Preparation of core-shell nanostructure hole transport material and application thereof in solar cell

Abstract

The application relates to the technical field of solar cells, and discloses a preparation of a core-shell nanostructure hole transport material and application of the core-shell nanostructure hole transport material in a solar cell, wherein the nano material comprises 2PACZ@CuCrO2 formed nanocrystals with a diameter of 3-6 nm and a thickness of 5-14 nm, a dense film is formed by the nanocrystals, and the dense film is used as a hole transport layer of a perovskite solar cell; the core-shell nanostructure hole transport material has the characteristics of a suitable energy level structure and high conductivity, is favorable for extraction and transmission of carriers, and has higher coverage; therefore, the 2PACZ@CuCrO2 provides a smoother substrate for perovskite deposition, avoids direct contact between perovskite and conductive glass, reduces generation of defects and recombination sites, and improves stability of the device.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to the preparation of a core-shell nanostructured hole transport material and its application in solar cells. Background Technology

[0002] Solar energy, as the most abundant energy source in nature, is one of the cleanest, safest, and most reliable energy sources for the future. Effective ways to utilize solar energy can be divided into photothermal conversion, photoelectric conversion, and photochemical conversion. Among them, photoelectric conversion, namely solar cells, converts solar energy into electrical energy through the photovoltaic effect of semiconductor materials. Its safety and environmental friendliness are far superior to the currently widely used thermal power generation, and it is one of the core technologies of the new energy industry. Perovskite solar cells possess excellent photoelectric properties, including high absorption coefficient, long carrier lifetime, tunable bandgap, and high carrier mobility. Furthermore, their fabrication process is simple and the required raw materials are inexpensive. Perovskite solar cells are mainly divided into two types: nip and pin structures. Specifically, they consist of a transparent conductive glass substrate, an electron / hole transport layer, a perovskite light-absorbing layer, a hole / electron transport layer, and metal electrodes. The hole transport layer, as a key functional layer in perovskite solar cells, primarily collects and transports holes, achieving effective electron-hole separation. It also protects the perovskite layer from external water, oxygen, and light erosion, significantly impacting cell efficiency and stability. SAM materials (such as 2PACZ) are currently the most typical hole transport materials for planar heterojunction perovskite solar cells with pin-type device structures. However, as an organic semiconductor material, 2PACZ also suffers from poor photothermal stability, and it is necessary to find high-performance p-type materials to replace the traditional SAM material 2PACZ. In addition, the contact interface of the perovskite layer has a large number of deep-level defects, severe positive and negative charge recombination, and insufficient carrier transport capacity. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a core-shell nanostructured hole transport material and its application in solar cells, thereby solving the problem of poor photothermal stability and other inherent limitations of commonly used hole transport layers in perovskite solar cells, which in turn affect device performance.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a core-shell nanostructure hole transport material, wherein the material is 2PACZ-modified CuCrO2 nanocrystals, denoted as 2PACZ@CuCrO2; wherein the diameter of the 2PACZ@CuCrO2 nanocrystals is 3~6 nm and the thickness is 5~14 nm.

[0005] A method for developing a core-shell nanostructured hole transport material includes the following steps: S1: Mix deionized water, anhydrous ethanol and oleic acid, stir, add sodium oleate and continue stirring to form a buffer solution; S2: Dissolve chromium nitrate nonahydrate and copper nitrate trihydrate in deionized water, and add the buffer solution and stir to mix; S3: Add sodium hydroxide to the mixed solution obtained in step S2, stir and place it in a reaction vessel, and hydrothermally react at 220℃ for 8 h to obtain CuCrO2 nanocrystals; S4: Disperse the CuCrO2 nanocrystals obtained in step S3 in n-hexane, add an ethanol solution of 2PACZ, and centrifuge after ultrasonic treatment. The solid phase is the 2PACZ@CuCrO2 core-shell nanostructure material.

