A doped and modified PEDOT:PSS hole transport layer perovskite solar cell and its preparation method

Abstract

This invention provides a perovskite solar cell with a doped and modified PEDOT:PSS hole transport layer and its preparation method. The method comprises an ITO conductive substrate, a sodium hypophosphite (NaH₂PO₂) doped and modified PEDOT:PSS hole transport layer, a perovskite light-absorbing layer, an electron transport layer, an interface modification layer, and a metal electrode, stacked sequentially. The modified hole transport layer is formed by directly doping sodium hypophosphite powder into a PEDOT:PSS aqueous solution, followed by spin coating and annealing. This invention utilizes the weak alkalinity and reducing properties of hypophosphite ions to effectively neutralize the acidity of PEDOT:PSS, reduce the film's hygroscopicity, optimize the surface morphology, and passivate interface defects at the bottom of the perovskite layer. The process is simple, low-cost, and fully compatible with existing solution-based preparation methods. Without adding complex processes, it significantly improves the photoelectric conversion efficiency and stability of inverted perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cell manufacturing technology, specifically to a doped and modified PEDOT:PSS hole transport layer perovskite cell and its preparation method. Background Technology

[0002] Perovskite solar cells have become the leading technology in next-generation photovoltaics due to their advantages such as rapidly improving photoelectric conversion efficiency, strong solution processability, and low raw material costs. Common perovskite solar cell structures fall into two main categories: upright structures (nip) and inverted structures (pin). A typical upright structure consists of a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. The inverted structure, however, interchanges the positions of the hole transport layer and the electron transport layer to adapt to different fabrication processes and performance requirements. Compared to traditional upright structures, inverted perovskite solar cells offer advantages such as simpler fabrication processes, low-temperature processing capabilities, suitability for flexible device fabrication, and good compatibility with tandem cells, and have attracted widespread attention in recent years. In the inverted structure, the hole transport layer is located at the bottom of the device, and its properties directly affect the crystal quality of the upper perovskite layer and the interface charge extraction efficiency. Therefore, optimizing the hole transport layer in the inverted structure is crucial for improving overall device performance. For the hole transport layer, the polymer PEDOT:PSS is one of the most widely used materials due to its high conductivity, high visible light transmittance, and ease of solution handling. However, in PEDOT:PSS, the conductive PEDOT chains are encased by insulating PSS chains, forming a core-shell structure that hinders charge transport between PEDOT chains. Although its original conductivity (approximately 0.1-1 S / cm) is sufficient for some applications, it still falls short of the requirements for an ideal hole transport material, limiting rapid hole extraction and transport, and affecting the device's fill factor and short-circuit current density. Simultaneously, the PSS chains in PEDOT:PSS are acidic, easily corroding indium tin oxide (ITO) transparent electrodes and interacting harmfully with the perovskite layer, thus affecting device stability. Furthermore, the high hydrophilicity of the PSS chain segments makes the PEDOT:PSS film readily absorb moisture from the environment, accelerating the decomposition of the perovskite material. In addition, the surface characteristics of the PEDOT:PSS film are unfavorable for the high-quality crystal growth of the upper perovskite layer, limiting further improvements in cell efficiency. Therefore, optimizing the performance of the PEDOT:PSS hole transport layer is crucial for manufacturing high-efficiency and long-term stable perovskite solar cells.

[0003] To address the aforementioned shortcomings, researchers in this field have explored various modification methods. For example: (1) Polar solvents such as dimethyl sulfoxide (DMSO) and ethylene glycol (EG) are incorporated into PEDOT:PSS to improve its conductivity. For example, Huang et al. improved the photoelectric conversion efficiency of the device by controlling the doping amount of DMSO in PEDOT:PSS (Nanoscale 2017, 9, 4236–4243). However, studies have shown that DMSO doping leads to an increase in the roughness of the PEDOT:PSS film with increasing doping concentration. The increase in roughness is not conducive to the uniform growth of the subsequent perovskite film and may introduce more interface defects. In addition, although the treatment of the PEDOT:PSS layer with polar solvents can improve conductivity by partially removing PSS components, the performance of perovskite solar cells deposited directly on the solvent-treated PEDOT:PSS film is actually worse.

