Hole transport layer, perovskite solar cell and preparation method

Abstract

The invention relates to a hole transport layer, a perovskite solar cell and a preparation method, and the method sequentially comprises the following steps: providing a substrate, and preparing a composite hole transport layer on the substrate; depositing an inorganic salt thin film on the composite hole transport layer by adopting a vacuum evaporation method; spin-coating an organic salt solution on the inorganic salt thin film, and then annealing to form a perovskite light absorption layer; preparing a passivation layer on the perovskite light absorption layer; and preparing an electron transport layer, a hole blocking layer and a back electrode in sequence to complete cell preparation. According to the invention, by introducing a'common SAMs' technology (that is, 3, 5-bis (trifluoromethyl) phenylhydrazine hydrochloride is doped into Me-4PACz), the surface property of the hole transport layer is fundamentally improved, and the interface property and the crystallization quality of the thin film are optimized.

Description

Technical Field

[0001] This invention relates to the technical field of perovskite solar cells, and in particular to a hole transport layer, a perovskite solar cell, and a method for its fabrication. Background Technology

[0002] With the global energy crisis and climate change becoming increasingly severe, the development and utilization of clean and renewable energy has become a consensus and an urgent need for countries around the world. Among numerous renewable energy sources, solar energy is considered a core pillar of the future energy structure due to its wide distribution, near-infinite reserves, and zero emissions. Solar cell technology, as a key carrier for directly converting solar energy into electricity, is undoubtedly the core of realizing this vision. In particular, perovskite solar cells, with their advantages of low cost, high efficiency, and adjustable bandgap, are considered one of the most promising photovoltaic technologies currently available.

[0003] Currently, with in-depth research and exploration of self-assembled monolayers (SAMs), the efficiency of PiN-type perovskite solar cells has steadily improved. However, traditional SAMs often face some problems in practical applications, such as poor wettability, insufficient monolayer coverage, and numerous interface defects, which will greatly affect the performance and stability of PiN-type perovskite solar cells.

[0004] Specifically: 1. Traditional SAMs materials have inherent interface defects. While inverted perovskite solar cells based on self-assembled monolayers (SAMs, such as 2PACz and Me-4PACz) show promise, traditional single-component SAMs suffer from poor wettability and uneven coverage on the substrate surface during actual film formation. This leads to uneven spreading of the perovskite precursor solution, ultimately resulting in increased porosity and grain boundary defects in the perovskite film, which become centers for non-radiative recombination of charge carriers, severely limiting cell efficiency and stability.

[0005] 2. The crystallization quality of perovskite thin films needs to be improved. In the two-step fabrication of wide-bandgap perovskite thin films (especially for the top cell of tandem solar cells), incomplete reaction between inorganic salts (such as PbI2) and organic salts is a common problem, resulting in inactive PbI2 residues. These residues are not only defects in themselves, but also disrupt the integrity of the perovskite lattice, reduce light absorption and carrier lifetime, and thus limit the open-circuit voltage (VOC) and fill factor (FF) of the cell.

[0006] 3. The interface loss problem of stacked batteries is prominent. In perovskite / crystalline silicon tandem solar cells, the perovskite sub-cell, serving as the top cell, has even more stringent interface quality requirements. The aforementioned interface defects and thin film quality issues are further amplified in the tandem structure, leading to severe interface recombination and optical losses. This prevents the open-circuit voltage and efficiency of the tandem solar cell from reaching theoretically expected values, becoming one of the key bottlenecks for industrialization.

[0007] In view of the above-mentioned shortcomings, the designer has actively researched and innovated in order to create a hole transport layer, a perovskite solar cell and a preparation method, so as to make it more industrially valuable. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to provide a hole transport layer, a perovskite solar cell, and a method for its fabrication.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: One of the objectives of this invention is: A hole transport layer is composed of a co-self-assembled monolayer containing a self-assembled monolayer material and a dopant molecule; the dopant molecule is 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride; wherein the mass ratio of the dopant molecule to the self-assembled monolayer material is in the range of 1:2 to 4.

[0010] The second objective of this invention is: A perovskite solar cell has a structure comprising, in sequence, a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a passivation layer, an electron transport layer, a hole blocking layer, and a back electrode layer, wherein the hole transport layer is a self-assembled monolayer as described above.

[0011] The third objective of this invention: A method for fabricating a perovskite solar cell includes the following steps: Step 1: Provide a substrate and prepare a composite hole transport layer on the substrate; the composite hole transport layer includes an inorganic metal oxide layer and a co-self-assembled monolayer formed thereon, the co-self-assembled monolayer is composed of a self-assembled monolayer material and 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride doped therein; Step 2: Deposit an inorganic salt film on the composite hole transport layer using vacuum evaporation. Step 3: Spin-coat an organic salt solution onto an inorganic salt film, then anneal to form a perovskite light-absorbing layer; Step 4: Prepare a passivation layer on the perovskite light-absorbing layer; Step 5: Sequentially prepare the electron transport layer, hole blocking layer and back electrode to complete the battery fabrication.

