Use of an additive in a hole transport layer of a solar cell and a solar cell

Abstract

The application provides application of an additive in a hole transport layer of an Ag2BiI5 solar cell, and the additive is 2-pentylpyridine. The application overcomes the corrosion effect of an additive tBP in a traditional hole material 2,2',7,7'-tetrakis-(dimethoxydiphenylamine)-spirofluorene (Spiro-OMeTAD) on an Ag2BiI5 light absorption layer, and after the 2-py is used to replace, the crystallization, morphology and visible light absorption intensity of a perovskite layer film are indirectly improved, so that the interface contact between the perovskite and the HTL is enhanced, the holes are effectively extracted, and the photo-generated carrier recombination is reduced, which plays a positive role. The mesoporous perovskite solar cell prepared by the application has a simple process flow, and after the additive is replaced, the photoelectric performance of the cell is obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to the application of an additive in the hole transport layer of an Ag2BiI5 solar cell and an Ag2BiI5 solar cell. Background Technology

[0002] Perovskite solar cells (PSCs) have attracted widespread attention in the solar cell field due to their advantages such as high photoelectric conversion efficiency, simple fabrication, and low cost. These cells mainly consist of a conductive substrate, an electron transport layer, a light absorption layer, a hole transport layer, and electrodes. Currently, solar cells based on organic-inorganic hybrid perovskite materials are developing rapidly, with the highest efficiency exceeding 25%. However, lead in this system can pollute the environment and has poor stability, hindering the further development and application of high-efficiency perovskite solar cells.

[0003] In recent years, Ag₂BiI₅ ternary materials have been used as light-absorbing layers in solar cells due to their good stability and lead-free properties, exhibiting excellent photoelectric performance. It is worth noting that Spiro-OMeTAD is commonly used as a hole transport layer material in perovskite solar cells, but the most commonly used additive in Spiro-OMeTAD, 4-tert-butylpyridine (tBP), significantly reduces the photoelectric performance of the light-absorbing layer due to its corrosive effect, especially noticeable in Ag₂BiI₅ solar cells. These factors hinder the further commercial application of perovskite solar cells. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an application of an additive in the hole transport layer of a solar cell and a solar cell. The additive provided by the present invention effectively overcomes the corrosive effect of the additive tBP in the hole transport layer on the Ag2BiI5 light-absorbing layer, indirectly improves the crystallization, morphology and light absorption intensity of the perovskite layer film, and greatly enhances the photoelectric performance of the cell.

[0005] This invention provides the application of an additive in the hole transport layer of an Ag2BiI5 solar cell, wherein the additive is 2-pentylpyridine.

[0006] Preferably, the hole transport layer is prepared from Spiro-OMeTAD, 2-pentylpyridine, and LiTFSI.

[0007] Preferably, the ratio of Spiro-OMeTAD, LiTFSI, and 2-pentylpyridine is 60–80 mg: 15–20 mg: 14–44 μL.

[0008] The present invention also provides an Ag2BiI5 solar cell, comprising a conductive glass layer, a dense layer, a framework layer, an Ag2BiI5 perovskite light-absorbing layer, a hole transport layer, and an electrode, which are sequentially composited, wherein the hole transport layer comprises 2-pentylpyridine.

[0009] Preferably, the dense layer is a c-TiO2 dense layer;

[0010] The framework layer is an m-TiO2 framework layer, and the nanoparticles used to prepare the framework layer have a particle size of 18-20 nm.

[0011] The electrode is selected from gold electrodes.

[0012] The present invention also provides a method for preparing the above-mentioned Ag2BiI5 solar cell, comprising the following steps:

[0013] A) Tetraisopropyl titanate, isopropanol and acetylacetone are mixed to obtain a mixed solution;

[0014] After coating the treated conductive glass surface with the mixed solution, heat treatment is performed to obtain a dense layer.

[0015] B) After coating the surface of the dense layer with m-TiO2 solution, the layer is heated to crystallize and obtain the framework layer.

[0016] C) Dissolve AgI and BiI3 in an organic solvent to obtain a precursor solution;

[0017] After coating the precursor solution onto the framework layer, annealing was performed to obtain the Ag2BiI5 perovskite light-absorbing layer.

[0018] D) Disperse Spiro-OMeTAD powder, 2-pentylpyridine and LiTFSI in a solvent to obtain a mixed dispersion;

[0019] The mixed dispersion was coated onto the surface of the perovskite light-absorbing layer to obtain a hole transport layer;

[0020] E) An electrode is fabricated on the surface of the hole transport layer.

