An all-inorganic csPbBr3 perovskite solar cell based on nh4cl additive regulation and application thereof

Abstract

The application provides a kind of all-inorganic CsPbBr3 perovskite solar cell based on NH4Cl additive regulation and application thereof, SnO2 quantum dot solution is spin-coated on conductive film substrate to prepare electron transport layer, after preheating, spin-coat PbBr2 solution containing NH4Cl, annealing forms PbBr2 porous film, then spin-coat CsBr solution again to prepare CsPbBr3 perovskite film, scrape carbon electrode on the surface of CsPbBr3 film to prepare solar cell.The application adds NH4Cl in PbBr2 solution, and the porosity of PbBr2 film is regulated by the gas generated by the decomposition of ammonium chloride during annealing, so that the reaction is more complete, and it is beneficial to the growth of perovskite large grains.At the same time, chloride ions can passivate halogen vacancy defects.The solar cell of the application has good stability and high cell efficiency, and has important practical value and economic value for promoting the industrialization process of perovskite solar cell.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new materials and new energy technologies, and particularly relates to a full-inorganic CsPbBr3 perovskite solar cell based on NH4Cl additive regulation and application thereof. BACKGROUND

[0002] The advantages of solar energy, such as clean, abundant resources and wide distribution, have become the core of the world's energy development strategy. Solar cells can directly convert light energy into electrical energy, which is one of the most direct ways to efficiently utilize solar energy. At present, the mainstream commercial cell is still a crystalline silicon solar cell, but the space for further cost reduction in the future is limited. With the rapid development of thin film preparation technology, perovskite solar cells based on semiconductor thin films have become an important direction in the field of solar photovoltaics due to their high photoelectric conversion efficiency and cost only half of that of crystalline silicon solar cells.

[0003] The photoelectric conversion efficiency of organic-inorganic hybrid perovskite solar cells can be as high as more than 25%, but the preparation conditions are harsh, and the stability under the conditions of humidity, heat, light and oxygen is poor. Inorganic perovskite solar cells use inorganic cesium ions (Cs + ) to replace organic cations, which significantly improves the intrinsic stability of perovskite materials. Among them, the full-inorganic CsPbBr3 perovskite solar cell has excellent chemical stability, humidity stability and thermal stability, can be completely prepared and assembled in air, has low process requirements, and can use inexpensive carbon electrodes, further reducing the cost of the device. Therefore, the full-inorganic CsPbBr3 perovskite solar cell has the potential for large-scale promotion due to its high stability and low cost. Researchers have gradually made the device efficiency exceed 11% by improving the perovskite thin film preparation process, interface engineering, component engineering, spectral engineering, stress regulation and other methods.

[0004] At present, there are the following difficulties in further improving the photoelectric conversion efficiency of the full-inorganic CsPbBr3 perovskite solar cell: first, the residual thermal stress exists in the CsPbBr3 perovskite thin film structure prepared by conventional technology, which leads to small perovskite grains, high defect state density of the thin film and serious recombination of photo-generated carriers in the perovskite layer; second, there is an energy level barrier between the carrier transport layer and the perovskite layer, which causes serious recombination of photo-generated carriers at the cell interface. SUMMARY

[0005] The application aims to provide a full-inorganic CsPbBr3 perovskite solar cell based on NH4Cl additive regulation and application thereof, which optimizes the performance of the full-inorganic CsPbBr3 perovskite solar cell and improves the photoelectric conversion efficiency of the solar cell.

[0006] To achieve the above application purposes, the application adopts the following technical solutions:

[0007] The first aspect of the present application provides a full inorganic CsPbBr3 film based on NH4Cl additive regulation, which is prepared by the following preparation method:

[0008] (1) SnCl2 and CH4N2S are dissolved in deionized water, stirred, centrifuged, and the precipitate is removed and filtered to obtain a SnO2 quantum dot solution;

[0009] (2) The SnO2 quantum dot solution in step (1) and FTO conductive glass are preheated; the preheated SnO2 quantum dot solution is spin-coated on the preheated FTO conductive glass to obtain an FTO / SnO2 substrate;

[0010] (3) The FTO / SnO2 substrate in step (2) is soaked in a TiCl4 aqueous solution, washed, and then annealed to obtain an FTO / SnO2 / TiO x Cl 4-2x substrate;

