the surface of the transparent conductive layer 2 through chemisorption, forming a self-assembled monolayer. The 3,4,5-trimethoxyphenyl substituents on both sides of the nitrogen atom extend from the molecular body towards the perovskite layer 4, serving as templates to guide the directional crystallization of the perovskite film.

[0034] For example, the hole transport material layer 3 is made of N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole, whose molecular structure contains a central nitrogen atom connected to two 3,4,5-trimethoxyphenyl groups, and further connected to a phosphonic acid group (-PO(OH)2) via a tetramethylene chain (-(CH2)4). That is, the 3 and 6 positions of the carbazole core skeleton are replaced by 3,4,5-trimethoxyphenyl groups, and the 9 position is replaced by a -(CH2)4-PO(OH)2 group.

[0035] Understandably, the -(CH2)4-PO(OH)2 phosphonic acid group attached to the central nitrogen atom forms a dense, pinhole-free self-assembled monolayer (SAM) on the surface of the transparent conductive layer through chemisorption. Two 3,4,5-trimethoxyphenyl substituents located on either side of the nitrogen atom extend from the carbazole core framework toward the perovskite layer 4, constructing a perovskite-facing interface rich in π-electron density and methoxy dipoles. This interface enhances compatibility with the perovskite precursor, improves wettability, guides templated nucleation, and reduces interface defects, thereby promoting template-directed crystallization of the perovskite film. Simultaneously, the highest occupied molecular orbital (HOMO) level of the carbazole core enables efficient hole extraction from the perovskite valence band.

[0036] In an embodiment of the present invention, the highest occupied molecular orbital (HOMO) energy level of the hole transport material layer 3 ranges from -5.2 eV to -5.6 eV, which is well matched with the valence band top energy level of the perovskite layer 4, which is beneficial for efficient hole extraction and suppression of interfacial recombination.

[0037] For example, the HOMO energy level range of the hole transport material layer 3 is -5.2 eV to -5.6 eV, such as -5.2 eV, -5.3 eV, -5.4 eV, -5.5 eV or -5.6 eV, to achieve optimal energy level matching with the 4-valence band of the perovskite layer.

[0038] Optionally, the thickness of the hole transport material layer 3 ranges from 1 nm to 5 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm or 5 nm.

[0039] Through the embodiments of the present invention, the asymmetric molecular structure of the hole transport material layer 3, with the phosphonic acid end anchored to FTO or ITO, and the aryl functionalized side interacting with the perovskite layer 4, thereby achieving doping-free operation and high reproducibility.

[0040] In an embodiment of the present invention, the material structure of the perovskite layer 4 is ABX3, wherein A represents methylammonium ion, formamidinium ion, cesium ion or a mixture thereof, B represents lead or tin, and X represents iodide ion, bromide ion, chloride ion or a mixture thereof; the band gap of the perovskite layer 4 is in the range of 1.60 eV to 1.75 eV.

[0041] Specifically, the perovskite layer 4 has a material structure of ABX3, and its band gap ranges from 1.60 eV to 1.75 eV. Here, A can represent methylammonium ions, formamidinium ions, cesium ions, or a mixture containing methylammonium ions, formamidinium ions, and cesium ions; B can represent lead or tin; and X can represent iodide ions, bromide ions, chloride ions, or a mixture thereof. For example, the materials of the perovskite layer 4 include MAPbI3, FAPbI3, and Cs. 0.1 FA 0.9 Pb(I 0.9 Br 0.1 )3 or mixtures thereof, with a band gap ranging from 1.50 eV to 1.75 eV.

[0042] Optionally, the thickness of the perovskite layer 4 ranges from 400 nm to 800 nm, for example, 400 nm, 500 nm, 600 nm, 700 nm or 800 nm.

[0043] In an embodiment of the present invention, the material of the electron transport layer 5 includes C. 60 and C 60 Derivatives, for example, can be C 60 Derivatives of C can also be C 60 The thickness of the electron transport layer 5 ranges from 18 nm to 25 nm, for example, 18 nm, 20 nm, 22 nm, or 25 nm. In this embodiment, the electron transport layer 5 can effectively extract electrons.