[0021] Preferably, in step A), the volume ratio of tetraisopropyl titanate, isopropanol, and acetylacetone is 0.6–1:7–10:0.4–0.6; the heat treatment temperature is 450–480°C, and the time is 1–1.2 h.

[0022] In step B), the temperature for heating and crystallization is 140–150°C, and the time is 13–15 min.

[0023] In step C), the organic solvent is selected from DMSO, the molar ratio of AgI to BiI3 is 1.98 to 2.02:1, the concentration of AgI in the precursor solution is 0.8 to 1.4 M, the concentration of BiI3 is 0.4 to 0.7 M, and the annealing temperature is 130 to 160 °C.

[0024] Preferably, in step D), the solvent is selected from chlorobenzene;

[0025] The ratio of Spiro-OMeTAD powder, 2-pentylpyridine, and LiTFSI is 60-80 mg of Spiro powder, 15-20 mg of LiTFSI, and 14-44 μL of 2-pentylpyridine added to 1 mL of chlorobenzene.

[0026] Preferably, in step E), the electrode is a gold electrode;

[0027] The electrode is prepared by vacuum evaporation.

[0028] Compared with existing technologies, this invention provides the application of an additive, 2-pentylpyridine, in the hole transport layer of an Ag₂BiI₅ solar cell. This invention overcomes the corrosive effect of the additive tBP in the traditional hole material 2,2',7,7'-tetra-(dimethoxydiphenylamine)-spirofluorene (Spiro-OMeTAD) on the Ag₂BiI₅ light-absorbing layer. Replacing tBP with 2-pyridine indirectly improves the crystallinity, morphology, and visible light absorption intensity of the perovskite film, thereby enhancing the interfacial contact between the perovskite and HTL layers. This plays a positive role in effectively extracting holes and reducing photogenerated carrier recombination. The mesoporous perovskite solar cell prepared by this invention has a simple process flow, and the photoelectric performance of the cell is significantly improved after the additive replacement.

[0029] The results show that Ag₂BiI₅ solar cells were successfully fabricated using the above method. Replacing tBP with 2-py reduced the corrosive effect of additives in the hole transport layer on the Ag₂BiI₅ light-absorbing layer, improved the crystallinity and morphology of the perovskite film, and inhibited the electron-hole recombination centers Bi. 0 The generation of this technology increased the efficiency of Ag2BiI5 solar cell devices from 0.61% to 1.32%. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the Ag2BiI5 solar cell provided by the present invention;

[0031] Figure 2XRD patterns of the thin film after introducing different amounts of tBP and 2-py Spiro-OMeTAD solution were obtained. As the concentration of tBP in Spiro-OMeTAD solution increased from the initial 14.4 μL / mL to 43.2 μL / mL, the diffraction peak intensities of the (003), (104), and (110) crystal planes of the Ag2BiI5 film continuously decreased when using tBP; however, with the addition of 2-py, the characteristic peak intensities of Ag2BiI5 did not change significantly.

[0032] Figure 3 This is a surface SEM image of Spiro-OMeTAD without additives, coated with an Ag2BiI5 film and then cleaned with chlorobenzene after the coating in Example 6.

[0033] Figure 4 SEM images of Spiro-OMeTAD spin-coated Ag2BiI5 films with added tBP and then cleaned with chlorobenzene were used to compare the results. The grain boundaries on the film surface were blurred and most of the grain sizes were smaller, with the average grain size decreasing from 300 nm to about 160 nm, indicating that tBP has a strong corrosive effect on Ag2BiI5 films.

[0034] Figure 5 SEM images of the Ag2BiI5 film after spin-coating with 2-py Spiro-OMeTAD in Example 7 and cleaning with chlorobenzene showed almost no change on the film surface, indicating that the introduction of 2-py to replace tBP can effectively reduce the corrosion of the Ag2BiI5 film by the hole transport layer.

[0035] Figure 6 The AFM is an A2BiI5 film coated with Spiro-OMeTAD without additives from Example 6 and then cleaned with chlorobenzene; the root mean square (RMS) roughness of the film is 31.381 nm.

[0036] Figure 7 The image shows the AFM after spin-coating an Ag2BiI5 film with Spiro-OMeTAD containing tBP in a proportional ratio and then cleaning it with chlorobenzene. The RMS roughness of the film is 20.836 nm, which is significantly lower than the RMS roughness. This may be due to the corrosion of the film by tBP.

[0037] Figure 8 The AFM of Spiro-OMeTAD with 2-py added in Example 7, after spin-coating Ag2BiI5 film and cleaning with chlorobenzene, is 30.307 nm. The RMS value is 30.307 nm, which is not significantly lower than that under the condition without additives. This result is consistent with SEM.

