Electron transport layer, perovskite solar cell and preparation method thereof

Abstract

The invention relates to an electron transport layer, a perovskite solar cell and a preparation method thereof. The electron transport layer comprises carbon-coated tin oxide nanoparticles. The electron transport layer provided by the invention comprises carbon-coated tin oxide nanoparticles, and a carbon shell layer is constructed on the surface of tin oxide to obtain a carbon-coated tin oxide material, so that on one hand, the surface defects of tin oxide can be effectively inhibited, and the conductivity of the tin oxide material is improved; and on the other hand, the carbon-coated tin oxide material can effectively inhibit the photocatalytic performance of tin oxide, so that the degradation reaction at the bottom of the perovskite is prevented, and compared with a pure tin oxide material serving as the electron transport layer, the ultraviolet stability of the perovskite solar cell can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to an electron transport layer, a perovskite solar cell and a preparation method thereof. Background Art

[0002] Organic-inorganic hybrid perovskite solar cells have attracted extensive attention in the academic and industrial fields due to many advantages such as adjustable bandgap and low cost. At present, the highest power conversion efficiency of single-junction perovskite solar cells has exceeded 26%, showing excellent commercialization prospects. In addition to the power conversion efficiency, the stability of perovskite solar cells is also crucial and is the entry threshold for their commercialization process. Traditional perovskite solar cells mainly have three structures, namely, mesoporous structure, planar heterojunction structure, and inverted structure. Regardless of which structure, they usually consist of an electron transport layer (ETL), a perovskite light absorption layer, a hole transport layer (HTL), electrode materials, etc. Currently, the mainstream electron transport layers include titanium dioxide, tin dioxide, C60 derivatives, etc.

[0003] In existing perovskite solar cells, inorganic materials such as tin oxide and NiO x etc. are often used as electron / hole transport layers. However, existing research shows that such inorganic materials have a photocatalytic effect themselves. Especially under ultraviolet light illumination, bottom interface materials such as tin oxide will cause degradation at the bottom of the perovskite, thereby causing performance degradation of the component.

[0004] The prior art CN116615076A discloses a method for improving the ultraviolet stability of perovskite solar cells, which prepares a 4,4'-oxydibenzoic acid (OBBA) ultraviolet isolation layer with a certain thickness between the titanium dioxide electron transport layer and the perovskite light absorption layer of the perovskite solar cell. While filtering ultraviolet rays through the OBBA ultraviolet isolation layer, the photocatalysis of titanium dioxide on the perovskite solar cell is reduced, thereby improving its ultraviolet stability. However, the thickness of the isolation layer in this method needs to be strictly controlled. Insufficient conductivity of the OBBA layer or poor energy level matching with the perovskite layer and the electron transport layer may lead to an increase in carrier recombination and a reduction in the efficiency of the battery.

[0005] The prior art CN112687805A discloses a perovskite solar cell electron transport layer and a preparation method thereof. It uses rutile-phase titanium dioxide quantum dots as the electron transport material, which has basically no photocatalytic activity, can eliminate the decomposition effect of the perovskite layer induced by ultraviolet light irradiation in the electron transport layer, and greatly improve the long-term stability of the perovskite light absorption layer; at the same time, it has excellent photogenerated electron extraction and transport performance. It also discloses a preparation method of a perovskite solar cell electron transport layer, which uses two-dimensional thin-layer Ti3C2 as a raw material, prepares rutile-phase titanium dioxide quantum dots through ball milling, oxidation decomposition and ultrasonic refinement, and finally constructs the perovskite solar cell electron transport layer with rutile-phase titanium dioxide quantum dots. However, its preparation method is relatively complex and the raw material cost is relatively high.

[0006] Therefore, how to inhibit the photocatalytic performance of tin oxide and provide an ultraviolet-stable electron transport layer and a preparation method thereof to improve the ultraviolet stability of perovskite solar cells has become an urgent problem to be solved at present. Summary of the Invention

[0007] To solve the above technical problems, the purpose of the present invention is to provide an electron transport layer, a preparation method thereof and a perovskite solar cell. The electron transport layer provided by the present invention includes carbon-coated tin oxide nanoparticles, which can effectively improve the ultraviolet stability of perovskite solar cells.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides an electron transport layer, and the electron transport layer includes carbon-coated tin oxide nanoparticles.

