Preparation method of a wide-bandgap perovskite solar cell and the cell

Abstract

The application relates to a preparation method of a wide-bandgap perovskite solar cell and the cell, which comprises the following steps in sequence: providing a transparent conductive substrate, and preparing a composite hole transport layer on the transparent conductive substrate; preparing a perovskite light-absorbing layer on the composite hole transport layer, wherein a precursor ink used for preparing the perovskite light-absorbing layer contains a bulk phase passivation material with a concentration of 0.1-1 mg / mL; spin-coating an interfacial modification material with a concentration of 0.1-1 mg / mL on the perovskite light-absorbing layer to form an interfacial modification layer through annealing; and preparing an electron transport layer and a back electrode layer on the interfacial modification layer in sequence to obtain the wide-bandgap perovskite solar cell. The application realizes the synergistic inhibition of bulk phase and interfacial defects, and the photoelectric performance is improved.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, and in particular to a method for fabricating a wide-bandgap perovskite solar cell and the cell itself. 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, the efficiency limit of perovskite tandem solar cells exceeds 40%, making it a promising photovoltaic technology for overcoming the efficiency limit of single-junction solar cells. The highest efficiency achieved so far is 34.8% for perovskite-silicon tandem solar cells, demonstrating the strong market competitiveness of this technology. Wide-bandgap perovskite cells play a crucial role as the top cell in these tandem cells; however, internal defects in wide-bandgap perovskite films, such as photoinduced phase separation and severe VOC losses, limit their efficiency improvement. Bulk passivation and interface engineering are typically effective methods to regulate and suppress these defects, thereby improving the efficiency of wide-bandgap perovskite cells.

[0004] The shortcomings of existing technology are: 1. There are limitations in our understanding and solutions to the unique defects of wide-bandgap perovskites. The technical problem is often oversimplified: most existing technologies attribute the performance loss of wide-bandgap perovskites to interface defects or surface morphology issues, and the proposed solutions (such as optimizing hole transport layer materials, improving the conductivity of composite layers, and modifying electrode interfaces) are mostly centered around a single interface engineering approach. These solutions fail to fully recognize and collaboratively address the more fundamental defects inherent in the bulk phase of wide-bandgap perovskite materials, particularly ion migration caused by halogen vacancies and the resulting photoinduced phase separation.

[0005] "Treats the symptoms but not the root cause": Simply optimizing the interface will not solve the problem. Bulk defects, as non-radiative recombination centers and sources of ion migration, will continue to damage device performance, leading to severe open-circuit voltage (VOC) loss and decreased operational stability, thus greatly diminishing the effectiveness of simple interface optimization.

[0006] 2. The one-sidedness and lack of synergy of existing passivation strategies While some existing technologies recognize the importance of additives or passivation, their strategies are often one-sided or isolated.

[0007] Some techniques (such as the introduction of crystal growth regulators) mainly focus on improving film morphology and crystallinity, but are insufficient in passivating deep-seated bulk point defects (such as lead vacancies and halogen vacancies).

[0008] Other techniques (such as interface modification using specific dipole molecules) focus primarily on energy level alignment and surface passivation, but fail to suppress the diffusion and impact of bulk defects to the interface from the source.

[0009] Currently, there is a lack of a systematic passivation strategy that combines source suppression of bulk defects with effective termination of interface defects and possesses inherent synergy.

[0010] 3. Lack of targeted and optimized guidance in material and process selection. There are many types of additives or interface materials disclosed in the prior art, but there is a lack of clear guidance on which material combinations can produce a synergistic effect of 1+1>2 for the specific system of wide-bandgap perovskite.

[0011] In particular, for the selected material, there is often no clear optimization window for determining what concentration range is effective and harmless. Excessively high concentrations may introduce new impurity recombination centers or impair the charge transport properties of the thin film, and existing technologies have not fully revealed the "toxicity" boundary and optimal operating window of this critical process parameter.