[0012] As a further improvement of the present invention, step 1 includes the following steps in sequence: Step 11: Spin-coat hole transport layer material onto the substrate and anneal to form an inorganic metal oxide layer; wherein, the spin-coating parameters are 1800~2200 rpm for 28~32 s; the annealing parameters are annealing on a hot stage at 140~160℃ for 8~12 min; Step 12: Spin-coat the mixed solution onto the inorganic metal oxide layer, and anneal to form a co-self-assembled monolayer; the mixed solution is prepared by dissolving 0.8~1.2 mg / mL of self-assembled monolayer material and 0.2~0.4 mg / mL of 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride in ethanol; wherein, the spin-coating parameters are 1800~2200 rpm for 28~32 s; the annealing parameters are annealing on a hot plate at 140~160℃ for 8~12 min.

[0013] As a further improvement of the present invention, the hole transport layer material is PTAA or NiO. x The self-assembled monolayer material is at least one or a combination of two or more of Spiro-TTB and PEDOT-PSS; the self-assembled monolayer material is at least one or a combination of two or more of 2PACz, Me-4PACz, MeO-2PACz, MeO-4PACz, DMA-CPA, 4PADBC and 4PABCz.

[0014] As a further improvement of the present invention, in step 2, PbI2 and CsBr are deposited by co-evaporation, wherein the evaporation rate ratio of PbI2 to CsBr is 8~12:1; and the thickness of PbI2 in the inorganic salt film is 200~400nm.

[0015] As a further improvement of the present invention, in step 3, the organic salt solution is a mixed solution of FAI, FABr, MAI, MACl and urea dissolved in ethanol; wherein, the annealing is carried out in an air environment with a relative humidity of 30-50%, an annealing temperature of 110-130°C, and a time of 8-12 minutes; wherein, the proportion of urea in the total mass of the organic salt is 0.4%-0.6%.

[0016] As a further improvement of the present invention, in step 4, the passivation layer is a piperazine monoiodine layer, which is formed by spin-coating a piperazine monoiodine isopropanol solution with a concentration of 0.4~0.6 mg / mL at 4500~5500 rpm for 28~32 s and annealing at 90~110°C for 4~6 minutes.

[0017] As a further improvement to the present invention, step 5 includes the following steps in sequence: Step 51: Using vacuum evaporation, C is sequentially deposited on the passivation layer. 60 film; Step 52: Using atomic layer deposition (ALD), on C 60A SnO2 film is deposited on the thin film as a hole blocking layer; In step 51, C is deposited. 60 Before the thin film is deposited, a LiF thin film with a thickness of 0.5~2.0 nm is first vacuum-deposited.

[0018] As a further improvement of the present invention, the substrate is glass covered with an ITO conductive layer or a crystalline silicon bottom cell with an ITO intermediate composite layer.

[0019] By means of the above-described solution, the present invention has at least the following advantages: I. This invention fundamentally improves the surface properties of the hole transport layer and optimizes the interface characteristics and film crystallization quality by introducing "co-SAMs" technology (that is, doping 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride into Me-4PACz).

[0020] 1. As shown in the SEM results, the co-SAMs layer guides the perovskite to form a dense, pore-free crystalline film, reducing bulk and grain boundary defects and improving morphology.

[0021] 2. As shown in the XRD results, the characteristic peaks of perovskite are obvious, and there are no residual PbI2 peaks, which proves that the organic-inorganic reaction is more complete and a high-purity perovskite photoactive phase is obtained.

[0022] Second, the high-quality thin film of this invention is directly converted into excellent device performance, thereby improving the photoelectric conversion performance of single-junction cells.

[0023] 1. Improved photoelectric conversion efficiency (PCE).

[0024] 2. The increase in open-circuit voltage (VOC) proves that interfacial recombination is effectively suppressed.

[0025] 3. An increase in the fill factor (FF) indicates that carrier extraction and transport are smoother.

[0026] 4. The near overlap of forward and reverse scan data indicates that defect-related phenomena such as ion migration are greatly suppressed, the hysteresis effect is reduced, and the device operates more stably.

[0027] Third, this invention has been successfully applied to high-performance stacked batteries, solving key bottlenecks.

[0028] 1. Improve the efficiency of perovskite / crystalline silicon tandem solar cells.

[0029] 2. The improved open-circuit voltage of the tandem battery directly proves the decisive role of this invention in reducing the interface loss of the top battery and achieving efficient voltage superposition, thus breaking through the voltage bottleneck.

[0030] 3. The preparation methods (such as spin coating, vapor deposition, and atomic layer deposition) are compatible with mainstream semiconductor and photovoltaic processes, have good prospects for industrial application, and have good process compatibility.

