Rubidium and cesium co-doped wide-band-gap perovskite material and preparation method therefor, and rubidium and cesium co-doped high-open-circuit-voltage solar cell

Abstract

The present invention relates to the field of solar cells, and in particular to a rubidium and cesium co-doped wide-band-gap perovskite material and a preparation method therefor, and a rubidium and cesium co-doped high-open-circuit-voltage solar cell. The crystal growth kinetics of a wide-band-gap perovskite thin film is regulated and controlled by means of rubidium and cesium co-doping, so that the defect density of the perovskite material is greatly reduced, the non-radiative recombination of a wide-band-gap perovskite solar cell is effectively suppressed, the loss of open-circuit voltage is reduced, and the efficiency of the wide-band-gap perovskite solar cell is improved.

Description

Rubidium-cesium co-doped wide bandgap perovskite material, high open circuit voltage solar cell and preparation method thereof Technical Field

[0001] The present invention relates to the field of solar cells, and in particular to a rubidium-cesium co-doped wide bandgap perovskite material, a high open circuit voltage solar cell and a preparation method thereof. Background Art

[0002] In the field of solar cells, perovskites generally refer to a class of compounds with the general ABX3 structure, named after the CaTiO3 mineral perovskite of the same name. Typically, the A position is occupied by one or more cations, the B position is a divalent metal cation, and the X position is an anion. A variety of perovskite materials are produced by replacing the A, B, and X positions with different elements.

[0003] As a new third-generation photovoltaic material, perovskite materials offer advantages such as adjustable band gap, solution-based preparation, and low energy consumption, making them ideal for the production of high-efficiency, low-cost tandem solar cells. Wide-bandgap perovskite solar materials with band gaps of 1.65 eV and above exhibit excellent photothermal stability, which results in exceptional durability for the resulting photovoltaic devices. Therefore, these materials have become the preferred materials for the light-absorbing layers of tandem solar cells.

[0004] Generally speaking, the preparation process of perovskite materials includes three steps: precursor solution preparation, thin film deposition, and crystallization control. To extend the band gap of perovskite materials to greater than 1.65eV, a large amount of bromine is usually introduced during the precursor solution preparation. This increases the difficulty of controlling the material growth dynamics during the crystallization process, resulting in poor crystallization quality of the obtained wide-bandgap perovskite materials.

[0005] Furthermore, perovskite materials with low-quality crystal structures usually have a relatively large number of deep energy level defects, that is, the deep energy level defect density is large, which increases the possibility of local charge capture and non-radiative recombination and reduces the freedom of carrier movement in the material.

[0006] The photovoltaic performance of tandem solar cells directly depends on the efficiency of carrier generation, transport, and collection. For example, tandem solar cells made from perovskite materials with high deep-level defect density have high open-circuit voltage losses and low photoelectric conversion efficiency. Therefore, there is still considerable room for performance improvement in tandem solar cells based on wide-bandgap perovskite materials.

[0007] To this end, existing research often uses surface modification techniques to passivate the deep-level defects in wide-bandgap perovskite materials in order to improve the performance of tandem solar cells. Surface modification is a post-processing process for modifying the surface of annealed perovskite films. This method cannot control the perovskite crystallization process and cannot fundamentally inhibit the formation of deep-level defects in wide-bandgap perovskites. As a result, the modification may be limited to certain areas or the effect may be unstable.

[0008] In summary, the existing preparation methods cannot fundamentally solve the problem of high deep energy level defect density in wide bandgap perovskite materials, resulting in the obtained solar cells having high open-circuit voltage loss and low photoelectric conversion efficiency, which needs to be solved urgently.

[0009] Summary of the Invention

[0010] The purpose of the present invention is to overcome the shortcomings of the existing technology, introduce rubidium ions into the cesium-doped perovskite system, and obtain a wide-bandgap perovskite material and solar cell prepared based on a rubidium-cesium co-doped precursor solution.

