A wide band gap perovskite solar cell with high open circuit voltage and a preparation method thereof

Abstract

This invention belongs to the field of solar cell technology, specifically relating to a wide-bandgap perovskite solar cell with high open-circuit voltage and its method. It achieves a significant improvement in cell performance by introducing ethylenediamine and phenylethylamine derivatives and their corresponding halide salts as a buried interface modification layer beneath the perovskite light-absorbing layer of the wide-bandgap perovskite solar cell. The ethylenediamine and phenylethylamine derivatives and their corresponding halide salts can provide free electron pairs, which interact with uncoordinated Pb in the perovskite. 2+ The ions form a stable coordination structure, enabling the regulation of perovskite crystallization kinetics. This invention improves the crystallinity quality of wide-bandgap perovskite films and has the potential to promote the rapid development of high-efficiency triple-junction tandem solar cell technology.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a wide-bandgap perovskite solar cell with high open-circuit voltage and its fabrication method. Background Technology

[0002] In the photovoltaic field, traditional single-junction solar cells have approached their theoretical efficiency limit. Tandem solar cells, by stacking materials with different band gaps, can overcome this limitation. Silicon, as a mature substrate material, has a well-established theoretical framework and processing technology. Perovskite materials, with their excellent light absorption coefficient, tunable band gap, and low-cost solution processing characteristics, are considered ideal candidates for manufacturing the top layer of tandem solar cells. Theoretically, the power conversion efficiency (PCE) of perovskite / perovskite / crystalline silicon triple-junction tandem solar cells can reach approximately 51%, significantly exceeding the efficiency limit of single-junction cells. Therefore, among various tandem solar cell technologies, perovskite / perovskite / crystalline silicon triple-junction tandem solar cells have become a research hotspot due to their potential high efficiency.

[0003] To date, the photoelectric conversion efficiency (PCE) of perovskite / perovskite / crystalline silicon triple-junction solar cells has exceeded 27%, demonstrating promising development prospects. However, there is still a significant gap between the achieved performance and the theoretical PCE limit, and many issues remain to be addressed. Wide-bandgap perovskite solar cells, as a key component of perovskite / perovskite / crystalline silicon triple-junction solar cells, have made significant progress in material design and photoelectric performance optimization, but still face numerous challenges, such as photoinduced phase separation, ion migration, thermal and humidity stability, and interfacial recombination. Improving the photoelectric conversion efficiency of wide-bandgap perovskite solar cells while ensuring stability is one of the most pressing issues to be addressed in current research.

[0004] Besides optimizing perovskite composition and crystallization kinetics, interface engineering has been considered an effective method to improve the efficiency and stability of perovskite solar cells. However, traditional interface treatment methods mainly focus on the upper interface between the perovskite and electron transport layer in the inverted structure. A series of problems also exist between the hole transport layer and the wide-bandgap perovskite light-absorbing layer, including poor crystallinity of the wide-bandgap perovskite film due to the poor hydrophilicity of the hole transport layer material, and carrier interface accumulation caused by energy level mismatch between the hole transport layer material and the wide-bandgap perovskite material. These problems have also seriously restricted the development of wide-bandgap perovskite solar cells. Summary of the Invention

[0005] In view of this, the present invention provides a wide-bandgap perovskite solar cell with high open-circuit voltage and its fabrication method. Addressing the aforementioned problems encountered in the top wide-bandgap perovskite layer of a wide-bandgap perovskite / intermediate-bandgap perovskite / narrow-bandgap crystalline silicon triple-junction solar cell, this invention optimizes the crystallization process of the wide-bandgap perovskite thin film by employing a buried interface modification method using derivative molecules of ethylenediamine and phenylethylamine and their corresponding halide salt materials. This simultaneously alleviates the interface energy level mismatch problem, thereby significantly increasing the open-circuit voltage of the wide-bandgap cell to above 1.41V, demonstrating the potential to promote the rapid development of high-efficiency triple-junction tandem solar cell technology.

[0006] The technical solution adopted in this invention is as follows:

[0007] A wide-bandgap perovskite solar cell with high open-circuit voltage includes an ITO conductive glass, and a hole transport layer, a buried interface modification layer, a wide-bandgap perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a metal electrode layer sequentially deposited on the ITO conductive glass; the buried interface modification layer is a thin film prepared by mixing one or more of ethylenediamine, phenylethylamine derivatives and their corresponding halide salts (e.g., ethylenediamine dihydroiodate, phenylethylamine bromide) in any proportion.