[0038] Figure 9XPS and corresponding Bi / Bi after spin-coating a small amount of tBP onto the Ag2BiI5 film in Example 8. 3+ Partial magnified views of the XPS spectra of 4f7 / 2 and 4f5 / 2; except for the presence of Bi at 158.5 eV and 163.84 eV. 3+ The peaks at 4f 7 / 2 and 4f 5 / 2 were observed, and new Bi elemental peaks at 156.60 eV and 161.92 eV also appeared. This result indicates that the valence state of Bi changed after tBP treatment of Ag2BiI5 film.

[0039] Figure 10 Example 9 shows XPS and corresponding Bi after spin-coating a small amount of 2-py onto an Ag2BiI5 film. 3+ Magnified views of the XPS spectra of 4f7 / 2 and 4f5 / 2; except for Bi 3+ Peak generation and Figure 9 Apart from the same offset, no peak position of elemental Bi was observed;

[0040] Figure 11 JV curves of solar cells fabricated using Spiro-OMeTAD containing tBP and 2-py as hole transport layers in Examples 3 and 10 are shown. When tBP is used as an additive, the efficiency of Ag2BiI5 perovskite solar cells decreases significantly to only 0.610%, with varying degrees of decrease in short-circuit current, open-circuit voltage, and fill factor. When 2-py is used as an additive, the efficiency of Ag2BiI5 perovskite solar cells increases significantly to 1.271%, which is more than twice that of devices using tBP. This is because 2-py, by replacing tBP, overcomes the drawback of tBP damaging the light-absorbing layer.

[0041] Figure 12 IPCE of Ag2BiI5 solar cells fabricated using Spiro-OMeTAD containing tBP and 2-py as the hole transport layer in Examples 3 and 10 in the 300-750 nm spectral range; IPCE values ​​and integrals. sc and Figure 11 The corresponding JV curve. Detailed Implementation

[0042] This invention provides the application of an additive in the hole transport layer of an Ag2BiI5 solar cell, wherein the additive is 2-pentylpyridine.

[0043] The hole transport layer is prepared from Spiro-OMeTAD, 2-pentylpyridine and LiTFSI.

[0044] The ratio of Spiro-OMeTAD, LiTFSI, and 2-pentylpyridine is 60–80 mg: 15–20 mg: 14–44 μL.

[0045] The present invention also provides an Ag2BiI5 solar cell, comprising a conductive glass layer, a dense layer, a framework layer, an Ag2BiI5 perovskite light-absorbing layer, a hole transport layer, and an electrode, which are sequentially composited, wherein the hole transport layer comprises 2-pentylpyridine.

[0046] Specifically, the Ag2BiI5 solar cell provided by this invention includes conductive glass, wherein the conductive glass is selected from FTO. The thickness of the FTO is 300-400 nm.

[0047] The Ag2BiI5 solar cell provided by the present invention further includes a dense layer, which is a c-TiO2 dense layer with a thickness of 40-70 nm.

[0048] The Ag2BiI5 solar cell provided by the present invention further includes a framework layer, which is an m-TiO2 framework layer. The nanoparticles used to prepare the framework layer have a particle size of 18-20 nm and a thickness of 200-300 nm.

[0049] The Ag2BiI5 solar cell provided by the present invention also includes an Ag2BiI5 perovskite light-absorbing layer with a thickness of 300-500 nm.

[0050] The Ag2BiI5 solar cell provided by this invention further includes a hole transport layer, which, as described above, is prepared from Spiro-OMeTAD, 2-pentylpyridine, and LiTFSI. The thickness is 350–450 nm.

[0051] The Ag2BiI5 solar cell provided by the present invention also includes an electrode, wherein the electrode is a gold electrode.

[0052] See Figure 1 , Figure 1 This is a schematic diagram of the structure of the Ag2BiI5 solar cell provided by the present invention.

[0053] This invention also provides a method for preparing an Ag2BiI5 solar cell, comprising the following steps:

[0054] A) Tetraisopropyl titanate, isopropanol and acetylacetone are mixed to obtain a mixed solution;

[0055] After coating the treated conductive glass surface with the mixed solution, heat treatment is performed to obtain a dense layer.

[0056] B) After coating the surface of the dense layer with m-TiO2 solution, the layer is heated to crystallize and obtain the framework layer.

[0057] C) Dissolve AgI and BiI3 in an organic solvent to obtain a precursor solution;

[0058] After coating the precursor solution onto the framework layer, annealing was performed to obtain the Ag2BiI5 perovskite light-absorbing layer.

