A flexible recoverable variable color thin film solar cell and a preparation method thereof

Abstract

The present application belongs to the technical field of thin film solar cell, and particularly relates to a flexible recoverable color-changing thin film solar cell and a preparation method thereof. The flexible recoverable color-changing thin film solar cell comprises a flexible substrate, an electron transport layer, a perovskite layer, a hole transport layer, a metal electrode layer and an encapsulation layer. The electron transport layer, the perovskite layer, the hole transport layer and the metal electrode layer are prepared on the flexible substrate by ultrasonic spraying in sequence, and then the electrode layer is solidified and encapsulated to form the encapsulation layer, thereby obtaining the flexible recoverable color-changing thin film solar cell. The preparation method comprises the following steps: S1, substrate pretreatment; S2, electron transport layer; S3, perovskite layer; S4, hole transport layer; S5, electrode layer; and S6, encapsulation layer of flexible photovoltaic, thereby completing the preparation of the solar cell. The flexible recoverable color-changing thin film solar cell prepared by using all-inorganic cesium lead bromide perovskite material through ultrasonic spraying can realize the recoverable color change with the change of environment while ensuring the high efficiency performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thin-film solar cells, and particularly relates to a flexible and recoverable color-changing thin-film solar cell and a preparation method thereof. BACKGROUND

[0002] As a new type of solar cell, the perovskite solar cell has the function of converting light signals into electrical signals, and is easy to prepare by using a solution method, which can greatly reduce the growth cost. Due to the low-temperature solution process, the perovskite solar cell can be combined with a printing process to prepare a perovskite flexible solar cell with light and thin characteristics. In recent years, with the rapid development of social demand for energy, the solar cell has become an indispensable part, and the high-speed growth of perovskite materials in the field of solar cells has a very large demand and market. However, the application of the perovskite solar cell is still limited to small-area devices on a rigid substrate, which limits the commercial application range of the device.

[0003] Xudong Yang et al. in their published paper “Thermochromic halide perovskite solar cells” (Nature Materials, vol. 17, pp. 261-267, 2018) disclose a thermally induced color-changing halide perovskite solar cell. The halide perovskite, although based on the advantages of the traditional perovskite solar cell, uses a spin-coating method to prepare a CsPbI 3-x Br x thin film, forms a vertical device with a structure of glass / FTO / NiO x / CsPbI 3-x Br x / ZnO / Al or ITO, and can realize reversible conversion of a transparent non-perovskite phase (visible transparency 81.7%) for low-power output and a deep-color perovskite phase (visible transparency 35.4%) for high-power output by using heat driving and water mediation. However, this method still has the following deficiencies: since the preparation method is not improved, the efficiency of the perovskite solar cell still has room for improvement, and the rigid substrate cannot realize commercial large-area application.

[0004] Bryan A. Rosales et al. in their published paper "Reversible multicolor chromism in layered formamidinium metal halide perovskites" (Nature Communications, vol. 11, pp. 5234, 2020) disclose a multicolor reversible chromic organic halide perovskite thin film. The halide perovskite thin film is a Ruddlesden-Popper phase FA n+1 PbnX 3n+1 Material, which has the property of adjustable quantum well thickness, so as to realize the performance of multicolor adjustable thin film color. However, the deficiency of this work is that the energy conversion efficiency of the Ruddlesden-Popper phase perovskite material prepared as a perovskite solar cell is not high, which cannot maintain high energy conversion efficiency while taking into account the performance of reversible color change. SUMMARY

[0005] In order to solve the above problems, the present application provides a flexible reversible color-changing thin film solar cell and a preparation method thereof, which uses a full-inorganic cesium lead bromide perovskite material sensitive to heat and humidity, which has excellent optical and electrical properties such as long diffusion length, large absorption coefficient, and long carrier lifetime, as a light absorption layer to prepare a large-area flexible thin film, and uses ultrasonic spraying to prepare a flexible reversible color-changing thin film solar cell, which realizes reversible color change with environmental changes while ensuring high efficiency performance, and can be used in the fields of green building materials, photovoltaic energy storage and smart home.

