A perovskite solar cell and its fabrication method

Abstract

This invention relates to the field of optoelectronic functional materials and devices, and provides a perovskite solar cell and its preparation method. A composite solution of ethylenediamine and ethylenedithiol is used as a solvent. The volume ratio of ethylenediamine and ethylenedithiol and the heating temperature are strictly controlled to ensure that PbS and PbF2 are completely dissolved in the composite solution. PbS and PbF2 are used as precursor solutions for preparing the perovskite solar cell, introducing PbS and PbF2 into the epitaxial template layer of the perovskite solar cell. This improves the stability of the perovskite thin film, further enhances the stability of the perovskite solar cell, extends its lifespan, and promotes the commercialization of perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic functional materials and devices, and in particular to a perovskite solar cell and its preparation method. Background Technology

[0002] The photoelectric conversion efficiency of perovskite solar cells has improved dramatically in just over a decade, demonstrating broad application prospects. However, the long-term stability of perovskite solar cells has not been completely resolved, which seriously hinders their commercialization.

[0003] The conventional method for preparing perovskite solar cells involves dissolving PbI2 in a mixed solution of DMF / DMSO to prepare a precursor solution, spin-coating the prepared electron transport layer with the precursor solution to obtain an epitaxial template layer, and then spin-coating the PbI2 solution onto the epitaxial template layer. However, the solvents DMF / DMSO in the PbI2 solution dissolve the PbI2 in the epitaxial template layer, affecting the subsequent perovskite solar cell preparation process and its performance.

[0004] Furthermore, research has shown that introducing compressive strain epitaxial engineering is beneficial for preparing high-quality and stable α-FAPbI3 thin films, and the photoelectric properties of perovskites can be improved by controlling the strain. Lead halides and lead chalcogenide compounds, such as PbS and PbF2, have smaller lattice constants than α-FAPbI3, therefore the stability of α-FAPbI3 epitaxial films can be improved through strain modulation.

[0005] Therefore, using lead halides and lead chalcogenides such as PbS and PbF2 as precursor solutions can improve the stability of perovskite solar cells. Furthermore, both PbS and PbF2 are sparingly soluble salts and are difficult to dissolve in DMF / DMSO mixed solutions. In existing technologies, nitric acid is typically used to dissolve PbS and PbF2, but nitric acid is highly corrosive and cannot be used as a precursor solution for perovskite solar cells. Therefore, there is an urgent need for a method to prepare perovskite solar cells that allows PbS and PbF2 to be used as precursor solutions in perovskite solar cells. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in related technologies. To this end, the present invention provides a method for preparing a perovskite solar cell, comprising the following steps:

[0007] S1: Pre-treat the transparent conductive glass to obtain a transparent conductive substrate;

[0008] S2: Spin-coat SnO2 colloidal dispersion onto the transparent conductive substrate and anneal it to obtain an electron transport layer;

[0009] S3: PbS and PbF2 are placed in a mixed solution of ethylenediamine and ethylenedithiol to obtain a first mixed solution. The first mixed solution is heated and stirred to obtain a precursor solution.

[0010] S4: Spin-coat the precursor solution onto the electron transport layer and anneal it to obtain an epitaxial template layer;

[0011] S5: Spin-coat PbI2 solution onto the epitaxial template layer and anneal it to obtain a perovskite precursor layer;

[0012] S6: Spin-coat an organic salt solution onto the perovskite precursor layer and perform a second annealing to obtain a perovskite thin film.

[0013] S7: Spin-coating a chlorobenzene solution of Spiro-OMeTAD onto a perovskite film to obtain a hole transport layer;

[0014] S8: Vacuum evaporation of a metal electrode layer on the hole transport layer to obtain a perovskite solar cell.

[0015] According to the method for fabricating a perovskite solar cell provided by the present invention, step S1 includes the following steps:

[0016] The transparent conductive glass was cleaned sequentially with a cleaning agent, deionized water, and isopropanol to obtain the first transparent conductive substrate;

[0017] The first transparent conductive substrate is ultrasonically cleaned to obtain the second transparent conductive substrate;

[0018] The second transparent conductive substrate is subjected to ultraviolet ozone treatment to obtain a transparent conductive substrate.

[0019] According to the method for preparing a perovskite solar cell provided by the present invention, the mixed solution of ethylenediamine and ethylenedithiol in step S3, by volume, is 100 parts of ethylenediamine and 12-40 parts of ethylenedithiol.