[0012] 4. Efficiency improvement encounters bottlenecks While existing technologies have pushed the efficiency of perovskite / crystalline silicon tandem solar cells to high levels (e.g., exceeding 33%) through various optimizations, further improvements face bottlenecks. This suggests that existing technological approaches may have reached their theoretical limits in addressing the aforementioned bulk and interface synergy defects, necessitating the development of new technological pathways to achieve breakthroughs.

[0013] In view of the above-mentioned shortcomings, the designer has actively researched and innovated in order to create a wide-bandgap perovskite solar cell preparation method and cell, making it more industrially valuable. Summary of the Invention

[0014] To address the aforementioned technical problems, the present invention aims to provide a method for fabricating a wide-bandgap perovskite solar cell and the cell itself. This invention discloses a method for improving the quality of perovskite thin films, regulating and suppressing the generation of film defects, and increasing the efficiency of wide-bandgap perovskite and tandem solar cells. Through bulk passivation and interface modification, wide-bandgap perovskite solar cells with efficiencies exceeding 22% and perovskite-silicon tandem solar cells with VOCs exceeding 1.95 V and efficiencies exceeding 32% were fabricated.

[0015] To achieve the above objectives, the present invention adopts the following technical solution: One of the objectives of this invention is: A method for fabricating a wide-bandgap perovskite solar cell includes the following steps: Step S1: Provide a transparent conductive substrate and fabricate a composite hole transport layer on the transparent conductive substrate; Step S2: Prepare a perovskite light-absorbing layer on the composite hole transport layer, wherein the precursor ink used to prepare the perovskite light-absorbing layer contains a bulk passivation material with a concentration of 0.1~1 mg / mL. Step S3: Spin-coat an interface modification material with a concentration of 0.1~1 mg / mL onto the perovskite light-absorbing layer, and anneal it to form an interface modification layer; Step S4: An electron transport layer and a back electrode layer are sequentially fabricated on the interface modification layer to obtain a wide-bandgap perovskite solar cell; In this process, the bulk passivating agent and the interface modification layer work together to synergistically reduce the density of perovskite bulk phase and interface defects.

[0016] As a further improvement of the present invention, step S1 includes the following steps in sequence: Step S11: Spin-coat an aqueous solution of hole transport layer material onto a transparent conductive substrate, and then anneal it to form a hole transport layer; The hole transport layer material is PTAA and NiO. x One of Spiro-TTB and PEDOT-PSS; the concentration of the hole transport layer material is 10~20 mg / mL; the spin coating parameters are 1800~2200 rpm, 28~32 s; the annealing temperature is 140~160℃, and the time is 8~12 minutes; Step S12: Spin-coat a self-assembled monolayer solution onto the hole transport layer, and anneal it to form a composite hole transport layer; The self-assembled monolayer was MeO-4PACz; the spin coating parameters were 2800~3200 rpm for 28~32 s; and the annealing temperature was 80~120℃ for 8~12 minutes.

[0017] As a further improvement of the present invention, step S2 includes the following steps in sequence: Step S21: Spin-coat the precursor ink onto the composite hole transport layer to form a perovskite wet film; Step S22: Place the perovskite wet film in a vacuum environment for flash evaporation. The vacuum flash evaporation configuration is to pump to 10 Pa in 10 seconds and the flash evaporation time is 28~32 seconds. Step S23: Place the flash-evaporated film in an environment with a humidity of no more than 20-40% and anneal it at 90-110℃ for 18-22 minutes to form a perovskite light-absorbing layer.

[0018] As a further improvement of the present invention, the bulk passivation material is one of potassium hexafluorophosphate, 2,3,4,5,6-pentafluorobenzylphosphonic acid, hexamethylenediaminetetramethylenephosphonic acid, 1,6-hexanediphosphonic acid, and histamine diphosphate; the concentration of the bulk passivation material is 0.1 mg / mL.

[0019] As a further improvement of the present invention, in step S3, the spin coating parameters are 4800~5200 rpm for 28~32 s; the annealing is performed at 90~110℃ for 4~6 minutes.

