Inorganic perovskite solar cell and preparation method thereof

Abstract

The present invention discloses an inorganic perovskite solar cell, comprising: a substrate; an electron transport layer, arranged on the substrate; an inorganic perovskite light-absorbing layer, arranged on the electron transport layer, configured to absorb sunlight and generate pairs of electrons and holes, wherein the electrons are transported to the substrate via the electron transport layer; a surface reconstruction layer, arranged on the inorganic perovskite light-absorbing layer, configured to dope fluoride ions into the inorganic perovskite light-absorbing layer, wherein the fluoride ions form strong chemical bonds with lead elements in the inorganic perovskite light-absorbing layer to passivate interstitial defects and halide vacancy defects of the lead and inhibit non-radiative recombination within the inorganic perovskite light-absorbing layer; a hole transport layer, arranged on the surface reconstruction layer; and a metal electrode, arranged on the hole transport layer; the hole transport layer is configured to receive holes generated by the inorganic perovskite light-absorbing layer and transport the holes to the metal electrode, which receives the holes and recombine with electrons from the substrate to form a conductive loop.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the technical field of perovskite solar cells, and in particular to an inorganic perovskite solar cell and a preparation method thereof. Background Art

[0002] By replacing the organic components in organic-inorganic hybrid perovskite materials with Cs, the inorganic halide perovskite material CsPbX3 (X = I, Br, Cl) can fundamentally prevent the volatilization or decomposition of organic components at high temperatures, thereby fundamentally solving the operational stability issues of perovskite solar cells under high temperature and light conditions. Inorganic halide perovskite materials have a wide and easily adjustable band gap (1.68 to 2.3 eV), making them ideal for constructing stacked solar cells with narrow-bandgap photovoltaic materials such as silicon. In recent years, through methods such as crystal quality optimization and defect suppression, inorganic perovskite solar cells have achieved rapid development, with photoelectric conversion efficiency gradually exceeding 20%.

[0003] However, existing inorganic perovskite solar cells, on the one hand, suffer from the rapid crystallization and small grain size of inorganic perovskite materials, which generate a high density of defects on the surface and within the material, leading to severe non-radiative recombination and a generally low carrier lifetime, for example, generally less than 50ns, which is still very short compared to the microsecond carrier lifetime of organic-inorganic hybrid perovskite materials, resulting in large device turn-on voltage losses. On the other hand, the large energy band step between the inorganic perovskite material and the charge transport layer causes interfacial recombination of photogenerated carriers, resulting in energy loss. As a result, their performance lags significantly behind that of organic-inorganic hybrid perovskite solar cells. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides an inorganic perovskite solar cell, which improves the open circuit voltage and photoelectric conversion efficiency of the inorganic perovskite solar cell by providing a surface reconstruction layer on the inorganic perovskite light absorption layer, wherein the surface reconstruction layer is configured to dope fluoride ions in the inorganic perovskite light absorption layer.

[0005] According to an embodiment of the present invention, an inorganic perovskite solar cell is provided, comprising: a substrate made of a transparent conductive material; an electron transport layer disposed on the substrate; an inorganic perovskite light absorption layer disposed on the electron transport layer, configured to absorb sunlight and generate paired electrons and holes, wherein the electrons are transmitted to the substrate via the electron transport layer; a surface reconstruction layer disposed on the inorganic perovskite light absorption layer, wherein the surface reconstruction layer is configured to dope fluoride ions in the inorganic perovskite light absorption layer, and the fluoride ions form a reinforcing element with the lead element in the inorganic perovskite light absorption layer. The surface reconstruction layer is provided on the inorganic perovskite light absorbing layer, and the surface reconstruction layer is provided on the inorganic perovskite light absorbing layer. ...

[0006] According to an embodiment of the present invention, the material of the inorganic perovskite light absorbing layer is CsPbIxBr3-x, and the thickness of the inorganic perovskite light absorbing layer is 400-800 nm, wherein 0<x<3.

[0007] According to an embodiment of the present invention, the surface reconstruction layer is made of CsPbIzBr3-z, and the thickness of the surface reconstruction layer is 5-20 nm, wherein 0<z<x.