[0004] (2) Incorporating graphene oxide (GO) and nitrogen-doped graphene oxide nanoribbons (NGONRs) into PEDOT:PSS. For example, Luo et al. used GO to modify PEDOT:PSS as a hole transport layer to improve device stability and photoelectric conversion efficiency (Nano-Micro Lett. 9, 39 (2017)). However, the synthesis and dispersion process of such nanomaterials is complex and costly, and the uniform dispersion of nanomaterials in PEDOT:PSS is difficult to control, which limits their reproducibility and large-scale application prospects in large-area device fabrication.

[0005] (3) Introducing a polymer interlayer (such as polytriarylamine PTAA) between PEDOT:PSS and the perovskite layer to optimize energy level matching and interfacial contact (J. Mater. Chem. A, 2019, 7, 26421-26428). However, polymer materials such as PTAA are generally expensive, their high hydrophobicity leads to complex deposition processes, and additional dopants are often required to achieve sufficient hole mobility. In addition, studies have found that even with the introduction of a polymer modification layer on PEDOT:PSS, the problem of poor interfacial contact between PEDOT:PSS and the perovskite layer has not been fundamentally solved.

[0006] In summary, while existing modification methods for the hole transport layer of PEDOT:PSS have shown some effectiveness, they still suffer from problems such as complex processes, high costs, narrow doping windows, and difficulty in balancing conductivity and interface compatibility. There is a lack of simple and efficient strategies that can simultaneously address its acidity, hygroscopicity, energy level mismatch, and interface defects. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a perovskite solar cell with a doped and modified PEDOT:PSS hole transport layer and its preparation method. It utilizes the weak alkalinity and reducing properties of hypophosphate ions to effectively neutralize the acidity of PEDOT:PSS, optimize the surface morphology, and passivate the interface defects at the bottom of the perovskite layer. The process of this invention is simple and low-cost, and is fully compatible with existing solution-based preparation processes. It can significantly improve the photoelectric conversion efficiency and stability of inverted perovskite solar cells without adding complex processes.

[0008] This invention is implemented as follows: A perovskite solar cell with a doped and modified PEDOT:PSS hole transport layer includes an ITO conductive substrate, a sodium hypophosphite (NaH2PO2) doped and modified PEDOT:PSS hole transport layer, a perovskite light-absorbing layer, an electron transport layer, an interface modification layer, and a metal electrode, which are stacked sequentially.

[0009] Furthermore, the doping concentration of sodium hypophosphite in the PEDOT:PSS solution is 3 mg / mL to 10 mg / mL.

[0010] Furthermore, the doping concentration of sodium hypophosphite in the PEDOT:PSS solution is 5 mg / mL.

[0011] Furthermore, the material of the perovskite light-absorbing layer is Cs. 0.05 FA 0.85 MA 0.1 PbI3.

[0012] Furthermore, the electron transport layer is a PCBM layer, the interface modification layer is a BCP layer, and the metal electrode is an Ag electrode.

[0013] Furthermore, the thickness of each layer is as follows: ITO conductive substrate 100nm~450nm, PEDOT:PSS hole transport layer 20nm~70nm, perovskite light-absorbing layer 200nm~1000nm, PCBM electron transport layer 10nm~50nm, BCP interface modification layer 1nm~5nm, Ag electrode 70nm~150nm.

[0014] Furthermore, the preparation method of the doped and modified PEDOT:PSS hole transport layer perovskite solar cell includes the following steps: (1) Cleaning and surface treatment of ITO conductive glass: ITO conductive glass was ultrasonically cleaned in sequence with cleaning solution, deionized water, acetone, and ethanol / isopropanol, dried and then treated with ultraviolet ozone to obtain hydrophilic ITO substrate. (2) Preparation of modified hole transport layer: Sodium hypophosphite powder was dissolved in PEDOT:PSS aqueous solution and mixed to obtain a doped precursor solution; the precursor solution was spin-coated onto an ITO substrate and annealed to obtain a NaH2PO2 doped modified PEDOT:PSS hole transport layer. (3) Preparation of perovskite light-absorbing layer: Prepare perovskite precursor solution, spin-coat it on hole transport layer, use antisolvent to assist film formation, and anneal to obtain perovskite film; (4) Preparation of electron transport layer and interface modification layer: PCBM solution and BCP solution were spin-coated sequentially on the perovskite film and annealed respectively; (5) Preparation of metal electrodes: Vacuum evaporation of Ag metal electrodes to obtain perovskite cells.