[0006] The first object of the present application is to provide a flexible reversible color-changing thin film solar cell, which comprises a substrate, an electron transport layer, a perovskite layer, a hole transport layer, an electrode layer and a packaging layer, and the electron transport layer, the perovskite layer, the hole transport layer and the electrode layer are sequentially sprayed on the substrate, then the electrode layer is solidified and packaged to form the packaging layer, i.e. the flexible reversible color-changing thin film solar cell is prepared.

[0007] The perovskite layer is a CsPbBr3 thin film layer.

[0008] Preferably, the flexible substrate is one of indium tin oxide or fluorine-doped tin oxide surface polyimide, polyethylene terephthalate, polyethylene naphthalate.

[0009] Preferably, the electron transport layer is one of titanium dioxide or tin dioxide solution.

[0010] Preferably, the hole transport layer is one of a triphenylamine derivative solution, 2,2',7,7'-tetrakis-(dimethoxyphenylamine)-spirobifluorene, poly(3-hexylthiophene), cuprous thiocyanate, a nickel oxide solution.

[0011] Preferably, the electrode layer is made of conductive silver paste or conductive carbon paste.

[0012] Preferably, the encapsulation layer is one of an ultraviolet light curing agent, a thermoplastic polyurethane, a light-cured resin.

[0013] A second object of the present application is to provide a preparation method of the flexible and recoverable color-changing thin-film solar cell described above, which is performed according to the following steps:

[0014] S1, substrate pretreatment: the substrate is respectively placed in deionized water, acetone, alcohol for ultrasonic cleaning, and then placed in ultraviolet ozone for pretreatment, to obtain a pretreated substrate;

[0015] S2, electron transport layer: the prepared electron transport layer precursor solution is ultrasonically sprayed onto the pretreated substrate of S1, and annealing treatment is performed, to obtain an electron transport layer;

[0016] S3, perovskite layer: a perovskite layer with a composition of CsPbBr3 is prepared on the electron transport layer by ultrasonic spraying;

[0017] S4, hole transport layer: the hole transport layer precursor solution is ultrasonically sprayed on the perovskite light absorption layer obtained in S3, to obtain a hole transport layer;

[0018] S5, electrode layer: the metal electrode of the top layer is printed on the hole transport layer obtained in S4, to obtain an electrode layer, and the preparation of the perovskite flexible photovoltaic device is completed;

[0019] S6, encapsulation layer of the flexible photovoltaic device: on the basis of the completed flexible photovoltaic device, the encapsulation material is scraped and coated, and curing encapsulation is performed, to complete the flexible and recoverable color-changing thin-film solar cell.

[0020] Preferably, in S3, PbBr2 and CsBr are respectively dissolved in dimethyl sulfoxide, to obtain a PbBr2 precursor solution and a CsBr precursor solution; the PbBr2 precursor solution is ultrasonically sprayed on the electron transport layer, and annealing treatment is performed at 150 DEG C; then the CsBr precursor solution is ultrasonically sprayed on the annealed PbBr2, and annealing treatment is performed at 150 DEG C; the above ultrasonic spraying method is repeated multiple times, to obtain a perovskite light absorption layer.

[0021] Preferably, in S3, cesium bromide CsBr and PbBr2 are dissolved in dimethyl sulfoxide to obtain a CsPbBr3 solution, the CsPbBr3 precursor solution is ultrasonically sprayed on the electron transport layer, and the annealing temperature is 150 DEG C to obtain the perovskite light absorption layer.

[0022] Preferably, in S6, the encapsulation layer (6) is one of ultraviolet curing agent, thermoplastic polyurethane and light curing resin.