[0008] According to an embodiment of the present invention, the substrate is transparent conductive glass; and / or the material of the electron transport layer is SnO2, and the thickness of the electron transport layer is 20-100 nm; and / or the material of the hole transport layer is 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene, and the thickness of the hole transport layer is 100-300 nm; and / or the material of the metal electrode is gold, and the thickness of the metal electrode is 50-150 nm.

[0009] According to an embodiment of the present invention, a method for preparing an inorganic perovskite solar cell is also provided, comprising: spin coating a SnO2 solution on a substrate to prepare an electron transport layer; spin coating a precursor solution on the electron transport layer to prepare an inorganic perovskite light absorbing layer; spin coating a cesium fluoride solution on the inorganic perovskite light absorbing layer to prepare a surface reconstruction layer; preparing a hole transport layer on the surface reconstruction layer; and preparing a metal electrode on the hole transport layer by vacuum thermal evaporation.

[0010] According to an embodiment of the present invention, the method of spin-coating a SnO2 solution on a substrate to prepare an electron transport layer includes: spinning an aqueous solution of SnO2 nanocolloids on a substrate at a rotation speed of 3000r / min-5000r / min to form a SnO2 thin film on the substrate; and annealing the SnO2 thin film formed on the substrate in air at 150°C-180°C for 20min-30min.

[0011] According to an embodiment of the present invention, the preparation of the inorganic perovskite light-absorbing layer by spin-coating a precursor liquid on the electron transport layer comprises: in an inert gas environment with a water and oxygen content of less than 0.1 ppm, spinning a precursor liquid composed of cesium iodide, lead iodide, lead bromide, and dimethylammonium iodide in a molar ratio of 1:y:(1-y):1 on the electron transport layer at a speed of 2000 r / min to form an inorganic perovskite precursor film on the electron transport layer, wherein 0<y<1 and the concentration of cesium iodide is 0.8 mol / L-1.2 mol / L; allowing the inorganic perovskite precursor film to stand for 20 min-30 min in an inert gas environment with a water and oxygen content of less than 0.1 ppm; and annealing the inorganic perovskite precursor film after standing in air at 160°C-180°C for 5 min-15 min, and the annealing environment humidity is less than 20% RH.

[0012] According to an embodiment of the present invention, the preparation of a surface reconstruction layer by spin-coating a cesium fluoride solution on the inorganic perovskite light-absorbing layer includes: rotating the substrate having the electron transport layer and the inorganic perovskite light-absorbing layer at a rotation speed of 3000r / min-6000r / min, dripping a cesium fluoride solution on the inorganic perovskite light-absorbing layer to spin-coat the cesium fluoride solution on the inorganic perovskite light-absorbing layer, and annealing at 90°C-110°C for 10min-30min in an inert gas environment with a water and oxygen content of less than 0.1ppm.

[0013] According to an embodiment of the present invention, the cesium fluoride solution is prepared by dissolving cesium fluoride in an isopropyl alcohol solvent, and the concentration of the cesium fluoride solution is 0.01 mol / L-0.06 mol / L.

[0014] According to an embodiment of the present invention, the preparation of the hole transport layer on the surface reconstruction layer includes: spin-coating a 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene solution whose solvent is chlorobenzene on the surface reconstruction layer; and / or, the preparation of the metal electrode on the hole transport layer by vacuum thermal evaporation includes: evaporating gold on the hole transport layer by vacuum thermal evaporation.

[0015] According to the inorganic perovskite solar cell of the above embodiment of the present invention, a surface reconstruction layer is provided on the inorganic perovskite light-absorbing layer, and the surface reconstruction layer is configured to dope fluoride ions in the inorganic perovskite light-absorbing layer. Fluoride ions form strong chemical bonds with the lead element in the inorganic perovskite light-absorbing layer to passivate the interstitial defects and halide vacancy defects of the lead, thereby passivating the sensitivity of the chemical reactivity of the inorganic perovskite light-absorbing layer and suppressing non-radiative recombination within the inorganic perovskite light-absorbing layer. The carrier lifetime is improved, and the surface reconstruction layer can increase the band gap width of the inorganic perovskite light-absorbing layer, reduce the recombination of interfacial charges, promote the extraction of photogenerated carriers, and improve the open circuit voltage and photoelectric conversion efficiency of the inorganic perovskite solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a partial cross-sectional schematic diagram of the inorganic perovskite solar cell of the present invention;