[0020] As a further improvement of the present invention, the interface modification material is one of piperazine monoiodine, piperazine monochloride, piperazine monobromide, phenylethyl ammonium iodide, piperazine iodine, oleylamine iodine, phenylethyl ammonium bromide, oleylamine chloride, ethylenediamine iodine, propylenediamine iodine, naphthylmethyl ammonium bromide, and 4-trifluoromethylphenylethylamine iodine; the concentration of the interface modification material is 0.1 mg / mL.

[0021] As a further improvement of the present invention, in step S4, the vacuum degree is 6 10 -4 Under the condition of Pa, electron transport layer materials with a thickness of 18~22nm were prepared by vacuum evaporation at a rate of 0.1~0.2Å / s as electron transport layers.

[0022] As a further improvement of the present invention, before preparing the electron transport layer, an interface modification layer is first prepared under a vacuum of 6... 10 -4 Under the condition of Pa, LiF passivation layers with a thickness of 0.5~2 nm were prepared by vacuum evaporation at a rate of 0.05~0.2 Å / s.

[0023] As a further improvement of the present invention, SnO2 is prepared as a hole blocking layer on the electron transport layer by atomic layer deposition. TDMASn is used as the tin source, water is used as the oxygen source, the chamber temperature is kept stable at 70~90℃, the source temperature is kept at 60~70℃, the number of purging cycles is 60~80, and the SnO2 layer with a thickness of about 10~20nm is prepared to obtain the hole blocking layer.

[0024] The second objective of this invention is: A wide-bandgap perovskite solar cell is prepared by any one of the above-described methods.

[0025] By means of the above-described solution, the present invention has at least the following advantages: 1. Synergistic suppression of bulk and interface defects was achieved, resulting in improved photoelectric performance. Significant Improvement in VOC and Efficiency: By combining bulk passivation with 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPAc) with interface modification with piperazine monoiodine (PiPl), the perovskite / crystalline silicon tandem solar cells prepared in this invention achieve excellent performance with an open-circuit voltage (VOC) exceeding 1.95 V and a stable photoelectric conversion efficiency exceeding 32%. This effect is far superior to using either strategy alone, demonstrating a synergistic enhancement effect between the two.

[0026] Key evidence supports: PL Mapping Test (see attached instruction manual) Figure 2 The results show that the photoluminescence intensity of the perovskite thin film prepared by the strategy of the present invention is significantly and uniformly enhanced, which directly proves that the non-radiative recombination of the bulk phase and interface is effectively suppressed and the defect state density is greatly reduced.

[0027] Performance parameter comparison (corresponding appendix) Figures 3-5 The data confirmed the final efficiency results, forming a complete chain of evidence for the effect.

[0028] 2. The key process window for achieving optimal synergy has been identified, demonstrating high feasibility and repeatability. The optimal concentration range for key additives was discovered and determined: Through systematic experiments, this invention revealed a clear "concentration window effect" for both the bulk passivator pFBPAc and the interface modifier PiPl. Optimal device performance was achieved when their concentrations were controlled within the range of 0.1 mg / mL to 1 mg / mL, particularly at approximately 0.1 mg / mL. This provides clear and operable process guidance for those skilled in the art to implement this invention, avoiding blind experimentation.

[0029] The study revealed the negative consequences of deviating from the optimal concentration: experiments showed that excessively high concentrations (e.g., exceeding 1 mg / mL) led to a decrease in all key performance parameters (VOC, JSC, FF). This finding underscores the non-obviousness and critical importance of the concentration range determined in this invention, which cannot be easily obtained by those skilled in the art through conventional experiments.

[0030] 3. The key failure mechanism of wide-bandgap perovskites was suppressed at its source. Effectively alleviates photoinduced phase separation: The introduced pFBPAc, as a bulk passivating agent, has a unique molecular structure (such as fluorine-containing groups) that is believed to effectively anchor halide ions, inhibiting the formation and migration of halide vacancies from the bulk source, thereby enhancing the intrinsic stability of the film under light irradiation and providing a new solution to fundamentally solve the VOC loss problem of wide-bandgap perovskites.