[0011] Specifically, the present invention provides the following technical solutions:

[0012] In a first aspect of the present invention, a rubidium-cesium co-doped perovskite precursor solution is provided, comprising an ABX3-type perovskite and a mixed solvent, wherein A comprises rubidium ions and cesium ions; B comprises lead ions; and X is a combination of one or more chloride ions, iodide ions, and bromide ions; and the molar percentage of the rubidium ions in the rubidium-cesium co-doped perovskite precursor solution is 4-7%.

[0013] In some embodiments, the molar ratio of the rubidium ions to the cesium ions is 1:1.0-1.5.

[0014] In some embodiments, the A further comprises one or more combinations of formamidine ions and methylamine ions.

[0015] In a second aspect of the present invention, a method for preparing a rubidium-cesium co-doped perovskite material is provided, comprising: depositing the above-mentioned rubidium-cesium co-doped perovskite precursor solution on a substrate, and annealing to obtain the rubidium-cesium co-doped perovskite material.

[0016] In some embodiments, the method for preparing the perovskite material further includes: adding an anti-solvent to the rubidium-cesium co-doped perovskite precursor solution formed on the substrate.

[0017] In some embodiments, the anti-solvent is chlorobenzene, and the volume ratio of the rubidium-cesium co-doped perovskite precursor solution to the chlorobenzene is 1:2.0-2.5.

[0018] In some embodiments, the annealing temperature is 95-105°C.

[0019] In some embodiments, the annealing time is 10-20 minutes.

[0020] In a third aspect of the present invention, a rubidium-cesium co-doped perovskite material is provided, which is prepared by the above-mentioned method for preparing the rubidium-cesium co-doped perovskite material.

[0021] In a fourth aspect of the present invention, a rubidium-cesium co-doped high open circuit voltage solar cell is provided, comprising a transparent conductive layer, a hole transport layer, a light absorption layer, an electron transport layer and an electrode layer, wherein the light absorption layer adopts the above-mentioned rubidium-cesium co-doped perovskite material.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The preparation method of the rubidium-cesium co-doped perovskite material provided by the present invention introduces the rubidium element to participate in the regulation of the wide-bandgap perovskite crystallization process, thereby suppressing the formation of perovskite bulk and surface defects from the source, greatly reducing the defect density of the perovskite, and obtaining a wide-bandgap perovskite material with high crystallization quality.

[0024] (2) The rubidium-cesium co-doped perovskite material provided by the present invention has good uniformity. The mixed halogen is evenly distributed in the material, showing excellent initial uniformity.

[0025] (3) The perovskite solar cell provided by the present invention uses rubidium-cesium co-doped wide-bandgap perovskite material as a light absorption layer, which effectively suppresses the non-radiative recombination of the wide-bandgap perovskite solar cell, reduces the open-circuit voltage loss, and thus improves the photoelectric conversion efficiency of the cell, and finally obtains a low open-circuit voltage loss of 409mV and a high photoelectric conversion efficiency of 21.57%.

[0026] (4) In the perovskite solar cell provided by the present invention, rubidium and cesium are both alkali metal elements with similar chemical properties and will not have a negative impact on the battery device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a Tauc diagram of a perovskite material in one embodiment;

[0028] FIG2 is an X-ray diffraction pattern of a perovskite material in an embodiment;

[0029] FIG3 is a PL spectrum diagram of a perovskite material in an embodiment;

[0030] FIG4 is a TRPL attenuation curve diagram of a perovskite material in an embodiment;

[0031] FIG5 is a flow chart of the preparation of a perovskite solar cell in one embodiment;

[0032] FIG6 is a chemical structure of MPA-CPA in one embodiment;

[0033] FIG7 is a chemical structure of a hole transport layer material in one embodiment;

[0034] FIG8 is a schematic structural diagram of a cesium-doped wide-bandgap perovskite solar cell in one embodiment;