[0017] Figure 2 It is a schematic flow chart of the method for preparing an inorganic perovskite solar cell of the present invention;

[0018] Figure 3 is the time-resolved photoluminescence spectrum of the inorganic perovskite light-absorbing layer with and without the surface reconstruction layer;

[0019] Figure 4 is the photoluminescence spectrum of the inorganic perovskite light absorbing layer with and without the surface reconstruction layer;

[0020] Figure 5 X-ray photoelectron spectra at different depths of the inorganic perovskite light absorbing layer with and without a surface reconstruction layer; and

[0021] Figure 6 The current-voltage curves of inorganic perovskite solar cells with and without a surface reconstruction layer.

[0022] In the picture:

[0023] 1-substrate;

[0024] 2-Electron transport layer;

[0025] 3-inorganic perovskite light absorbing layer;

[0026] 4- surface reconstruction layer;

[0027] 5-hole transport layer;

[0028] 6-Metal electrodes. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0030] According to the inventive concept of one aspect of the present invention, an inorganic perovskite solar cell is provided, comprising: a substrate made of a transparent conductive material; an electron transport layer disposed on the substrate; an inorganic perovskite light-absorbing layer disposed on the electron transport layer, configured to absorb sunlight and generate pairs of electrons and holes, the electrons being transported to the substrate via the electron transport layer; a surface reconstruction layer disposed on the inorganic perovskite light-absorbing layer, the surface reconstruction layer being configured to dope fluoride ions in the inorganic perovskite light-absorbing layer, the fluoride ions forming strong chemical bonds with the lead element in the inorganic perovskite light-absorbing layer to passivate the interstitial defects and halide vacancy defects of the lead, thereby passivating the sensitivity of the chemical reactivity of the inorganic perovskite light-absorbing layer and suppressing non-radiative recombination within the inorganic perovskite light-absorbing layer; a hole transport layer disposed on the surface reconstruction layer; and a metal electrode disposed on the hole transport layer; wherein the hole transport layer is configured to receive holes generated by the inorganic perovskite light-absorbing layer and transport the holes to the metal electrode, the metal electrode receives the holes and recombine with electrons from the substrate to form a conductive circuit.

[0031] Figure 1 It is a partial cross-sectional schematic diagram of the inorganic perovskite solar cell of the present invention.

[0032] According to an exemplary embodiment of the present invention, please refer to Figure 1 , provides an inorganic perovskite solar cell, comprising a substrate 1, an electron transport layer 2, an inorganic perovskite light absorbing layer 3, a surface reconstruction layer 4, a hole transport layer 5, and a metal electrode 6. The substrate 1 is made of a transparent conductive material. The electron transport layer 2 is disposed on the substrate 1. The inorganic perovskite light absorbing layer 3 is disposed on the electron transport layer 2 and is configured to absorb sunlight and generate paired electrons and holes, and the electrons are transported to the substrate 1 via the electron transport layer 2. The surface reconstruction layer 4 is disposed on the inorganic perovskite light absorbing layer 3, and is configured to dope fluoride ions in the inorganic perovskite light absorbing layer 3. The fluoride ions form strong chemical bonds with the lead element in the inorganic perovskite light absorbing layer 3 to passivate the interstitial defects and halide vacancy defects of the lead, thereby passivating the sensitivity of the chemical reactivity of the inorganic perovskite light absorbing layer 3 and suppressing non-radiative recombination within the inorganic perovskite light absorbing layer 3. The hole transport layer 5 is disposed on the surface reconstruction layer 4. The metal electrode 6 is disposed on the hole transport layer 5. The hole transport layer 5 is configured to receive holes generated by the inorganic perovskite light absorbing layer 3 and transport the holes to the metal electrode 6 . The metal electrode 6 receives the holes and recombines them with electrons from the substrate 1 to form a conductive loop.