[0023] Preferably, in S6, when the encapsulation layer is ultraviolet curing agent, the encapsulation is formed by curing under the irradiation of 365 nm ultraviolet light; when the encapsulation layer is thermoplastic polyurethane, the encapsulation is formed by annealing for 10 min on a 100 DEG C hot stage; when the encapsulation layer is light curing resin, the encapsulation is formed by curing under the irradiation of a visible light source.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The present application uses the perovskite light absorption layer which is full-inorganic perovskite CsPbBr3 with high phase purity and reversible phase change under different humidity and light conditions, overcomes the problem that the light absorption layer of the perovskite solar cell prepared by the solution spin coating method in the prior art has deep color and strong light shielding property, and does not have the problem of single function, so that the full-inorganic perovskite flexible thin film solar cell based on the present application has high energy conversion efficiency and has the recoverable color change function; the encapsulation layer isolates the thin film solar cell from the outside, ensures the appearance gloss of the thin film solar cell, and makes the inside in a vacuum, oxygen-free and water-free environment to prevent the corrosion of water vapor on the thin film solar cell and cause the decrease of energy conversion efficiency, protect the solar cell and enhance the heat conduction performance and the function of flexible protection, and realize the recoverable color change function.

[0026] 2. The preparation method of the full-inorganic perovskite light absorption layer using a flexible substrate overcomes the problem of the limitation of the flexibility and device size of the full-inorganic perovskite thin film substrate material prepared by the solution spraying method in the prior art, so that the flexible recoverable color change thin film solar cell prepared by the method of the present application has the advantages of large-area flexible film as the light absorption layer, high efficiency performance, recoverable color change with environmental change, and can be used in the fields of green building materials, photovoltaic energy storage and smart home, and the application scenarios are expanded. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The structure diagram of the flexible recoverable color change thin film prepared by the present application;

[0028] Explanation of reference signs:

[0029] 1. Substrate, 2. Electron transport layer, 3. Perovskite layer, 4. Hole transport layer, 5. Metal electrode layer, 6. Encapsulation layer;

[0030] Figure 2 The recoverable color-changing film prepared in Example 1 of the present application is subjected to a light color-changing process in a water vapor atmosphere; (1) is a film color-changing graph in a water vapor atmosphere, and (2) is a film recovery graph under simulated low humidity and sunlight irradiation;

[0031] Figure 3 The recoverable color-changing film prepared in Example 1 of the present application is subjected to a temperature color-changing process in a water vapor atmosphere; wherein a is the initial state of the film, b is the film color-changing graph under water vapor, and c is the self-recovery graph under temperature action;

[0032] Figure 4 The photoelectric conversion efficiency graph of the recoverable color-changing film prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] It should be noted that the professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the scope of protection of the present application. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present application can be purchased from the market or prepared by the existing method.

[0035] Example 1

[0036] A flexible recoverable color-changing film solar cell includes a substrate 1, an electron transport layer 2, a perovskite layer 3, a hole transport layer 4, an electrode layer 5 and an encapsulation layer 6. The flexible recoverable color-changing film solar cell is formed by sequentially spraying the electron transport layer 2, the perovskite layer 3, the hole transport layer 4 and the electrode layer 5 on the substrate 1 to form a photovoltaic device, and then encapsulating the photovoltaic device by the encapsulation layer 6.

[0037] The substrate 1 is a polyimide substrate with an indium tin oxide surface, the electron transport layer 2 is tin dioxide, the perovskite layer 3 is a full-inorganic cesium lead bromide perovskite CsPbBr3, the hole transport layer 4 is a 2,2',7,7'-tetra-(dimethoxydiphenylamine)-spirofluorene solution, and the metal electrode is a conductive silver paste.