[0031] A robust defect "blockade" is constructed: the PiPl interface layer not only passivates defects such as uncoordinated lead ions on the perovskite surface, but also complements the bulk passivation strategy. The high-quality bulk film reduces the transport of defects to the interface, while the robust interface modification layer prevents the external environment from eroding the bulk phase, forming a synergistic protection effect that is both internal and external, and is expected to improve the long-term operational stability of the device.

[0032] 4. It provides a universally applicable path to improve efficiency. The "bulk passivation + interface modification" synergistic strategy of this invention is not limited to a specific battery structure (whether it is an inverse planar structure or a formal structure) or tandem battery type. It provides an effective and transferable technical paradigm for solving the common scientific problems faced by a large class of wide-bandgap perovskite materials, and has important methodological significance and broad application potential.

[0033] 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

[0034] 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.

[0035] Figure 1 This is a flowchart illustrating the present invention; Figure 2 This is a schematic diagram of PL mapping images of perovskite thin films with or without the addition of bulk passivating agents in the first or second experimental example of the present invention. Figure 3 This is a schematic diagram showing the effect of different concentrations of bulk passivation material pFBPAc on device performance in the first or second experimental example of this invention. Figure 4 This is a schematic diagram illustrating the effect of different concentrations of the interface modification material Pipl on device performance in the first or second experimental example of this invention. Figure 5 This is a schematic diagram of the photovoltaic performance parameters of the tandem solar cell prepared using the bulk passivation and interface modification strategy in the first or second experimental example of this invention. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] First embodiment of the present invention: The purpose of this embodiment is to provide a method for fabricating wide-bandgap perovskite solar cells and tandem solar cells. By using bulk passivation and interface modification methods, the thin film quality is controlled, defect generation is suppressed, VOC loss in perovskite solar cells is reduced, and the conversion efficiency of wide-bandgap perovskite solar cells and tandem solar cells is improved.

[0039] A wide-bandgap perovskite solar cell, the structure of which includes a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an interface modification layer, an electron transport layer, and a back electrode layer.

[0040] The hole transport layer material is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) or nickel oxide (NiO). x One of the following, Spiro-TTB, PEDOT-PSS, along with SAMs, serves as the hole transport layer.

[0041] The perovskite light-absorbing layer incorporates a bulk passivating material, including one of potassium hexafluorophosphate, 2,3,4,5,6-pentafluorobenzylphosphonic acid, hexamethylenediaminetetramethylenephosphonic acid, 1,6-hexylenediphosphonic acid, and histamine diphosphate.

[0042] In one embodiment, the bulk passivating material is 2,3,4,5,6-pentafluorobenzylphosphonic acid, and the concentration range of the material is 0.1~1 mg / mL.

[0043] The interface modification layer is one of piperazine monoiodine, piperazine monochloride, piperazine monobromide, phenylethyl ammonium iodide, piperazine iodine, oleylamine iodine, phenylethyl ammonium bromide, oleylamine chloride, ethylenediamine iodine, propylenediamine iodine, naphthylmethyl ammonium bromide, and 4-trifluoromethylphenylethylamine iodine.

[0044] In one embodiment, the interface modification layer material is piperazine monoiodine, and the concentration range of the material is 0.1~1 mg / mL.

[0045] The second embodiment of the present invention: The method for fabricating a perovskite solar cell according to this embodiment includes the following steps: 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.

[0046] The perovskite thin film can be prepared by any one or two of spin coating, blade coating, slot coating, inkjet printing, and vacuum evaporation.

[0047] The passivation layer can be prepared by any one of spin coating, blade coating, slot coating, inkjet printing, or vacuum evaporation. The electron transport layer material is C. 60 Any one or more of the following materials: PCBM, zinc oxide, tin oxide, and titanium oxide; The electron transport layer can be prepared by any one of spin coating, blade coating, slot coating, inkjet printing, vacuum evaporation, or atomic layer deposition. The back electrode layer can be any one of Au, Ag, Al, Cu, or carbon electrodes; Furthermore, the back electrode layer can be prepared by any one of vacuum evaporation, magnetron sputtering, screen printing, or inkjet printing.