[0035] FIG9 is a schematic structural diagram of a wide-bandgap perovskite solar cell co-doped with rubidium and cesium in one embodiment;

[0036] FIG10 is a graph showing JV characteristics of cesium-doped and rubidium-cesium co-doped perovskite solar cells in an embodiment;

[0037] FIG11 is a JV characteristic curve of a rubidium-cesium co-doped perovskite solar cell with different rubidium-cesium ratios according to an embodiment;

[0038] FIG12 is a graph showing JV characteristic curves of rubidium-cesium co-doped perovskite solar cells with different rubidium ion ratios in one embodiment;

[0039] FIG13 is a graph showing JV characteristic curves of a rubidium-cesium co-doped perovskite solar cell at different annealing temperatures according to an embodiment;

[0040] FIG14 is a graph showing JV characteristic curves of a rubidium-cesium co-doped perovskite solar cell with different annealing times according to an embodiment;

[0041] FIG. 15 is a graph showing JV characteristic curves of rubidium-cesium co-doped perovskite solar cells with different anti-solvent volumes in an embodiment. DETAILED DESCRIPTION

[0042] The technical solution of this patent will be further described in detail below in conjunction with specific embodiments. It should be noted that the following detailed description is exemplary and is intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs.

[0043] Example 1: Preparation and performance characterization of rubidium-cesium co-doped wide bandgap perovskite materials

[0044] (1) Preparation of precursor solution. 14.9 mg of rubidium iodide (RbI), 18.2 mg of cesium iodide (CsI), 33.4 mg of methylammonium iodide (MAI), 192.7 mg of lead bromide (PbBr2), 180.6 mg of formamidine hydroiodide (FAI), and 403.4 mg of lead iodide (PbI2) were dissolved in a mixed solution of 800 μL of N,N-dimethylformamide (DMF) and 200 μL of dimethyl sulfoxide (DMSO), and stirred at room temperature for more than 2 h to obtain a RbI-Cs co-doped wide bandgap perovskite precursor solution.

[0045] As a control, a cesium-doped wide-bandgap perovskite precursor solution was prepared. Specifically, 18.2 mg of cesium iodide (CsI), 33.4 mg of methylammonium iodide (MAI), 192.7 mg of lead bromide (PbBr2), 192.6 mg of formamidine hydroiodide (FAI), and 403.4 mg of lead iodide (PbI2) were dissolved in a mixed solution of 800 μL of N,N-dimethylformamide (DMF) and 200 μL of dimethyl sulfoxide (DMSO), and stirred at room temperature for more than 2 hours to obtain a cesium-doped wide-bandgap perovskite precursor solution.

[0046] (2) Substrate cleaning: The quartz glass substrate was ultrasonically cleaned with deionized water, acetone, and isopropyl alcohol for 20 minutes respectively. After drying, the surface of the quartz glass substrate was cleaned with ultraviolet ozone for 15 minutes.

[0047] (3) Preparation of perovskite materials. 60 μL of the rubidium-cesium co-doped and cesium-doped wide-bandgap perovskite precursor solutions prepared in step (1) were added dropwise to the surface of the quartz glass substrate obtained in step (2). In the first stage, the coating was performed at a speed of 1000 rpm for 10 seconds, and in the second stage, the coating was performed at a speed of 6000 rpm for 30 seconds. In the 20th second of the second stage, 150 μL of chlorobenzene solution was added dropwise. After the coating was completed, the film was annealed at 100°C for 20 minutes to obtain a rubidium-cesium co-doped wide-bandgap perovskite film and a cesium-doped wide-bandgap perovskite film.

[0048] It should be understood that while spin coating is used as an example in this embodiment to describe the precursor solution deposition method of this application, commonly used inkjet printing, screen printing, doctor blade coating, and slit coating methods can also be used. In actual applications, if doctor blade coating or slit coating is used, air / nitrogen extraction can be used during film formation to replace the use of anti-solvents such as chlorobenzene, further enhancing safety.