[0038] The preparation method of the flexible recoverable color-changing thin-film solar cell comprises the following steps:

[0039] S1, substrate 1 pretreatment: the polyimide substrate 1 with an indium tin oxide surface is sequentially placed in deionized water, acetone and alcohol for ultrasonic cleaning, the cleaning temperature of ultrasonic cleaning is 50 DEG C, the time of each ultrasonic cleaning is 20 min, then the polyimide substrate 1 with an indium tin oxide surface cleaned by ultrasonic is treated by UV-Ozone for 20 min, and a pretreated polyimide substrate 1 with an indium tin oxide surface is obtained;

[0040] S2, electron transport layer 2: a 15% concentration tin dioxide aqueous solution is diluted to 5% concentration with deionized water in a volume ratio of 1:2 to obtain a tin dioxide precursor solution, the tin dioxide precursor solution is ultrasonic sprayed on the pretreated polyimide substrate 1 with an indium tin oxide surface in S1, and then annealed on a 150 DEG C hot table for 30 min to obtain an electron transport layer 2;

[0041] S3, perovskite layer 3: 0.2M lead bromide PbBr2 and 0.2M cesium bromide CsBr are respectively dissolved in dimethyl sulfoxide, and heated at 70 DEG C for 2 hours to obtain a lead bromide PbBr2 precursor solution and a cesium bromide CsBr precursor solution; then the PbBr2 precursor solution is ultrasonic sprayed on the electron transport layer 2, annealed on a 150 DEG C hot table for 10 min, then the CsBr precursor solution is ultrasonic sprayed on the annealed lead bromide, annealed on a 150 DEG C hot table for 10 min, and the above-mentioned ultrasonic spraying of the PbBr2 precursor solution and the CsBr precursor solution is repeated four times to obtain a perovskite layer 3;

[0042] S4, hole transport layer 4: 72.5mg of 2,2',7,7'-tetra-(dimethoxydiphenylamine)-spirofluorene is dissolved in 99% concentration 1mL chlorobenzene, and 18μL lithium salt solution, 29μL cobalt salt and 29μL 4-tert-butylpyridine solution are added at a time, and 2,2',7,7'-tetra-(dimethoxydiphenylamine)-spirofluorene precursor solution is prepared by constant temperature stirring at room temperature for 2 hours, the solution is sprayed on the perovskite layer 3 obtained in S3 by using an ultrasonic spraying device to obtain a hole transport layer 4;

[0043] S5, electrode layer 5: the substrate 1 with the hole transport layer 4 obtained in S4 is used for screen printing conductive silver paste to obtain a patterned silver electrode layer 5 through a mask, and the preparation of the perovskite flexible photovoltaic device is completed;

[0044] S6, encapsulation layer 6 of the flexible photovoltaic device: based on the flexible photovoltaic device prepared in S5, ultraviolet curing agent is scraped on the electrode layer 5 by using a scraping device, and curing encapsulation is carried out under the irradiation of ultraviolet light 360nm, and the preparation of the whole perovskite flexible recoverable color-changing thin-film solar cell is completed.

[0045] A structure diagram of the flexible recoverable color-changing thin-film solar cell is shown in FIG. 1, the thickness of the electron transport layer 2 is 50 nm, the thickness of the hole transport layer 4 is 200 nm, and the thickness of the electrode layer 5 is 500 nm-1 μm. Figure 1

[0046] Embodiment 2

[0047] A flexible recoverable color-changing thin-film solar cell, comprising a substrate 1, an electron transport layer 2, a perovskite layer 3, a hole transport layer 4, an electrode layer 5, and an encapsulation layer 6, the flexible recoverable color-changing thin-film solar cell is prepared by sequentially spraying the electron transport layer 2, the perovskite layer 3, the hole transport layer 4, and the electrode layer 5 on the substrate 1 to form a photovoltaic device, and then encapsulating the photovoltaic device by the encapsulation layer 6;

[0048] The substrate 1 is polyethylene naphthalate with an indium tin oxide surface, the electron transport layer 2 is tin dioxide, the perovskite layer 3 is a full-inorganic cesium lead bromide perovskite CsPbBr3, the hole transport layer 4 is poly(3-hexylthiophene), and the electrode is conductive carbon paste.