[0048] First experimental example of the present invention: like Figure 1 As shown, this experimental example illustrates the fabrication process of an inverted wide-bandgap perovskite solar cell, using ITO as the conductive substrate and NiO as the conductive substrate. x The perovskite precursor solution uses a self-contained monolayer (MeO-4PACz) as the hole transport layer and 2,3,4,5,6-pentafluorobenzylphosphonic acid as the bulk passivation material, with piperazine monoiodide (PiPl) as the interface modification layer, and C... 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.

[0049] Step 2: Prepare 15 mg / mL NiO x Solution, weigh 15 mg of NiO x The nanoparticles were dissolved in 1 mL of deionized water and sonicated for 15 min to achieve uniform dispersion. The prepared ITO glass 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 glass. 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.

[0050] Step 3: Weigh 1 mg of MeO-4PACz and dissolve it in 1 mL of ethanol to prepare a SAM solution; NiO prepared in Step 2... x SAM solution was spin-coated onto the surface of the hole transport layer as a hole transport layer. The spin-coating parameters were set to 3000 rpm and 30 s. 80 μL of solution was taken with a pipette. After spin-coating, the layer was annealed on a hot stage at 100 °C for 10 min to prepare the MeO-4PACz hole transport layer.

[0051] Step 4: Weigh 0.1 mg of 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPAc), 187.6 mg of formamidine iodide (FAI), 80 mg of cesium iodide (CsI), 115.5 mg of lead bromide (PbBr2), 500 mg of lead iodide (PbI2), 4.4 mg of methylamine chloride (MACl), and 19.4 mg of lead chloride (PbCl2). Add them to a mixture of DMF and NMP solvents in a volume ratio of 9:1. The experimental group perovskite precursor ink was prepared by mixing 1 mL of DMF and NMP solvent. Then, 187.6 mg of formamidinium iodide (FAI), 80 mg of cesium iodide (CsI), 115.5 mg of lead bromide (PbBr2), 500 mg of lead iodide (PbI2), 4.4 mg of methylamine chloride (MACl), and 19.4 mg of lead chloride (PbCl2) were weighed and added to 1 mL of DMF and NMP solvent in a volume ratio of 9:1 to prepare the control group perovskite precursor ink.

[0052] Step 5: Drop the perovskite precursor solution prepared in Step 4 onto the substrate with the hole transport layer prepared. Set the spin coating parameters to 4000 rpm for 30 s. Use a pipette to draw 100 μL of solution. After spin coating, the perovskite wet film is obtained and placed in a vacuum flash furnace. The vacuum flash evaporation is set to 10 Pa in 10 s and the total flash evaporation time is set to 30 s. After flash evaporation, a dry perovskite film is obtained. Then, it is placed on a 100℃ hot stage with an ambient humidity of 30% for annealing for 20 min. After annealing, it is removed and allowed to cool naturally to obtain a wide-bandgap perovskite film.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] Second experimental example of the present invention: like Figure 1 As shown in this example, a perovskite / heterocrystalline silicon tandem solar cell fabrication process is described, using heterocrystalline silicon as the base cell, ITO as the intermediate composite layer, and NiO as the intermediate composite layer. x The perovskite precursor solution uses a self-assembled monolayer (MeO-4PACz) as the hole transport layer and 2,3,4,5,6-pentafluorobenzylphosphonic acid as the bulk passivation material. Piperazine monoiodide (PiPl) is used as the interface modification layer, and ultrathin LiF is used as the passivation layer. C... 60 The electron transport layer is formed, SnO2 is used as the hole blocking layer, ITO is used as the transparent top electrode, and a silver gate is used 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 10nm, thus obtaining the intermediate composite layer.

[0058] Step 2: Prepare 15 mg / mL NiO x Solution, weigh 15 mg of NiO x The nanoparticles were dissolved in 1 mL of deionized water and sonicated for 15 min to achieve uniform dispersion. 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.