[0044] In an embodiment of the invention, the material of the buffer layer 6 comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline. The thickness of the buffer layer 6 ranges from 4 nm to 8 nm, for example, 4 nm, 6 nm, 7 nm, or 8 nm. In this embodiment, the use of an ultrathin BCP buffer layer 6 can block hole leakage and reduce cathode interface recombination.

[0045] In embodiments of the present invention, the material of the metal electrode 7 includes silver, copper, and gold. For example, the material of the metal electrode 7 can be silver, copper, or gold.

[0046] In an embodiment of the present invention, the metal electrode 7 is deposited in the form of a continuous thin film with a thickness ranging from 50 nm to 200 nm. The metal electrode 7 defines the effective area through a patterned metal mask and is capable of providing low-resistance charge collection.

[0047] In embodiments of the present invention, the antireflection layer 8 is made of lithium fluoride. The thickness of the antireflection layer 8 ranges from 1 nm to 5 nm, for example, 1 nm, 2 nm, 3 nm, 4 nm, or 5 nm. For example, thermally depositing a lithium fluoride antireflection layer 8 with a thickness of 0.5 to 2 nm on a silver metal electrode 7 can enhance light output and reduce reflection loss.

[0048] Through embodiments of this invention, the simultaneous improvement of efficiency and stability of perovskite solar cells is achieved by employing asymmetric molecular design and self-assembled monolayer structures: phosphonic acid anchoring groups form dense and stable chemical bonds with the transparent conductive layer, fundamentally avoiding the use of hygroscopic dopants and significantly improving the environmental durability of the device; simultaneously, the two 3,4,5-trimethoxyphenyl substituents located on either side of the central nitrogen atom extend from the molecular plane towards the perovskite layer, inducing an interfacial template effect and promoting the formation of a highly crystalline, low-defect structure at the buried interface of the perovskite film; combined with its highest occupied molecular orbital (HOMO) of deep energy level, which is well matched with the top of the perovskite valence band, efficient hole extraction and high open-circuit voltage are achieved. Ultimately, this solar cell achieves both high photoelectric conversion efficiency and long-term operational stability without the need for dopants, while simplifying the process flow.

[0049] Figure 2 A flowchart illustrating a method for fabricating a perovskite solar cell according to an embodiment of the present invention is shown.

[0050] Based on the above-mentioned perovskite solar cells, a method for fabricating perovskite solar cells is proposed in an embodiment of the present invention. The following, in conjunction with... Figure 1 and Figure 2 Provide a detailed description.

[0051] like Figure 2 As shown, the method for preparing this perovskite solar cell specifically includes steps S210-240.

[0052] In step S210, a glass substrate 1 is provided, and a transparent conductive layer 2 is deposited on the glass substrate 1 by sputtering.

[0053] In step S220, a hole transport material layer 3 is deposited on the transparent conductive layer 2. The hole transport material layer 3 is a amine derivative with the molecular structure N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl). The molecular structure of the hole transport material layer 3 contains a triarylamine core, each aryl group is 3,4,5-trimethoxyphenyl, and the nitrogen atom is replaced by a -(CH2)4-PO(OH)2 group.