[0031] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following are preferred embodiments of the present invention described in detail with reference to the accompanying drawings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart of a method for preparing a perovskite solar cell according to the present invention; Figure 2 This is a schematic diagram of the morphology of a wide-bandgap perovskite thin film, representing the control group (undoped with SAM) in the first or second experimental example of this invention. Figure 1 ; Figure 3 This is a schematic diagram of the morphology of a wide-bandgap perovskite thin film, representing the control group (undoped with SAM) in the first or second experimental example of this invention. Figure 2 ; Figure 4 This is a schematic diagram of the morphology of the wide-bandgap perovskite thin film (doped with SAM) in the experimental group of the first or second experimental example of this invention. Figure 1 ; Figure 5 This is a schematic diagram of the morphology of the wide-bandgap perovskite thin film (doped with SAM) in the experimental group of the first or second experimental example of this invention. Figure 2 ; Figure 6 These are XRD patterns of wide-bandgap perovskite thin films in the experimental group (doped SAM) and control group (undoped SAM) in the first or second experimental example of this invention. Figure 7 This is a JV curve of a wide-bandgap perovskite solar cell with SAM dopant in the first experimental example of the present invention. Figure 8 This is a JV curve of a wide-bandgap perovskite solar cell with SAM dopant in the second experimental example of the present invention. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] like Figures 1-8 As shown, the purpose of this invention is to provide a perovskite solar cell and its fabrication method. The co-SAMs technology, which involves doping or mixing other molecules into SAMs, can solve the problem of interface defects caused by traditional SAMs in the actual fabrication of cells, while simultaneously improving the efficiency of perovskite solar cells.

[0037] First embodiment of the present invention: A hole transport layer in this embodiment is composed of a co-self-assembled monolayer containing a self-assembled monolayer material and a dopant molecule; the dopant molecule is 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride; wherein the mass ratio of the dopant molecule to the self-assembled monolayer material is in the range of 1:2~4.

[0038] The second embodiment of the present invention: This embodiment of a perovskite solar cell comprises, in sequence, a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a passivation layer, an electron transport layer, a hole blocking layer, and a back electrode layer, wherein the hole transport layer is the aforementioned co-self-assembled monolayer.

[0039] The hole transport layer material is one or more of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), nickel oxide (NiOx), Spiro-TTB, and PEDOT-PSS, which together with SAMs serve as the hole transport layer.

[0040] Furthermore, the other molecules doped or mixed in the SAMs are 3,5-bis(trifluoromethyl)phenylhydrazine hydrochloride.

[0041] Furthermore, the concentration range of the doped material is 0.1~1 mg / mL.

[0042] Furthermore, the SAMs molecule is at least one of 2PACz, Me-4PACz, MeO-2PACz, MeO-4PACz, DMA-CPA, 4PADBC, and 4PABCz.

[0043] Furthermore, the perovskite is a wide-bandgap perovskite.

[0044] The third embodiment of the present invention: This embodiment provides a method for fabricating a perovskite solar cell, the steps of which are as follows: a hole transport layer is fabricated on a transparent conductive substrate, wherein the hole transport layer can be fabricated by any one or two of spin coating, blade coating, slot coating, inkjet printing, magnetron sputtering, and vacuum evaporation.

[0045] The method for preparing the perovskite thin film includes a first step of evaporating inorganic salts and a second step of coating organic salts.

[0046] Furthermore, the vapor-deposited inorganic salt comprises any one or more substances selected from lead halides, alkali metal halides, and inorganic metal lead halides.

[0047] Furthermore, the coated organic salt comprises any one or more substances selected from ammonium halide salts, organic ammonium salts, and pseudohalogenated ammonium salts.

[0048] Furthermore, the lead halide in the vapor-deposited inorganic salt includes any one or more of lead iodide, lead bromide, and lead chloride.

[0049] The alkali metal halide salts include any one or more of the following materials: cesium chloride, rubidium chloride, potassium chloride, lithium chloride, cesium bromide, cesium iodide, rubidium iodide, potassium iodide, and potassium bromide.

[0050] The inorganic metal lead halide includes any one or more of the following materials: cesium lead iodine, cesium lead chloride, cesium lead bromine, and cesium lead iodine bromine.

[0051] Furthermore, the thickness of the evaporated inorganic salt is 250nm~400nm.

[0052] Furthermore, the coated ammonium halide salt includes any one or more of the following materials: formamidinium iodine, methylammonium iodine, formamidinium bromide, formamidinium chloride, methylammonium chloride, methylammonium bromide, methyldiamine iodine, ethylenediamine iodine, and propylenediamine iodine.

[0053] The coated organic ammonium salt includes any one or more of the following materials: urea, thiourea, acrylamide, and benzenesulfonamide.

[0054] The coated pseudohalogen ammonium salt includes any one or more of the following materials: ammonium thiocyanate, methylamine thiocyanate, formamidine thiocyanate, ethylamine thiocyanate, and guanidine thiocyanate.

[0055] Furthermore, the concentration of the coated organic salt is 0.5~1.5M.