[0006] A core-shell nanostructured hole transport layer, wherein the hole transport layer is composed of 2PACZ@CuCrO2 core-shell nanostructured material with a thickness of 5~14 nm.

[0007] A method for preparing a hole transport layer, characterized by comprising: dispersing 2PACZ@CuCrO2 core-shell nanostructure material in an organic solvent, and forming a thin film by spin coating the resulting dispersion.

[0008] A solar cell includes a transparent conductive substrate, a hole transport layer, a perovskite active layer, an electron transport layer, a buffer layer, and an electrode layer stacked sequentially from bottom to top, wherein the hole transport layer is the core-shell nanostructure hole transport layer as described in claim 3.

[0009] A further provision of the present invention is that the material of the perovskite active layer is ABX3, wherein A is selected from one or more of CH3NH3, NH2CHNH2, and Cs; B is selected from one or more of Pb and Sn; and X is selected from one or more of I, Br, Cl, CN, and SCN.

[0010] A method for fabricating a solar cell includes the steps of sequentially forming a hole transport layer, a perovskite active layer, an electron transport layer, a buffer layer, and an electrode layer on a transparent conductive substrate, wherein the hole transport layer is fabricated using the method described above.

[0011] A solar cell includes a transparent conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer, and an electrode layer stacked sequentially from bottom to top, wherein the hole transport layer is a core-shell nanostructured hole transport layer.

[0012] A further provision of the present invention is that the material of the perovskite active layer is ABX3, wherein A is selected from one or more of CH3NH3, NH2CHNH2, and Cs; B is selected from one or more of Pb and Sn; and X is selected from one or more of I, Br, Cl, CN, and SCN.

[0013] A method for fabricating a solar cell includes the steps of sequentially forming an electron transport layer, a perovskite active layer, a hole transport layer, and an electrode layer on a transparent conductive substrate, wherein the hole transport layer is fabricated using the method described above.

[0014] In summary, this invention has the following beneficial effects: This invention prepares 2PACZ@CuCrO2 nanocrystalline materials by controlling Cr(NO3)3·9H2O, Cu(NO3)2·3H2O, NaOH, and 2PACZ. This 2PACZ@CuCrO2 nanocrystalline material is dispersed in DMF or n-butylamine, and the resulting dispersion is then spin-coated onto a transparent conductive substrate to form a thin film, which serves as the hole transport layer of an inverted perovskite solar cell. The core-shell nanostructured 2PACZ@CuCrO2 material serves as the hole transport layer of an inverted perovskite solar cell. Hole transport materials for solar cells, due to their suitable energy level structure and high conductivity, are beneficial for carrier extraction and transport. Furthermore, 2PACZ@CuCrO2 has a higher coverage, providing a smoother substrate for perovskite deposition, avoiding direct contact between the perovskite and conductive glass, reducing defects and recombination sites, and improving device stability. 2PACZ@CuCrO2 also has higher conductivity, resulting in a faster hole transport rate. The formation of PO•••Cu bonds leads to a higher work function (WF) in 2PACZ@CuCrO2, which improves the energy level matching at the perovskite / 2PACZ@CuCrO2 interface, thus facilitating hole extraction and collection. Therefore, using this core-shell nanomaterial as a hole transport layer can yield highly efficient and stable perovskite solar cells. Attached Figure Description

[0015] Figure 1 This is a transmission electron microscope image of the 2PACZ@CuCrO2 nanocrystals prepared in Example 1 of the present invention; Figure 2 This is a schematic diagram of the solar cell device structure according to Embodiment 3 of the present invention; Figure 3 This is a schematic diagram of the solar cell device structure according to Embodiment 4 of the present invention; Figure 4 This is a JV characteristic curve of the perovskite solar cell SC-2 prepared in Example 4 of the present invention; Figure 5The graph shows the stability test of the maximum output power of the perovskite solar cell SC-2 prepared in Example 4 of this invention under a standard solar irradiance.