[0010] The electron transport layer provided by the present invention includes carbon-coated tin oxide nanoparticles. A carbon shell layer is constructed on the surface of tin oxide to obtain a carbon-coated tin oxide material. On the one hand, it can effectively inhibit the surface defects of tin oxide and improve the conductivity of the tin oxide material; on the other hand, the carbon-coated tin oxide material can effectively inhibit the photocatalytic performance of tin oxide as an electron transport layer, thereby preventing the degradation reaction occurring at the bottom of the perovskite in close contact with it. Compared with the pure tin oxide material, the carbon-coated tin oxide material as an electron transport layer can greatly improve the ultraviolet stability of perovskite solar cells.

[0011] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical purposes and beneficial effects of the present invention can be better achieved.

[0012] In the second aspect, the present invention provides a preparation method of the electron transport layer as described in the first aspect, and the preparation method of the electron transport layer includes the following steps:

[0013] Mix tin oxide nanoparticles with an organic carbon source, and carbon-coated tin oxide nanoparticles are obtained through a hydrothermal reaction; the carbon-coated tin oxide nanoparticles are washed, dispersed, and coated to obtain an electron transport layer.

[0014] The present invention synthesizes carbon-coated tin oxide nanoparticles through a simple hydrothermal reaction, and an electron transport layer is obtained through coating, without high-temperature calcination, with a simple process and low cost, and has broad application prospects.

[0015] Preferably, the organic carbon source includes organic small molecules having a benzene ring or pyridine structure and amino and / or carboxyl substituents, the number of carbon atoms of the organic small molecules is less than 10, or the molecular weight is less than 500.

[0016] Preferably, the organic small molecules having a benzene ring or pyridine structure and amino and / or carboxyl substituents include any one or at least two combinations of o-, m-, p-phenylenediamine and its derivatives, or o-, m-, p-phthalic acid and its derivatives, or trimesic acid, or 3-aminopyridine-2-carboxylic acid, or 4-aminopyridine-3-carboxylic acid. Typical but non-limiting combinations include the combination of o-phenylenediamine and p-phenylenediamine, the combination of phthalic acid and isophthalic acid, the combination of o-phenylenediamine and phthalic acid, the combination of p-phenylenediamine derivative and phthalic acid, the combination of 3-aminopyridine-2-carboxylic acid and 4-aminopyridine-3-carboxylic acid, the combination of trimesic acid and 3-aminopyridine-2-carboxylic acid, or the combination of trimesic acid, 3-aminopyridine-2-carboxylic acid, and 4-aminopyridine-3-carboxylic acid.

[0017] The organic carbon source used in the present invention is an organic small molecule material, the organic small molecule material has a benzene ring or pyridine structure and amino and / or carboxyl substituents, and it is easier to form a coating layer on the surface of tin oxide nanoparticles. The purpose of the presence of amino / carboxyl is to anchor metal oxides, and structures such as benzene rings or pyridines are to provide a carbon source for carbonization.

[0018] Preferably, the mass ratio of the tin oxide nanoparticles to the organic carbon source is 1:(0.3 - 1), for example, it can be 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0019] In the present invention, by further controlling the mass ratio of tin oxide nanoparticles to the organic carbon source to be 1:(0.3 - 1), within this mass ratio range, tin oxide nanoparticles with a complete carbon coating layer can be obtained, thereby effectively suppressing the defects of tin oxide, improving the conductivity of tin oxide while suppressing the photocatalytic performance of tin oxide. If the addition amount of the organic carbon source is too much, it will cause the carbon coating layer to be too thick, affecting the work function of tin oxide, and further resulting in a decrease in the open circuit voltage of the corresponding perovskite battery; if the addition amount of the organic carbon source is too little, it will lead to a low degree of carbon coating and cannot effectively suppress the photocatalytic performance of tin oxide nanoparticles.

[0020] Preferably, the temperature of the hydrothermal reaction is 150°C - 220°C, for example, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C or 220°C, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0021] Preferably, the time of the hydrothermal reaction is 1h - 5h, for example, it can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0022] Preferably, the solvent used for washing includes water and / or ethanol.

[0023] Preferably, the dispersion method includes ultrasonic dispersion in water.

[0024] Preferably, the average particle size of the carbon-coated tin oxide nanoparticles is 1nm - 10nm, for example, it can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm or 10nm, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0025] The average particle size of the carbon-coated tin oxide nanoparticles provided by the present invention is 1nm - 10nm. The small-sized nanoparticles are more conducive to improving the film-forming uniformity and can effectively reduce the defects of the tin oxide functional layer.