[0056] The passivation layer material is any one or more of the following: phenylethyl ammonium iodide, piperazine monoiodide, piperazine iodide, oleylamine iodide, phenylethyl ammonium bromide, oleylamine chloride, ethylenediamine iodide, propylenediamine iodide, and lithium fluoride.

[0057] The passivation layer can be prepared by any of the following methods: spin coating, blade coating, slot coating, inkjet printing, or vacuum evaporation.

[0058] The electron transport layer material is C. 60 Any one or more of the following materials: PCBM, zinc oxide, tin oxide, and titanium oxide.

[0059] The electron transport layer can be prepared by any of the following methods: spin coating, blade coating, slot coating, inkjet printing, vacuum evaporation, or atomic layer deposition.

[0060] The back electrode layer can be any one of Au, Ag, Al, Cu, or carbon electrodes.

[0061] Furthermore, the back electrode layer can be prepared by any one of vacuum evaporation, magnetron sputtering, screen printing, or inkjet printing.

[0062] Fourth embodiment of the present invention: like Figure 1 A method for fabricating a perovskite solar cell includes the following steps: Step 1: Provide a substrate (the substrate is glass covered with an ITO conductive layer or a crystalline silicon bottom cell with an ITO intermediate composite layer), and prepare a composite hole transport layer on the substrate; the composite hole transport layer includes an inorganic metal oxide layer and a co-self-assembled monolayer formed thereon, the co-self-assembled monolayer is composed of a self-assembled monolayer material and 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride doped therein.

[0063] Step 1 includes the following steps in sequence: Step 11: Spin-coat hole transport layer material onto the substrate and anneal to form an inorganic metal oxide layer; wherein, the spin-coating parameters are 1800~2200 rpm for 28~32 s; the annealing parameters are annealing on a hot stage at 140~160℃ for 8~12 min; Step 12: Spin-coat the mixed solution onto the inorganic metal oxide layer, and anneal to form a co-self-assembled monolayer; the mixed solution is prepared by dissolving 0.8~1.2 mg / mL of self-assembled monolayer material and 0.2~0.4 mg / mL of 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride in ethanol; wherein, the spin-coating parameters are 1800~2200 rpm for 28~32 s; the annealing parameters are annealing on a hot plate at 140~160℃ for 8~12 min.

[0064] The above concentration range ensures that the "co-SAMs" can effectively cover and passivate NiO. x The surface has a critical equilibrium window where excessive molecular buildup does not impede hole transport. Beyond this range, the synergistic effect diminishes sharply.

[0065] The hole transport layer material is PTAA and NiO. x The self-assembled monolayer material is at least one or a combination of two or more of Spiro-TTB and PEDOT-PSS; the self-assembled monolayer material is at least one or a combination of two or more of 2PACz, Me-4PACz, MeO-2PACz, MeO-4PACz, DMA-CPA, 4PADBC and 4PABCz.

[0066] In step 1, the main objective is to prepare a composite hole transport layer (NiO). x +Total SAMs).

[0067] The innovation of this step lies in the selection of a co-SAMs composed of Me-4PACz and 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride as a specific functional layer. It is not a conventional single SAM, but a specific molecular combination designed to solve the specific interface problems of poor wettability and insufficient coverage of traditional SAMs. In essence, it introduces a new interface modification material.

[0068] Step 2: Deposit an inorganic salt film on the composite hole transport layer using vacuum evaporation.

[0069] In step 2, PbI2 and CsBr are deposited using a co-evaporation method, wherein the evaporation rate ratio of PbI2 to CsBr is 8~12:1; and the thickness of PbI2 in the inorganic salt film is 200~400 nm.

[0070] The aforementioned ratios are crucial parameters for obtaining an inorganic salt framework suitable for the complete reaction of subsequent organic salts and possessing the correct band gap (~1.65 eV). Deviations in the ratios will directly lead to PbI2 residue or band gap deviation, disrupting the current matching of the tandem solar cell.

[0071] Step 3: Spin-coat an organic salt solution onto an inorganic salt film, and then anneal to form a perovskite light-absorbing layer.

[0072] In step 3, the organic salt solution is a mixed solution of FAI, FABr, MAI, MACl and urea dissolved in ethanol; the annealing is carried out in an air environment with a relative humidity of 30-50%, an annealing temperature of 110-130°C, and a time of 8-12 minutes; and the proportion of urea in the total mass of the organic salt is 0.4%-0.6%.

[0073] The aforementioned humidity range is a targeted optimization that synergistically matches the characteristics of the co-SAMs interface and urea-containing organic salts. It precisely controls the crystallization kinetics, utilizing moisture to promote crystallization while avoiding potential adverse effects of moisture on the co-SAMs layer.

[0074] In this study, trace amounts of urea do not function as independent additives, but rather synergistically regulate crystallization with the co-SAMs layer. It is specifically designed to help eliminate the CsBr / PbI2 phase separation problem unique to the co-distillation method for preparing wide-bandgap perovskites, and the dosage is matched to this particular system.