[0049] (4) Characterization of the properties of perovskite materials. The two perovskite films prepared in step (3) were subjected to UV-visible light absorption characterization, X-ray diffraction characterization, photoluminescence characterization, and time-resolved photoluminescence characterization.

[0050] Results: Figure 1 shows the Tauc plots of the two perovskite materials, with photon energy plotted on the abscissa and absorbance plotted on the ordinate. It can be seen that both the Rb-Cs co-doped and Cs-doped perovskite films have a band gap of 1.68 eV, placing them within the range of wide-bandgap perovskite materials.

[0051] Figure 2 shows the X-ray diffraction patterns of the two perovskite materials, with the diffraction angle on the abscissa and the diffraction intensity on the ordinate. It can be seen that the diffraction intensity of the wide-bandgap perovskite film co-doped with Rb(III)-Cs(III) is higher than that of the wide-bandgap perovskite film doped with Cs(III), indicating superior crystal quality. Furthermore, the wide-bandgap perovskite film co-doped with Rb(III)-Cs(III) exhibits preferential growth of the (100) crystal plane, suppressing the formation of the PbI2 impurity phase.

[0052] Figure 3 shows the PL spectra of the two perovskite materials, with wavelength on the abscissa and luminescence intensity on the ordinate. It can be seen that the PL intensity of the wide-bandgap perovskite film co-doped with Rb and Cs is higher than that of the wide-bandgap perovskite film doped with Cs, indicating that Rb and Cs co-doping significantly reduces the defect density of the wide-bandgap perovskite film and reduces non-radiative recombination.

[0053] Figure 4 shows the TRPL decay curves of the two perovskite materials, with time plotted on the abscissa and luminescence intensity on the ordinate. It can be seen that the carrier lifetime of the wide-bandgap perovskite film co-doped with rubidium and cesium is 1.57 μs, twice that of the wide-bandgap perovskite film doped with cesium, indicating that the co-doping of rubidium and cesium significantly suppresses non-radiative recombination.

[0054] Example 2: Preparation and performance characterization of perovskite solar cells

[0055] As shown in Figure 5, the preparation process of perovskite solar cells includes: cleaning the ITO substrate with deionized water, acetone, and isopropyl alcohol in sequence, then preparing a hole transport layer on the substrate, preparing a perovskite layer on the hole transport layer, then preparing an electron transport layer and a barrier layer on the perovskite layer, and finally evaporating a metal electrode. The details are as follows:

[0056] (1) Substrate cleaning. The indium tin oxide (ITO) glass substrate was ultrasonically cleaned with deionized water, acetone, and isopropyl alcohol for 20 min, respectively. After drying, the surface of the ITO glass substrate was cleaned with ultraviolet ozone for 15 min.

[0057] (2) Preparation of hole transport layer: 1 mg of hole transport material was dissolved in 1 mL of ethanol and stirred at room temperature for 2 h. The hole transport material was then spin-coated on the ITO glass surface at a speed of 3000 rpm and then annealed at 100°C for 10 min to obtain a hole transport layer.

[0058] Specifically, this embodiment uses the self-assembled small molecule material MPA-CPA as shown in the structure of Figure 6. In practical applications, factors such as interface matching, charge transfer performance, light transmittance, and stability can be considered, and self-assembled small molecule materials such as 2PACz ([[2-(9H-carbazole-9-yl)ethyl]phosphonic acid) and 4PACz ([4-(9H-carbazole-9-yl)butyl]phosphonic acid) as shown in the structure of Figure 7 can be selected, or organic hole transport materials such as poly(3,4-acetylenedioxythiophene) (PEDOT), polythiophene derivatives (PT), and polyfluorene derivatives, or inorganic hole transport materials such as molybdenum oxide (MoOx) and cadmium oxide (CdO) can be selected.