[0008] Furthermore, the hole transport layer is a composite structure made of nickel oxide (NiOx) and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate (Me-4PACz).

[0009] Furthermore, the electron transport layer is made of isomethyl [6,6]-phenyl-C61-butyrate (PCBM); the buffer layer is made of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).

[0010] A method for fabricating a wide-bandgap perovskite solar cell with high open-circuit voltage includes the following steps:

[0011] Step 1: Clean and dry the ITO conductive glass; place it in an ultraviolet ozone cleaning device and treat it with ultraviolet ozone for 15 to 30 minutes in an atmospheric atmosphere and at room temperature.

[0012] Step 2: Prepare a hole transport layer on the ITO conductive glass obtained in Step 1 using a spin-coating method;

[0013] Step 3: Dissolve phenylethyl ammonium bromide (PEABr) in DMSO to obtain a PEABr solution with a concentration of 0.5-1 mg / mL; then spin coat the PEABr solution onto the hole transport layer using a spin coater at a speed of 3000-4000 rpm for 5-10 s to obtain the buried interface modification layer.

[0014] Step 4: Prepare a wide-bandgap perovskite precursor solution. Spin-coat the wide-bandgap perovskite precursor solution onto the buried interface modification layer using the anti-solvent method. Anneal the solution to obtain the wide-bandgap perovskite light-absorbing layer.

[0015] Step 5: Sequentially deposit an electron transport layer, a buffer layer, and a metal electrode on the wide-bandgap perovskite light-absorbing layer to obtain a wide-bandgap perovskite solar cell with high open-circuit voltage.

[0016] Furthermore, the implementation method of step 2 includes the following steps:

[0017] Step 2.1: Dissolve NiOx nanoparticles in deionized water to prepare a NiOx nanoparticle dispersion solution with a concentration of 10-20 mg / mL;

[0018] Step 2.2: Spin coat the NiOx solution onto the ITO conductive glass using a spin coater at a speed of 3000-4000 rpm for 30-40 seconds, and then anneal it on a hot stage at a temperature of 100-120°C for 10-15 minutes.

[0019] Step 2.3: Dissolve Me-4PACz in anhydrous ethanol to prepare a Me-4PACz solution with a concentration of 0.5-1 mg / mL.

[0020] Step 2.4: Spin coat the Me-4PACz solution onto the product obtained in step 2.2 using a spin coater at a speed of 3000-4000 rpm for 30-40 seconds. Then anneal the product on a hot plate at 100-120°C for 10-15 minutes to obtain the hole transport layer.

[0021] Furthermore, the implementation method of step 4 includes the following steps:

[0022] Step 4.1: According to formula Cs 0.1 MA 0.1 FA 0.8 PbIBr 1.8 Cl 0.2 Prepare a wide-bandgap perovskite precursor solution;

[0023] Step 4.2: The prepared wide-bandgap perovskite precursor solution is spin-coated onto the obtained buried substrate interface modification layer using a spin coater. The spin coater speed is divided into two stages: the first stage has a speed of 1000-2000 rpm and a spin coating time of 10 s; the second stage has a speed of 4000-5000 rpm and a spin coating time of 40 s. At the beginning of the second stage, 0.1-0.2 mL of chlorobenzene anti-solvent is dropped onto the rotating substrate surface 20-25 s. After the second stage spin coating is completed, the substrate is annealed at a temperature range of 80-100℃ for 10-15 min to obtain the wide-bandgap perovskite light-absorbing layer.

[0024] Furthermore, the implementation method of step 5 includes the following steps:

[0025] Preparation of the electron transport layer: PCBM was dissolved in chlorobenzene (CB) to prepare a PCBM solution with a concentration of 15 mg / mL; the solution was spin-coated onto a wide-bandgap perovskite light-absorbing layer using a spin coater at a speed of 1000-2000 rpm for 30-40 s, and then annealed on a hot stage at a temperature range of 100-120 °C for 5-10 min to obtain the electron transport layer;

[0026] Preparation of the buffer layer: BCP was dissolved in isopropanol (IPA) to prepare a BCP solution with a concentration of 2 mg / mL; the solution was spin-coated onto the electron transport layer by a spin coater at a speed of 4000-5000 rpm for 20-30 s, and then annealed on a hot plate at a temperature range of 80-100℃ for 1-3 min to obtain the buffer layer.