[0075] In steps 2 and 3, the main objective is a two-step process of vapor-depositing inorganic salts followed by spin-coating organic salts.

[0076] The innovation of this step lies in defining the co-distillation of PbI2 and CsBr at the co-SAMs interface, followed by a reaction with a specific organic salt containing FAI / FABr / MAI / MACl / urea. This is a specific process route optimized for the preparation of high-quality wide-bandgap perovskites, and its creativity lies in the material selection (CsBr is used to adjust the bandgap) and process combination.

[0077] Step 4: Prepare a passivation layer on the perovskite light-absorbing layer.

[0078] In step 4, the passivation layer is a piperazine monoiodine layer, which is formed by spin-coating a piperazine monoiodine isopropanol solution with a concentration of 0.4~0.6 mg / mL at 4500~5500 rpm for 28~32 s and annealing at 90~110°C for 4~6 minutes.

[0079] Step 5: Sequentially prepare the electron transport layer, hole blocking layer and back electrode to complete the battery fabrication.

[0080] Step 5 includes the following steps in sequence: Step 51: Using vacuum evaporation, C is sequentially deposited on the passivation layer. 60 film; Step 52: Using atomic layer deposition (ALD), on C 60 A SnO2 film is deposited on the thin film as a hole blocking layer; In step 51, C is deposited. 60Before the thin film is deposited, a LiF thin film with a thickness of 0.5~2.0 nm is first vacuum-deposited.

[0081] The coordination mechanism between the above steps in this embodiment: First-layer synergy (interface-crystallization): The co-SAMs layer in step 1 improves the wettability of the perovskite precursor through its optimized surface energy. This directly creates an ideal substrate for the deposition of a uniform and dense inorganic salt (PbI2 / CsBr) film in step 2 and greatly promotes the penetration and complete reaction of the organic salt in step 3.

[0082] The second layer of synergy (crystallization-performance): The synergistic effect described above directly leads to an improvement in the quality of the perovskite film (dense, free of PbI2 residue) (corresponding to...). Figures 2-6 A high-quality light-absorbing layer is the physical basis for achieving high device performance, and therefore naturally and inextricably leads to an improvement in the final device performance (VOC, FF, efficiency, etc.). Figure 7 and Figure 8 (and Tables 1 and 2).

[0083] First experimental example of the present invention: This experimental example describes a fabrication process for an inverted wide-bandgap perovskite solar cell, using ITO as the conductive substrate and NiO as the conductive substrate. x The self-assembled monolayer (Me-4PACz) serves as the hole transport layer, PbI2 and CsBr are vapor-deposited as the inorganic salt framework, a perovskite light-absorbing layer is formed by spin-coating a mixed solution of formamidine iodide (FAI), formamidine bromide (FABr), methylamine iodide (MAI), methylamine chloride (MACl), and urea, and a piperazine monoiodide (PiPl) serves as the passivation layer. 60 The electron transport layer is SnO2, the hole blocking layer is SnO2, and the back electrode is Ag. The specific steps are as follows: Step 1: Add glass cleaner, deionized water and ethanol to the ITO glass in sequence for ultrasonic cleaning. After cleaning, perform ultraviolet ozone surface treatment for 15 minutes and then take it out for use.

[0084] Step 2: Prepare 15 mg / mL NiO x For the solution preparation, weigh 15 mg of NiOx nanoparticles and dissolve them in 1 mL of deionized water, then sonicate for 15 min to ensure uniform dispersion. Place the prepared ITO glass on a spin coater, set the spin coating parameters to 2000 rpm for 30 s, and use a pipette to draw 100 μL of NiOx nanoparticles. x The solution was evenly spread onto the ITO glass, and after spin coating, it was annealed on a hot plate at 150°C for 10 min to obtain NiO. x Hole transport layer.

[0085] Step 3: Weigh 1 mg of Me-4PACz and 0.3 mg of 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride and dissolve them in 1 mL of ethanol to prepare the experimental group SAM solution. Weigh 1 mg of Me-4PACz and dissolve it in 1 mL of ethanol to prepare the control group SAM solution. The NiO prepared in Step 2... x The surface of the hole transport layer was spin-coated with SAM solution from the experimental group and the control group, respectively, as the hole transport layer. The spin-coating parameters were set to 2000 rpm and 30 s. 80 μL of solution was drawn up using a pipette. After spin-coating, the solution was annealed on a hot stage at 100 °C for 10 min to prepare the Me-4PACz hole transport layer.

[0086] Step 4: Weigh a certain amount of PbI2 and CsBr and add them to different evaporation crucibles. Use a beam source evaporation device to co-evaporate PbI2 and CsBr. The evaporation rate ratio of PbI2 to CsBr is 10:1. Stop evaporating PbI2 when the thickness is 300 nm. Prepare an inorganic salt film co-evaporated with PbI2 and CsBr.