[0059] D) Disperse Spiro-OMeTAD powder, 2-pentylpyridine and LiTFSI in a solvent to obtain a mixed dispersion;

[0060] The mixed dispersion was coated onto the surface of the perovskite light-absorbing layer to obtain a hole transport layer;

[0061] E) An electrode is fabricated on the surface of the hole transport layer.

[0062] The present invention first processes the conductive glass, the specific method of which is as follows:

[0063] The conductive glass was rinsed with ethanol and dried, then placed in a UV ozone cleaner for treatment, and subsequently heated in a flat-plate oven.

[0064] Then, tetraisopropyl titanate, isopropanol, and acetylacetone are mixed to obtain a mixed solution. The volume ratio of tetraisopropyl titanate, isopropanol, and acetylacetone is 0.6–1 mL: 7–10 mL: 0.4–0.6 mL, preferably 0.6 mL: 7 mL: 0.4 mL.

[0065] After the mixed solution is coated onto the treated conductive glass surface, it is subjected to heat treatment at a temperature of 450–480°C, preferably 450, 460, 470, or 480°C, or any value between 450 and 480°C, for a time of 1–1.2 hours. The present invention does not impose any particular limitation on the coating method; any method known to those skilled in the art is acceptable, with spraying being preferred.

[0066] After heat treatment, the mixture is allowed to cool naturally to room temperature to obtain a dense layer. Next, an m-TiO2 solution is coated onto the surface of the dense layer, wherein the TiO2 slurry is diluted in anhydrous ethanol at a mass ratio of 1:5. This invention does not impose any particular limitation on the coating method; any coating method known to those skilled in the art is acceptable. In this invention, the coating is preferably spin-coating, with a spin-coating speed of 3000–5000 rpm, preferably 3000, 4000, or 5000 rpm, or any value between 3000 and 5000 rpm, and a time of 25–35 seconds.

[0067] After spin coating, heating crystallization is performed at a temperature of 100–150°C, preferably 100, 110, 120, 130, 140, or 150°C, or any value between 100–150°C, for a time of 10–20 minutes, preferably 10, 15, or 20 minutes, or any value between 10–20 minutes. In this invention, the heating crystallization is performed on a programmable temperature-controlled heating stage. After heating crystallization is completed, a framework layer is obtained.

[0068] Next, an Ag₂BiI₅ perovskite light-absorbing layer is prepared. Specifically, AgI and BiI₃ are dissolved in an organic solvent to obtain a precursor solution; wherein the organic solvent is selected from DMSO, the molar ratio of AgI to BiI₃ is 1.98–2.02:1, the AgI concentration in the precursor solution is 0.8–1.4 M, preferably 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or any value between 0.8 and 1.4 M, and the BiI₃ concentration is 0.4–0.7 M, preferably 0.4, 0.5, 0.6, 0.7, or any value between 0.4 and 0.7 M. Before use, the solution is heated and stirred at 60°C to ensure complete dissolution.

[0069] After coating the precursor solution onto the framework layer, annealing is performed to obtain the Ag2BiI5 perovskite light-absorbing layer. The present invention does not impose any particular limitation on the coating method; any coating method known to those skilled in the art is acceptable, preferably spin coating. The spin coating speed is 4000–5000 rpm, and the time is 25–35 s, preferably any value between 25, 30, 35, or 25–35 s. In some specific embodiments of the present invention, after the precursor solution is dropped onto the framework layer, it is allowed to stand for 10–20 s before spin coating to ensure that the solution more fully covers the surface of the mesoporous layer and penetrates it appropriately.

[0070] After spin coating, annealing is performed at a temperature of 130℃ to 160℃, preferably 130, 140, 150, 160, or any value between 130℃ and 160℃.

[0071] After obtaining the Ag2BiI5 perovskite light-absorbing layer, Spiro-OMeTAD powder, 2-pentylpyridine and LiTFSI were dispersed in a solvent to obtain a mixed dispersion.