[0054] For example, a hole transport material layer 3 is deposited on the transparent conductive layer 2, wherein the material of the hole transport material layer 3 is N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole, whose molecular structure contains a central nitrogen atom, which is connected to two 3,4,5-trimethoxyphenyl groups, and further connected to a phosphonic acid group (-PO(OH)2) through a tetramethylene chain (-(CH2)4). That is, the 3 and 6 positions of the carbazole core backbone are replaced by 3,4,5-trimethoxyphenyl groups, and the 9 position is replaced by a -(CH2)4-PO(OH)2 group. Understandably, the -(CH2)4-PO(OH)2 phosphonic acid group attached to the central nitrogen atom forms a dense, pinhole-free self-assembled monolayer (SAM) on the surface of the transparent conductive layer through chemisorption. Two 3,4,5-trimethoxyphenyl substituents located on either side of the nitrogen atom extend from the carbazole core framework towards the perovskite layer 4, constructing a perovskite-facing interface rich in π-electron density and methoxy dipoles. This interface enhances compatibility with the perovskite precursor, improves wettability, guides templated nucleation, and reduces interface defects, thereby promoting template-directed crystallization of the perovskite film. Simultaneously, the highest occupied molecular orbital (HOMO) energy level of the carbazole core achieves a good match with the valence band top energy level of the perovskite layer 4, which is beneficial for efficient hole extraction and inhibits interfacial recombination.

[0055] In an embodiment of the present invention, a hole transport material layer 3 is deposited on the transparent conductive layer 2. This process specifically includes: dissolving an N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl)amine derivative in an anhydrous organic solvent to prepare a target solution with a concentration range of 0.5 mg / mL to 5 mg / mL, and then coating the target solution onto the transparent conductive layer 2 by spin coating. Further, the target solution coated on the transparent conductive layer 2 is subjected to annealing treatment (e.g., annealing at 100 °C to 110 °C for 10 to 15 minutes) to allow the phosphonic acid groups (-(CH2)4-PO(OH)2) to chemically adsorb onto the metal oxide on the surface of the transparent conductive layer 2, forming a self-assembled monolayer (e.g., forming a self-assembled monolayer with a thickness of 1 to 5 nm). Its phosphate groups are bonded to the FTO surface, and the two trimethoxyphenyl groups extend toward the perovskite layer, inducing an interface template effect and promoting the formation of a highly crystalline, low-defect structure of the perovskite film at the buried interface.

[0056] Figure 3 A flowchart illustrating a method for preparing a hole transport material layer according to an embodiment of the present invention is shown.

[0057] It should be noted that before step S220, the preparation of the hole transport material layer 3 is also included. Below, in conjunction with... Figure 1 and Figure 2 , Figure 3 Provide a detailed description.

[0058] like Figure 3 As shown, the method for preparing the hole transport material layer 3 specifically includes steps S310 to S340.

[0059] In step S310, 3,6-dibromo-9H-carbazole and 3,4,5-trimethoxyphenylboronic acid are placed in tetrahydrofuran solvent in the presence of a palladium catalyst, a ligand, and a base to complete the reaction at a first temperature and a first time to obtain 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole.

[0060] For example, 3,6-dibromo-9H-carbazole is reacted with 3,4,5-trimethoxyphenylboronic acid in tetrahydrofuran (THF) solvent via a Suzuki–Miyaura cross-coupling reaction catalyzed by palladium (e.g., Pd2(dba)3, X-Phos, K2CO3 can be used here, with a first temperature of 95 °C and a first time of 24 hours) to generate 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole.

[0061] Specifically, step S310 is a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction, linking two 3,4,5-trimethoxyphenyl groups to the 3 and 6 positions of the carbazole ring. The starting materials are 3,6-dibromo-9H-carbazole (e.g., 2.5 g, 7.69 mmol) and 3,4,5-trimethoxyphenylboronic acid (e.g., 3.2 g, 15 mmol). The catalyst used is Pd2(dba)3 (tris(dibenzylacetone)dipalladium(0)), for example, at 2 mol% (100 mg); the ligand is X-Phos (2-dicyclohexylphosphine-2′,4′,6′-triisopropylbiphenyl); the base is K2CO3 (potassium carbonate, 3 equivalents). The solvent is tetrahydrofuran (THF), and the reaction is carried out at 95 °C for 24 hours under an inert atmosphere. The product is 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole, with the molecular formula C2. 30 H 28 NO6, with a molar mass of 498.6 g / mol. The reaction yield was 83%, yielding 3.2 g (6.4 mmol) of product. The chemical equation for the reaction is as follows:

[0062]

[0063] In step S320, in the presence of a phase transfer catalyst and a base, 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole and 1,4-dibromobutane are placed in toluene solvent to complete the reaction at a second temperature and a second time to obtain N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole.