[0026] Preferably, the mass concentration of the slurry obtained by dispersion is 5mg / mL - 20mg / mL, for example, it can be 5mg / mL, 8mg / mL, 10mg / mL, 12mg / mL, 14mg / mL, 15mg / mL, 16mg / mL, 17mg / mL, 18mg / mL, 19mg / mL or 20mg / mL, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises the following steps:

[0028] Mix tin oxide nanoparticles and an organic carbon source in a mass ratio of 1:(0.3 - 1), and perform hydrothermal reaction at 150°C - 220°C for 1 h - 5 h to obtain carbon-coated tin oxide nanoparticles; after the carbon-coated tin oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a slurry with a mass concentration of 5 mg / mL - 20 mg / mL, and the slurry is coated to obtain an electron transport layer with a thickness of 10 nm - 300 nm; the organic carbon source includes any one or a combination of at least two of o-, m-, p-phenylenediamine and its derivatives, o-, m-, p-phthalic acid and its derivatives, trimesic acid, 3-aminopyridine-2-carboxylic acid, or 4-aminopyridine-3-carboxylic acid.

[0029] In a third aspect, the present invention provides a perovskite solar cell, which includes the electron transport layer described in the first aspect.

[0030] The perovskite solar cell provided by the present invention has excellent photoelectric conversion efficiency and ultraviolet stability, has excellent conductivity, can maintain the perovskite from degrading under long-term ultraviolet light irradiation, and significantly improves the service life of the perovskite solar cell.

[0031] Preferably, the structure of the perovskite solar cell is successively a transparent conductive layer, an electron transport layer, a perovskite absorption layer, a hole transport layer, and an electrode.

[0032] Preferably, the thickness of the electron transport layer is 10 nm - 300 nm, for example, it can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 80 nm, 100 nm, 200 nm, or 300 nm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0033] Preferably, the material of the transparent conductive layer includes any one or a combination of at least two of FTO, ITO, IZO, or AZO.

[0034] Preferably, the material of the perovskite absorption layer includes MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3, CH3NH3PbI3, CsPbI3, FAPbI3, or any one or a combination of at least two of CsPbI2Br.

[0035] Preferably, the material of the hole transport layer includes any one or a combination of at least two of Spiro-OMeTAD, PTAA, CuSCN, or nickel oxide.

[0036] Preferably, the electrode includes any one or a combination of at least two of Cu, Au, Ag, or Al.

[0037] Fourthly, the present invention provides a preparation method of the perovskite solar cell as described in the third aspect. The preparation method includes the following steps:

[0038] (1) An electron transport layer as described in claim 1 is disposed on the surface of the transparent conductive layer;

[0039] (2) A perovskite absorption layer is disposed on the surface of the electron transport layer away from the transparent conductive layer;

[0040] (3) A hole transport layer is disposed on the surface of the perovskite absorption layer away from the electron layer;

[0041] (4) An electrode is disposed on the surface of the hole transport layer away from the perovskite absorption layer.

[0042] In the preparation method of the perovskite solar cell described in the present invention, except for the electron transport layer, the other layers can be prepared by the conventional preparation method of the perovskite solar cell without special requirements.

[0043] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges not listed. Due to space limitations and for the sake of brevity, the specific point values included in the ranges of the present invention are not exhaustively listed.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] The electron transport layer provided by the present invention includes carbon-coated tin oxide nanoparticles. A carbon shell layer is constructed on the surface of tin oxide. The obtained carbon-coated tin oxide material can, on the one hand, effectively inhibit the surface defects of tin oxide and improve the conductivity of the tin oxide material; on the other hand, the carbon-coated tin oxide material can effectively inhibit the photocatalytic performance of tin oxide, thereby preventing the degradation reaction occurring at the bottom of the perovskite. Compared with the pure tin oxide material used as the electron transport layer, the ultraviolet stability of the perovskite solar cell can be greatly improved. Description of the Drawings

[0046] Figure 1 It is a schematic structural diagram of the perovskite solar cell prepared in Application Example 1 of the present invention. Among them, 1 is the FTO glass substrate, 2 is the tin oxide electron transport layer, 3 is the perovskite absorption layer, 4 is the Spiro-OMeTAD hole transport layer, and 5 is the Ag electrode. Detailed implementation mode

[0047] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation modes. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0048] In the following examples and comparative examples, unless otherwise specified, all reagents and consumables are purchased from conventional reagent manufacturers in the art; unless otherwise specified, the experimental methods and technical means used are conventional methods and means in the art.