[0049] The preparation method of the flexible recoverable color-changing thin-film solar cell is the same as that in Embodiment 1, except that:

[0050] S3, the perovskite layer 3: a perovskite precursor solution is prepared, 53.2 mg of cesium bromide CsBr and 73.4 mg of lead bromide PbBr2 are dissolved in 1 mL of dimethyl sulfoxide DMSO, heated and stirred at 75°C until completely dissolved to obtain a CsPbBr3 solution. Then, the CsPbBr3 precursor solution is ultrasonically sprayed on the electron transport layer 2, and then the sample is placed on a hot stage, the annealing temperature is 150°C, and the hot stage annealing time is 10 min. Then the above ultrasonic spraying and annealing operation is repeated twice to obtain the perovskite layer 3;

[0051] S4, the hole transport layer 4: 20 mg of poly(3-hexylthiophene) is dissolved in a chlorobenzene solution, heated and stirred at 70°C until completely dissolved to obtain a poly(3-hexylthiophene) precursor solution, and then the poly(3-hexylthiophene) precursor solution is sprayed on the perovskite layer 3 obtained in S3 to obtain the hole transport layer 4;

[0052] S5, the electrode layer 5: a conductive carbon paste is used to screen print the substrate 1 with the hole transport layer 4 obtained in S4 to obtain a patterned carbon electrode layer 5 through a mask, and the preparation of the flexible recoverable color-changing thin-film solar cell is completed.

[0053] ​S6, encapsulation layer 6 of flexible photovoltaic: after the completion of the flexible photovoltaic in S5, using a doctor blade equipment, doctor blade hot plastic polyurethane on the electrode layer 5, placed on the 100℃ hot table annealing 10min, curing encapsulation, complete the preparation of the whole perovskite flexible recoverable color film solar cell.

[0054] The thickness of the electron transport layer 2 in the flexible recoverable color film solar cell is 80nm, the thickness of the hole transport layer 4 is 200nm, and the thickness of the electrode layer 5 is 500nm-1μm.

[0055] Example 3

[0056] A flexible recoverable color film solar cell, comprising a substrate 1, an electron transport layer 2, a perovskite layer 3, a hole transport layer 4, an electrode layer 5 and an encapsulation layer 6, by spraying on the substrate 1 in turn to prepare the electron transport layer 2, the perovskite layer 3, the hole transport layer 4 and the electrode layer 5 to form a photovoltaic device, and then encapsulating by the encapsulation layer 6 to form a flexible recoverable color film solar cell.

[0057] Wherein, the substrate 1 adopts polyethylene naphthalate substrate with fluorine-doped tin oxide surface, the electron transport layer 2 adopts titanium dioxide, the perovskite layer 3 adopts all-inorganic cesium lead bromide perovskite CsPbBr3, the hole transport layer 4 adopts cuprous thiocyanate, and the electrode adopts conductive carbon paste.

[0058] The preparation method of the above flexible recoverable color film solar cell is the same as that of example 1, and the difference lies in that:

[0059] S2, electron transport layer 2: first prepare zinc oxide precursor solution, dissolve 1g zinc acetate dihydrate and 0.28g ethanolamine in 10mL 2-methoxyethanol to form zinc oxide stock solution, then add 90mL 2-methoxyethanol to the zinc oxide stock solution to obtain the zinc oxide precursor solution; ultrasonic spray the zinc oxide precursor solution on the pretreated polyethylene naphthalate substrate 1 with fluorine-doped tin oxide surface in S1, then anneal on a 150℃ hot table for 30min to obtain the electron transport layer 2;

[0060] S3, perovskite layer 3: dissolve 0.4M lead bromide PbBr2 and 0.2M cesium bromide CsBr in dimethyl sulfoxide DMSO respectively, and heat and stir at 70℃ for 2h to obtain PbBr2 precursor solution and CsBr precursor solution. First, ultrasonic spray the CsBr precursor solution on the electron transport layer 2, and anneal the sample on a 150℃ hot table for 10min, then ultrasonic spray the PbBr2 precursor solution on the annealed CsBr film, and anneal the sample on a 150℃ hot table for 10min. Then, according to the above CsBr-PbBr2-CsBr sequence, repeat the ultrasonic spraying and annealing once to obtain the perovskite layer 3;