[0033] In this embodiment, a surface reconstruction layer 4 is provided on the inorganic perovskite light absorbing layer 3, and the surface reconstruction layer 4 is configured to dope fluoride ions into the inorganic perovskite light absorbing layer 3. The fluoride ions form strong chemical bonds with the lead element in the inorganic perovskite light absorbing layer 3 to passivate the interstitial defects and halide vacancy defects of the lead, thereby passivating the sensitivity of the chemical reactivity of the inorganic perovskite light absorbing layer 3 and suppressing non-radiative recombination within the inorganic perovskite light absorbing layer 3. This improves the carrier lifetime, and the surface reconstruction layer 4 can increase the band gap width of the inorganic perovskite light absorbing layer 3 to reduce the recombination of interfacial charges, promote the extraction of photogenerated carriers, and improve the open circuit voltage and photoelectric conversion efficiency of the inorganic perovskite solar cell.

[0034] It should be noted that, in this embodiment, the electron transport layer 2 is made of SnO 2 . The substrate 1 is made of transparent conductive glass, preferably ITO or FTO conductive glass. The substrate 1 also serves as a support.

[0035] In some exemplary embodiments, the material of the inorganic perovskite light absorbing layer 3 is CsPbI x Br 3-x The thickness of the inorganic perovskite light absorbing layer 3 is 400-800 nm, wherein 0<x<3. The material of the inorganic perovskite light absorbing layer 3 is preferably CsPbI 2.7 Br 0.3 .

[0036] In some exemplary embodiments, the material of the surface reconstruction layer 4 is CsPbI z Br 3-z The thickness of the surface reconstruction layer 4 is 5-20 nm, wherein 0<z<x. The material of the surface reconstruction layer 4 is preferably CsPbI 1.6 Br 1.4 The surface reconstruction layer 4 can passivate the interstitial defects and halide vacancy defects of lead, thereby passivating the sensitivity of the chemical reactivity of the inorganic perovskite light absorbing layer 3 and forming a gradient heterojunction for carrier extraction.

[0037] In some exemplary embodiments, the substrate 1 is transparent conductive glass.

[0038] The material of the electron transport layer 2 is SnO 2 , and the thickness of the electron transport layer 2 is 20-100 nm.

[0039] The hole transport layer 5 is made of 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD), and has a thickness of 100-300 nm.

[0040] The material of the metal electrode 6 is gold, and the thickness of the metal electrode 6 is 50-150 nm.

[0041] It should be noted that in this embodiment, the thickness limits of the electron transport layer 2, the inorganic perovskite light absorbing layer 3, the surface reconstruction layer 4, the hole transport layer 5, and the metal electrode 6 are set forth above to achieve higher light transmittance and absorptivity, thereby improving the performance of the inorganic perovskite solar cell. Furthermore, the materials of the substrate 1, the electron transport layer 2, the hole transport layer 5, and the metal electrode 6 listed in this embodiment are not limited to the materials listed, and other commonly used materials can be flexibly selected as needed; among them, the inorganic perovskite light absorbing layer 3 and the surface reconstruction layer 4 can be adjusted in composition as needed.

[0042] Figure 2 It is a schematic flow chart of the preparation method of the inorganic perovskite solar cell of the present invention.

[0043] According to an exemplary embodiment of the present invention, please refer to Figure 1-Figure 2 , provides a method for preparing an inorganic perovskite solar cell, comprising:

[0044] S01: Spin-coating SnO2 solution on substrate 1 to prepare electron transport layer 2;

[0045] S02: spin coating a precursor solution on the electron transport layer 2 to prepare an inorganic perovskite light absorbing layer 3;

[0046] S03: Spin-coating a cesium fluoride solution on the inorganic perovskite light-absorbing layer 3 to prepare a surface reconstruction layer 4;

[0047] S04: preparing a hole transport layer 5 on the surface reconstruction layer 4; and

[0048] S05: preparing a metal electrode 6 on the hole transport layer 5 by using a vacuum thermal evaporation method.