[0015] Further, the spin coating parameters in step (2) are: accelerate from 500 rpm to 4000 rpm and spin coat for 30 s; the annealing conditions are heating at 100 ℃ for 20 minutes.

[0016] Further, in step (3), the perovskite precursor solution is prepared by dissolving PbI2, FAI, MAI, CsI, and MACl in a mixed solvent of DMF and DMSO; the spin coating is a two-step spin coating: the first step is spin coating at 1000 rpm for 10 s, and the second step is spin coating at 5000 rpm for 40 s, with chlorobenzene anti-solvent added dropwise at the end of the spin coating; the annealing condition is heating at 100℃ for 30 minutes.

[0017] Furthermore, in step (2), the PEDOT:PSS hole transport layer after sodium hypophosphite doping does not require additional surface treatment and can be directly spin-coated with a perovskite layer.

[0018] The present invention has the following advantages: This invention utilizes the reducing and coordinating properties of hypophosphatemoid ions to neutralize the acidity of PEDOT:PSS through weak alkalinity, optimize the film morphology and energy level structure, and passivate defects at the bottom of the perovskite layer. This synergistically improves hole extraction efficiency, reduces non-radiative recombination, and avoids performance degradation caused by excessive doping. Experimental data show that the photoelectric conversion efficiency of the device at the optimal doping concentration is improved by approximately 8.7% compared to the undoped device, with significant improvements in short-circuit current density and fill factor.

[0019] The sodium hypophosphite used in this invention is an inexpensive and readily available inorganic salt with excellent water solubility and is fully compatible with PEDOT:PSS aqueous solution. Compared with nanomaterial doping, the sodium hypophosphite in this invention exhibits excellent solubility and dispersion uniformity in solution. The doping process only requires simple dissolution and mixing, without any additional synthesis, dispersion, or post-processing steps. It can be directly and seamlessly integrated into the existing low-temperature spin-coating process of inverted perovskite solar cells without increasing any process complexity. It has great potential for large-scale production and provides a new path for achieving efficient and stable inverted perovskite solar cells. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell with a doped and modified PEDOT:PSS hole transport layer according to the present invention.

[0022] Figure 2 These are atomic force microscopy (AFM) surface morphology comparison images of PEDOT:PSS films doped with different concentrations of NaH2PO2 in embodiments of the present invention. Among them, (ae) are two-dimensional height maps of undoped and doped with 5 mg / mL, 10 mg / mL, 15 mg / mL, and 30 mg / mL NaH2PO2; (fj) are the corresponding three-dimensional morphology images.

[0023] Figure 3 The above are AFM morphology comparison images of perovskite films grown on hole transport layers of PEDOT:PSS with different concentrations of NaH2PO2 doped in this embodiment of the invention. Among them, (ae) is a two-dimensional height map of perovskite films based on undoped and doped with 5mg, 10mg, 15mg and 30mg NaH2PO2 PEDOT:PSS; (fj) is the corresponding three-dimensional morphology map.

[0024] Figure 4 The images show the photoluminescence (PL) spectra of perovskite films doped with different concentrations of NaH2PO2 based on PEDOT:PSS in embodiments of the present invention.

[0025] Figure 5 This is a comparison of the current density-voltage (JV) characteristic curves of perovskite solar cells based on PEDOT:PSS doped with different concentrations of NaH2PO2 in embodiments of the present invention. Detailed Implementation

[0026] The following will be combined with the appendix Figure 1-5The technical solution of the present invention will be clearly and completely described in detail with specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products. Example

[0027] 1. Preparation method 1) First, fix the ITO conductive glass on a PTFE cleaning rack and place it vertically into a beaker. Place it in an ultrasonic bath and clean it for 30 minutes each with conductive glass cleaning solution, deionized water, acetone, and ethanol / isopropanol. Then, dry it in a 70°C oven and then treat it in a UV ozone generator for 30 minutes to increase the hydrophilicity of the ITO surface.