[0016] in: Instruction manual attached Figure 2 In the middle, 1 is a transparent conductive substrate, 2 is an electron transport layer, 3 is a perovskite layer, 4 is a hole transport layer and 5 is an electrode layer; Instruction manual attached Figure 3 The structure consists of: 1. a transparent conductive substrate; 2. a hole transport layer; 3. a perovskite layer; 4. an electron transport layer; 5. a buffer layer; and 6. an electrode layer. Detailed Implementation

[0017] This application provides a novel core-shell nanostructure 2PACZ@CuCrO2 material for use as a hole transport layer in perovskite solar cells.

[0018] The core-shell nanostructured hole transport material 2PACZ@CuCrO2 provided in this application forms nanocrystals with a diameter of 3-6 nm and a thickness of 5-14 nm. By controlling the size of the nanocrystals within the specified range, the thin films prepared from this 2PACZ@CuCrO2 nanocrystalline material can be used in perovskite solar cells.

[0019] The preparation method of the novel core-shell nanostructure (2PACZ@CuCrO2) material used in this application is as follows: Take a certain volume ratio of deionized water, anhydrous ethanol and oleic acid, and stir continuously for a period of time; Weigh out a certain mass of sodium oleate and add it to the above mixed solution. Continue stirring for a period of time to form a buffer solution. Weigh a certain amount of chromium nitrate nonahydrate (Cr(NO3)3·9H2O) powder and copper nitrate trihydrate (Cu(NO3)2·3H2O) powder, add a certain volume of deionized water (H2O), add the above buffer solution, and stir continuously. Weigh out a certain amount of sodium hydroxide (NaOH) powder and add it to the above mixed solution, then continue stirring for a period of time; The resulting solution was transferred to a reaction vessel and subjected to a hydrothermal reaction at 220°C for 8 hours. The obtained yellow-green precipitate was washed several times with n-hexane and anhydrous ethanol and then dispersed in n-hexane for further use.

[0020] Take a certain volume of the product in a hexane solution, add a certain proportion of 2PACZ ethanol solution, sonicate for a period of time, centrifuge, and collect the solid, which is the 2PACZ@CuCrO2 nanocrystals. The 2PACZ@CuCrO2 nanocrystalline material was dispersed in DMF to obtain a dispersion for later use. The core-shell nanostructure material contains nanocrystals formed by 2PACZ@CuCrO2 with a diameter of 1~5 nm and a thickness of 5~14 nm.

[0021] A novel 2PACZ@CuCrO2 thin film can be prepared using the 2PACZ@CuCrO2 nanocrystalline material of this application. The thin film electrode contains the 2PACZ@CuCrO2 nanocrystalline material of this application and is used as a hole transport layer in perovskite solar cells.

[0022] Preferably, the thickness of the 2PACZ@CuCrO2 hole transport layer is 5~14 nm, more preferably 6~10 nm. Controlling the thickness of the hole transport layer within this range can ensure the effective extraction of charge in the device.

[0023] According to some embodiments of this application, the 2PACZ@CuCrO2 hole transport layer can be prepared by dispersing 2PACZ@CuCrO2 nanocrystalline material in an organic solvent to obtain a dispersion, and then forming a thin film by spin coating the dispersion.

[0024] Preferably, one or more organic solvents selected from DMF and n-butylamine can be used to form the dispersion.

[0025] This application provides a solar cell using a hole transport layer made of a core-shell nanostructured 2PACZ@CuCrO2 material. The structure of the solar cell, from bottom to top, includes: a transparent conductive substrate, an electron transport layer, a perovskite layer, a hole transport layer, and an electrode layer. The hole transport layer is a thin film layer containing 2PACZ@CuCrO2 nanocrystalline material.

[0026] Preferably, the perovskite light-absorbing material is ABX3, where A = CH3NH3, NH2CHNH2, Cs or a mixture thereof; B = Pb or Sn or a mixture thereof; and X = I, Br, Cl, CN, SCN or a mixture thereof.

[0027] Preferably, the transparent conductive substrate is FTO conductive glass or ITO conductive glass.