[0087] Step 5: Weigh 35 mg of formamidine iodide (FAI), 25 mg of formamidine bromide, 10 mg of methylamine iodide, 8 mg of methylamine chloride, and 0.5 mg of urea, and dissolve them in 1 mL of ethanol to prepare an organic salt solution. Spin-coat the organic salt solution onto the inorganic salt film obtained in Step 4. Set the spin-coating parameters to 4000 rpm and 30 s. Use a pipette to draw 150 μL of solution, drop it onto the film, let it stand for 3 s to ensure sufficient contact, and then begin spin-coating. After spin-coating, anneal the film at 120°C for 10 min in an air environment with a relative humidity of 40%. After annealing, remove the film and allow it to cool naturally to obtain a wide-bandgap perovskite film.

[0088] Step 6: Weigh 5 mg of Pipl drug, add 10 mL of isopropanol solvent in a glove box to prepare a 0.5 mg / mL passivation layer solution, shake to fully dissolve, and then spin-coat the Pipl passivation layer onto the wide bandgap film prepared in step 5. Set the spin-coating parameters to 5000 rpm and 30 s, and use a pipette to draw 100 μL of solution. After completion, place it on a hot plate heated to 100 °C for annealing for 5 min to prepare the perovskite passivation layer.

[0089] Step 7: Apply an electron transport layer C to the passivation layer obtained in Step 6 using a vacuum evaporation method. 60 For preparation, the sample is placed on a matching mask and subjected to a vacuum of 6... 10 -4 Under the condition of Pa, approximately 20 nm of C is deposited through a linear evaporation source at a rate of 0.15 Å / s. 60 A thin film was used to prepare an electron transport layer.

[0090] Step 8: A hole-blocking layer (SnO2) is prepared on the electron transport layer surface obtained in Step 7 using atomic layer deposition (ALD). The sample is placed in a process vacuum chamber, the chamber temperature is set to a stable 80°C, the tin source is TDMASn, the oxygen source is pure water, the outlet temperature is 65°C, and the number of purging cycles is 80. The hole-blocking layer is thus prepared.

[0091] Step 9: A back electrode is fabricated on the surface of the hole-blocking layer obtained in Step 8 using vacuum evaporation. The sample is placed on a matching mask, and the deposition is carried out at a vacuum level of 6... 10 -4 Ag metal electrodes were prepared by evaporating approximately 100 nm of Ag at a rate of 0.8 Å / s under Pa conditions, and finally, an inverted wide-bandgap perovskite solar cell was obtained.

[0092] Second experimental example of the present invention: This experimental example describes a fabrication process for a perovskite / heterocrystalline silicon tandem solar cell, using heterocrystalline silicon as the base cell, ITO as the intermediate composite layer, and NiO as the intermediate composite layer. x The perovskite light-absorbing layer is formed by spin-coating a mixture of formamidine iodide (FAI), formamidine bromide (FABr), methylamine iodide (MAI), methylamine chloride (MACl), and urea. Piperazine monoiodide (PiPl) serves as the passivation layer, as do ultrathin LiF layers. 60 The electron transport layer is composed of SnO2 as the hole blocking layer, ITO as the transparent top electrode, and a silver gate as the back electrode. The specific steps are as follows: Step 1: An intermediate composite layer ITO is prepared on the n-side of a heterocrystalline silicon substrate using a vacuum sputtering deposition (PVD) system. After fixing the sample on the substrate holder, it is fed into the deposition chamber through the transmission system of the equipment. After reaching the set vacuum level, the sputtering process is performed. The sputtering power is set to 1KW, the gas mixture is argon-oxygen (oxygen content 10%), and the thickness of ITO is 20nm, thus obtaining the intermediate composite layer.

[0093] Step 2: Prepare a 15 mg / mL NiOx solution by weighing 15 mg of NiO. x The nanoparticles were dissolved in 1 mL of deionized water and sonicated for 15 min to disperse them evenly. The heterocrystalline silicon substrate prepared in step 1 was placed on a spin coater, and the spin coating parameters were set to 2000 rpm for 30 s. 100 μL of NiO was then pipetted into the substrate. x After the solution was evenly spread and spin-coated, it was annealed on a hot plate at 150°C for 10 min to obtain NiO. x Hole transport layer.

[0094] Step 3: Weigh 1 mg of Me-4PACz and 0.3 mg of 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride and dissolve them in 1 mL of ethanol to prepare the experimental group SAM solution. Weigh 1 mg of Me-4PACz and dissolve it in 1 mL of ethanol to prepare the control group SAM solution. The NiO prepared in Step 2... x The surface of the hole transport layer was spin-coated with SAM solution from the experimental group and the control group, respectively, as the hole transport layer. The spin-coating parameters were set to 2000 rpm and 30 s. 80 μL of solution was drawn up using a pipette. After spin-coating, the solution was annealed on a hot stage at 100 °C for 10 min to prepare the Me-4PACz hole transport layer.