[0061] S4, hole transport layer 4: 35 mg of cuprous thiocyanate with 99% concentration was dissolved in 1 mL of diethyl sulfide with 98% concentration, and a cuprous thiocyanate precursor solution was prepared by constant temperature stirring at room temperature for 30 min, the cuprous thiocyanate precursor solution was ultrasonic spray coated on the perovskite layer 3 obtained in S3 to obtain the hole transport layer 4;

[0062] S5, electrode layer 5: using screen printing conductive carbon paste on the substrate 1 of the hole transport layer 4 obtained in S4, a patterned carbon electrode layer 5 was obtained through a mask, and the preparation of the flexible and recoverable color-changing thin film solar cell was completed.

[0063] The thickness of the electron transport layer 2 in the flexible and recoverable color-changing thin film solar cell is 80 nm, the thickness of the hole transport layer 4 is 200 nm, and the thickness of the electrode layer 5 is 500 nm-1 μm.

[0064] As shown in Figure 2 Fig. 1 is a color-changing process diagram of the recoverable color-changing thin film of Example 1 of the present application under water vapor atmosphere, wherein (1) is a diagram of the color change of the thin film under water vapor atmosphere, and (2) is a diagram of the recovery of the thin film under simulated low humidity and sunlight irradiation. Figure 1 In (1), when the humidity of 100% under the simulated process of rain day is simulated, the thin film changes from yellow to white; after the colored thin film is placed under sunlight irradiation, the thin film recovers to yellow as shown in Figure 1 (2).

[0065] Figure 3 Fig. 2 is a temperature color-changing process diagram of the recoverable color-changing thin film of Example 1 of the present application under water vapor atmosphere; wherein a is the initial state of the thin film, b is a diagram of the color change of the thin film under water vapor, and c is a self-recovery diagram under temperature action; when the 100% humidity and temperature act simultaneously, the thin film is mainly affected by water vapor, the yellow color disappears, the perovskite layer becomes transparent and white, and the overall thin film presents a purple color which is the color of the hole transport layer as shown in Figure 3 b, and after the water vapor is removed, the perovskite layer recovers to yellow, and the overall thin film also recovers to yellow.

[0066] Figure 4 Fig. 3 is a current-voltage curve diagram of the recoverable color-changing thin film prepared in Example 1 of the present application, as shown in Figure 4 Fig. 3, the energy conversion efficiency (PCE) of the thin film solar cell is 6.77% without water vapor action, the energy conversion efficiency of the thin film solar cell is 3.08% under water vapor atmosphere, and the energy conversion efficiency of the thin film solar cell is 6.03% after the self-recovery process under a certain temperature after the water vapor is removed.

[0067] It is to be understood that every range of values disclosed herein is to be understood to encompass any and every sub-range of values within the range. Although the preferred embodiments of the invention have been described above, it will be appreciated that those skilled in the art, on consideration of this disclosure, will be able to devise additional embodiments that, although not explicitly described or shown herein, nonetheless fall within the scope of the present invention. Accordingly, the appended claims are intended to include within their scope all such alternatives, modifications and variations as fall within the scope of the present invention. Various features and aspects of the present invention will become apparent from the following examples, which are intended only to exemplify the invention. It should be understood, of course, that in the various examples of the present invention, the specific phrasing of the claims will depend on the exact nature of the claims sought.

[0068] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the present application can be practiced otherwise than as specifically described herein.