[0020] According to a method for preparing a perovskite solar cell provided by the present invention, in step S3, the first mixed solution is heated and stirred, wherein the heating temperature is 50~70℃ and the stirring time is 30~180min.

[0021] According to the method for preparing a perovskite solar cell provided by the present invention, in step S4, the spin coating speed is 3000~5000 rpm and the spin coating time is 25~40 s; the annealing temperature is 70~110℃ and the annealing time is 5~30 min.

[0022] The present invention also provides a perovskite solar cell fabricated by a method for fabricating perovskite solar cells, comprising the transparent conductive substrate, the electron transport layer, the epitaxial template layer, the perovskite active layer, the hole transport layer, and the metal electrode layer; the electron transport layer is located above the transparent conductive substrate, the epitaxial template layer is located above the electron transport layer, the perovskite active layer is located above the epitaxial template layer, the hole transport layer is located above the epitaxial template layer, and the metal electrode layer is located above the hole transport layer.

[0023] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0024] 1. The present invention provides a perovskite solar cell and its preparation method, which uses a composite solution of ethylenediamine and ethylenedithiol as a solvent, and strictly controls the volume ratio of ethylenediamine and ethylenedithiol and the heating temperature to cause proton transfer from ethylenedithiol to ethylenediamine to form thiolate anions. The negatively charged thiolate anions have strong nucleophilicity and are continuously adsorbed on the Pb surface, causing the bonds between Pb and S and F to dissociate. Furthermore, PbS and PbF2 are completely dissolved in the composite solution of ethylenediamine and ethylenedithiol to obtain a precursor solution containing PbS and PbF2.

[0025] 2. The present invention provides a perovskite solar cell and its preparation method, which uses a precursor solution containing PbS and PbF2 to prepare an epitaxial template layer. When spin-coating a PbI2 solution onto the epitaxial template layer, the DMF / DMSO solution in the PbI2 solution is difficult to dissolve PbS and PbF2, and will not affect the subsequent preparation of the perovskite solar cell, thereby improving the stability of the perovskite solar cell and extending the service life of the cell.

[0026] 3. The present invention provides a perovskite solar cell and its preparation method, which introduces PbS and PbF2 from lead halide and lead chalcogenide compounds into the epitaxial template layer of the perovskite solar cell. Due to their small lattice constant, the stability of the perovskite thin film is improved by strain modulation, which further enhances the stability of the perovskite solar cell, extends the service life of the cell, and promotes the commercialization of perovskite solar cells.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 These are XRD characterization comparison images of perovskite precursor layers containing PbI2, PbS, or PbS / PbF2.

[0030] Figure 2 These are XRD characterization comparison images of perovskite films containing PbI2, PbS, or PbS / PbF2.

[0031] Figure 3 This is a Tauc curve of a perovskite thin film containing PbI2.

[0032] Figure 4 This is a Tauc curve of a perovskite thin film containing PbS.

[0033] Figure 5 This is a Tauc curve of a perovskite thin film containing PbF2.

[0034] Figure 6 This is a Tauc curve of a perovskite thin film containing PbS / PbF2.

[0035] Figure 7 This is a comparison chart of PL test characterization of perovskite thin films containing PbI2, PbS, PbF2, or PbS / PbF2.

[0036] Figure 8 It is a stability curve showing the efficiency of perovskite solar cells containing PbI2 or PbS / PbF2 over time. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but should not be used to limit the scope of this invention.

[0038] Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] The following examples 1-8 describe a perovskite solar cell and its fabrication method provided by the present invention:

[0041] Example 1:

[0042] This invention provides a method for preparing a perovskite solar cell, comprising the following steps:

[0043] S1: The transparent conductive glass is cleaned sequentially with a cleaning agent, deionized water and isopropanol to obtain a first transparent conductive substrate; the first transparent conductive substrate is ultrasonically cleaned for 30 minutes to obtain a second transparent conductive substrate; the second transparent conductive substrate is treated with ultraviolet ozone for 20 minutes to obtain a transparent conductive substrate.

[0044] S2: Spin-coat SnO2 colloidal dispersion onto the transparent conductive substrate at a spin speed of 4000 rpm for 30 s, and anneal at 180°C for 30 min to obtain an electron transport layer.