[0028] Preferably, the electron transport layer is a dense TiO2 layer, and more preferably, the thickness of the dense TiO2 layer is 40~100nm.

[0029] Preferably, the thickness of the perovskite layer is 300~500 nm.

[0030] Preferably, the hole transport layer is a 2PACZ@CuCrO2 thin layer, and more preferably, the hole transport layer has a thickness of 5~14 nm.

[0031] Preferably, the electrode layer is Au or Ag, and more preferably, the electrode layer has a thickness of 80~120 nm.

[0032] The solar cells containing the 2PACZ@CuCrO2 nanocrystalline hole transport layer described above can be prepared by the following method: Prepare a transparent conductive substrate; An electron transport layer is formed on the transparent conductive substrate; A perovskite layer is formed on the electron transport layer; A hole transport layer is formed in the perovskite layer; An electrode layer is formed on the hole transport layer. The hole transport layer is a thin film containing a 2PACZ@CuCrO2 core-shell nanostructure material, wherein the core-shell nanostructure material contains nanocrystals formed by 2PACZ@CuCrO2 with a diameter of 3~6 nm and a thickness of 5~14 nm.

[0033] More specifically, the preparation of the transparent conductive substrate may be a step of cleaning the transparent conductive substrate; for example, the FTO or ITO conductive glass substrate may be cleaned in an ultrasonic cleaner, more preferably, it may be cleaned in sequence with a weak alkaline glass cleaner with pH=8-10, deionized water, acetone and isopropanol for 5-20 minutes each; the cleaning of the transparent conductive substrate may be performed using other methods available in the art.

[0034] The step of forming an electron transport layer on the transparent conductive substrate can be carried out by spraying a solution of an organic titanium source onto the transparent conductive substrate and heating it. The organic titanium source can be, for example, isopropyl titanate. More specifically, for example, a cleaned FTO conductive glass substrate can be heated at 400-600 °C, and a 0.01-0.05 mol / L isopropyl titanate isopropanol solution can be sprayed onto the substrate and heated for 20-60 minutes to form a dense TiO2 electron transport layer with a thickness of 40-100 nm.

[0035] The perovskite layer, preferably made of the perovskite material as described above, can be ABX3, wherein A = CH3NH3, NH2CHNH2, Cs or a mixture thereof; B = Pb or Sn or a mixture thereof; X = I, Br, Cl, CN, SCN or a mixture thereof; more specifically, a 1.0~1.5 mol / L perovskite solution is deposited on the substrate by a one-step or two-step spin-coating method, and heated at 100~150 °C for 0.5~1 h to form a 200~1000 nm perovskite active layer.

[0036] The hole transport layer is formed by spin-coating a 2PACZ@CuCrO2 nanocrystalline dispersion onto the perovskite layer and heating it; more specifically, a 10 mg / mL DMF dispersion of 2PACZ@CuCrO2 is spin-coated onto the perovskite layer and heated at 50–100 °C for 10–60 minutes to form a 5–14 nm thick 2PACZ@CuCrO2 hole transport layer; as mentioned above, the 2PACZ@CuCrO2 nanocrystalline dispersion can be obtained by dispersing the 2PACZ@CuCrO2 nanocrystalline material of this application in an organic solvent. Preferably, one or more organic solvents selected from DMF and n-butylamine can be used to form the dispersion.

[0037] The electrode layer can be deposited on the hole transport layer by vacuum deposition of Au or Ag; more specifically, the thickness of the electrode can be controlled by adjusting the Au or Ag, the evaporation rate and the evaporation time, thereby forming an electrode layer with a thickness of 80~200 nm.

[0038] Utilizing the 2PACZ@CuCrO2 hole transport layer, some other embodiments of this application also provide a solar cell whose structure, from bottom to top, includes: a transparent conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, a buffer layer, and an electrode layer.