[0049] In some exemplary embodiments, spin coating a SnO2 solution on the substrate 1 to prepare the electron transport layer 2 includes spin coating an aqueous solution of SnO2 nanocolloids on the substrate 1 at a rotation speed of 3000 rpm to 5000 rpm to form a SnO2 thin film on the substrate 1. The SnO2 thin film formed on the substrate 1 is annealed in air at 150° C. to 180° C. for 20 min to 30 min.

[0050] It should be noted that in this embodiment, the substrate 1 needs to be ultrasonically cleaned before use. Specifically, the substrate 1 is ultrasonically cleaned with detergent, deionized water, acetone, and isopropyl alcohol (IPA) for 20 minutes each. After the cleaned substrate 1 is dried with an N2 gun, its surface is subjected to UV-ozone treatment for 10-20 minutes.

[0051] In some exemplary embodiments, spin coating a precursor solution on the electron transport layer 2 to prepare the inorganic perovskite light absorbing layer 3 includes spin coating a precursor solution composed of cesium iodide, lead iodide, lead bromide, and dimethylammonium iodide in a molar ratio of 1:y:(1-y):1 on the electron transport layer 2 at a speed of 2000 rpm in an inert gas environment with a water and oxygen content of less than 0.1 ppm, thereby forming an inorganic perovskite precursor film on the electron transport layer 2, wherein 0 < y < 1 and the concentration of cesium iodide is 0.8 mol / L-1.2 mol / L. The inorganic perovskite precursor film is allowed to stand for 20 minutes to 30 minutes in the inert gas environment with a water and oxygen content of less than 0.1 ppm. The inorganic perovskite precursor film is annealed in air at 160° C. to 180° C. for 5 minutes to 15 minutes, and the annealing environment humidity is less than 20% RH. The inorganic perovskite precursor film, after standing, is annealed in air at 160°C-180°C for 10 minutes. The precursor solution is preferably composed of a mixture of cesium iodide, lead iodide, lead bromide, and dimethylammonium iodide in a molar ratio of 1:0.5:0.5:1. The organic solvent of the precursor solution includes N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The concentration of cesium iodide is preferably 1.0 mol / L.

[0052] In some exemplary embodiments, spin-coating a cesium fluoride solution on the inorganic perovskite light-absorbing layer 3 to prepare the surface reconstruction layer 4 includes rotating the substrate 1 having the electron transport layer 2 and the inorganic perovskite light-absorbing layer 3 at a rotation speed of 3000 rpm to 6000 rpm, dropwise adding the cesium fluoride solution onto the inorganic perovskite light-absorbing layer 3 to spin-coat the cesium fluoride solution on the inorganic perovskite light-absorbing layer 3, and annealing the cesium fluoride solution at 90° C. to 110° C. for 10 min to 30 min in an inert gas environment with a water and oxygen content of less than 0.1 ppm. The annealing process is performed in an inert gas glove box with a water and oxygen content of less than 0.1 ppm.

[0053] In some exemplary embodiments, the cesium fluoride solution is prepared by dissolving cesium fluoride in isopropyl alcohol, and the concentration of the cesium fluoride solution is 0.01 mol / L-0.06 mol / L, wherein the concentration of the cesium fluoride solution is preferably 0.04 mol / L (6 mg / mL).

[0054] In some exemplary embodiments, preparing the hole transport layer 5 on the surface reconstruction layer 4 includes spin-coating a 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-oMeTAD) solution in chlorobenzene as a solvent on the surface reconstruction layer 4 .

[0055] The method of preparing the metal electrode 6 on the hole transport layer 5 by using the vacuum thermal evaporation method includes evaporating gold on the hole transport layer 5 by using the vacuum thermal evaporation method.

[0056] Figure 3 The time-resolved photoluminescence (TRPL) spectra of the inorganic perovskite light-absorbing layer with and without the surface reconstruction layer are shown.