[0064] For example, 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole is reacted with 1,4-dibromobutane under phase transfer catalysis to generate N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole.

[0065] Specifically, step S320 is an N-alkylation reaction (nucleophilic substitution), introducing a four-carbon brominated alkyl chain onto the core nitrogen atom of carbazole. The starting material is 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole (e.g., 2.5 g, 5.0 mmol); the reagent used is 1,4-dibromobutane (e.g., 4 g, 18.60 mmol); the base is aqueous potassium hydroxide (KOH), the phase transfer catalyst is tetrabutylammonium bromide (TBABr); the solvent is toluene; the reaction conditions are room temperature (i.e., the second temperature) for 48 hours (i.e., the second time). The product is N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole, with the molecular formula C2. 34 H 37BrNO6. The reaction yield was 82%, yielding 2.6 g (4.1 mmol) of product. The chemical equation for the reaction is as follows:

[0066]

[0067] In step S330, N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole is reacted with triethyl phosphite at a third temperature under nitrogen protection to generate diethyl[4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl]phosphonate.

[0068] For example, N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole is reacted with triethyl phosphite under an inert atmosphere and under elevated temperature to generate diethyl(4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl)phosphonate.

[0069] Specifically, step S330 is an Arbuzov reaction, which converts a brominated alkyl intermediate into a phosphonate via nucleophilic substitution and rearrangement. The starting material is N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole (e.g., 2.0 g, 3.1 mmol); the reagent used is triethyl phosphite (e.g., 3.0 g, 18.0 mmol); the reaction is typically carried out in a solvent-free or inert atmosphere, under conditions such as nitrogen atmosphere and at 120°C (the third temperature) for 24 hours. The product is diethyl(4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl)phosphonate, with the molecular formula C2. 38 H 46 NO9P. The reaction yield was 84%, yielding 1.8 g (2.6 mmol) of product. The chemical equation for this reaction is as follows:

[0070]

[0071] In step S340, diethyl[4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl]phosphonate and trimethylbromosilane are placed in dichloromethane solvent to complete the removal of the ethyl protecting group at the second temperature and the third time, thereby obtaining the hole transport material layer 3.

[0072] For example, diethyl(4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl)phosphonate is reacted with trimethylbromosilane (TMSBr) in anhydrous dichloromethane at room temperature to remove the ethyl protecting group, thereby obtaining the final material used for hole transport material layer 3: N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole.

[0073] Specifically, step S340 is a phosphonate deprotection reaction, hydrolyzing diethylphosphonate to the corresponding free phosphonic acid, which can then form a strong chemisorption on the surface of metal oxides (such as FTO or ITO) via P=O⋯M–O bonds. The starting material is diethyl(4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl)phosphonate (e.g., 0.8 g, 1.2 mmol); the reagent used is trimethylbromosilane (TMSBr), usually used in excess; the solvent is anhydrous dichloromethane (DCM), and the reaction is carried out under a nitrogen atmosphere at room temperature (i.e., the second temperature) for 24 hours (i.e., the third time). The product is N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole, with the molecular formula C 34 H 38 NO9P. The reaction yield was 53%, yielding 0.4 g (0.63 mmol) of the final hole transport material. The chemical equation for the reaction is as follows:

[0074]

[0075] Based on the description of step S220 above, please continue to refer to... Figure 1 and Figure 2 The following is a detailed description of steps S230 to S240.

[0076] In step S230, a perovskite layer 4 is deposited on the hole transport material layer 3.

[0077] For example, a perovskite precursor solution is coated onto the hole transport material layer 3 by a solution method. The perovskite precursor solution coated on the hole transport material layer 3 is then annealed (e.g., annealed at 80 °C to 150 °C for 5 to 30 minutes) to form a perovskite polycrystalline thin film with a thickness ranging from 400 nm to 800 nm.