[0028] 2) Take clean, dry glass bottles and weigh out 0 mg, 5 mg, 10 mg, 15 mg, and 30 mg of sodium hypophosphite (NaH2PO2) powder, respectively. Filter the PEDOT:PSS aqueous solution through a 0.45 µm PTFE filter, and add 1 mL of each solution to the aforementioned glass bottles. Dissolve and mix thoroughly to obtain PEDOT:PSS precursor solutions with doping concentrations of 0 mg / mL, 5 mg / mL, 10 mg / mL, 15 mg / mL, and 30 mg / mL, respectively. Place the ITO glass slide prepared in step 1) on the vacuum chuck of a spin coater. Use a pipette to draw 75 µL of the above PEDOT:PSS precursor solution and drop it onto the center of the ITO glass slide. Start the spin coater and accelerate from 500 rpm / s to 4000 rpm, spin-coating for 30 seconds. After spin-coating, immediately transfer the glass slide to a 100 °C heating plate for annealing for 20 minutes to obtain PEDOT:PSS hole transport layers with different doping concentrations. The process takes place in a fume hood.

[0029] 3) In a glove box, accurately weigh out 789.02 mg of PbI₂, 238.26 mg of FAI, 25.91 mg of MAI, 21.17 mg of CsI, and 9.91 mg of MACl using an electronic balance. Add 800 µL of dimethylformamide (DMF) and 200 µL of dimethyl sulfoxide (DMSO) to a total solvent volume of 1 mL. Tightly cap the bottle and vortex at room temperature for at least 3 hours until the precursors are completely dissolved. Filter through a 0.45 µm PTFE filter before use.

[0030] 4) Place the ITO glass slide with the hole transport layer prepared in step 2) onto the vacuum chuck of a spin coater. Use a pipette to draw 80 µL of the filtered perovskite precursor solution and uniformly drop it onto the surface of the PEDOT:PSS layer. Start the spin coater and execute a two-step spin coating program: the first step is spin coating at 1000 rpm (acceleration 500 rpm / s) for 10 seconds; the second step is spin coating at 5000 rpm (acceleration 1000 rpm / s) for 40 seconds. When there are 12 seconds left in the spin coating, quickly and continuously add 250 µL of chlorobenzene as an anti-solvent. After spin coating, immediately transfer the substrate to a 100 ℃ hot plate for annealing for 30 minutes to obtain a well-crystallized perovskite film. The entire process is carried out in a glove box.

[0031] 5) A PCBM electron transport layer was spin-coated onto the perovskite film at 2000 rpm for 30 seconds, followed by annealing on a 100 °C hot plate for 5 minutes. The PCBM solution was prepared by dissolving PCBM nanoparticles in chlorobenzene at a concentration of 23 mg / mL. The process was carried out in a glove box.

[0032] 6) Subsequently, the BCP interface modification layer was spin-coated using a dynamic spin-coating method at 5000 rpm for 30 seconds, followed by annealing on a 100 ℃ hot plate for 3 minutes. The BCP solution was prepared by dissolving BCP nanoparticles in isopropanol to a concentration of 0.5 mg / mL, and using the supernatant. The process was performed in a glove box.

[0033] 7) Place the sample obtained in step 6) into a vacuum evaporation apparatus, and heat it at a vacuum level better than 6×10⁻⁶. -4 Under the condition of Pa, 120 nm of Ag was thermally vaporized as the metal electrode. The vaporization process employed stepwise rate control: first, the first 10 nm was vaporized at a slow rate of 0.5 Å / s to form a dense nucleation layer; then, the rate was increased to 1 Å / s to continue vaporization until the total thickness reached 120 nm. The electrode area was defined as 0.07 cm² using a mask. 2 A complete perovskite solar cell was thus obtained. The structural diagram of this perovskite solar cell device is shown below. Figure 1 As shown.