[0057] like Figure 3 As shown in the figure, the average carrier lifetime of the inorganic perovskite light absorption layer 3 without the surface reconstruction layer 4 is 12ns, and the average carrier lifetime of the inorganic perovskite light absorption layer 3 with the surface reconstruction layer 4 is 737ns. This shows that setting the surface reconstruction layer 4 on the inorganic perovskite light absorption layer 3 can greatly improve the average carrier lifetime of the inorganic perovskite light absorption layer 3 and significantly inhibit the non-radiative recombination in the inorganic perovskite light absorption layer 3.

[0058] Figure 4 The photoluminescence (PL) spectra of the inorganic perovskite light-absorbing layer with and without the surface reconstruction layer.

[0059] like Figure 4 As shown, the inorganic perovskite light-absorbing layer 3 provided with the surface reconstruction layer 4 has a side peak at a short-wave position near 645 nm in addition to the main PL peak at 710 nm.

[0060] Figure 5 The X-ray photoelectron spectra (XPS) at different depths of the inorganic perovskite light-absorbing layer with and without the surface reconstruction layer are shown.

[0061] Among them, the intensity of the XPS peak can represent the relative content of the element, such as Figure 5 As shown, in the inorganic perovskite light-absorbing layer 3 provided with the surface reconstruction layer 4, the content of the Br component in the surface layer is increased relative to that in the interior of the material, and the content of the I component in the surface layer is decreased relative to that in the interior of the material.

[0062] Therefore, refer to Figure 4 and Figure 5 , which together indicate that the surface reconstruction layer 4 disposed on the inorganic perovskite light-absorbing layer 3 has a wider band gap and contains more Br components.

[0063] Figure 6 The current-voltage curves of inorganic perovskite solar cells with and without a surface reconstruction layer.

[0064] like Figure 6 As shown, the inorganic perovskite solar cell provided with the surface reconstruction layer 4 has an open circuit voltage increased to 1.27 V and a photoelectric conversion efficiency increased to 21.02%. This shows that providing the surface reconstruction layer 4 on the inorganic perovskite light-absorbing layer 3 can significantly improve the performance of the inorganic perovskite solar cell.

[0065] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An inorganic perovskite solar cell, comprising: A substrate (1) made of a transparent conductive material; An electron transport layer (2) is provided on the substrate (1); The inorganic perovskite light absorbing layer (3) is arranged on the electron transport layer (2) and is configured to absorb sunlight and generate paired electrons and holes, wherein the electrons are transported to the substrate (1) via the electron transport layer (2). The material of the inorganic perovskite light absorbing layer (3) is CsPbI x Br 3-x , where 0<x<3; A surface reconstruction layer (4) is provided on the inorganic perovskite light absorbing layer (3). The surface reconstruction layer is prepared by spin-coating a cesium fluoride solution on the inorganic perovskite light absorbing layer. Fluoride ions form a strong chemical bond with the lead element in the inorganic perovskite light absorbing layer (3) to passivate the interstitial defects and halide vacancy defects of the lead, thereby passivating the sensitivity of the chemical reactivity of the inorganic perovskite light absorbing layer (3), inhibiting the non-radiative recombination inside the inorganic perovskite light absorbing layer (3), and forming a gradient heterojunction for carrier extraction. The material of the surface reconstruction layer is CsPbI z Br 3-z , where 0<z<x; a hole transport layer (5) disposed on the surface reconstruction layer (4); and A metal electrode (6) is disposed on the hole transport layer (5); The hole transport layer (5) is configured to receive the holes generated by the inorganic perovskite light absorbing layer (3) and transport the holes to the metal electrode (6); the metal electrode (6) receives the holes and recombines with the electrons from the substrate (1) to form a conductive loop.

2. The inorganic perovskite solar cell according to claim 1, wherein The thickness of the inorganic perovskite light-absorbing layer (3) is 400-800 nm.

3. The inorganic perovskite solar cell according to claim 2, wherein: The thickness of the surface reconstruction layer (4) is 5-20 nm.

4. The inorganic perovskite solar cell according to claim 1, wherein The substrate (1) is transparent conductive glass; and / or, The material of the electron transport layer (2) is SnO2, and the thickness of the electron transport layer (2) is 20-100 nm; and / or, The hole transport layer (5) is made of 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene, and has a thickness of 100-300 nm; and / or, The material of the metal electrode (6) is gold, and the thickness of the metal electrode (6) is 50-150 nm.