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] Example 1: Preparation of a novel core-shell nanostructure (2PACZ@CuCrO2) material: Prepare 2PACZ@CuCrO2 nanocrystals using the following steps: (1) Take a certain volume ratio of deionized water, anhydrous ethanol and oleic acid, and stir continuously for a period of time; (2) Weigh a certain amount of sodium oleate and add it to the above mixed solution. Continue stirring for a period of time to form a buffer solution. (3) Weigh a certain amount of chromium nitrate nonahydrate (Cr(NO3)3·9H2O) powder and copper nitrate trihydrate (Cu(NO3)2·3H2O) powder, add a certain volume of deionized water (H2O), add the above buffer solution, and stir continuously; (4) Weigh a certain amount of sodium hydroxide (NaOH) powder and add it to the above mixed solution, and continue stirring for a period of time; (5) The obtained solution was transferred to a reaction vessel and subjected to hydrothermal reaction at 220°C for 8 hours; (6) The obtained yellow-green precipitate was washed several times with n-hexane and anhydrous ethanol and then dispersed in n-hexane for further use; (7) Take a certain volume of the product in hexane solution, add a certain proportion of 2PACZ ethanol solution, sonicate for a period of time and then centrifuge. Collect the solid, which is 2PACZ@CuCrO2 nanocrystals, and finally disperse it in N,N-dimethylformamide (DMF) or n-butylamine.

[0041] Example 2: Hole transport layer prepared by spin coating of core-shell nanostructure material 2PACZ@CuCrO2 The hole transport layer is prepared by spin coating according to the following steps: After the ITO substrate is processed, it is immediately transferred to a nitrogen glove box. A DMF or n-butylamine dispersion of 2PACZ@CuCrO2 is dropped onto the ITO substrate and spin-coated at 3000 rpm / min for 30 s. Then, it is annealed at 100 °C for 10 min to form a uniform and dense film.

[0042] Example 3: Fabrication of perovskite solar cell SC-1 Prepared according to the following steps Figure 2 The perovskite solar cell SC-1 shown in the diagram comprises, from bottom to top, a transparent conductive substrate, an electron transport layer, a perovskite layer, a hole transport layer, and an electrode layer. (1) Cleaning of conductive glass: First, scrub the surface of the conductive glass substrate with a weak alkaline glass cleaner, and then clean it with deionized water, acetone and isopropanol in sequence for 15 min each. (2) Electron transport layer preparation: The treated FTO conductive glass substrate was placed on a heating stage and heated at 500 °C for 10 min. Then, a 0.05 mol / L isopropyl titanate solution was prepared and sprayed onto the substrate by spraying. After annealing on a heating stage for 20 min, a dense TiO2 electron transport layer with a thickness of about 60 nm was formed. (3) Preparation of perovskite layer: A 1.5 mol / L perovskite precursor solution was prepared according to a certain ratio. 50 uL of the prepared perovskite precursor solution was spin-coated onto the above electron transport layer. The spin-coating parameters were 5000 rpm / s for 40 s. At the 12th s before the end, 100 uL of antisolvent chlorobenzene was dropped evenly and quickly. After spin-coating, the perovskite active layer was obtained by placing it on a heating table at 100 ℃ for annealing for 30 minutes. (4) Hole transport layer preparation: The prepared 10 mg / mL 2PACZ@CuCrO2 DMF dispersion was spin-coated onto the perovskite active layer at 3000 rpm for 30 s, and heated on a heating stage at 100 ℃ for 10 min to obtain a 6 nm hole transport layer. (5) Electrode layer preparation: The half cell prepared in the above steps is placed in a vacuum evaporation apparatus and a 100 nm thick Au electrode layer is obtained by evaporation under high vacuum conditions. After completing the above steps, the perovskite solar cell SC-1 is obtained.