[0045] S3: Place 100 mg of PbS or PbF2 in a mixed solution of ethylenediamine and ethylenedithiol, wherein the volume ratio of ethylenediamine to ethylenedithiol is 100:15, to obtain a first mixed solution, wherein the mass ratio of PbS or PbF2 to the volume of the mixed solution of ethylenediamine and ethylenedithiol is 1 g:11.5 mL, and heat and stir the first mixed solution at 60 °C for 60 min to obtain a precursor solution;

[0046] S4: Spin-coat the precursor solution onto the electron transport layer at a speed of 4500 rpm for 30 s, and anneal at 100°C for 15 min to obtain an epitaxial template layer.

[0047] S5: Spin-coat PbI2 solution onto the epitaxial template layer at a speed of 1500 rpm, and anneal at 70°C for 1 min to obtain a perovskite precursor layer.

[0048] S6: Cool the perovskite precursor layer to room temperature, spin-coat an organic salt solution onto the perovskite precursor layer at a speed of 2000 rpm, and perform a second annealing at 30~40% humidity for 15 minutes to obtain a perovskite film.

[0049] S7: Spin-coating a chlorobenzene solution of Spiro-OMeTAD onto a perovskite film at a speed of 4000 rpm for 30 s to obtain a hole transport layer.

[0050] S8: Vacuum evaporation of 80nm thick gold as a metal electrode layer on the hole transport layer to obtain a perovskite solar cell.

[0051] The organic salt solution is prepared by dissolving 90 mg FAI, 6.39 mg MAI and 9 mg MACl in 1 mL of isopropanol to obtain the organic salt solution.

[0052] Example 2:

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

[0054] S1: The transparent conductive glass is cleaned sequentially with cleaning agent, deionized water and isopropanol to obtain a first transparent conductive substrate. The first transparent conductive substrate is ultrasonically cleaned for 30 minutes to obtain a second transparent conductive substrate. The second transparent conductive substrate is treated with ultraviolet ozone for 20 minutes to obtain a transparent conductive substrate.

[0055] S2: Spin-coat SnO2 colloidal dispersion onto the transparent conductive substrate at a spin speed of 4000 rpm for 30 s, and anneal at 180°C for 30 min to obtain an electron transport layer.

[0056] S3: Place 100 mg of PbS or PbF2 in a mixed solution of ethylenediamine and ethylenedithiol, wherein the volume ratio of ethylenediamine to ethylenedithiol is 100:15, to obtain a first mixed solution, wherein the mass ratio of PbS or PbF2 to the volume of the mixed solution of ethylenediamine and ethylenedithiol is 1 g:11.5 mL, and stir the first mixed solution for 60 min.

[0057] In this embodiment, compared to Example 1, the first mixed solution was not heated and stirred, which resulted in PbS or PbF2 being unable to dissolve in the mixed solution of ethylenediamine and ethylenedithiol, making it impossible to carry out the subsequent operation of preparing perovskite solar cells.

[0058] Based on the experimental results, the inventors monitored the effect of temperature on the solubility of PbS or PbF2 at different temperatures, as shown in Table 1:

[0059] Table 1. Effect of temperature on the solubility of PbS or PbF2

[0060]

[0061] As shown in Table 1, PbS or PbF2 can only be completely dissolved in the mixed solution of ethylenediamine and ethylenedithiol when heated at 50~70℃. This is because if the heating temperature is too low, the degree of dissolution of PbS or PbF2 is small and therefore cannot be completely dissolved. If the heating temperature is too high, the normal dissolution process of PbS or PbF2 is disrupted, and it becomes a black suspension, which cannot be effectively used as a precursor solution and affects subsequent experimental operations.

[0062] Example 3:

[0063] This invention provides a method for preparing a perovskite solar cell, comprising the following steps:

[0064] S1: The transparent conductive glass is cleaned sequentially with cleaning agent, deionized water and isopropanol to obtain a first transparent conductive substrate. The first transparent conductive substrate is ultrasonically cleaned for 30 minutes to obtain a second transparent conductive substrate. The second transparent conductive substrate is treated with ultraviolet ozone for 20 minutes to obtain a transparent conductive substrate.

[0065] S2: Spin-coat SnO2 colloidal dispersion onto the transparent conductive substrate at a spin speed of 4000 rpm for 30 s, and anneal at 180°C for 30 min to obtain an electron transport layer.

[0066] S3: Place 100 mg of PbS or PbF2 in a mixed solution of ethylenediamine and ethylenedithiol, wherein the volume ratio of ethylenediamine to ethylenedithiol is 10:1, to obtain a first mixed solution. Heat and stir the first mixed solution at 60°C for 60 min.