5. A method for preparing an inorganic perovskite solar cell, comprising: Spin coating a SnO2 solution on a substrate (1) to prepare an electron transport layer (2); The inorganic perovskite light absorbing layer (3) is prepared by spin coating a precursor liquid on the electron transport layer (2), wherein the material of the inorganic perovskite light absorbing layer (3) is CsPbI x Br 3-x , where 0<x<3; A surface reconstruction layer (4) is prepared by spin-coating a cesium fluoride solution on the inorganic perovskite light-absorbing layer (3). The surface reconstruction layer passivates the interstitial defects and halide vacancy defects of lead, thereby passivating the sensitivity of the chemical reactivity of the inorganic perovskite light-absorbing layer and forming a gradient heterojunction for carrier extraction. The material of the surface reconstruction layer is CsPbI z Br 3-z , where 0<z<x; preparing a hole transport layer (5) on the surface reconstruction layer (4); and A metal electrode (6) is prepared on the hole transport layer (5) by using a vacuum thermal evaporation method.

6. The method for preparing an inorganic perovskite solar cell according to claim 5, wherein: The method of spin coating a SnO2 solution on a substrate (1) to prepare an electron transport layer (2) comprises: Spinning an aqueous solution of SnO2 nano-colloid on a substrate (1) at a rotation speed of 3000 r / min-5000 r / min to form a SnO2 thin film on the substrate (1); and The SnO2 film formed on the substrate (1) is annealed in air at 150° C.-180° C. for 20 min-30 min.

7. The method for preparing an inorganic perovskite solar cell according to claim 5, wherein: The method of spin coating a precursor liquid on the electron transport layer (2) to prepare the inorganic perovskite light absorbing layer (3) comprises: In an inert gas environment with a water and oxygen content of less than 0.1 ppm, a precursor solution composed of cesium iodide, lead iodide, lead bromide, and dimethylammonium iodide mixed in a molar ratio of 1:y:(1-y):1 is applied on the electron transport layer (2) at a rotation speed of 2000 r / min to form an inorganic perovskite precursor film on the electron transport layer (2), wherein 0<y<1 and the concentration of cesium iodide is 0.8 mol / L-1.2 mol / L; placing the inorganic perovskite precursor film in an inert gas environment with a water and oxygen content of less than 0.1 ppm for 20 min to 30 min; and The inorganic perovskite precursor film after standing is annealed in air at 160° C.-180° C. for 5 min-15 min, and the annealing environment humidity is lower than 20% RH.

8. The method for preparing an inorganic perovskite solar cell according to claim 5, wherein: The method of preparing a surface reconstruction layer (4) by spin-coating a cesium fluoride solution on the inorganic perovskite light-absorbing layer (3) comprises: The substrate (1) having the electron transport layer (2) and the inorganic perovskite light absorbing layer (3) is rotated at a rotation speed of 3000 r / min-6000 r / min, a cesium fluoride solution is dripped onto the inorganic perovskite light absorbing layer (3), so that the cesium fluoride solution is spin-coated on the inorganic perovskite light absorbing layer (3), and annealed at 90° C.-110° C. for 10 min-30 min in an inert gas environment with a water and oxygen content of less than 0.1 ppm.

9. The method for preparing an inorganic perovskite solar cell according to claim 8, wherein: The cesium fluoride solution is prepared by dissolving cesium fluoride in an isopropyl alcohol solvent, and the concentration of the cesium fluoride solution is 0.01 mol / L-0.06 mol / L.

10. The method for preparing an inorganic perovskite solar cell according to claim 5, wherein: The method of preparing a hole transport layer (5) on the surface reconstruction layer (4) comprises: Spin-coating a solution of 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene in which chlorobenzene is the solvent on the surface reconstruction layer (4); and / or, The method of preparing the metal electrode (6) on the hole transport layer (5) by using a vacuum thermal evaporation method comprises: Gold is evaporated on the hole transport layer (5) using a vacuum thermal evaporation method.

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