[0043] Example 4: Fabrication of perovskite solar cell SC-2 Prepared according to the following steps Figure 3 The perovskite solar cell SC-2 shown in the diagram comprises, from bottom to top: a transparent conductive substrate, a hole transport layer, a perovskite layer, an electron transport layer, a buffer layer, and an electrode layer. (1) Cleaning of conductive glass: First, scrub the surface of FTO conductive glass substrate with a weak alkaline glass cleaner, and then clean it with deionized water, acetone and anhydrous ethanol for 15 min each in sequence. (2) Hole transport layer preparation: The treated FTO conductive glass substrate was placed on a heating stage and heated at 500℃ for 10 min. Then, the prepared 10 mg / mL 2PACZ@CuCrO2 DMF dispersion was spin-coated onto the substrate at 3000 rpm for 30 s. The substrate was heated on a heating stage at 100℃ for 10 min to obtain a 6 nm dense hole transport layer. (3) Preparation of perovskite active layer: A 1.5 mol / L perovskite precursor solution was prepared according to a certain ratio. 50 uL of the prepared perovskite precursor solution was spin-coated onto the hole transport layer. The spin-coating parameters were 5000 rpm for 40s. At the 12th second from the end, 100 uL of anti-solvent chlorobenzene was dropped evenly and quickly. After spin-coating, the perovskite active layer was annealed at 100 ℃ for 30 minutes on a heating table. (4) Preparation of electron transport layer: Anhydrous chlorobenzene was used to prepare a PCBM solution with a concentration of 25 mg / mL, which was then spin-coated onto the perovskite active layer. The spin-coating parameters were 3000 rpm for 30 s. After annealing at 70℃ for 10 min, an electron transport layer with a thickness of 60 nm was obtained. (5) Preparation of buffer layer: Dissolve excess BCP material in anhydrous ethanol, take 70 uL of the prepared supersaturated solution and spin coat it onto the above electron transport layer at 6600 rpm for 30s, and then anneal it on a heating stage at 70 ℃ for 10 min to obtain a buffer layer with a thickness of 20 nm. (6) Electrode layer preparation: The half cell prepared in the above steps is placed in a vacuum evaporation apparatus and an Au electrode layer with a thickness of 100 nm is obtained by evaporation under high vacuum conditions. After completing the above steps, the perovskite solar cell SC-2 is obtained.

[0044] The SC-2 was tested under a standard sunlight simulator, as shown in Table 1 and... Figure 3 As shown, the inverted perovskite solar cell incorporating the core-shell nanostructure 2PACZ@CuCrO2 material as the hole transport layer exhibits superior photoelectric performance. The cell device SC-2 in Example 6, which does not use the core-shell nanostructure 2PACZ@CuCrO2 material (in this case, the conventional hole transport material 2PACZ is used), has an open-circuit voltage of 1.16 V, a short-circuit current of 25.50 mA / cm², a fill factor of 80.36%, and a photoelectric conversion efficiency of 23.67%. In contrast, the cell device SC-2 in Example 6, which uses the core-shell nanostructure 2PACZ@CuCrO2 hole transport material, has an open-circuit voltage of 1.18 V and a short-circuit current of 26.18 mA / cm². 2 The fill factor was 84.17%, and the photoelectric conversion efficiency was 26.08%. The test results show that the 2PACZ@CuCrO2 nanocrystalline material, acting as a hole transport layer, significantly improved the open-circuit voltage and fill factor of the perovskite solar cell device. This is mainly attributed to the fact that the 2PACZ@CuCrO2 core-shell nanomaterial improves the energy levels of the perovskite light-absorbing layer, passivates defects, promotes carrier extraction and transport, reduces non-radiative recombination, and effectively enhances the open-circuit voltage and fill factor of the device, thereby significantly improving the photoelectric conversion efficiency.