[0072] The solvent is selected from chlorobenzene; the ratio of Spiro-OMeTAD powder, 2-pentylpyridine, and LiTFSI is 60-80 mg of Spiro powder, 15-20 mg of LiTFSI, and 14-44 μL of 2-pentylpyridine per mL of chlorobenzene, preferably 72.3 mg of Spiro powder, 17.5 mg of LiTFSI, and 14.4 μL of 2-pentylpyridine per mL of chlorobenzene, 72.3 mg of Spiro powder, 17.5 mg of LiTFSI, and 21.6 μL of 2-pentylpyridine per mL of chlorobenzene, and 14-44 μL of 2-pentylpyridine per mL of chlorobenzene. Any ratio between 72.3 mg Spiro powder, 17.5 mg LiTFSI and 28.8 μL 2-pentylpyridine, 72.3 mg Spiro powder, 17.5 mg LiTFSI and 36.0 μL 2-pentylpyridine in 1 mL of chlorobenzene, or 60–80 mg Spiro powder, 15–20 mg LiTFSI and 14–44 μL 2-pentylpyridine in 1 mL of chlorobenzene.

[0073] The mixed dispersion is coated onto the surface of the perovskite light-absorbing layer to obtain a hole transport layer. This invention does not impose any particular limitation on the coating method; any coating method known to those skilled in the art is acceptable. In this invention, spin coating is preferred, with a spin coating speed of 3500–4500 rpm, preferably 3500, 4000, or 4500 rpm, or any value between 3500 and 4500 rpm, and a spin coating time of 25–30 s.

[0074] Finally, an electrode is fabricated on the surface of the hole transport layer. The electrode is fabricated by vacuum evaporation. Preferably, the electrode is a gold electrode.

[0075] In some specific embodiments of the present invention, the product is placed in a vacuum coating machine at a temperature of 1×10⁻⁶. -5 In a Pa environment, 70-90 nm gold is plated on it as an electrode.

[0076] In the process described in this invention, except for the heating process of the program-controlled temperature heating table and the vacuum coating process, all other steps are carried out in a nitrogen glove box.

[0077] The mesoporous perovskite solar cell provided by this invention effectively overcomes the corrosive effect of the additive tBP in the hole transport layer on the Ag2BiI5 light-absorbing layer due to the introduction of 2-py, indirectly improving the crystallinity, morphology, and light absorption intensity of the perovskite film, thus greatly enhancing the photoelectric performance of the cell. This plays a positive role in the further development of perovskite solar cells using Spiro-OMeTAD as the hole transport layer.

[0078] To further understand the present invention, the application of the additive provided by the present invention in the hole transport layer of Ag2BiI5 solar cell and an Ag2BiI5 solar cell are described below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0079] Example 1:

[0080] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0081] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 min, then placed in a plate furnace and heated to 500℃ and held for 20 min, followed by cooling to 460℃ for 20 min. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0082] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0083] 4) Preparation of the perovskite layer:

[0084] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0085] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0086] 5) Preparation of the hole transport layer:

[0087] Dissolve 72.3 mg Spiro-OMeTAD powder, 14.4 μL 2-py, and 17.5 μL LiTFSI in 1 mL of chlorobenzene. After the sample from step 4) has cooled to room temperature, spin-coat the Spiro-OMeTAD solution using the following parameters: 20 μL, 4000 rpm, and 20 s.

[0088] 6) Evaporation deposition of counter electrode: using an ultra-vacuum deposition machine at 1×10 -580nm gold was deposited as an electrode under Pa.

[0089] See Figure 2 , Figure 2 XRD analysis of the Ag₂BiI₅ film was conducted after introducing different amounts of tBP and 2-py into Spiro-OMeTAD solutions. As the concentration of tBP in the Spiro-OMeTAD solution increased from an initial 14.4 μL / mL to 43.2 μL / mL, the diffraction peak intensities of the (003), (104), and (110) crystal planes of the Ag₂BiI₅ film continuously decreased when using tBP. However, with the addition of 2-py, the characteristic peak intensities of Ag₂BiI₅ did not show significant changes.

[0090] Figure 2 In this context, "14.4 μL 2-py" corresponds to the XRD pattern of the thin film prepared in Example 1, and "14.4 μL tBP" corresponds to the XRD pattern of the thin film prepared by replacing 2-py with tBP in Example 1.

[0091] “28.8 μL 2-py” corresponds to the XRD pattern of the thin film prepared in Example 3, and “28.8 μL tBP” corresponds to the XRD pattern of the thin film prepared by replacing 2-py with tBP in Example 3.

[0092] "43.2 μL 2-py" corresponds to the XRD pattern of the thin film prepared in Example 5, and "43.2 μL tBP" corresponds to the XRD pattern of the thin film prepared by replacing 2-py with tBP in Example 5.