[0059] (3) Preparation of perovskite layer. 60 μL of the rubidium-cesium co-doped or cesium-doped wide-bandgap perovskite precursor solution prepared in step (3) of Example 1 was added dropwise to the surface of the hole transport layer. The first stage was spin-coated at a speed of 1000 rpm for 10 seconds, and the second stage was spin-coated at a speed of 6000 rpm for 30 seconds. 150 μL of chlorobenzene solution was added dropwise at the 20th second of the second stage. After the spin-coating, the layer was annealed at 100°C for 20 minutes.

[0060] (4) Preparation of electron transport layer. -4 35nm fullerene (C 60 )Prepare the electron transport layer.

[0061] (5) Preparation of barrier layer. -4 The barrier layer was prepared by evaporating 7 nm 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) in a vacuum environment below Pa.

[0062] (6) Preparation of metal electrodes. -4 100nm copper (Cu) was evaporated in a vacuum environment below Pa as a metal electrode to obtain rubidium-cesium co-doped perovskite solar cells and cesium-doped perovskite solar cells.

[0063] (7) Performance Characterization of Perovskite Solar Cells The two perovskite solar cells prepared in step (6) were subjected to current-voltage performance tests.

[0064] Results: Figures 7 and 8 show the structures of cesium-doped and rubidium-cesium co-doped perovskite solar cells, respectively. From top to bottom, the two solar cells consist of a transparent conductive electrode, a hole transport layer, a wide-bandgap perovskite layer, an electron transport layer, a barrier layer, and a metal electrode. The difference between the two lies in the wide-bandgap perovskite layer materials used: one is a cesium-doped wide-bandgap perovskite material, and the other is a rubidium-cesium co-doped wide-bandgap perovskite material.

[0065] Table 1 Specific performance parameters of perovskite solar cells

[0066] Figure 9 shows the JV characteristic curves of the two perovskite solar cells, with the open-circuit voltage on the horizontal axis and the short-circuit current density on the vertical axis. Correspondingly, Table 1 shows the specific performance parameters of the two perovskite solar cells, including open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency.

[0067] It can be seen that compared with cesium-doped perovskite solar cells, rubidium-cesium co-doped perovskite solar cells have higher cell open circuit voltage and short-circuit current density, which indicates that under light conditions, the solar cell can produce higher voltage and current output, thereby providing greater power. The fill factor of the rubidium-cesium co-doped perovskite solar cell is also higher, which means that the solar cell has less loss during the separation and transmission of carriers, and the electrons and holes inside it can be more efficiently collected and transferred to the electrodes, improving the current output efficiency. In addition, after doping with rubidium, the photoelectric conversion efficiency of the solar cell is also improved, indicating that more solar energy is converted into usable electrical energy.

[0068] Example 3: Preparation and performance characterization of perovskite materials and solar cells

[0069] (1) Preparation of perovskite materials.

[0070] The preparation process of the rubidium-cesium co-doped perovskite material provided in this embodiment is basically the same as that in Example 1, with the main difference being that in the preparation of the precursor solution in step (1), the molar ratio of rubidium ions to cesium ions in Example 1 is 1:1, while the molar ratio of rubidium ions to cesium ions in this embodiment is 1:1.5, as detailed below.

[0071] 11.9 mg of rubidium iodide (RbI), 21.8 mg of cesium iodide (CsI), 33.4 mg of methylammonium iodide (MAI), 192.7 mg of lead bromide (PbBr2), 180.6 mg of formamidine hydroiodide (FAI) and 403.4 mg of lead iodide (PbI2) were dissolved in a mixed solution of 800 μL of N,N-dimethylformamide (DMF) and 200 μL of dimethyl sulfoxide (DMSO), and stirred at room temperature for more than 2 hours to obtain a rubidium-cesium co-doped wide band gap perovskite precursor solution.

[0072] (2) Preparation and performance characterization of solar cells.

[0073] Accordingly, the preparation process and performance characterization of the rubidium-cesium co-doped perovskite solar cell provided in this embodiment are basically the same as those in Example 2, with the main difference being that in the preparation of the perovskite layer in step (3), the perovskite precursor solution used is obtained according to the above-mentioned preparation method provided in this embodiment.