[0011] (4) NH4Cl is added to a PbBr2 solution to obtain a PbBr2 solution containing NH4Cl, and the FTO / SnO2 / TiO x Cl 4-2x substrate in step (3) and the PbBr2 solution containing NH4Cl are preheated, the preheated PbBr2 solution containing NH4Cl is spin-coated on the FTO / SnO2 / TiO x Cl 4-2x substrate, and annealing is performed to obtain a PbBr2 film;

[0012] (5) A CsBr solution is spin-coated on the PbBr2 film in step (4), and then annealing is performed to obtain a full inorganic CsPbBr3 film based on NH4Cl additive regulation.

[0013] The application releases the residual stress of the perovskite film by adding NH4Cl in the PbBr2 solution. The volume of the PbBr2 film expands by 2.18 times when the PbBr2 film reacts with the CsBr solution to generate the CsPbBr3 film. Due to the strong adhesion of the PbBr2 film to the substrate, the film cannot expand freely, and thus phase transition stress (compressive stress) is introduced in the CsPbBr3 film. At the same time, during the annealing and cooling process of the CsPbBr3 film, thermal stress (tensile stress) is introduced in the CsPbBr3 film due to the mismatch of the thermal expansion coefficients of the CsPbBr3 film and the substrate material. The size of the tensile stress is determined by the difference between the thermal expansion coefficients of the substrate and the perovskite film and the difference between the annealing temperature of the perovskite film and the room temperature. Therefore, by adjusting the porosity of the PbBr2 film, the size of the phase transition stress can be adjusted to compensate for the thermal stress in situ, release the residual stress of the perovskite film, form larger grains, reduce carrier recombination, and improve the efficiency and stability of the device.

[0014] Further, the concentration of NH4Cl in the PbBr2 solution in step (4) is 0.015 mol / L to 0.050 mol / L.

[0015] Further, the concentration of NH4Cl in the PbBr2 solution in step (4) is 0.025 mol / L.

[0016] Further, the FTO / SnO2 / TiO x Cl 4-2x The preheating time of the substrate is 3 minutes to 12 minutes, the preheating time of the PbBr2 solution containing NH4Cl is 15 minutes to 30 minutes, and the preheating temperature is 88℃ to 92℃.

[0017] Further, the specific operation of annealing in step (4) is: first, the annealing temperature is 88℃ to 92℃, and the annealing time is 15 to 30 minutes, then continue to anneal, the annealing temperature is 240℃ to 260℃, and the annealing time is 5 to 10 minutes.

[0018] Further, the molar ratio of SnCl2 to CH4N2S in step (1) is 0.8 to 1.2:1, and the molar concentration of SnCl2 is 0.1 mol / L to 0.2 mol / L.

[0019] Further, the preheating temperature in step (2) is 70 to 90℃, the preheating time of the SnO2 quantum dot solution is 15 minutes to 30 minutes, and the preheating time of the FTO conductive glass is 3 minutes to 12 minutes.

[0020] Further, the temperature of the TiCl4 aqueous solution in the step (3) is kept at 70-80 DEG C, the soaking time is 15-30 minutes, the annealing temperature is 190-210 DEG C, and the annealing time is 15-30 minutes.

[0021] The second aspect of the present application provides the all-inorganic CsPbBr3 perovskite solar cell prepared from the all-inorganic CsPbBr3 film.

[0022] Further, the preparation method of the all-inorganic CsPbBr3 perovskite solar cell is as follows: scraping a carbon electrode on the surface of the all-inorganic CsPbBr3 film based on NH4Cl additive regulation, and heating.

[0023] Further, the open circuit voltage of the all-inorganic CsPbBr3 perovskite solar cell is 1.50-1.75 V, the short circuit current is 7 mA·cm -2 -8.5 mA·cm -2 , the fill factor is 0.75-0.85, and the photoelectric conversion efficiency is 9%-11%.