[0095] Step 4: Weigh a certain amount of PbI2 and CsBr and add them to different evaporation crucibles. Use a beam source evaporation device to co-evaporate PbI2 and CsBr. The evaporation rate ratio of PbI2 to CsBr is 10:1. Stop evaporating PbI2 when the thickness is 400 nm. Prepare an inorganic salt film co-evaporated with PbI2 and CsBr.

[0096] Step 5: Weigh 35 mg of formamidine iodide (FAI), 25 mg of formamidine bromide, 10 mg of methylamine iodide, 8 mg of methylamine chloride, and 0.5 mg of urea, respectively, and dissolve them in 1 mL of ethanol to prepare an organic salt solution. Spin-coat the organic salt solution onto the inorganic salt film obtained in Step 4. Set the spin-coating parameters to 3000 rpm and 30 s. Use a pipette to draw 150 μL of solution, drop it onto the film, let it stand for 5 s to ensure sufficient contact, and then begin spin-coating. After spin-coating, anneal the film on a hot plate at 120°C for 10 min in an air environment with a relative humidity of 40%. After annealing, remove the film and allow it to cool naturally to obtain a wide-bandgap perovskite film.

[0097] Step 6: Weigh 5 mg of Pipl drug, add 10 mL of isopropanol solvent in a glove box to prepare a 0.5 mg / mL passivation layer solution, shake to fully dissolve, and then spin-coat the Pipl passivation layer onto the wide bandgap film prepared in step 5. Set the spin-coating parameters to 5000 rpm and 30 s, and use a pipette to draw 100 μL of solution. After completion, place it on a hot plate heated to 100 °C for annealing for 5 min to prepare the perovskite passivation layer.

[0098] Step 7: An ultrathin passivation layer LiF and an electron transport layer C are deposited on the surface of the passivation layer obtained in Step 6 using vacuum evaporation. 60 For preparation, the sample is placed on a matching mask and subjected to a vacuum of 6... 10 -4Under the condition of Pa, a 1 nm ultrathin LiF passivation layer was deposited at a rate of 0.1 Å / s, followed by the deposition of approximately 10 nm of C through a linear evaporation source at a rate of 0.15 Å / s. 60 A thin film was used to prepare an electron transport layer.

[0099] Step 8: An atomic layer deposition (ALD) method is used to prepare a hole-blocking layer (SnO2) on the surface of the electron transport layer obtained in Step 7. The sample is placed in a process vacuum chamber, the chamber temperature is set to a stable 80℃, the tin source is TDMASn, the oxygen source is pure water, the outlet temperature is 65℃, and the number of purge cycles is 70, resulting in a SnO2 layer with a thickness of approximately 15 nm. The hole-blocking layer is thus prepared.

[0100] Step 9: A transparent conductive electrode, ITO, is prepared on the surface of the hole-blocking layer obtained in Step 8 using a vacuum sputtering deposition (PVD) system. After fixing the sample on the substrate holder, it is fed into the deposition chamber via the equipment's transmission system. Once the set vacuum level is reached, the sputtering process is performed. The sputtering power is set to 0.3 kW, the gas mixture is argon-oxygen (oxygen content 10%), and the ITO thickness is 35 nm, thus obtaining the ITO transparent electrode. Step 10: An Ag electrode is prepared on the surface of the ITO transparent electrode obtained in Step 9 using vacuum evaporation. The vacuum level is 6... 10 -4 Under the condition of Pa, an Ag gate of about 400 nm is deposited as the back electrode for collecting current, and finally a perovskite / heterocrystalline silicon tandem solar cell is obtained.

[0101] The effects of the preparation method of the present invention will be illustrated below using experimental data as an example.

[0102] Figures 2-5 The images shown are morphological diagrams of wide-bandgap perovskite films with and without SAM dopant. Figure 2 and Figure 3 SEM surface morphology analysis of the control group sample without SAM showed obvious pores between the perovskite grains, while the experimental group doped with SAM... Figure 4 and Figure 5 However, it exhibits a dense crystalline morphology. This comparison shows that perovskite crystallizes and grows differently on different SAM substrates. Doping with SAM can effectively reduce obvious defects generated during the preparation of perovskite, thereby improving the quality of perovskite films.

[0103] Figure 6The figures show XRD patterns of wide-bandgap perovskite films with and without SAM dopant. As can be seen from the figures, the undoped control group sample exhibits obvious lead iodide diffraction peaks, while the SAM-doped experimental group shows no lead iodide diffraction peaks. This indicates that the coated organic salt reacts completely with the evaporated inorganic lead iodide, leaving no lead iodide residue. Furthermore, it also shows distinct characteristic peaks of the perovskite photoactive phase (α phase) on different crystal planes, indicating better crystallinity of the perovskite film.

[0104] Figure 7 The graph shows the JV curves of wide-bandgap perovskite solar cells with and without SAM dopant. The comparison shows that the undoped control group exhibits lower VOC and greater hysteresis, resulting in poorer photovoltaic performance, while the SAM-doped experimental group shows higher VOC and lower hysteresis, indicating improved device efficiency. Specific parameters are shown in Table 1 below.