[0034] 2. Performance Testing (1) Thin film morphology analysis: The effects of different concentrations of NaH₂PO₂ doping on the surface morphology of PEDOT:PSS films and perovskite films were measured, specifically as follows: Figure 2-3 As shown. Figure 2 As shown, the surface roughness (RMS) of the undoped PEDOT:PSS film is 6.146 nm. Figure 2a, 2f). After doping with 5 mg / mL NaH2PO2, the film surface became smoother and more uniform, with clear grain outlines, small size, and dense distribution, and the roughness was significantly reduced to 2.318 nm. Figure 2 b, 2g). This indicates that the introduction of an appropriate amount of sodium hypophosphite effectively optimized the crystallization process of the film and reduced surface defects. However, when the doping concentration was further increased (10, 15 mg / mL), the surface gradually became blurred, and the roughness increased again. Figure 2 (c) and (2d) have RMS values ​​of 6.667 nm and 3.527 nm, respectively, indicating that excessive doping may lead to grain agglomeration or the formation of a non-uniform phase. When the doping concentration reaches 30 mg / mL, the surface morphology changes further, with the roughness decreasing to 1.243 nm. However, considering its blurred morphological characteristics, this may be related to amorphization or compositional segregation caused by excessive doping. Therefore, appropriate doping can effectively improve the interface quality of the hole transport layer, providing a better substrate for the growth of the upper perovskite layer. Figure 3 As shown, the surface roughness of perovskite films grown based on hole transport layers of PEDOT:PSS doped with different concentrations of NaH2PO2 initially increases slightly and then continuously decreases with increasing doping concentration of the underlying layer. The RMS values ​​are 20.85 nm (0 mg / mL), 22.95 nm (5 mg / mL), 20.80 nm (10 mg / mL), 18.46 nm (15 mg / mL), and 15.68 nm (30 mg / mL), respectively. These results indicate that the doping modification of PEDOT:PSS with NaH2PO2 significantly alters its surface properties, thereby systematically affecting the crystallization kinetics and film growth mode of the upper perovskite layer, ultimately resulting in a smoother and denser perovskite film.

[0035] (2) Optical performance analysis: like Figure 4 As shown, all perovskite film samples exhibited a bimodal emission characteristic at approximately 805 nm and 824 nm. The sample with a doping concentration of 5 mg / mL showed the highest emission peak intensity, indicating that the introduction of an appropriate amount of NaH₂PO₂ effectively reduced non-radiative recombination centers, improving the film's luminescence efficiency and crystallinity. The undoped sample showed the second highest PL intensity. However, as the doping concentration further increased to 10 mg / mL, 15 mg / mL, and 30 mg / mL, the PL peak intensity gradually decreased, indicating that excessively high concentrations of NaH₂PO₂ could introduce defects or cause phase separation, which is detrimental to photoluminescence performance.

[0036] (3) Device performance analysis: like Figure 5As shown in Table 1, the photovoltaic performance of perovskite solar cells based on different concentrations of NaH2PO2-doped PEDOT:PSS exhibits a trend of initial optimization followed by degradation. Under standard test conditions, the undoped device has an open-circuit voltage (Voc) of 0.81 V, a short-circuit current density (Jsc) of 17.45 mA / cm², a fill factor (FF) of 0.76, and a power conversion efficiency (PCE) of 10.67%. When the doping concentration is 5 mg / mL, the device performance reaches its optimal level, with the short-circuit current density (Jsc) increasing to 19.21 mA / cm² and the PCE increasing to 11.60%, representing a relative efficiency improvement of 8.7%. This indicates that appropriate sodium hypophosphite doping effectively improves hole extraction and interfacial recombination.

[0037] When the doping concentration continued to increase to 15 mg / mL, the device efficiency gradually decreased, and the efficiency dropped to 7.11% at a concentration of 30 mg / mL, indicating that excessive doping severely damaged the crystallinity and photoelectric properties of the film. The sodium hypophosphite used in this invention is an inexpensive and readily available inorganic salt with good water solubility and is fully compatible with PEDOT:PSS aqueous solution. The doping process only requires dissolving the sodium hypophosphite powder directly in the PEDOT:PSS stock solution, without additional synthesis, dispersion, or post-processing steps. It can be directly integrated into the existing low-temperature spin-coating preparation process of inverted perovskite solar cells without increasing process complexity, making it suitable for large-scale production.