[0024] The third aspect of the present application provides the application of the all-inorganic CsPbBr3 perovskite solar cell in preparing battery components and in power stations.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] (1) The present application prepares the all-inorganic CsPbBr3 film based on NH4Cl additive regulation. By adding NH4Cl in the PbBr2 solution, the porosity in the PbBr2 film is regulated by means of the ammonia gas and hydrogen chloride gas generated by the decomposition of ammonium chloride during annealing, the phase transition stress is regulated, the thermal stress is compensated in situ, the residual stress of the perovskite film is released, the carrier recombination is reduced, and the photoelectric conversion efficiency of the device is improved. At the same time, by adding NH4Cl, the chloride ions combine with the halogen vacancy defects in the perovskite, the defect state density of the perovskite film is reduced, the defects are passivated, the electron transport process is accelerated, the space charge accumulation is reduced, the carrier recombination is reduced, and the battery performance is obviously improved.

[0027] (2) The maximum crystal grain of the CsPbBr3 film prepared by the present application can reach 2.83 microns, and the FTO / SnO2 / TiO x Cl 4-2x / CsPbBr3+NH4Cl / Carbon solar cell assembled therefrom has a photoelectric conversion efficiency of 10.61%, an open circuit voltage of 1.650 V, good stability, high photoelectric conversion rate, important practical value and economic value for promoting the industrialization process of perovskite solar cells. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Schematic diagram of in-situ compensation of thermal stress by phase transition stress according to the present application.

[0029] Figure 2 GIXRD pattern of CsPbBr3 film prepared according to the present application, and residual stress distribution map obtained from GIXRD.

[0030] Figure 3 XRD pattern of FTO / SnO2 / TiO x Cl 4-2x XPS pattern of FTO / SnO2 / TiO

[0031] Figure 4 Schematic diagram of NH4Cl passivation of defects in all-inorganic CsPbBr3 perovskite solar cell prepared according to the present application.

[0032] Figure 5 XPS pattern of FTO / SnO2 / TiO x Cl 4-2x XPS pattern of FTO / SnO2 / TiO

[0033] Figure 6 XPS pattern of FTO / SnO2 / TiO x Cl 4-2x XPS pattern of FTO / SnO2 / TiO

[0034] Figure 7 Defect state characterization of FTO / SnO2 / TiO x Cl 4-2x Defect state characterization of FTO / SnO2 / TiO

[0035] Figure 8 Surface and cross-section SEM images of PbBr2 film prepared according to the present application.

[0036] Figure 9 Surface and cross-section SEM images of CsPbBr3 film prepared according to the present application.

[0037] Figure 10 Atomic force microscope (AFM) image of CsPbBr3 film prepared according to the present application.

[0038] Figure 11 Efficiency characterization of all-inorganic CsPbBr3 perovskite solar cell prepared according to the present application.

[0039] Figure 12 Reproducibility of all-inorganic CsPbBr3 perovskite solar cell prepared according to the present application.

[0040] Figure 13 Efficiency curve of the added all-inorganic CsPbBr3 perovskite solar cell with added properties.

[0041] Figure 14 Long-term stability results of the all-inorganic CsPbBr3 perovskite solar cell prepared by the present application under room temperature conditions.

[0042] Figure 15 Long-term stability results of the all-inorganic CsPbBr3 perovskite solar cell prepared by the present application under continuous high temperature conditions. DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be further described in detail below in combination with specific embodiments.

[0044] Example 1, preparation of CsPbBr3 thin film

[0045] The present embodiment provides an all-inorganic CsPbBr3 thin film prepared based on an NH4Cl additive, which is obtained by the following preparation method:

[0046] (1) 850 mg of SnCl2 and 340 mg of CH4N2S were dissolved in 30 mL of deionized water, and stirred at high speed in an open container at room temperature for 36 h. The white precipitate was removed by centrifugation, and filtered with a PTFE filter membrane to obtain a yellow transparent SnO2 quantum dot solution.

[0047] (2) The FTO conductive glass with the conductive side up was placed in a plasma cleaning machine for cleaning, and the cleaning time was 5 minutes. The SnO2 quantum dot solution described in (1) and the plasma cleaned FTO conductive glass were placed on a heating table for preheating, and the preheating temperature was 80°C. The preheating time of the SnO2 quantum dot solution was 10 minutes, and the preheating time of the FTO conductive glass was 10 minutes.