[0074] Results: Figure 11 shows the JV characteristic curves of the rubidium-cesium co-doped perovskite solar cell at different molar ratios of rubidium ions to cesium ions. Table 2 correspondingly shows the specific performance parameters of the solar cell.

[0075] Table 2 Specific performance parameters of perovskite solar cells

[0076] It can be seen that when the molar ratio of rubidium ions to cesium ions is 1:1.0 or 1:1.5, the rubidium-cesium co-doped perovskite solar cells all have high cell open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency. In addition, the solar cell obtained with a 1:1.5 rubidium-cesium molar ratio has a higher fill factor, which may have less light rate loss, that is, higher cell efficiency. When the molar ratio of the rubidium and cesium ions is 1:1.0, the cell open-circuit voltage, short-circuit current density, and photoelectric conversion efficiency parameters of the rubidium-cesium co-doped perovskite solar cell are even better. This indicates that under the same lighting conditions, the solar cell obtained with a 1:1.0 rubidium-cesium molar ratio can generate more electricity and has better overall performance.

[0077] Example 4: Preparation and performance characterization of perovskite materials and solar cells

[0078] (1) Preparation of perovskite materials.

[0079] The preparation process of the rubidium-cesium co-doped perovskite material provided in this embodiment is basically the same as that in Example 3, with the main difference being that in the preparation of the precursor solution in step (1), the molar percentage of rubidium ions in Example 3 is 4%, while the molar percentage of rubidium ions in this embodiment is 7%, as shown below.

[0080] 20.8 mg of rubidium iodide (RbI), 25.5 mg of cesium iodide (CsI), 33.4 mg of methylammonium iodide (MAI), 192.7 mg of lead bromide (PbBr2), 170.9 mg of formamidine hydroiodide (FAI) and 403.4 mg of lead iodide (PbI2) were dissolved in a mixed solution of 800 μL of N,N-dimethylformamide (DMF) and 200 μL of dimethyl sulfoxide (DMSO), and stirred at room temperature for more than 2 hours to obtain a rubidium-cesium co-doped wide band gap perovskite precursor solution.

[0081] (2) Preparation and performance characterization of solar cells.

[0082] Accordingly, the preparation process and performance characterization of the rubidium-cesium co-doped perovskite solar cell provided in this embodiment are basically the same as those in Example 2, with the main difference being that in the preparation of the perovskite layer in step (3), the perovskite precursor solution used is obtained according to the above-mentioned preparation method provided in this embodiment.

[0083] Results: Figure 12 shows the JV characteristic curves of the rubidium-cesium co-doped perovskite solar cell at different rubidium ion ratios, and Table 3 shows the specific performance parameters of the solar cell accordingly.

[0084] Table 3 Specific performance parameters of perovskite solar cells

[0085] It can be seen that compared with cesium-doped perovskite solar cells, when the rubidium ion proportion is 4 mol% or 7 mol%, the rubidium-cesium co-doped perovskite solar cells have high cell open circuit voltage, short-circuit current density, fill factor and photoelectric conversion efficiency, indicating that the photoelectric conversion efficiency and current output efficiency have been improved, and more solar energy will be utilized.

[0086] Example 5: Preparation and performance characterization of perovskite materials and solar cells

[0087] (1) Preparation of perovskite materials.

[0088] The preparation process of the rubidium-cesium co-doped perovskite material provided in this embodiment is basically the same as that in Example 1, with the main difference being that in step (3) of preparing the perovskite material, the annealing temperature in Example 1 is 100°C, while the annealing temperatures set in this embodiment are 95°C and 105°C.

[0089] (2) Preparation and performance characterization of solar cells.