[0049] Example 1

[0050] This example provides an electron transport layer. The preparation method of the electron transport layer includes the following steps:

[0051] Mix tin oxide nanoparticles and phthalic acid according to a mass ratio of 1:0.5, and perform a hydrothermal reaction at 170 °C for 3 h to obtain carbon-coated tin oxide nanoparticles; after the carbon-coated tin oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a slurry with a mass concentration of 5 mg / mL. The slurry is coated to obtain an electron transport layer with a thickness of 10 nm.

[0052] Example 2

[0053] This example provides an electron transport layer. The preparation method of the electron transport layer includes the following steps:

[0054] Mix tin oxide nanoparticles and p-phenylenediamine according to a mass ratio of 1:0.3, and perform a hydrothermal reaction at 160 °C for 5 h to obtain carbon-coated tin oxide nanoparticles; after the carbon-coated tin oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a slurry with a mass concentration of 10 mg / mL. The slurry is coated to obtain an electron transport layer with a thickness of 20 nm.

[0055] Example 3

[0056] This example provides an electron transport layer. The preparation method of the electron transport layer includes the following steps:

[0057] Mix tin oxide nanoparticles with 3-aminopyridine-2-carboxylic acid and 4-aminopyridine-3-carboxylic acid (the mass ratio of 3-aminopyridine-2-carboxylic acid to 4-aminopyridine-3-carboxylic acid is 1:1) according to a mass ratio of 1:1, and perform a hydrothermal reaction at 210 °C for 1 h to obtain carbon-coated tin oxide nanoparticles; after the carbon-coated tin oxide nanoparticles are washed with water and / or ethanol, they are ultrasonically dispersed in water to obtain a slurry with a mass concentration of 20 mg / mL. The slurry is coated to obtain an electron transport layer with a thickness of 50 nm.

[0058] Example 4

[0059] This example provides an electron transport layer. The difference from Example 1 is only that when preparing this electron transport layer, the mass ratio of tin oxide nanoparticles to phthalic acid is 1:0.1.

[0060] Example 5

[0061] This example provides an electron transport layer. The difference from Example 1 is only that when preparing this electron transport layer, the mass ratio of tin oxide nanoparticles to phthalic acid is 1:2.

[0062] Example 6

[0063] This example provides an electron transport layer. The difference from Example 1 is only that when preparing this electron transport layer, phthalic acid is replaced with an equal amount of citric acid.

[0064] Comparative Example 1

[0065] This comparative example provides an electron transport layer. The difference from Example 1 is only that the electron transport layer is tin oxide nanoparticles without carbon coating, and the tin oxide nanoparticles are directly dispersed and coated to obtain the electron transport layer.

[0066] Application Example 1

[0067] This application example provides a perovskite solar cell and a preparation method thereof. The preparation method includes the following steps:

[0068] (1) Spin-coat the electron transport layer 2 as described in Example 1 on the surface of the FTO glass substrate 1;

[0069] (2) Spin-coat MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3 perovskite absorption layer 3 on the surface of the electron transport layer obtained in Example 1 away from the FTO;

[0070] Among them, the perovskite precursor solution structure composition is: MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05)3. The specific formulation of each component is as follows: CsI (19.5 mg); MABr (8.4 mg); FAI (219.5 mg); PbI2 (659.5 mg); PbBr2 (27.5 mg). Add an appropriate amount of 2-ME, DMF, and DMSO to the weighed drug powder (the more specific solvent ratio is 2-ME:DMF:DMSO = 8:1:1), and prepare a perovskite solution with a concentration of 1.0 M. Place it on a heating and stirring platform and stir at room temperature for 4 h to fully dissolve it. Prepare a uniform wet film of the perovskite solution on the FTO glass substrate through a slot coating device, dry it with a vacuum drying device, and anneal and crystallize it in a tunnel furnace to obtain a perovskite absorption layer.

[0071] (3) Spin-coat a Spiro-OMeTAD hole transport layer 4 on the surface of the perovskite absorption layer away from the electron layer.

[0072] (4) Spin-coat an Ag electrode 5 on the surface of the hole transport layer Spiro-OMeTAD away from the perovskite absorption layer.

[0073] The structural schematic diagram of the prepared perovskite solar cell is as Figure 1 shown. As can be seen from Figure 1 it, 1 is the FTO glass substrate, 2 is the tin oxide electron transport layer, 3 is the perovskite functional layer, 4 is the Spiro-OMeTAD hole transport layer, and 5 is the Ag electrode.

[0074] Application Example 2 - Application Example 6

[0075] This application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 1 is only that: in step (1), the electron transport layers described in Examples 2 - 6 are respectively provided on the surface of the transparent conductive layer, and other steps remain unchanged.