[0048] The preheated SnO2 quantum dot solution was spin-coated on the preheated FTO conductive glass at a speed of 2000 rpm / s for 30 s to obtain an FTO / SnO2 substrate.

[0049] (3) The FTO / SnO2 substrate was immersed in a TiCl4 aqueous solution, and was placed in a 75°C water bath for heating for 30 min. After washing with deionized water and ethanol, it was annealed to obtain an FTO / SnO2 / TiO x Cl 4-2x substrate.

[0050] (4) PbBr2 was dissolved in DMF, the concentration of PbBr2 was 1 mol / L, and different amounts of NH4Cl were added to make the concentration of NH4Cl 0 mol / L, 0.015 mol / L, 0.025 mol / L, and 0.050 mol / L, respectively, to obtain PbBr2 solutions with different NH4Cl contents, and the solutions were placed on a heating table at 90°C for 3-5 hours to fully dissolve.

[0051] The FTO / SnO2 / TiO x Cl 4-2x The substrate and the PbBr2 solution with different NH4Cl contents were preheated on a heating table at a certain temperature, the preheating time of the FTO / SnO2 / TiO x Cl 4-2x substrate was 10 minutes, the preheating time of the PbBr2 solution with NH4Cl was 10 minutes, the preheating temperature was 90°C, and the preheated PbBr2 solution with NH4Cl was spin-coated on the FTO / SnO2 / TiO x Cl 4-2x substrate at a speed of 2000 rpm / s for 30 seconds. Then it was annealed on a heating table at the same temperature for 30 minutes, and the annealing temperature needed to be consistent with the preheating temperature to obtain a PbBr2 film. The solvent was slowly volatilized at a certain temperature, so that the solute was supersaturated and crystallized into a film. Then it was annealed on a heating table at 250°C for 5 minutes to decompose the ammonium chloride.

[0052] (5) CsBr was dissolved in anhydrous methanol to prepare a 0.07 mol / L CsBr solution, and ultrasonic treatment was performed for 60 minutes to fully dissolve. The PbBr2 film prepared in (4) was spin-coated with the CsBr solution at a speed of 2000 rpm / s for 30 seconds, and annealed on a heating table at 250°C for 5 minutes. This process was repeated 6-8 times until a uniform yellow CsPbBr3 perovskite film was formed.

[0053] Example 2, stress characterization of the prepared CsPbBr3 film

[0054] 1. By changing the concentration of NH4Cl in the PbBr2 solution, the porosity in the PbBr2 film was regulated by the ammonia and hydrogen chloride gases generated by the decomposition of ammonium chloride during annealing, so as to regulate the phase transition stress, compensate for the thermal stress in situ, release the residual stress of the perovskite film, and produce larger grains, as shown in the schematic diagram Figure 1 .

[0055] From Figure 1It can be seen that, after CsPbBr3 is annealed at 250°C to crystallize and then cooled to room temperature, due to the constraint of the substrate, the perovskite film cannot freely shrink, and thus thermal stress is generated in the perovskite film, the nature of the thermal stress is tensile stress, and the thermal stress is caused by lattice distortion due to the mismatch of the thermal expansion coefficients of the perovskite material and the substrate material. On the other hand, when the PbBr2 film reacts with the CsBr solution to generate the CsPbBr3 film, the volume expands by 2.18 times, and due to the strong adhesion of the PbBr2 film to the substrate, the film cannot freely expand, and thus a phase transition stress (compressive stress) is introduced into the CsPbBr3 film. Therefore, by adjusting the porosity of the PbBr2 film, the size of the phase transition stress can be adjusted to compensate for the thermal stress in situ, and the residual stress of the perovskite film is released.

[0056] 2, GIXRD patterns of FTO / SnO2 / TiO x Cl 4-2x / CsPbBr3 films with and without NH4Cl, and the residual stress distribution (2θ data as a function of sin 2 θ) obtained from GIXRD, as shown in Figure 2 .

[0057] The NH4Cl concentrations are 0 mol / L, 0.015 mol / L, 0.025 mol / L and 0.050 mol / L, respectively. It can be seen from Figure 2 that the tensile stress on the FTO / SnO2 / TiO x Cl 4-2x / CsPbBr3 film with 0.025 mol / L of NH4Cl is the smallest.