[0093] Example 2:

[0094] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0095] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0096] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0097] 4) Preparation of the perovskite layer:

[0098] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0099] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0100] 5) Preparation of the hole transport layer:

[0101] Dissolve 72.3 mg Spiro-OMeTAD powder, 21.6 μL 2-py, and 17.5 μL LiTFSI in 1 mL of chlorobenzene. After the sample from step 4) has cooled to room temperature, spin-coat the Spiro-OMeTAD solution using the following parameters: 20 μL, 4000 rpm, and 20 s.

[0102] 6) Evaporation deposition of counter electrode: using an ultra-vacuum deposition machine at 1×10 -5 80nm gold was deposited as an electrode under Pa.

[0103] Example 3:

[0104] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0105] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0106] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0107] 4) Preparation of the perovskite layer:

[0108] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0109] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0110] 5) Preparation of the hole transport layer:

[0111] Dissolve 72.3 mg Spiro-OMeTAD powder, 28.8 μL 2-py, and 17.5 μL LiTFSI in 1 mL of chlorobenzene. After the sample from step 4) has cooled to room temperature, spin-coat the Spiro-OMeTAD solution using the following parameters: 20 μL, 4000 rpm, and 20 s.

[0112] 6) Evaporation deposition of counter electrode: using an ultra-vacuum deposition machine at 1×10 -5 80nm gold was deposited as an electrode under Pa.

[0113] Example 4:

[0114] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0115] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0116] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0117] 4) Preparation of the perovskite layer:

[0118] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0119] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0120] 5) Preparation of the hole transport layer:

[0121] Dissolve 72.3 mg Spiro-OMeTAD powder, 36.0 μL 2-py, and 17.5 μL LiTFSI in 1 mL of chlorobenzene. After the sample from step 4) has cooled to room temperature, spin-coat the Spiro-OMeTAD solution using the following parameters: 20 μL, 4000 rpm, and 20 s.

[0122] 6) Evaporation deposition of counter electrode: using an ultra-vacuum deposition machine at 1×10 -5 80nm gold was deposited as an electrode under Pa.

[0123] Example 5:

[0124] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0125] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0126] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0127] 4) Preparation of the perovskite layer:

[0128] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0129] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0130] 5) Preparation of the hole transport layer:

[0131] Dissolve 72.3 mg Spiro-OMeTAD powder, 43.2 μL 2-py, and 17.5 μL LiTFSI in 1 mL of chlorobenzene. After the sample from step 4) has cooled to room temperature, spin-coat the Spiro-OMeTAD solution using the following parameters: 20 μL, 4000 rpm, and 20 s.

[0132] 6) Evaporation deposition of counter electrode: using an ultra-vacuum deposition machine at 1×10 -5 80nm gold was deposited as an electrode under Pa.

[0133] Example 6:

[0134] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0135] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0136] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0137] 4) Preparation of the perovskite layer:

[0138] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0139] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0140] 5) Cleaning after spin-coating the hole transport layer:

[0141] 72.3 mg Spiro-OMeTAD powder, 43.2 μL tBP, and 17.5 μL LiTFSI were dissolved in 1 mL chlorobenzene. After the sample from step 4) cooled to room temperature, the Spiro-OMeTAD solution was spin-coated using the following parameters: 20 μL, 4000 rpm, 20 s. The sample was then washed with chlorobenzene.

[0142] See Figure 3 , Figure 3 SEM image of the surface after spin-coating an Ag2BiI5 film onto Spiro-OMeTAD without additives and then cleaning with chlorobenzene. Figure 6 The AFM is an A2BiI5 film coated with Spiro-OMeTAD without additives by spin coating and then cleaned with chlorobenzene. The root mean square (RMS) roughness of the film is 31.381 nm.

[0143] Example 7:

[0144] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0145] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0146] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0147] 4) Preparation of the perovskite layer:

[0148] Prepare a 0.7 M Ag2BiI5 precursor solution with 1.4 M AgI and 0.7 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0149] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0150] 5) Cleaning after spin-coating the hole transport layer:

[0151] Dissolve 72.3 mg Spiro-OMeTAD powder, 43.2 μL 2-py, and 17.5 μL LiTFSI in 1 mL of chlorobenzene. After the sample from step 4) has cooled to room temperature, spin-coat the Spiro-OMeTAD solution using the parameters 20 μL, 4000 rpm, and 20 s. Then wash with chlorobenzene.

[0152] 6) Evaporation deposition of counter electrode: using an ultra-vacuum deposition machine at 1×10 -5 80nm gold was deposited as an electrode under Pa.

[0153] Figure 5 SEM images of the Ag2BiI5 film after spin-coating with 2-py Spiro-OMeTAD (Example 7) and cleaning with chlorobenzene showed almost no change on the film surface, indicating that introducing 2-py to replace tBP can effectively reduce the corrosion of the Ag2BiI5 film by the hole transport layer.