[0045] In addition, according to Figure 5 Stability testing results show that the efficiency of the inverted perovskite solar cell without 2PACZ@CuCrO2 decreased significantly after 400 hours of operation. However, the SC-2 device, using 2PACZ@CuCrO2 as the hole transport layer, maintained an efficiency above 90% after 1300 hours of sunlight exposure at a single intensity. The test conditions were a sealed device under a nitrogen atmosphere. These results demonstrate that due to the good chemical stability and wide bandgap of 2PACZ@CuCrO2, its application as a hole transport layer in inverted perovskite solar cells can achieve higher photoelectric conversion efficiency. Furthermore, the enhanced interface properties suppress ion migration, resulting in higher device stability. Therefore, using a novel core-shell nanostructure (2PACZ@CuCrO2) as the hole transport layer can yield highly efficient and stable perovskite solar cells, providing new insights for future research and commercial development.

[0046] The above description is only a preferred embodiment of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of this patent application are included in the scope of this patent application.

Claims

1. A core-shell nanostructured hole transport material, characterized in that, The material is 2PACZ-modified CuCrO2 nanocrystals, denoted as 2PACZ@CuCrO2; wherein the diameter of the 2PACZ@CuCrO2 nanocrystals is 3~6 nm and the thickness is 5~14 nm.

2. A method for preparing the core-shell nanostructured hole transport material as described in claim 1, characterized in that, Includes the following steps: S1: Mix deionized water, anhydrous ethanol and oleic acid, stir, add sodium oleate and continue stirring to form a buffer solution; S2: Dissolve chromium nitrate nonahydrate and copper nitrate trihydrate in deionized water, and add the buffer solution and stir to mix; S3: Add sodium hydroxide to the mixed solution obtained in step S2, stir and place it in a reaction vessel, and hydrothermally react at 220℃ for 8 h to obtain CuCrO2 nanocrystals; S4: Disperse the CuCrO2 nanocrystals obtained in step S3 in n-hexane, add an ethanol solution of 2PACZ, and centrifuge after ultrasonic treatment. The solid phase is the 2PACZ@CuCrO2 core-shell nanostructure material.

3. A core-shell nanostructured hole transport layer, characterized in that, The hole transport layer is composed of the 2PACZ@CuCrO2 core-shell nanostructure material as described in claim 1, and its thickness is 5~14 nm.

4. A method for preparing the hole transport layer as described in claim 3, characterized in that, include: The 2PACZ@CuCrO2 core-shell nanostructure material of claim 1 is dispersed in an organic solvent, and the resulting dispersion is used to form a thin film by spin coating.

5. A solar cell, comprising, from bottom to top, a transparent conductive substrate, a hole transport layer, a perovskite active layer, an electron transport layer, a buffer layer, and an electrode layer, stacked sequentially, characterized in that, The hole transport layer is the core-shell nanostructured hole transport layer as described in claim 3.

6. The solar cell according to claim 5, characterized in that, The material of the perovskite active layer is ABX3, wherein A is selected from one or more of CH3NH3, NH2CHNH2, and Cs; B is selected from one or more of Pb and Sn; and X is selected from one or more of I, Br, Cl, CN, and SCN.

7. A method for preparing a solar cell as described in claim 5 or 6, characterized in that, The method includes the steps of sequentially forming a hole transport layer, a perovskite active layer, an electron transport layer, a buffer layer, and an electrode layer on a transparent conductive substrate, wherein the hole transport layer is prepared using the method described in claim 4.

8. A solar cell, comprising a transparent conductive substrate, an electron transport layer, a perovskite active layer, a hole transport layer, and an electrode layer stacked sequentially from bottom to top, characterized in that, The hole transport layer is the core-shell nanostructured hole transport layer as described in claim 3.

9. The solar cell according to claim 8, characterized in that, The material of the perovskite active layer is ABX3, wherein A is selected from one or more of CH3NH3, NH2CHNH2, and Cs; B is selected from one or more of Pb and Sn; and X is selected from one or more of I, Br, Cl, CN, and SCN.

10. A method for preparing a solar cell as described in claim 8 or 9, characterized in that, The method includes the steps of sequentially forming an electron transport layer, a perovskite active layer, a hole transport layer, and an electrode layer on a transparent conductive substrate, wherein the hole transport layer is prepared using the method described in claim 4.

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