[0027] This invention significantly improves battery performance by introducing ethylenediamine and phenylethylamine derivatives and their corresponding halide salts as a buried interface modification layer beneath the perovskite light-absorbing layer of a wide-bandgap perovskite solar cell. The ethylenediamine and phenylethylamine derivatives and their corresponding halide salts can provide free electron pairs, which can interact with uncoordinated Pb in the wide-bandgap perovskite during the preparation of the perovskite thin film. 2+ A stable coordination structure is formed, enabling the regulation of perovskite crystallization kinetics and improving the crystallinity quality of wide-bandgap perovskite films. Simultaneously, the modified hole transport layer exhibits a higher energy level matching degree with the perovskite light-absorbing layer. This optimization effectively reduces the energy level barrier for charge carriers at the perovskite-hole transport layer interface, promoting rapid carrier extraction and reducing energy loss. Furthermore, the hydrophilicity of the modified hole transport layer is improved, addressing the problem of poor film formation on the surface of poorly hydrophilic self-assembled molecular layers in wide-bandgap perovskite solar cells, further optimizing carrier transport efficiency. These improvements not only enhance the film quality of the wide-bandgap perovskite light-absorbing layer but also reduce the voltage loss of inverted perovskite solar cells under open-circuit conditions, ultimately resulting in higher photoelectric conversion efficiency and better long-term stability. Through this innovative buried interface modification strategy, this invention provides an effective solution for optimizing the performance of wide-bandgap perovskite solar cells.

[0028] In summary, the present invention can achieve at least the following beneficial effects:

[0029] 1. The method for preparing wide-bandgap perovskite thin films proposed in this invention, by precisely controlling the buried interface between the perovskite and the hole transport layer, not only improves the crystal quality of the perovskite, but also significantly reduces the interfacial energy level barrier for carrier transport, accelerates carrier extraction, and reduces energy loss, thereby laying a solid material foundation for the manufacture of high-performance perovskite solar cells.

[0030] 2. This invention proposes a method for preparing wide-bandgap perovskite thin films, which can significantly reduce the open-circuit voltage loss of inverted perovskite solar cells during operation. This technological improvement effectively enhances the photoelectric conversion efficiency of solar cells, thus providing an innovative technical approach to improving the utilization efficiency of solar energy. Through the application of this preparation method, this invention opens up new research directions for the advancement and efficiency improvement of solar cell technology.

[0031] 3. The method for preparing wide-bandgap perovskite thin films proposed in this invention has excellent compatibility with the manufacturing process of perovskite-perovskite-silicon triple-junction tandem solar cells, and can be integrated into the preparation process of the wide-bandgap perovskite light-absorbing layer. This integration strategy not only promotes further optimization of the performance of perovskite-perovskite-silicon triple-junction tandem solar cells, but also provides a new direction for the development of solar cell technology with higher photoelectric conversion efficiency. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a solar cell structure for comparison.

[0033] Figure 2 This is a schematic diagram of the solar cell structure in an embodiment.

[0034] Figure 3 The images show the surface morphology of the wide-bandgap perovskite thin films in the comparative examples and embodiments under a scanning electron microscope (SEM).

[0035] Figure 4 The X-ray diffraction (XRD) patterns of the wide-bandgap perovskite thin films in the comparative examples and embodiments are shown.

[0036] Figure 5 The current density-voltage (JV) curves of the inverted perovskite solar cells obtained in the comparative examples and embodiments are shown. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. Where specific experimental steps or conditions are not specified in the embodiments, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all conventional reagent products that can be purchased.

[0038] Example 1

[0039] This embodiment provides a method for preparing an inverted perovskite solar cell, which includes the method for preparing the wide-bandgap perovskite thin film 1 proposed in this invention, comprising the following steps:

[0040] Step 1: Clean the substrate:

[0041] In this embodiment, indium tin oxide (ITO) glass is used as the substrate. First, the substrate is ultrasonically cleaned for 15 minutes each with deionized water, acetone, and anhydrous ethanol. The cleaned substrate is dried with a nitrogen gun and stored in a dry environment. Before use, it is treated with an ultraviolet-ozone cleaning device for 30 minutes.