[0090] Accordingly, the preparation process and performance characterization of the rubidium-cesium co-doped perovskite solar cell provided in this embodiment are basically the same as those in Example 2, with the main difference being that in the preparation of the perovskite layer in step (3), the annealing temperature in Example 2 is 100°C, while the annealing temperatures set in this embodiment are 95°C and 105°C.

[0091] Results: Figure 13 shows the JV characteristic curves of the Rb-Cs co-doped perovskite solar cell at different annealing temperatures. Table 4 shows the specific performance parameters of the solar cell accordingly.

[0092] Table 4 Specific performance parameters of perovskite solar cells

[0093] It can be seen that when the annealing temperature is 95℃ or 105℃, the rubidium-cesium co-doped perovskite solar cells have high cell open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency. In addition, compared with the solar cells obtained after annealing at 100℃, the solar cells obtained after annealing at 95℃ or 105℃ have a higher fill factor, indicating that the internal resistance of the cell is lower and it can more efficiently convert light energy into electrical energy. In addition, when the annealing temperature is 100℃, the cell open circuit voltage, short circuit current density and photoelectric conversion efficiency parameters of the rubidium-cesium co-doped perovskite solar cell are better, indicating that under the same lighting conditions, the cell has a higher output power and better overall performance.

[0094] Example 6: Preparation and performance characterization of perovskite materials and solar cells

[0095] (1) Preparation of perovskite materials.

[0096] The preparation process of the rubidium-cesium co-doped perovskite material provided in this embodiment is basically the same as that in Example 1, the main difference is that in the preparation of the perovskite material in step (3), the annealing time in Example 1 is 20 minutes, while the annealing time set in this embodiment is 10 minutes.

[0097] (2) Preparation and performance characterization of solar cells.

[0098] Accordingly, the preparation process and performance characterization of the rubidium-cesium co-doped perovskite solar cell provided in this embodiment are basically the same as those in Example 2, with the main difference being that in the preparation of the perovskite layer in step (3), the annealing time in Example 2 is 20 minutes, while the annealing time set in this embodiment is 10 minutes.

[0099] Results: Figure 14 shows the JV characteristic curves of the Rb-Cs co-doped perovskite solar cell at different annealing temperatures, and Table 5 shows the specific performance parameters of the solar cell accordingly.

[0100] Table 5 Specific performance parameters of perovskite solar cells

[0101] It can be seen that when the annealing time is 10 minutes or 20 minutes, the Rb-Cs co-doped perovskite solar cells have high cell open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency. In addition, the Rb-Cs co-doped perovskite solar cells after annealing for 20 minutes have better cell open circuit voltage, short circuit current density and photoelectric conversion efficiency parameters, which indicates that the 20-minute annealing treatment may optimize the crystal structure and improve charge transport, thereby achieving better performance in key performance parameters and improving the overall efficiency and stability of the solar cell.

[0102] Example 7: Preparation and performance characterization of perovskite materials and solar cells

[0103] (1) Preparation of perovskite materials.

[0104] The preparation process of the rubidium-cesium co-doped perovskite material provided in this embodiment is basically the same as that in Example 1, the main difference is that in the preparation of the perovskite material in step (3), the volume of the anti-solvent chlorobenzene solution added dropwise in Example 1 is 150 μL, while the volume of the chlorobenzene solution added dropwise in this embodiment is 120 μL.

[0105] (2) Preparation and performance characterization of solar cells.

[0106] Accordingly, the preparation process and performance characterization of the rubidium-cesium co-doped perovskite solar cell provided in this embodiment are basically the same as those in Example 2, with the main difference being that in the preparation of the perovskite layer in step (3), the volume of the anti-solvent chlorobenzene solution added dropwise in Example 2 is 150 μL, while the volume of the chlorobenzene solution added dropwise in this embodiment is 120 μL.

[0107] Results: Figure 15 shows the JV characteristic curves of the rubidium-cesium co-doped perovskite solar cell under different chlorobenzene solution addition volumes, and Table 6 correspondingly shows the specific performance parameters of the solar cell.