[0154] Figure 8 The AFM is the result of spin-coating an Ag2BiI5 film with 2-py Spiro-OMeTAD added in Example 7, followed by cleaning with chlorobenzene. The RMS value was 30.307 nm, which did not show a significant decrease compared to the condition without additives, a result consistent with SEM.

[0155] Example 8:

[0156] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0157] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0158] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0159] 4) Preparation of the perovskite layer:

[0160] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0161] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0162] 5) Spin-coating a small amount of tBP:

[0163] After the sample in step 4) has cooled to room temperature, spin-coat 43.2 μL of tBP dissolved in 1 mL of chlorobenzene. The spin-coating parameters are 20 μL, 4000 rpm, and 20 s.

[0164] See Figure 9 , Figure 9 XPS and corresponding Bi / Bi after spin-coating a small amount of tBP onto the Ag2BiI5 film in Example 8. 3+ Partial magnified views of the XPS spectra of 4f7 / 2 and 4f5 / 2. Except for the presence of Bi at 158.5 eV and 163.84 eV. 3+ The peaks at 4f 7 / 2 and 4f 5 / 2 were observed, and new zero-valent Bi peaks also appeared at 156.60 eV and 161.92 eV. This result indicates that the valence state of Bi changed after tBP treatment of Ag2BiI5 film.

[0165] Example 9:

[0166] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0167] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0168] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0169] 4) Preparation of the perovskite layer:

[0170] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0171] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0172] 5) Spin-coat a small amount of 2-py:

[0173] After the sample in step 4) has cooled to room temperature, spin-coat 43.2 μL of 2-py dissolved in 1 mL of chlorobenzene. The spin-coating parameters are 20 μL, 4000 rpm, and 20 s.

[0174] Figure 10 Example 9 shows XPS and corresponding Bi after spin-coating a small amount of 2-py onto an Ag2BiI5 film. 3+ Magnified views of the XPS spectra of 4f7 / 2 and 4f5 / 2. (Except for Bi...) 3+ Peak generation and Figure 9 Apart from the same offset, no peak position of elemental Bi was observed.

[0175] Example 10:

[0176] 1) Cut the conductive glass into 15mm×13mm pieces, soak them in the washing solution, and sonicate them in an ultrasonic instrument for 2 hours. Then take them out, rinse them with clean water, deionized water, and ethanol, and dry them in an oven.

[0177] 2) Preparation of dense layer (c-TiO2): The FTO obtained in step 1) was treated in a UV ozone cleaner for 20 mins, then placed in a plate furnace and heated to 500℃ and held for 20 mins, followed by cooling to 460℃ for 20 mins. 7 mL of isopropanol, 0.6 mL of tetraisopropyl titanate and 0.4 mL of acetylacetone were added to a spray bottle, shaken slightly, connected to the airflow, moved left and right, and sprayed evenly. The mixture was then kept at 460℃ for 1 h.

[0178] 3) Preparation of the framework layer (m-TiO2): After cooling the sample obtained in step 2) to room temperature, the framework layer slurry was spin-coated onto the sample at a volume of 40 μL, a rotation speed of 5000 rpm, and a time of 30 s. After spin-coating, the sample was placed on a programmable temperature-controlled heating stage for heating and crystallization.

[0179] 4) Preparation of the perovskite layer:

[0180] Prepare a 0.6 M Ag2BiI5 precursor solution with 1.2 M AgI and 0.6 M BiI3, and heat and stir at 60 °C until completely dissolved.

[0181] After cooling the sample to room temperature in step 3), transfer it into a glove box, add 40 μL of precursor solution, let it stand for 15 s, rotate it at 4000 rpm for 30 s, and then transfer it to a heating stage to anneal at 145 °C for 15 mins.

[0182] 5) Preparation of the hole transport layer:

[0183] Dissolve 72.3 mg Spiro-OMeTAD powder, 28.8 μL tBP, and 17.5 μL LiTFSI in 1 mL of chlorobenzene. After the sample from step 4) has cooled to room temperature, spin-coat the Spiro-OMeTAD solution using the following parameters: 20 μL, 4000 rpm, and 20 s.

[0184] 6) Evaporation deposition of counter electrode: using an ultra-vacuum deposition machine at 1×10 -5 80nm gold was deposited as an electrode under Pa.