[0105] Table 1 Figure 8 The graph shows the JV curves of perovskite-silicon tandem solar cells with and without SAM dopant. The comparison in the graph shows that the SAM-doped experimental group also exhibits higher VOC in the tandem cells, corresponding to superior photovoltaic performance. Specific parameters are shown in Table 2 below.

[0106] Table 2 In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0107] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hole transport layer, characterized in that, It is composed of a co-self-assembled monolayer containing a self-assembled monolayer material and a dopant molecule; the dopant molecule is 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride; wherein the mass ratio of the dopant molecule to the self-assembled monolayer material is in the range of 1:2 to 4.

2. A perovskite solar cell, comprising, in sequence, a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a passivation layer, an electron transport layer, a hole blocking layer, and a back electrode layer, characterized in that, The hole transport layer is the co-self-assembled monolayer as described in claim 1.

3. A method for fabricating a perovskite solar cell, characterized in that, The steps are as follows: Step 1: Provide a substrate and prepare a composite hole transport layer on the substrate; the composite hole transport layer includes an inorganic metal oxide layer and a co-self-assembled monolayer formed thereon, the co-self-assembled monolayer being composed of a self-assembled monolayer material and 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride doped therein; Step 2: An inorganic salt thin film is deposited on the composite hole transport layer using a vacuum evaporation method; Step 3: Spin-coat an organic salt solution onto the inorganic salt film, and then anneal to form a perovskite light-absorbing layer; Step 4: Prepare a passivation layer on the perovskite light-absorbing layer; Step 5: Sequentially prepare the electron transport layer, hole blocking layer and back electrode to complete the battery fabrication.

4. The method for preparing a perovskite solar cell as described in claim 3, characterized in that, Step 1 includes the following steps in sequence: Step 11: Spin-coat hole transport layer material onto the substrate and anneal it to form the inorganic metal oxide layer; wherein, the spin-coating parameters are 1800~2200 rpm for 28~32 s; the annealing parameters are annealing on a hot stage at 140~160℃ for 8~12 min; Step 12: Spin-coat the mixed solution onto the inorganic metal oxide layer, and anneal to form the co-self-assembled monolayer; the mixed solution is prepared by dissolving a self-assembled monolayer material with a concentration of 0.8~1.2 mg / mL and 3,5-bis(trifluoromethylphenylhydrazine) hydrochloride with a concentration of 0.2~0.4 mg / mL in ethanol; wherein, the spin-coating parameters are 1800~2200 rpm for 28~32 s; the annealing parameters are annealing on a hot plate at 140~160℃ for 8~12 min.

5. The method for preparing a perovskite solar cell as described in claim 4, characterized in that, The hole transport layer material is PTAA or NiO. x The self-assembled monolayer material is at least one or a combination of two or more of Spiro-TTB and PEDOT-PSS; the self-assembled monolayer material is at least one or a combination of two or more of 2PACz, Me-4PACz, MeO-2PACz, MeO-4PACz, DMA-CPA, 4PADBC and 4PABCz.

6. The method for preparing a perovskite solar cell as described in claim 3, characterized in that, In step 2, PbI2 and CsBr are deposited using a co-evaporation method, wherein the evaporation rate ratio of PbI2 to CsBr is 8~12:1; and the thickness of PbI2 in the inorganic salt film is 200~400 nm.

7. The method for preparing a perovskite solar cell as described in claim 3, characterized in that, In step 3, the organic salt solution is a mixed solution of FAI, FABr, MAI, MACl and urea dissolved in ethanol; wherein the annealing is carried out in an air environment with a relative humidity of 30-50%, an annealing temperature of 110-130°C and a time of 8-12 minutes; wherein the proportion of urea in the total mass of the organic salt is 0.4%-0.6%.

8. The method for preparing a perovskite solar cell as described in claim 3, characterized in that, In step 4, the passivation layer is a piperazine monoiodine layer, which is formed by spin-coating a piperazine monoiodine isopropanol solution with a concentration of 0.4~0.6 mg / mL at 4500~5500 rpm for 28~32 s and annealing at 90~110°C for 4~6 minutes.

9. The method for preparing a perovskite solar cell as described in claim 3, characterized in that, Step 5 includes the following steps in sequence: Step 51: Using vacuum evaporation, C is sequentially deposited on the passivation layer. 60 film; Step 52: Using atomic layer deposition, on the C 60 A SnO2 film is deposited on the thin film as the hole blocking layer; In step 51, C is deposited. 60 Before the thin film is deposited, a LiF thin film with a thickness of 0.5~2.0 nm is first vacuum-deposited.

10. The method for preparing a perovskite solar cell as described in claim 3, characterized in that, The substrate is either glass covered with an ITO conductive layer or a crystalline silicon bottom cell with an ITO intermediate composite layer.

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