[0078] In step S240, an electron transport layer 5, a buffer layer 6, a metal electrode 7, and an antireflection layer 8 are sequentially deposited on the perovskite layer 4 by vacuum thermal evaporation.

[0079] For example, C20 layers with a thickness ranging from 18 nm to 25 nm were deposited at an evaporation rate of 0.1 Å / s to 0.3 Å / s. 60 As an electron transport layer 5; 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline with a thickness ranging from 4 nm to 8 nm deposited at an evaporation rate of 0.1 Å / s to 0.3 Å / s as a buffer layer 6; a metal electrode 7 with a thickness ranging from 50 nm to 200 nm deposited at an evaporation rate of 2 Å / s to 3 Å / s; and lithium fluoride with a thickness ranging from 1 nm to 5 nm as an antireflection layer 8.

[0080] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0081] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A perovskite solar cell, characterized in that, include: Glass substrate (1); A transparent conductive layer (2) is disposed on the glass substrate (1) along a first direction; Hole transport material layer (3) is disposed along the first direction on the side of the transparent conductive layer (2) away from the glass substrate (1). The molecular structure of the hole transport material layer (3) includes a triarylamine core, each aryl group is 3,4,5-trimethoxyphenyl, and the nitrogen atom is replaced by -(CH2)4-PO(OH)2 group. A perovskite layer (4) is disposed along a first direction on the side of the hole transport material layer (3) away from the glass substrate (1); An electron transport layer (5) is disposed along the first direction on the side of the perovskite layer (4) away from the glass substrate (1); A buffer layer (6) is disposed along the first direction on the side of the electron transport layer (5) away from the glass substrate (1); A metal electrode (7) is disposed along a first direction on the side of the buffer layer (6) away from the glass substrate (1); and an anti-reflection layer (8) is disposed along a first direction on the side of the metal electrode (7) away from the glass substrate (1).

2. The perovskite solar cell according to claim 1, characterized in that, The hole transport material layer (3) is made of an amine derivative with the molecular structure N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl); Among them, the -(CH2)4-PO(OH)2 phosphonic acid group located on the nitrogen atom acts on the surface of the transparent conductive layer (2) through chemical adsorption and forms a self-assembled monolayer; the 3,4,5-trimethoxyphenyl substituents located on both sides of the nitrogen atom extend from the molecular body in the direction toward the perovskite layer (4) and serve as templates to guide the directional crystallization of the perovskite film.

3. The perovskite solar cell according to claim 2, characterized in that, The hole transport material layer (3) has a highest occupied molecular orbital (HOMO) energy level ranging from -5.2 eV to -5.6 eV, which matches the valence band top energy level of the perovskite layer (4).

4. The perovskite solar cell according to claim 1, characterized in that, The material structure of the perovskite layer (4) is ABX3, where A represents methylammonium ion, formamidinium ion, cesium ion or a mixture, B represents lead or tin, and X represents iodide ion, bromide ion, chloride ion or a mixture; The band gap of the perovskite layer (4) ranges from 1.60 eV to 1.75 eV.

5. The perovskite solar cell according to claim 1, characterized in that, Includes at least one of the following: The transparent conductive layer (2) is made of fluorine-doped tin oxide and indium tin oxide; The material of the electron transport layer (5) includes C 60 and C 60 Derivatives; The material of the buffer layer (6) includes 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; The materials of the metal electrode (7) include silver, copper and gold; The antireflective layer (8) is made of lithium fluoride.

6. The perovskite solar cell according to claim 1, characterized in that, Includes at least one of the following: The thickness of the hole transport material layer (3) ranges from 1 nm to 5 nm; The thickness of the perovskite layer (4) ranges from 400 nm to 800 nm; The thickness of the electron transport layer (5) ranges from 18 nm to 25 nm; The thickness of the buffer layer (6) ranges from 4 nm to 8 nm; The thickness of the metal electrode (7) ranges from 50 nm to 200 nm; The thickness of the antireflective layer (8) ranges from 1 nm to 5 nm; The thickness of the transparent conductive layer (2) ranges from 100 nm to 200 nm.