[0042] Step 2: Prepare the hole transport layer:

[0043] In this embodiment, a composite structure of nickel oxide (NiOx) and [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphate (Me-4PACz) is selected as the hole transport layer. The preparation steps are as follows:

[0044] Step 2.1: Weigh a certain amount of NiOx nanoparticles and dissolve them in deionized water to prepare a NiOx nanoparticle dispersion solution with a concentration of 10 mg / mL.

[0045] Step 2.2: Spin coat the NiOx solution onto the ITO substrate using a spin coater at a speed of 4000 rpm for 30 s, and then anneal it on a hot plate at 100 °C for 10 min.

[0046] Step 2.3: Weigh a certain amount of Me-4PACz and dissolve it in anhydrous ethanol to prepare a Me-4PACz solution with a concentration of 1 mg / mL.

[0047] Step 2.4: The Me-4PACz solution was spin-coated onto the NiOx surface using a spin coater at 3000 rpm for 30 seconds, followed by annealing at 100°C for 10 minutes on a hot plate. This yielded the hole transport layer.

[0048] Step 3: Prepare the embedded interface modification layer

[0049] Step 3.1: Dissolve phenylethyl ammonium bromide (PEABr) in DMSO to obtain a PEABr solution with a concentration of 0.5–1 mg / mL;

[0050] Step 3.2: Spin coat the PEABr solution onto the hole transport layer using a spin coater at a speed of 4000 rpm for 10 s to obtain the embedded interface modification layer.

[0051] Step 4: Prepare a wide-bandgap perovskite layer:

[0052] Step 4.1: Preparation of wide-bandgap perovskite precursor solution: Weigh 26.0 mg of CsI, 15.9 mg of MAI, 137.6 mg of FAI, 330.3 mg of PbBr2, and 27.8 mg of PbCl2 and dissolve them in 1 mL of a mixed solvent and stir for 12 h. The mixed solvent consists of dimethylformamide (DMF) and DMSO with a volume ratio of DMF to DMSO of 4:1. This yields the wide-bandgap perovskite precursor solution.

[0053] Step 4.2: Spin-coating the perovskite film: The wide-bandgap perovskite precursor solution was spin-coated onto the obtained buried interface modification layer using a spin coater. The spin coater speed was divided into two stages: the first stage was at 1000 rpm for 10 s, and the second stage was at 4000 rpm for 40 s. At the 25th second of the second stage, 0.15 mL of chlorobenzene antisolvent was dropped onto the surface of the rotating perovskite precursor solution.

[0054] Step 4.3: Thin film annealing: Place the spin-coated sample on a hot plate and anneal at 100°C for 10 min to obtain a wide-bandgap perovskite thin film.

[0055] Step 5: Fabrication of the electron transport layer:

[0056] In this embodiment, isomethyl [6,6]-phenyl-C61-butyrate (PCBM) was selected as the electron transport layer material, and the preparation steps are as follows:

[0057] Step 5.1: Weigh a certain amount of PCBM and dissolve it in chlorobenzene (CB) to prepare a PCBM solution with a concentration of 15 mg / mL.

[0058] Step 5.2: Spin coat the PCBM solution onto the surface of the wide-bandgap perovskite film using a spin coater at a speed of 1500 rpm for 30 s, and then anneal it on a hot plate at 100 °C for 5 min.

[0059] Step 6: Prepare the buffer layer:

[0060] In this embodiment, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was selected as the buffer layer material, and the preparation steps are as follows:

[0061] Step 6.1: Weigh a certain amount of BCP and dissolve it in isopropanol (IPA) to prepare a BCP solution with a concentration of 2 mg / mL.

[0062] Step 6.2: Spin coat the BCP solution onto the PCBM surface using a spin coater at 5000 rpm for 20 seconds, then anneal at 80°C for 1 minute on a hot plate. This yields the electron transport layer.

[0063] Step 7: Prepare the metal electrode:

[0064] In this embodiment, silver is selected as the metal electrode, and the preparation method is as follows: 120 nm of silver is deposited on the surface of the electron transport layer using vacuum thermal evaporation through a mask. This yields the following... Figure 2 The complete wide-bandgap perovskite solar cell is shown.