[0059] Step 3: Weigh 1 mg of MeO-4PACz and dissolve it in 1 mL of ethanol to prepare a SAM solution; NiO prepared in Step 2... x SAM solution was spin-coated onto the surface of the hole transport layer as a hole transport layer. The spin-coating parameters were set to 3000 rpm and 30 s. 80 μL of solution was taken with a pipette. After spin-coating, the layer was annealed on a hot stage at 100 °C for 10 min to prepare the MeO-4PACz hole transport layer.

[0060] Step 4: Weigh 0.1 mg of 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPAc), 227.8 mg of formamidine iodide (FAI), 97.1 mg of cesium iodide (CsI), 140.3 mg of lead bromide (PbBr2), 607.1 mg of lead iodide (PbI2), 5.4 mg of methylamine chloride (MACl), and 23.6 mg of lead chloride (PbCl2). Add these to a mixture of DMF and NMP solvent in a volume ratio of 9:1. The experimental group perovskite precursor ink was prepared by mixing 1 mL of DMF and NMP solvent. Then, 227.8 mg of formamidine iodide (FAI), 97.1 mg of cesium iodide (CsI), 140.3 mg of lead bromide (PbBr2), 607.1 mg of lead iodide (PbI2), 5.4 mg of methylamine chloride (MACl), and 23.6 mg of lead chloride (PbCl2) were weighed and added to 1 mL of DMF and NMP solvent in a volume ratio of 9:1 to prepare the control group perovskite precursor ink.

[0061] Step 5: Drop the perovskite precursor solution prepared in Step 4 onto the substrate with the hole transport layer prepared. Set the spin coating parameters to 2500 rpm for 20 s. Use a pipette to draw 100 μL of solution. After spin coating, the perovskite wet film is obtained and placed in a vacuum flash furnace. The vacuum flash evaporation is set to 10 Pa in 10 s and the total flash evaporation time is set to 30 s. After flash evaporation, a dry perovskite film is obtained. Then, it is placed on a 100℃ hot stage with an ambient humidity of 30% for annealing for 20 min. After annealing, it is removed and allowed to cool naturally to obtain a wide-bandgap perovskite film.

[0062] 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 it, and then spin-coat the Pipl passivation layer on 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.

[0063] 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 -4 Under 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.

[0064] Step 8: A hole-blocking layer (SnO2) is prepared on the electron transport layer obtained in Step 7 using atomic layer deposition (ALD). The sample is placed in a process vacuum chamber, with the chamber temperature 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 purge cycles is 70, resulting in a SnO2 layer with a thickness of approximately 15 nm. The hole-blocking layer is thus prepared.

[0065] 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.

[0066] In the above experimental example, 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPAc) was introduced as a bulk passivating agent. The pentafluorobenzyl group in the pFBPAc molecule has a "" structure. Its strongly electronegative fluorine atom may react with organic cations in perovskites (such as FA). + The unique dipole interactions or hydrogen bonds generated by halogen vacancies or halogen sites allow for more effective anchoring of halide ions, a feature not found in other common phosphonic acid or amine additives. This step targets the photoinduced phase separation unique to wide-bandgap perovskites, rather than general crystallization regulation. The primary function of the additive is to inhibit ion migration.

[0067] In the above experimental example, the spin-coating of the PiPl interface modification layer was performed using monoiodopiperazine (PiPl) instead of other ammonium salts because: its small molecular size facilitates penetration into grain boundaries; the dinitrogen structure of the piperazine ring may provide bidentate coordination, more firmly passivating uncoordinated lead; and iodine ions may repair iodine vacancies on the surface in situ. This solves the specific chemical environment problem at the top interface. This step acts on the perovskite and C... 60 The top interface of the electron transport layer is susceptible to the effects of underlying processing (such as bulk additives) and is crucial for electron extraction.

[0068] NiO was used in the above experimental examples. x Combined with SAMs, the hole transport layer in a wide-bandgap perovskite system, single NiO x Recombination may occur due to imperfect energy level matching or surface defects in the layers. SAMs are introduced to finely control the work function, improve interfacial contact, and passivate NiO. x Surface defects, complementary functions. The "inorganic first, organic later" layering sequence (first spin-coating NiO) x The process of spin-coating SAMs is not simply a matter of parallel arrangement. NiO x It provides a mechanically and thermally stable substrate, allowing subsequent SAMs molecules to be more regularly arranged on NiO. x Surface self-assembly forms a dense composite interface with better energy level matching. This structure is specially designed to accommodate subsequent perovskite layers containing additives.