[0058] 3, XRD patterns of FTO / SnO2 / TiO x Cl 4-2x / CsPbBr3 films with and without NH4Cl, and the strain calculated by the Williamson-Hall equation, as shown in Figure 3 .

[0059] It can be seen from Figure 3 that the tensile strain of the FTO / SnO2 / TiO x Cl 4-2x / CsPbBr3 film with 0.025 mol / L of NH4Cl is 0.00228, and the tensile strain of the FTO / SnO2 / TiO x Cl 4-2x / CsPbBr3 film without NH4Cl is 0.00321.

[0060] Example 3, characterization of defect state passivation of the prepared CsPbBr3 film

[0061] 1. By adding 0.025 mol / L NH4Cl, chloride ions combine with halide vacancies in the perovskite film, reducing the defect state density of the perovskite film, passivating the defects, accelerating the electron transport process, reducing space charge accumulation, and decreasing carrier recombination reactions, thus significantly improving battery performance. The schematic diagram is shown below. Figure 4 .

[0062] from Figure 4 It can be seen that the added chloride ions can effectively combine with halogen vacancies in the CsPbBr3 film, thereby passivating film defects.

[0063] 2. Test whether 0.025 mol / L NH4Cl was added to FTO / SnO2 / TiO2. x Cl 4-2x XPS images of PbBr2 thin films, as shown Figure 5 As shown.

[0064] from Figure 5 It can be seen that the added chloride ions passivate the insufficiently coordinated Pb, causing the binding energy of Pb to shift to a lower binding energy, while filling the Br vacancy, causing it to shift to a higher binding energy.

[0065] 3. Test whether 0.025 mol / L NH4Cl was added to FTO / SnO2 / TiO2. x Cl 4-2x XPS images of the CsPbBr3 thin film, as shown Figure 6 As shown.

[0066] from Figure 6 It can be seen that after the formation of perovskite crystals, the added chloride ions generate additional negative charges around the insufficiently coordinated Cs and Pb, and at the same time replenish the Br vacancies, causing them to shift towards higher binding energies, effectively passivating the defects in the perovskite.

[0067] 4. Test whether 0.025 mol / L NH4Cl was added to FTO / SnO2 / TiO2. x Cl 4-2x Characterization of defect states in CsPbBr3 thin films, such as Figure 7 As shown.

[0068] As shown in Figures a, b, and c, the surface potential of the sample with added 0.025 mol / L NH4Cl was higher after KPFM testing. Figure d shows the trap-filling limit voltage (V) of the NH4Cl passivated perovskite film calculated using the space charge-limited current (SCLC) model. TFL The decrease from 1.072V to 1.026V indicates that the defect density Nt From 1.287 x 10 16 cm -3 decreased to 1.231 x 10 16 cm -3 From Figure e, it can be seen that the photoluminescence intensity of the sample with 0.025 mol / L NH4Cl added is higher.

[0069] The NH4Cl concentrations were 0 mol / L, 0.015 mol / L, 0.025 mol / L, and 0.050 mol / L, respectively. From Figure f, it can be seen that the sample with 0.025 mol / L NH4Cl added has a longer decay time of photoluminescence TRPL. From Figure g, it can be seen that the sample with 0.025 mol / L NH4Cl added has a significantly lower current density leakage under dark conditions. From Figure h, it can be seen that the sample with 0.025 mol / L NH4Cl added has a larger V bi From Figure i, it can be seen that the sample with NH4Cl added has a larger R rec The above results cross-verify that the sample with NH4Cl added has a lower defect state density, enhanced charge transfer, and effectively suppresses carrier recombination.

[0070] Example 4, performance test of prepared perovskite solar cell

[0071] A carbon electrode was scraped on the surface of the all-inorganic CsPbBr3 film prepared in Example 1 and heated to prepare an all-inorganic CsPbBr3 perovskite solar cell.