[0108] Table 6 Specific performance parameters of perovskite solar cells

[0109] It can be seen that when the antisolvent volume is 120μL or 150μL, the Rb-Cs co-doped perovskite solar cells all have high cell open circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency. In addition, the Rb-Cs co-doped perovskite solar cells using 120μL of chlorobenzene as the antisolvent have better short-circuit current density, fill factor, and photoelectric conversion efficiency parameters, indicating that using an appropriate volume of antisolvent may help form a more uniform and dense perovskite film structure, thereby improving the lifetime of photogenerated carriers and reducing surface defects.

[0110] It should be understood that this embodiment introduces the specific implementation method of the present application using a specific compound or a specific compound additive dosage as an example, but in actual application, other compounds containing specific ions can also be used, or the dosage can be magnified or reduced in a certain proportion to achieve the effect obtained by the solution provided in this application.

[0111] In summary, the present invention provides a wide-bandgap perovskite material co-doped with rubidium and cesium, a high open-circuit voltage solar cell, and a preparation method thereof. By regulating the crystallization growth dynamics of the wide-bandgap perovskite film through rubidium / cesium co-doping, the defect density of the perovskite material is greatly reduced, the non-radiative recombination of the wide-bandgap perovskite solar cell is effectively suppressed, the open-circuit voltage loss is reduced, and the efficiency of the wide-bandgap perovskite solar cell is improved.

[0112] In addition, rubidium and cesium are both alkali metal elements with similar chemical properties. Compared with the introduction of additional additives such as halogen compounds and ammonium salts into the perovskite precursor solution or anti-solvent, they will not cause side effects and will not adversely affect the performance of solar cell devices.

[0113] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A rubidium-caesium co-doped perovskite precursor solution, comprising an ABX3-type perovskite and a mixed solvent, characterized in that: A comprises rubidium ions and caesium ions; B comprises lead ions; X is one or a combination of chloride ions, iodide ions, and bromide ions; In the rubidium-caesium co-doped perovskite precursor solution, the molar percentage of the rubidium ions is 4-7%.

2. The rubidium-cesium co-doped perovskite precursor solution according to claim 1, wherein The molar ratio of the rubidium ions to the caesium ions is 1:1.0-1.

5.

3. The rubidium-caesium co-doped perovskite precursor solution according to claim 1, wherein A further comprises one or a combination of formamidinium ions and methylammonium ions.

4. A preparation method of a rubidium and cesium co-doped perovskite material, characterized in that, Comprising: Depositing the rubidium-caesium co-doped perovskite precursor solution according to any one of claims 1-4 on a substrate, and annealing to obtain the rubidium-caesium co-doped perovskite material.

5. The preparation method of the rubidium-caesium co-doped perovskite material according to claim 4, characterized in that, Further comprising: Dropping an anti-solvent onto the rubidium-caesium co-doped perovskite precursor solution formed on the substrate.

6. The preparation method of the rubidium-caesium co-doped perovskite material according to claim 5, wherein, The anti-solvent is chlorobenzene, and the volume ratio of the rubidium-caesium co-doped perovskite precursor solution to the chlorobenzene is 1:2.0-2.

5.

7. The preparation method of the rubidium-caesium co-doped perovskite material according to claim 6, characterized in that, The temperature during annealing is 95-105 °C.

8. The preparation method of the rubidium and cesium co-doped perovskite material according to claim 7, characterized in that, The time during annealing is 10-20 min.

9. A rubidium-caesium co-doped perovskite material, characterized in that, The rubidium-caesium co-doped perovskite material is obtained by the preparation method of the rubidium-caesium co-doped perovskite material according to claim 4.

10. A rubidium and cesium co-doped high open-circuit voltage solar cell, comprising a transparent conductive layer, a hole transport layer, a light absorption layer, an electron transport layer and an electrode layer, characterized in that, The light absorption layer uses the rubidium-caesium co-doped perovskite material according to claim 9.

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