[0069] In the above experimental examples, for high-concentration precursor inks containing additives like pFBPAc that can affect crystallization kinetics, conventional single annealing easily leads to component segregation or phase separation. Vacuum flash evaporation can remove most of the solvent extremely quickly, inducing instantaneous and uniform nucleation, thereby "locking" the additives in the rapidly formed crystal nucleus network and inhibiting their macroscopic aggregation. This is a crucial and non-obvious complementary process for obtaining high-quality, uniform passivation films.

[0070] The synergistic effect between the steps in the above embodiments: The first layer of synergy (internal stability and external solidity): pFBPAc (bulk phase) inhibits ion migration and phase separation from within, generating an intrinsically more stable bulk perovskite. This provides PiPl (interface) with a surface that has fewer defects and a more chemically stable environment, making the passivation effect of PiPl more complete and efficient, and preventing it from being "poisoned" by ions continuously migrating out of the bulk.

[0071] The second layer of synergy (transport matching): The NiOx / SAMs composite layer provides an optimized hole extraction interface, reducing interfacial recombination losses. Simultaneously, the perovskite active layer modified with pFBPAc and PiPl exhibits greater quasi-Fermi level splitting (manifesting as high VOC). Optimized interfacial transport and improved bulk quality must be matched to effectively convert high VOC into high output power. The step combination of this invention precisely achieves this matching.

[0072] The third layer of synergy (process closed loop): The vacuum flash evaporation process ensures the uniform distribution and effective action of the additives in the first two steps. Without it, the additives may be unevenly distributed, and the synergistic effect will be greatly reduced. The entire process chain forms a closed loop of "interface optimization - bulk phase stabilization - rapid solidification".

[0073] The effects of the preparation method of the present invention will be illustrated below using experimental data as an example.

[0074] Figure 2 The image shows PL mapping images of perovskite films with and without bulk passivation agents. As can be seen from the image, the perovskite film on the right without bulk passivation agents has lower PL intensity, more perovskite defects, and severe nonradiative recombination. In contrast, the perovskite film on the left with bulk passivation agents shows significantly higher PL intensity, indicating that nonradiative recombination of the perovskite is suppressed, the internal defect state density is reduced, and this is beneficial for improving the VOC of perovskite solar cells.

[0075] Figure 3The figure shows the effect of different concentrations of the bulk passivating material pFBPAc on device performance. As can be seen from the figure, with the increase of the pFBPAc concentration, the photovoltaic performance parameters of the perovskite solar cell, VOC, FF, and JSC, all decreased to some extent. This indicates that excessively high concentrations can negatively impact the quality of the perovskite film and degrade device performance. The optimal pFBPAc concentration was determined to be 0.1 mg / mL.

[0076] Figure 4 The figure shows the effect of different concentrations of the interface modification material Pipl on device performance. As can be seen from the figure, with the increase of Pipl concentration, the photovoltaic performance parameters VOC and JSC of the perovskite solar cell first increase and then decrease. This indicates that at a certain concentration, Pipl significantly improves the performance of the cell. However, further increases in concentration affect the charge transport between the interfaces, leading to a decrease in cell performance. The optimal Pipl concentration was ultimately determined to be 0.1 mg / mL.

[0077] Figure 5 The display shows the photovoltaic performance parameters of the tandem solar cell prepared using a bulk passivation and interface modification strategy. A perovskite-silicon tandem solar cell with a VOC exceeding 1.95 V and an efficiency exceeding 32% was prepared using bulk passivation and interface modification. This demonstrates that this method can effectively improve the quality of the perovskite thin film, regulate and suppress the generation of film defects, thereby improving the efficiency of both perovskite and tandem solar cells.

[0078] 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.

[0079] 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.