[0072] 1. The FTO / SnO2 / TiO x Cl 4-2x / PbBr2+NH4Cl films prepared from PbBr solutions with different concentrations of NH4Cl were tested, respectively. Figure 8 as shown in the photographs, surface SEM images, and cross-sectional SEM images of the FTO / SnO2 / TiO

[0073] As can be seen from Figure 8 Figures a1-a4 and b1-b4 are surface and cross-sectional SEM images of PbBr2 films prepared at NH4Cl concentrations of 0 mol / L, 0.015 mol / L, 0.025 mol / L, and 0.050 mol / L, respectively. From the figures, it can be seen that as the concentration of NH4Cl increases, the porosity in the PbBr2 film gradually increases, and the film becomes thicker. Therefore, by controlling the concentration of NH4Cl in the PbBr2 solution, the pore structure of the PbBr2 film can be successfully regulated.

[0074] 2. The FTO / SnO2 / TiO x Cl 4-2xSurface SEM images and cross-sectional SEM images of / CsPbBr3+NH4Cl thin films, as shown in Figure 9

[0075] NH4Cl concentrations were 0 mol / L, 0.015 mol / L, 0.025 mol / L, and 0.050 mol / L, respectively. Figure 9 It can be seen that with the increase of NH4Cl concentration, the prepared CsPbBr3 crystal grains first increase and then decrease, and the thickness of the CsPbBr3 thin film also increases. This is because the increase of NH4Cl concentration increases the porosity of the PbBr2 thin film evaporated by ammonia, and the porous PbBr2 thin film is beneficial to the rapid infiltration of the CsBr solution and the full contact with it, which is beneficial to the faster and more sufficient reaction between PbBr2 and CsBr. In addition, it is calculated that the volume of CsPbBr3 generated by the reaction of PbBr2 and CsBr will expand by 2.18 times. Because of the firm adhesion of the PbBr2 thin film to the substrate, the thin film cannot freely expand, so phase transition stress (compressive stress) will be introduced into the CsPbBr3 thin film. Therefore, by adjusting the porosity of the PbBr2 thin film to adjust the size of the phase transition stress in the thin film, it is balanced with the thermal stress, and part of the residual stress of the perovskite thin film is released. When the NH4Cl concentration is 0.24M-0.26M, the crystal grain of the CsPbBr3 thin film can reach 2.83 microns.

[0076] 3, respectively test whether to add 0.025mol / L NH4Cl FTO / SnO2 / TiO x Cl 4-2x Atomic force microscope (AFM) images of / CsPbBr3 thin films, as shown in Figure 10

[0077] It can be seen from Figure 10 that the roughness of the sample added with 0.025mol / L NH4Cl is 0.797, which is lower than the roughness 0.818 of the control group, indicating that the sample added with 0.025mol / L NH4Cl has a smoother surface.

[0078] 4, respectively test the efficiency curve of all-inorganic CsPbBr3 perovskite solar cells, as shown in Figure 11

[0079] It can be seen from Figure 11 that the efficiency, photoelectric conversion efficiency, cumulative current density, steady-state output, and visible light absorption intensity of the all-inorganic CsPbBr3 perovskite solar cells prepared by adding 0.025mol / L NH4Cl are higher.

[0080] ​​​5, respectively test whether the full inorganic CsPbBr3 perovskite solar cell added with 0.025 mol / L NH4Cl has reproducible repeatability, as shown in Figure 12

[0081] From Figure 12 It can be seen that the full inorganic CsPbBr3 perovskite solar cell prepared by adding 0.025 mol / L NH4Cl has considerable reproducibility.

[0082] 6, respectively test the efficiency curve of the full inorganic CsPbBr3 perovskite solar cell added with an additive with similar properties, as shown in Figure 13

[0083] From Figure 13 It can be seen that the addition of an additive with similar properties improves the efficiency of the solar cell, and when the additive is NH4Cl, the full inorganic CsPbBr3 perovskite solar cell prepared has the highest efficiency.

[0084] 7, test the long-term stability of the full inorganic CsPbBr3 perovskite solar cell modified by 0.025 mol / L NH4Cl at room temperature, and the test results are shown in Figure 14

[0085] From Figure 14 It can be seen that the CsPbBr3 perovskite solar cell described in the present application can still maintain excellent efficiency after being placed in a room temperature environment for 120 days.

[0086] 8, test the long-term stability of the full inorganic CsPbBr3 perovskite solar cell modified by 0.025 mol / L NH4Cl under continuous high temperature, and the test results are shown in Figure 15

[0087] From Figure 15 It can be seen that the CsPbBr3 perovskite solar cell described in the present application can still maintain excellent efficiency after being placed in an environment with a temperature of 80℃ and a humidity of 0% for 120 days.