7. A method for preparing a perovskite solar cell as described in any one of claims 1 to 6, characterized in that, The method includes: A glass substrate (1) is provided, and a transparent conductive layer (2) is deposited on the glass substrate (1) by sputtering. A hole transport material layer (3) is deposited on the transparent conductive layer (2), wherein the hole transport material layer (3) is a material of an amine derivative with the molecular structure of N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl), and the molecular structure of the hole transport material layer (3) contains a triarylamine core, each aryl group is 3,4,5-trimethoxyphenyl, and the nitrogen atom is replaced by a -(CH2)4-PO(OH)2 group; A perovskite layer (4) is deposited on the hole transport material layer (3); and On the perovskite layer (4), an electron transport layer (5), a buffer layer (6), a metal electrode (7) and an anti-reflection layer (8) are sequentially deposited by vacuum thermal evaporation.

8. The preparation method according to claim 7, characterized in that, It also includes the material preparation of the hole transport material layer (3), and the method for preparing the hole transport material layer (3) includes: In the presence of a palladium catalyst, ligand, and base, 3,6-dibromo-9H-carbazole and 3,4,5-trimethoxyphenylboronic acid were placed in a tetrahydrofuran solvent to complete the reaction at a first temperature and a first time to give 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole. In the presence of a phase transfer catalyst and a base, the 3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole and 1,4-dibromobutane were placed in toluene solvent to complete the reaction at a second temperature and a second time to obtain N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole. The N-(4-bromobutyl)-3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole was reacted with triethyl phosphite at a third temperature under nitrogen protection to generate diethyl[4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl]phosphonate; The diethyl[4-(3,6-bis(3,4,5-trimethoxyphenyl)-9H-carbazole-9-yl)butyl]phosphonate and bromotrimethylsilane were placed in dichloromethane solvent to complete the removal of the ethyl protecting group at a second temperature and a third time, thereby obtaining the material of the hole transport material layer (3).

9. The preparation method according to claim 7, characterized in that, The deposition of a hole transport material layer (3) on the transparent conductive layer (2) includes: The N-(4-(dihydroxyphosphoryl)butyl)-3,6-bis(3,4,5-trimethoxyphenyl)amine derivative was dissolved in an anhydrous organic solvent to prepare a target solution with a concentration range of 0.5 mg / mL to 5 mg / mL, and the target solution was coated onto the transparent conductive layer (2) by spin coating. The target solution coated on the transparent conductive layer (2) is annealed so that the phosphonic acid groups (-(CH2)4-PO(OH)2) are chemically adsorbed onto the metal oxides on the surface of the transparent conductive layer (2) to form a self-assembled monolayer.

10. The preparation method according to claim 7, characterized in that, The deposition of a perovskite layer (4) on the hole transport material layer (3) includes: A perovskite precursor solution is coated onto the hole transport material layer (3) by a solution method; The perovskite precursor solution coated on the hole transport material layer (3) is annealed to form a perovskite polycrystalline thin film with a thickness ranging from 400 nm to 800 nm.

11. The preparation method according to claim 7, characterized in that, An electron transport layer (5), a buffer layer (6), a metal electrode (7), and an antireflection layer (8) are sequentially deposited using a vacuum thermal evaporation method, including: C2 layers with a thickness ranging from 18 nm to 25 nm were deposited at evaporation rates ranging from 0.1 Å / s to 0.3 Å / s. 60 As an electron transport layer (5); 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline was deposited as a buffer layer with a thickness ranging from 4 nm to 8 nm at an evaporation rate of 0.1 Å / s to 0.3 Å / s (6). Metal electrodes with thicknesses ranging from 50 nm to 200 nm were deposited at evaporation rates of 2 Å / s to 3 Å / s (7); and Lithium fluoride with a thickness ranging from 1 nm to 5 nm was deposited as an antireflection layer (8).

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