[0067] In this embodiment, the volume ratio of ethylenediamine and ethylenedithiol was changed compared to Example 1. Because the proportion of ethylenedithiol was too low, PbS or PbF2 could not be completely dissolved within 60 minutes. To address this experimental result, the inventors conducted experiments by changing the volume ratio of ethylenediamine and ethylenedithiol. The specific experimental results are shown in Table 2.

[0068] Table 2. Effect of the volume ratio of ethylenediamine to ethylenedithiol on the experimental results.

[0069]

[0070] As shown in Table 2, the volume ratio of ethylenediamine to ethylenedithiol needs to be strictly controlled in order to effectively dissolve PbS or PbF2. If the volume ratio is too high, PbS or PbF2 cannot be completely dissolved, making it impossible to carry out the subsequent preparation of perovskite solar cells.

[0071] The reason for this is that the proton transfer from ethylenedithiol to ethylenediamine readily forms thiolate anions. These negatively charged thiolate anions are highly nucleophilic and continuously adsorb onto the Pb surface, causing the bonds between Pb and S and F to dissociate, thus leading to dissolution. If the volume ratio of ethylenediamine to ethylenedithiol is too high, not enough thiolate anions will be generated, preventing the nucleophilic attack that dissociates PbS and PbF2, thus hindering complete dissolution.

[0072] Example 4

[0073] This invention provides a method for preparing a perovskite solar cell, comprising the following steps:

[0074] S1: The transparent conductive glass is cleaned sequentially with cleaning agent, deionized water and isopropanol to obtain a first transparent conductive substrate. The first transparent conductive substrate is ultrasonically cleaned for 30 minutes to obtain a second transparent conductive substrate. The second transparent conductive substrate is treated with ultraviolet ozone for 20 minutes to obtain a transparent conductive substrate.

[0075] S2: Spin-coat SnO2 colloidal dispersion onto the transparent conductive substrate at a spin speed of 4000 rpm for 30 s, and anneal at 180°C for 30 min to obtain an electron transport layer.

[0076] S3: Place 100 mg of PbS and PbF2 in a mixed solution of ethylenediamine and ethylenedithiol, wherein the volume ratio of ethylenediamine to ethylenedithiol is 100:15, to obtain a first mixed solution, wherein the mass ratio of PbF2 to the volume of the mixed solution of ethylenediamine and ethylenedithiol is 1 g:11.5 mL. Heat and stir the first mixed solution at 60 °C for 120 min to obtain a precursor solution.

[0077] S4: Spin-coat the precursor solution onto the electron transport layer at a speed of 4500 rpm for 30 s, and anneal at 100°C for 15 min to obtain an epitaxial template layer.

[0078] S5: Spin-coat PbI2 solution onto the epitaxial template layer at a speed of 1500 rpm, and anneal at 70°C for 1 min to obtain a perovskite active layer.

[0079] S6: Cool the perovskite active layer to room temperature, spin-coat an organic salt solution onto the perovskite active layer at a speed of 2000 rpm, and perform a second annealing for 15 minutes at a humidity of 30~40% to obtain a perovskite film.

[0080] S7: Spin-coating a chlorobenzene solution of Spiro-OMeTAD onto a perovskite film at a speed of 4000 rpm for 30 s to obtain a hole transport layer.

[0081] S8: Vacuum evaporation of 80nm thick gold as a metal electrode layer on the hole transport layer to obtain a perovskite solar cell.

[0082] The organic salt solution is prepared by dissolving 90 mg FAI, 6.39 mg MAI and 9 mg MACl in 1 mL of isopropanol to obtain the organic salt solution.

[0083] Example 5:

[0084] Example 1 added PbS or PbF2 to prepare perovskite solar cells, and Example 4 added PbS and PbF2 to prepare perovskite solar cells. In order to further study the influence of the epitaxial template layer of PbS and PbS / PbF2 on the crystallinity quality of the perovskite active layer and the perovskite thin film, XRD was used to characterize the prepared perovskite active layer and perovskite thin film.

[0085] like Figure 1 As shown, from top to bottom, the first image line represents the XRD test results of a perovskite active layer prepared using PbI2 as the main component of the precursor solution in the prior art. The second image line represents the XRD test results of a perovskite active layer prepared using PbS as the main component of the precursor solution. The third image line represents the XRD test results of a perovskite active layer prepared using PbS / PbF2 as the main component of the precursor solution. The diffraction peaks at 12.7° and 26.5° both originate from PbI2. Compared to the perovskite precursor layer containing PbI2, the second diffraction peak of the perovskite precursor layers treated with PbS and PbS / PbF2 shows a shift to a higher angle. This indicates that the lattice constant of the perovskite precursor layers treated with PbS and PbS / PbF2 is smaller, suggesting the introduction of compressive strain into the perovskite precursor layer. The presence of compressive strain makes the perovskite precursor layer more stable.