[0088] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, for those skilled in the art, the technical solutions described in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions claimed by the present application.​​​​

Claims

1. A fully inorganic CsPbBr3 thin film regulated by NH4Cl additive, characterized in that, The NH4Cl additive enables chloride ions to combine with halide vacancies in perovskite, reducing the defect state density of the perovskite film, passivating the defects, accelerating electron transport, reducing space charge accumulation, and decreasing carrier recombination reactions; the defect density of the all-inorganic CsPbBr3 film is 1.231 × 10⁻⁶. 16 cm -3 The roughness is 0.

797. The all-inorganic CsPbBr3 thin film was specifically prepared by the following method: (1) Dissolve SnCl2 and CH4N2S in deionized water, stir, centrifuge, remove precipitate, and filter to obtain SnO2 quantum dot solution; the molar ratio of SnCl2 to CH4N2S is 0.8~1.2:1, and the molar concentration of SnCl2 is 0.1 mol / L~0.2 mol / L; (2) Preheat the SnO2 quantum dot solution and FTO conductive glass described in step (1); spin-coat the preheated SnO2 quantum dot solution onto the preheated FTO conductive glass to obtain an FTO / SnO2 substrate; (3) Immerse the FTO / SnO2 substrate described in step (2) in an aqueous TiCl4 solution, wash, and then anneal to obtain FTO / SnO2 / TiO2. x Cl 4-2x The substrate; the temperature of the TiCl4 aqueous solution is maintained at 70℃~80℃, the soaking time is 15~30 minutes, the annealing temperature is 190℃~210℃, and the annealing time is 15~30 minutes; (4) Add NH4Cl to the PbBr2 solution to obtain a PbBr2 solution containing NH4Cl. Then, add the FTO / SnO2 / TiO2 solution prepared in step (3). x Cl 4-2x The substrate and the PbBr2 solution containing NH4Cl were preheated, and the preheated PbBr2 solution containing NH4Cl was spin-coated onto FTO / SnO2 / TiO2. x Cl 4-2x Annealing on the substrate yields a PbBr2 thin film. The concentration of NH4Cl in the PbBr2 solution was 0.025 mol / L; (5) Spin-coating CsBr solution onto the PbBr2 film described in step (4), and then annealing to obtain an all-inorganic CsPbBr3 film regulated by NH4Cl additive.

2. The all-inorganic CsPbBr3 thin film based on NH4Cl additive regulation according to claim 1, characterized in that: In step (4), FTO / SnO2 / TiO x Cl 4-2x The preheating time for the substrate is 3 to 12 minutes, and the preheating time for the PbBr2 solution containing NH4Cl is 15 to 30 minutes. The preheating temperature is 88℃ to 92℃.

3. The all-inorganic CsPbBr3 thin film based on NH4Cl additive regulation according to claim 1, characterized in that: The specific annealing operation in step (4) is as follows: first, the annealing temperature is 88℃~92℃ and the annealing time is 15~30 minutes, and then the annealing continues at a temperature of 240℃~260℃ and an annealing time of 5~10 minutes; in step (2), the preheating temperature is 70~90℃, the preheating time of the SnO2 quantum dot solution is 15 minutes~30 minutes, and the preheating time of the FTO conductive glass is 3 minutes~12 minutes.

4. An all-inorganic CsPbBr3 perovskite solar cell fabricated using the all-inorganic CsPbBr3 thin film according to any one of claims 1 to 3, characterized in that, The open-circuit voltage of the all-inorganic CsPbBr3 perovskite solar cell is 1.50–1.75 V, and the short-circuit current is 7 mA·cm⁻¹. -2 ~8.5 mA·cm -2 The fill factor is 0.75 to 0.85, and the photoelectric conversion efficiency is 9% to 11%. The preparation method of the all-inorganic CsPbBr3 perovskite solar cell is as follows: carbon electrode is coated on the surface of an all-inorganic CsPbBr3 thin film controlled by NH4Cl additive, and then heated.

5. The application of the all-inorganic CsPbBr3 perovskite solar cell according to claim 4 in the fabrication of battery modules and power plants.

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