[0065] Example 2

[0066] This comparative example provides a method for preparing an inverted perovskite solar cell. The preparation steps are basically the same as those in Example 1, except that the material used in the buried interface modification layer in Example 2 is ethylenediamine dihydroiodate.

[0067] Comparative Example

[0068] This comparative example provides a method for preparing an inverted perovskite solar cell. The preparation steps are basically the same as in Example 1, except that: in the comparative example, after depositing the hole transport layer, it is not necessary to deposit a buried interface modification layer. Instead, the obtained wide-bandgap perovskite precursor solution is directly spin-coated onto the hole transport layer using a spin coater, and its structure is as follows. Figure 1 As shown.

[0069] The comparative examples and embodiments described above will be analyzed and tested below:

[0070] SEM analysis was performed on the wide-bandgap perovskite films obtained in the examples and comparative examples, and the results are as follows: Figure 3 As shown, where Figure 3 (a) The corresponding film obtained in proportion, Figure 3 (b) The film obtained in Example 1, Figure 3 (c) The film obtained in Example 2. Compared with the comparative example, the wide-bandgap perovskite film after the buried interface modification treatment not only showed a significant increase in grain size, but also clearer grain boundaries. This resulted in a better surface morphology for the wide-bandgap perovskite film, indicating that it has good crystallinity.

[0071] XRD analysis was performed on the wide-bandgap perovskite films obtained in the examples and comparative examples, and the results are as follows: Figure 4 As shown, compared to the comparative examples, the intensity of the characteristic peaks of perovskite (corresponding to a 2θ value of 14.6°) in Examples 1 and 2 increased after the buried interface modification treatment, reflecting the good crystallinity of the perovskite. Meanwhile, after the buried interface modification treatment in the examples, the characteristic peaks of the secondary phase (corresponding to a 2θ value of 11.8°) decreased significantly, indicating that PEABr, EDADI, and uncoordinated Pb in the perovskite... 2+ The formation of stable coordination structures by ions reduces the generation of non-photoactive phases and improves the crystallinity of wide-bandgap perovskite films.

[0072] Photovoltaic tests were conducted on the inverse perovskite solar cells obtained in the examples and comparative examples, and the effective active area was 0.053 cm². 2 The test conditions were standard simulated sunlight AM1.5 G and a temperature of 25°C. The JV curves for the example and comparative examples are shown below. Figure 5 As shown, the open-circuit voltage of the inverted perovskite solar cell obtained in Example 1 is 1.40V, and the short-circuit current is 13.3mA / cm. 2 The fill factor was 73.7%, and the energy conversion efficiency was 13.8%. The open-circuit voltage of the inverse perovskite solar cell obtained in Example 2 was 1.41V, and the short-circuit current was 13.0mA / cm². 2 The fill factor was 73.3%, and the energy conversion efficiency was 13.5%. The comparative inverted perovskite solar cell had an open-circuit voltage of 1.37V and a short-circuit current of 12.5mA / cm². 2 The fill factor is 73.0%, and the power conversion efficiency is 12.4%. Compared with the comparative example, the open-circuit voltage of the embodiment is significantly improved, and the improvement in fill factor also indicates that the carrier transport capability is improved. This shows that the photovoltaic performance of the solar cell device is optimized after the above-mentioned wide-bandgap perovskite thin film is modified by the buried interface.

[0073] The photovoltaic parameters of the inverted perovskite solar cells obtained in the embodiments and comparative examples of this invention are shown in Table 1:

[0074] Table 1:

[0075]

[0076] The above embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, is within the scope of protection of the present invention.

Claims

1. A wide-bandgap perovskite solar cell with high open-circuit voltage, characterized in that: The structure includes an ITO conductive glass, on which a hole transport layer, a buried interface modification layer, a wide-bandgap perovskite light-absorbing layer, an electron transport layer, a buffer layer, and a metal electrode layer are sequentially deposited; wherein: The buried interface modification layer is a thin film made of at least one of ethylenediamine, phenylethylamine derivative molecules and their corresponding halide salts; The hole transport layer is a composite structure made of NiOx and Me-4PACz; The electron transport layer is made of PCBM; the buffer layer is made of BCP.