[0086] like Figure 2As shown, from top to bottom, the first image line represents the XRD test results of perovskite films prepared using PbI2 as the main component of the precursor solution in the prior art; the second image line represents the XRD test results of perovskite films prepared using PbS as the main component of the precursor solution; and the third image line represents the XRD test results of perovskite films prepared using PbS / PbF2 as the main component of the precursor solution. The diffraction peaks at 14.0°, 20.0°, and 28.2° correspond to the diffraction peaks of the (110), (112), and (220) crystal planes of the perovskite films, respectively. Compared to perovskite films containing PbI2, the diffraction peaks of the (110) and (112) crystal planes of perovskite films treated with PbS and PbS / PbF2 show a shift towards higher angles, indicating that the lattice constant of the perovskite treated with PbS and PbS / PbF2 is smaller. This indicates that the epitaxial template layer containing PbS and PbF2 introduces compressive strain, which modulates the performance and stability of the perovskite film, thereby helping to further improve the stability of perovskite solar cells.

[0087] Example 6:

[0088] Example 1 added PbS or PbF2 to prepare perovskite solar cells, and Example 4 added PbS and PbF2 to prepare perovskite solar cells. In order to further study the influence of the epitaxial template layers of PbS, PbF2 and PbS / PbF2 on the optical properties of perovskite thin films, UV-Vis testing was used to characterize the prepared perovskite thin films, and the absorption spectra were converted into Tauc curves, which can more intuitively study the changes in the band gap of perovskite thin films.

[0089] Figure 3 The characterization results of perovskite thin films prepared using PbI2 as the main component of the precursor solution in the prior art show a band gap of 1.539 eV. Figure 4 The characterization results are for perovskite films prepared using PbS as the main component of the precursor solution, with a band gap of 1.553 eV. Figure 5 The characterization results are for perovskite films prepared using PbF2 as the main component of the precursor solution, with a band gap of 1.550 eV. Figure 6 The characterization results of perovskite films prepared using PbS / PbF2 as the main component of the precursor solution show a band gap of 1.550 eV. It can be found that the band gap of perovskite films treated with PbS, PbF2, and PbS / PbF2 increases. This indicates that the treatment with PbS, PbF2, and PbS / PbF2 has a certain passivation effect on perovskite films, which can reduce the band tail defect states in the perovskite body, thereby suppressing the nonradiative recombination of photogenerated carriers and further improving the stability of perovskite films.

[0090] Perovskite films treated only with PbS have a small band gap, which can cause severe parasitic light absorption. PbF2, which is cubic in both PbS and PbS at room temperature, has a similar lattice constant to PbS, but a larger band gap. Therefore, the introduction of PbF2 can achieve controllable modulation of the optical band gap. Thus, the introduction of PbS and PbF2 epitaxial template layers into perovskite solar cells can further improve the stability of perovskite solar cells.

[0091] Example 7:

[0092] Example 1 added PbS or PbF2 to prepare perovskite solar cells, and Example 4 added PbS and PbF2 to prepare perovskite solar cells. In order to further study the influence of the epitaxial template layers of PbS, PbF2 and PbS / PbF2 on the buried interface of the perovskite film and the carrier lifetime in the perovskite body, the prepared perovskite film was characterized by PL test.

[0093] like Figure 7 As shown, from top to bottom, the first image line shows the test results of perovskite films prepared using PbS as the main component of the precursor solution; the second image line shows the test results of perovskite films prepared using PbI2 as the main component of the precursor solution; the third image line shows the test results of perovskite films prepared using PbF2 as the main component of the precursor solution; and the fourth image line shows the test results of perovskite films prepared using PbS / PbF2 as the main components of the precursor solution in the prior art.