[0185] Figure 11 JV curves for solar cells fabricated using Spiro-OMeTAD containing tBP and 2-py as the hole transport layer in Examples 3 and 10 are shown. When tBP is used as an additive, the efficiency of the Ag2BiI5 perovskite solar cell decreases significantly to only 0.610%, with varying degrees of reduction in short-circuit current, open-circuit voltage, and fill factor. When 2-py is used as an additive, the efficiency of the Ag2BiI5 perovskite solar cell increases significantly to 1.271%, more than twice that of the device using tBP. This is because 2-py, by replacing tBP, overcomes the drawback of tBP damaging the light-absorbing layer.

[0186] Figure 12 IPCE of Ag2BiI5 solar cells fabricated using Spiro-OMeTAD containing tBP and 2-py as the hole transport layer in Examples 3 and 10 in the 300-750 nm spectral range. IPCE values ​​and integrals J sc and Figure 11 The corresponding JV curve.

[0187] Comparative Example

[0188] Following the method provided in Example 7, only in step 5), 2-py is replaced with tBP; all other steps remain unchanged. See the results below. Figure 4 , Figure 4SEM images of a Spiro-OMeTAD-coated Ag₂BiI₅ film with added tBP, followed by cleaning with chlorobenzene. The film surface shows blurred grain boundaries and a reduction in the size of most grains, with the average grain size decreasing from 300 nm to approximately 160 nm, indicating that tBP has a strong corrosive effect on the Ag₂BiI₅ film.

[0189] See results Figure 7 , Figure 7 The image shows an AFM (Al2O3- ...

[0190] The above description is only a preferred embodiment of 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 principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of an additive in the hole transport layer of an Ag2BiI5 solar cell, characterized in that, The additive is 2-pentylpyridine; the hole transport layer is prepared from Spiro-OMeTAD, 2-pentylpyridine and LiTFSI.

2. The application according to claim 1, characterized in that, The ratio of Spiro-OMeTAD, LiTFSI, and 2-pentylpyridine is 60–80 mg: 15–20 mg: 14–44 μL.

3. An Ag2BiI5 solar cell, characterized in that, It includes a conductive glass layer, a dense layer, a framework layer, an Ag2BiI5 perovskite light absorption layer, a hole transport layer, and an electrode, which are sequentially compounded together. The hole transport layer includes 2-pentylpyridine.

4. The solar cell according to claim 3, characterized in that, The dense layer is a c-TiO2 dense layer; The framework layer is an m-TiO2 framework layer, and the nanoparticles used to prepare the framework layer have a particle size of 18-20 nm. The electrode is selected from gold electrodes.

5. A method for preparing an Ag₂BiI₅ solar cell as described in claim 3 or 4, characterized in that, Includes the following steps: A) Tetraisopropyl titanate, isopropanol and acetylacetone are mixed to obtain a mixed solution; After coating the treated conductive glass surface with the mixed solution, heat treatment is performed to obtain a dense layer. B) After coating the surface of the dense layer with m-TiO2 solution, the layer is heated to crystallize and obtain the framework layer. C) Dissolve AgI and BiI3 in an organic solvent to obtain a precursor solution; After coating the precursor solution onto the framework layer, annealing was performed to obtain the Ag2BiI5 perovskite light-absorbing layer. D) Disperse Spiro-OMeTAD powder, 2-pentylpyridine and LiTFSI in a solvent to obtain a mixed dispersion; The mixed dispersion was coated onto the surface of the perovskite light-absorbing layer to obtain a hole transport layer; E) An electrode is fabricated on the surface of the hole transport layer.

6. The preparation method according to claim 5, characterized in that, In step A), the volume ratio of tetraisopropyl titanate, isopropanol, and acetylacetone is 0.6–1:7–10:0.4–0.6; the heat treatment temperature is 450–480°C, and the time is 1–1.2 h. In step B), the temperature for heating and crystallization is 140–150°C, and the time is 13–15 min. In step C), the organic solvent is selected from DMSO, the molar ratio of AgI to BiI3 is 1.98 to 2.02:1, the concentration of AgI in the precursor solution is 0.8 to 1.4 M, the concentration of BiI3 is 0.4 to 0.7 M, and the annealing temperature is 130 to 160 °C.

7. The preparation method according to claim 5, characterized in that, In step D), the solvent is selected from chlorobenzene; The ratio of Spiro-OMeTAD powder, 2-pentylpyridine, and LiTFSI is 60-80 mg of Spiro powder, 15-20 mg of LiTFSI, and 14-44 μL of 2-pentylpyridine added to 1 mL of chlorobenzene.

8. The preparation method according to claim 5, characterized in that, In step E), the electrode is a gold electrode; The electrode is prepared by vacuum evaporation.

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