[0038] Table 1. Photovoltaic performance parameters of perovskite solar cells based on PEDOT:PSS doped with different concentrations of NaH2PO2.

[0039] In summary, this invention systematically improves the crystallinity and surface morphology of perovskite thin films by appropriately doping with sodium hypophosphite, reduces non-radiative recombination, and ultimately enhances the photoelectric conversion efficiency of perovskite solar cells. This approach provides a practical and feasible technical path for realizing high-efficiency, low-cost inverted perovskite solar cells.

[0040] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A perovskite solar cell with a doped and modified PEDOT:PSS hole transport layer, characterized in that: It includes an ITO conductive substrate, a sodium hypophosphite (NaH2PO2) doped and modified PEDOT:PSS hole transport layer, a perovskite light-absorbing layer, an electron transport layer, an interface modification layer, and a metal electrode, which are stacked sequentially.

2. The perovskite solar cell according to claim 1, characterized in that: The doping concentration of sodium hypophosphite in the PEDOT:PSS solution is 3 mg / mL to 10 mg / mL.

3. The perovskite solar cell according to claim 2, characterized in that: The doping concentration of sodium hypophosphite in the PEDOT:PSS solution is 5 mg / mL.

4. The perovskite solar cell according to claim 1, characterized in that: The perovskite light-absorbing layer is made of Cs. 0.05 FA 0.85 MA 0.1 PbI3.

5. The perovskite solar cell according to claim 1, characterized in that: The electron transport layer is a PCBM layer, the interface modification layer is a BCP layer, and the metal electrode is an Ag electrode.

6. The perovskite solar cell according to claim 1, characterized in that: The thickness of each layer is as follows: ITO conductive substrate 100nm~450nm, PEDOT:PSS hole transport layer 20nm~70nm, perovskite light-absorbing layer 200nm~1000nm, PCBM electron transport layer 10nm~50nm, BCP interface modification layer 1nm~5nm, Ag electrode 70nm~150nm.

7. A method for preparing a perovskite solar cell with a doped and modified PEDOT:PSS hole transport layer as described in any one of claims 1 to 6, characterized in that: Includes the following steps: (1) Cleaning and surface treatment of ITO conductive glass: ITO conductive glass was ultrasonically cleaned in sequence with cleaning solution, deionized water, acetone, and ethanol / isopropanol, dried and then treated with ultraviolet ozone to obtain hydrophilic ITO substrate. (2) Preparation of modified hole transport layer: Sodium hypophosphite powder was dissolved in PEDOT:PSS aqueous solution and mixed to obtain doped precursor solution; The precursor solution was spin-coated onto an ITO substrate and annealed to obtain a NaH2PO2-doped modified PEDOT:PSS hole transport layer. (3) Preparation of perovskite light-absorbing layer: Prepare perovskite precursor solution, spin-coat it on hole transport layer, use antisolvent to assist film formation, and anneal to obtain perovskite film; (4) Preparation of electron transport layer and interface modification layer: PCBM solution and BCP solution were spin-coated sequentially on the perovskite film and annealed respectively; (5) Preparation of metal electrodes: Vacuum evaporation of Ag metal electrodes to obtain perovskite cells.

8. The preparation method according to claim 7, characterized in that: In step (2), the spin coating parameters are: accelerate from 500 rpm to 4000 rpm and spin coat for 30 s; the annealing conditions are heating at 100 ℃ for 20 minutes.

9. The preparation method according to claim 7, characterized in that: In step (3), the perovskite precursor solution is prepared by dissolving PbI2, FAI, MAI, CsI, and MACl in a mixed solvent of DMF and DMSO; the spin coating is a two-step spin coating: the first step is spin coating at 1000 rpm for 10 s, and the second step is spin coating at 5000 rpm for 40 s, with chlorobenzene anti-solvent added dropwise at the end of the spin coating; the annealing condition is heating at 100℃ for 30 minutes.

10. The preparation method according to claim 7, characterized in that: In step (2), the PEDOT:PSS hole transport layer after sodium hypophosphite doping does not require additional surface treatment and can be directly spin-coated with a perovskite layer.

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