Claims

1. A flexible, recoverable, color-changing thin-film solar cell, characterized by, The flexible recoverable color-changing thin film solar cell comprises a flexible substrate (1), an electron transport layer (2), a perovskite layer (3), a hole transport layer (4), an electrode layer (5) and an encapsulation layer (6), the electron transport layer (2), the perovskite layer (3), the hole transport layer (4) and the electrode layer (5) are sequentially ultrasonic sprayed on the flexible substrate (1), then the electrode layer (5) is solidified and encapsulated to form the encapsulation layer (6), namely the flexible recoverable color-changing thin film solar cell is prepared. The perovskite layer (3) is a CsPbBr3 thin film layer. The preparation method of the perovskite layer (3) comprises the following steps: PbBr2 and CsBr are respectively dissolved in dimethyl sulfoxide to obtain PbBr2 precursor solution and CsBr precursor solution; the PbBr2 precursor solution is ultrasonic sprayed on the electron transport layer (2) and is subjected to heat annealing treatment at 150 DEG C, then the CsBr precursor solution is ultrasonic sprayed on the annealed PbBr2 and is subjected to heat annealing treatment at 150 DEG C, the above-mentioned ultrasonic spraying mode is repeated four times to obtain the perovskite light absorption layer (3); or CsBr and PbBr2 are dissolved in dimethyl sulfoxide to obtain CsPbBr3 solution, the CsPbBr3 precursor solution is ultrasonic sprayed on the electron transport layer (2), and the annealing temperature is 150 DEG C to obtain the perovskite light absorption layer (3).

2. The flexible restorable color-changing thin-film solar cell of claim 1, wherein, The flexible substrate (1) is one of indium tin oxide, fluorine-doped tin oxide surface polyimide, polyethylene terephthalate and polyethylene naphthalate.

3. The flexible restorable color-changing thin-film solar cell of claim 1, wherein, The electron transport layer (2) is one of titanium dioxide solution and tin dioxide solution.

4. The flexible recoverable color-changing thin film solar cell according to claim 1, wherein The hole transport layer (4) is one of triphenylamine derivative solution, 2,2',7,7'-tetra-(dimethoxydiphenylamine)-spirofluorene, poly (3-hexylthiophene), cuprous thiocyanate and nickel oxide solution.

5. The flexible recoverable color-changing thin film solar cell according to claim 1, wherein The electrode layer (5) adopts conductive silver paste or conductive carbon paste.

6. A method of making the flexible restorable color-changing thin film solar cell of any one of claims 1-5, wherein, The following steps are performed: S1, substrate (1) pretreatment: the substrate (1) is respectively ultrasonic cleaned in deionized water, acetone and alcohol, and then is pretreated in ultraviolet ozone to obtain the pretreated substrate; S2, electron transport layer (2): the prepared electron transport layer precursor solution is ultrasonic sprayed on the pretreated substrate (1) of S1 to obtain the electron transport layer (2) after annealing; S3, perovskite layer (3): the perovskite layer (3) with CsPbBr3 composition is prepared on the electron transport layer (2) by ultrasonic spraying; S4, hole transport layer (4): the hole transport layer precursor solution is ultrasonic sprayed on the perovskite light absorption layer (3) obtained in S3 to obtain the hole transport layer (4); S5, electrode layer (5): the electrode layer (5) is obtained by printing the top electrode on the hole transport layer (4) obtained in S4, and the preparation of the perovskite flexible photovoltaic device is completed. S6, encapsulation layer (6) of flexible photovoltaic: after the completion of the flexible photovoltaic, the encapsulation material is scraped and coated, and the encapsulation is cured to complete the flexible and recoverable color-changing thin film solar cell.

7. The method for preparing a flexible, recoverable color-changing thin-film solar cell according to claim 6, characterized in that, In S6, the encapsulation layer (6) is one of ultraviolet curing agent, thermoplastic polyurethane and light curing resin.

8. The method for preparing a flexible, recoverable color-changing thin-film solar cell according to claim 7, characterized in that, When the encapsulation layer (6) is the ultraviolet curing agent, the encapsulation is formed by curing under the irradiation of 365 nm ultraviolet light; when the encapsulation layer (6) is the thermoplastic polyurethane, the encapsulation is formed by curing by annealing for 10 min on a 100℃ hot stage; when the encapsulation layer (6) is the light curing resin, the encapsulation is formed by curing under the irradiation of a visible light source.

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