2. A wide-bandgap perovskite solar cell with high open-circuit voltage according to claim 1, characterized in that, The method for preparing this solar cell includes the following steps: Step 1: Clean and dry the ITO conductive glass; place it in an ultraviolet ozone cleaning device and treat it with ultraviolet ozone for 15 to 30 minutes in an atmospheric atmosphere and at room temperature. Step 2: Prepare a hole transport layer on the ITO conductive glass obtained in Step 1 using a spin-coating method; Step 3: Dissolve PEABr in DMSO to obtain a PEABr solution with a concentration of 0.5–1 mg / mL; then spin coat the PEABr solution onto the hole transport layer using a spin coater at a speed of 3000–4000 rpm for 5–10 s to obtain the buried interface modification layer. Step 4: Prepare a wide-bandgap perovskite precursor solution. Spin-coat the wide-bandgap perovskite precursor solution onto the buried interface modification layer using the anti-solvent method. Anneal the solution to obtain the wide-bandgap perovskite light-absorbing layer. Step 5: Sequentially deposit an electron transport layer, a buffer layer, and a metal electrode on the wide-bandgap perovskite light-absorbing layer to obtain a wide-bandgap perovskite solar cell with high open-circuit voltage.

3. A wide-bandgap perovskite solar cell with high open-circuit voltage according to claim 2, characterized in that, The implementation method of step 2 includes the following steps: Step 2.1: Dissolve NiOx nanoparticles in deionized water to prepare a NiOx nanoparticle dispersion solution with a concentration of 10-20 mg / mL; Step 2.2: Spin coat the NiOx nano-dispersion onto ITO conductive glass using a spin coater at a speed of 3000-4000 rpm for 30-40 s. Then anneal it on a hot stage at a temperature of 100-120℃ for 10-15 min. Step 2.3: Dissolve Me-4PACz in anhydrous ethanol to prepare a Me-4PACz solution with a concentration of 0.5-1 mg / mL; Step 2.4: Spin coat the Me-4PACz solution onto the product obtained in step 2.2 using a spin coater at a speed of 3000-4000 rpm for 30-40 seconds. Then anneal the product on a hot plate at a temperature of 100-120 °C for 10-15 minutes to obtain the hole transport layer.

4. A wide-bandgap perovskite solar cell with high open-circuit voltage according to claim 3, characterized in that, The implementation method of step 4 includes the following steps: Step 4.1: According to formula Cs 0.1 MA 0.1 FA 0.8 Pb I Br 1.8 Cl 0.2 Prepare a wide-bandgap perovskite precursor solution; Step 4.2: The prepared wide-bandgap perovskite precursor solution is spin-coated onto the obtained buried substrate interface modification layer using a spin coater. The spin coater speed is divided into two stages: the first stage has a speed of 1000-2000 rpm and a spin coating time of 10 s; the second stage has a speed of 4000-5000 rpm and a spin coating time of 40 s. At the beginning of the second stage, 0.1-0.2 mL of chlorobenzene anti-solvent is dropped onto the rotating substrate surface 20-25 s. After the second stage spin coating is completed, the substrate is annealed at a temperature range of 80-100 ℃ for 10-15 min to obtain the wide-bandgap perovskite light-absorbing layer.

5. A wide-bandgap perovskite solar cell with high open-circuit voltage according to claim 4, characterized in that, The method for preparing the electron transport layer in step 5 includes the following steps: PCBM was dissolved in chlorobenzene to prepare a PCBM solution with a concentration of 15 mg / mL. The solution was then spin-coated onto a wide-bandgap perovskite light-absorbing layer using a spin coater at a speed of 1000–2000 rpm for 30–40 s. Subsequently, the layer was annealed on a hot stage at a temperature range of 100–120 °C for 5–10 min to obtain an electron transport layer.

6. A wide-bandgap perovskite solar cell with high open-circuit voltage according to claim 5, characterized in that, The buffer layer preparation method in step 5 includes the following steps: BCP was dissolved in IPA to prepare a BCP solution with a concentration of 2 mg / mL. The BCP solution was then spin-coated onto the electron transport layer using a spin coater at a speed of 4000–5000 rpm for 20–30 s. Subsequently, the solution was annealed on a hot plate at a temperature range of 80–100 °C for 1–3 min to obtain the buffer layer.

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