[0080] 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 method for fabricating a wide-bandgap perovskite solar cell, characterized in that: The steps are as follows: Step S1: Provide a transparent conductive substrate and fabricate a composite hole transport layer on the transparent conductive substrate; Step S2: Prepare a perovskite light-absorbing layer on the composite hole transport layer, wherein the precursor ink used to prepare the perovskite light-absorbing layer contains a bulk passivation material with a concentration of 0.1~1 mg / mL. Step S3: Spin-coat an interface modification material with a concentration of 0.1~1 mg / mL onto the perovskite light-absorbing layer, and then anneal to form an interface modification layer; Step S4: An electron transport layer and a back electrode layer are sequentially prepared on the interface modification layer to obtain the wide-bandgap perovskite solar cell; The bulk passivating agent and the interface modification layer work together to synergistically reduce the density of perovskite bulk phase and interface defects.

2. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, Step S1 includes the following steps in sequence: Step S11: Spin-coat an aqueous solution of hole transport layer material onto the transparent conductive substrate, and then anneal it to form a hole transport layer; The hole transport layer material is PTAA or NiO. x One of Spiro-TTB and PEDOT-PSS; the concentration of the hole transport layer material is 10~20mg / mL; the spin coating parameters are 1800~2200rpm, 28~32s; the annealing temperature is 140~160℃, and the time is 8~12 minutes; Step S12: Spin-coat a self-assembled monolayer solution onto the hole transport layer, and then anneal it to form a composite hole transport layer; The self-assembled monolayer is MeO-4PACz; the spin coating parameters are 2800~3200 rpm, 28~32 s; the annealing temperature is 80~120℃, and the time is 8~12 minutes.

3. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, Step S2 includes the following steps in sequence: Step S21: Spin-coat the precursor ink onto the composite hole transport layer to form a perovskite wet film; Step S22: Place the perovskite wet film in a vacuum environment for flash evaporation. The vacuum flash evaporation configuration is to pump the pressure to 10 Pa in 10 seconds and the flash evaporation time is 28-32 seconds. Step S23: Place the flash-evaporated film in an environment with a humidity of no more than 20-40% and anneal it at 90-110°C for 18-22 minutes to form the perovskite light-absorbing layer.

4. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, The bulk passivating material is one of potassium hexafluorophosphate, 2,3,4,5,6-pentafluorobenzylphosphonic acid, hexamethylenediaminetetramethylenephosphonic acid, 1,6-hexylenediphosphonic acid, and histamine diphosphate; the concentration of the bulk passivating material is 0.1 mg / mL.

5. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, In step S3, the spin coating parameters are 4800~5200 rpm for 28~32 s; the annealing is performed at 90~110℃ for 4~6 minutes.

6. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, The interface modification material is one of piperazine monoiodine, piperazine monochloride, piperazine monobromide, phenylethyl ammonium iodide, piperazine iodine, oleylamine iodine, phenylethyl ammonium bromide, oleylamine chloride, ethylenediamine iodine, propylenediamine iodine, naphthylmethyl ammonium bromide, and 4-trifluoromethylphenylethylamine iodine; the concentration of the interface modification material is 0.1 mg / mL.

7. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, In step S4, the vacuum level is 6 10 -4 Under the condition of Pa, an electron transport layer material with a thickness of 18-22 nm was prepared by vacuum evaporation at a rate of 0.1-0.2 Å / s as the electron transport layer.

8. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, Before fabricating the electron transport layer, the interface modification layer is first subjected to a vacuum of 6... 10 -4 Under the condition of Pa, LiF passivation layers with a thickness of 0.5~2 nm were prepared by vacuum evaporation at a rate of 0.05~0.2 Å / s.

9. The method for fabricating a wide-bandgap perovskite solar cell as described in claim 1, characterized in that, SnO2 was prepared as a hole blocking layer on the electron transport layer using atomic layer deposition. TDMASn was used as the tin source and water as the oxygen source. The chamber temperature was kept stable at 70~90℃, the source temperature was kept at 60~70℃, and the number of purge cycles was 60~80. The SnO2 layer with a thickness of about 10~20nm was prepared.

10. A wide-bandgap perovskite solar cell, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 9.

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