[0094] Compared to perovskite films containing only PbI2 in existing technologies, the photoluminescence (PL) peak intensity of PbS-treated perovskite films showed a significant upward trend, while the PL peak intensity of PbS / PbF2-treated perovskite films showed a downward trend. This is mainly attributed to the different conductivity of PbS and PbS / PbF2. PL fluorescence quenching is the result of photogenerated carriers transferring from the perovskite bulk to the electron transport layer. When perovskite is directly prepared on a conductive SnO2 substrate, photogenerated carriers within the perovskite bulk can directly transfer to the SnO2 electron transport layer under light excitation. After PbS treatment, a poorly conductive PbS modification layer is introduced between the perovskite film and the SnO2 electron transport layer, which can prevent the transfer of photogenerated carriers from the perovskite bulk to the SnO2 electron transport layer. Therefore, compared to perovskite films containing only PbI2, the photoluminescence intensity of PbS-treated perovskite films is significantly increased. The addition of PbF2 to the PbS / PbF2 epitaxial template layer improves the conductivity of the modified layer. Introducing the PbS / PbF2 epitaxial template layer between the perovskite film and the SnO2 electron transport layer helps the SnO2 electron transport layer extract photogenerated carriers from the perovskite. Therefore, unlike perovskite films treated only with PbS, the photoluminescence intensity of perovskite films treated with PbS / PbF2 shows a decreasing trend.

[0095] Example 8:

[0096] Example 1 added PbS or PbF2 to prepare perovskite solar cells, and Example 4 added PbS and PbF2 to prepare perovskite solar cells. In order to further study the effect of PbS / PbF2 on the stability of perovskite solar cells, we conducted stability tests on perovskite solar cells containing only PbI2 and perovskite solar cells treated with PbS / PbF2.

[0097] At a light intensity of 100mW / cm 2 Under simulated sunlight irradiation, the current density-voltage curve of the perovskite solar cell was measured. The perovskite solar cell was placed in a room-temperature, N2-filled environment, and the test was repeated at regular intervals to obtain the stability curve of the perovskite solar cell's efficiency over time. Figure 8 As shown, the stability of perovskite solar cells treated with PbS / PbF2 is significantly improved. This is attributed to the fact that the introduction of the PbS / PbF2 epitaxial template layer can improve the stability of the perovskite film through strain modulation, thereby providing a basis for further improving the stability of perovskite solar cells.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a perovskite solar cell, characterized in that, Includes the following steps: S1: Pre-treat the transparent conductive glass to obtain a transparent conductive substrate; S2: Spin-coat SnO2 colloidal dispersion onto the transparent conductive substrate and anneal it to obtain an electron transport layer; S3: PbS and PbF2 are placed in a mixed solution of ethylenediamine and ethylenedithiol to obtain a first mixed solution. The first mixed solution is heated and stirred to obtain a precursor solution. S4: Spin-coat the precursor solution onto the electron transport layer and anneal it to obtain an epitaxial template layer; S5: Spin-coat PbI2 solution onto the epitaxial template layer and anneal it to obtain a perovskite precursor layer; S6: Spin-coat an organic salt solution onto the perovskite precursor layer and perform a second annealing to obtain a perovskite thin film. S7: Spin-coating a chlorobenzene solution of Spiro-OMeTAD onto a perovskite film to obtain a hole transport layer; S8: Vacuum evaporation of a metal electrode layer on the hole transport layer to obtain a perovskite solar cell; The mixed solution of ethylenediamine and ethylenedithiol mentioned in step S3, by volume, is 100 parts of ethylenediamine and 12-40 parts of ethylenedithiol; In step S3, the first mixed solution is heated and stirred, wherein the heating temperature is 50~70℃ and the stirring time is 30~180min.

2. The method for preparing a perovskite solar cell according to claim 1, characterized in that, Step S1 includes the following steps: The transparent conductive glass was cleaned sequentially with a cleaning agent, deionized water, and isopropanol to obtain the first transparent conductive substrate; The first transparent conductive substrate is ultrasonically cleaned to obtain the second transparent conductive substrate; The second transparent conductive substrate is subjected to ultraviolet ozone treatment to obtain a transparent conductive substrate.

3. The method for preparing a perovskite solar cell according to claim 1, characterized in that, In step S4, the spin coating speed is 3000~5000 rpm, the spin coating time is 25~40s, the annealing temperature is 70~110℃, and the annealing time is 5~30min.

4. A perovskite solar cell prepared according to the method for preparing a perovskite solar cell according to any one of claims 1-3, characterized in that, It includes a transparent conductive substrate, an electron transport layer, an epitaxial template layer, a perovskite active layer, a hole transport layer, and a metal electrode layer; the electron transport layer is located above the transparent conductive substrate, the epitaxial template layer is located above the electron transport layer, the perovskite active layer is located above the epitaxial template layer, the hole transport layer is located above the epitaxial template layer, and the metal electrode layer is located above the hole transport layer.

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