[0076] Application Example 7

[0077] This application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 1 is that: in step (1), the transparent conductive layer is AZO, in step (2), the perovskite absorption layer is CsPbI2Br, in step (3), the hole transport layer is PTAA, in step (4), the electrode is Cu, and other steps remain unchanged.

[0078] Comparative Application Example 1

[0079] This comparative application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 1 is only that: in step (1), the electron transport layers described in Comparative Example 1 are respectively provided on the surface of the transparent conductive layer, and other steps remain unchanged.

[0080] Comparative Application Example 2

[0081] This comparative application example provides a perovskite solar cell. The difference between the preparation method of the perovskite solar cell and that of Application Example 7 is only that: in step (1), an electron transport layer as described in Comparative Example 1 is respectively provided on the surface of the transparent conductive layer, and other steps remain unchanged.

[0082] Testing method: For the perovskite solar cells prepared in the application examples and comparative application examples, under the conditions of different ultraviolet irradiation amounts, the photoelectric conversion efficiency (PCE) test is carried out, and the test results are shown in Table 1 below.

[0083] Table 1

[0084]

[0085]

[0086] It can be seen from the test results that:

[0087] (1) It can be seen from Application Examples 1 - 3 that the electron transport layer provided by the present invention includes carbon-coated tin oxide nanoparticles. A carbon shell layer is constructed on the surface of tin oxide to obtain a carbon-coated tin oxide material. On the one hand, it can effectively inhibit the surface defects of tin oxide and improve the conductivity of the tin oxide material; on the other hand, the carbon-coated tin oxide material can effectively inhibit the photocatalytic performance of tin oxide, thereby preventing the degradation reaction occurring at the bottom of the perovskite. Compared with the pure tin oxide material as the electron transport layer, it can greatly improve the ultraviolet stability of the perovskite solar cell and significantly extend the service life of the perovskite solar cell.

[0088] (2) By comparing Application Example 1 with Application Examples 4 - 5, it can be seen that the present invention further controls the mass ratio of tin oxide nanoparticles to the organic carbon source to be 1:(0.3 - 1). Within this mass ratio range, tin oxide nanoparticles with a complete carbon coating layer can be obtained, thereby effectively inhibiting tin oxide defects, improving the conductivity of tin oxide while inhibiting the photocatalytic performance of tin oxide, and obtaining a perovskite solar cell with excellent photoelectric conversion efficiency. If the addition amount of the organic carbon source is too much, it will cause the carbon coating layer to be too thick, affecting the work function of tin oxide, and then resulting in a decrease in the open circuit voltage of the corresponding perovskite cell; if the addition amount of the organic carbon source is too little, it will lead to a low degree of carbon coating and unable to effectively inhibit the photocatalytic performance of tin oxide nanoparticles.

[0089] (3) It can be seen from the comparison between Application Example 1 and Application Example 6 that the organic carbon source used in the present invention is an organic small molecule material. The organic small molecule material has a benzene ring or a pyridine structure and amino and / or carboxyl substituents, and it is easier to form a coating layer on the surface of tin oxide nanoparticles. Subsequently, no calcination is required to form a carbon coating layer. In the conventional coating method, non-conjugated structure organic substances such as citric acid or glucose are used, and a high-temperature calcination step is required in the subsequent process to form a carbon coating layer.

[0090] (4) It can be seen from the comparison between Application Example 1 and Comparative Application Example 1 that if the tin oxide nanoparticles are used as the electron transport layer without carbon coating, under ultraviolet light irradiation, the photoelectric conversion efficiency of the perovskite solar cell decreases significantly. This result is related to the photocatalytic performance of tin oxide, and the generated free hydroxyl radicals cause degradation reactions at the bottom of the perovskite.

[0091] (5) It can be seen from the comparison between Application Example 7 and Comparative Application Example 2 that when other conventional components are selected for each layer in the perovskite solar cell of the present invention except for the electron transport layer, the ultraviolet stability of the perovskite solar cell can also be improved.

[0092] In summary, the electron transport layer provided by the present invention includes carbon-coated tin oxide nanoparticles. A carbon shell layer is constructed on the surface of tin oxide to obtain a carbon-coated tin oxide material. On the one hand, it can effectively suppress the surface defects of tin oxide and improve the conductivity of the tin oxide material; on the other hand, the carbon-coated tin oxide material can effectively inhibit the photocatalytic performance of tin oxide, thereby preventing the degradation reaction occurring at the bottom of the perovskite. Compared with the pure tin oxide material used as the electron transport layer, it can greatly improve the ultraviolet stability of the perovskite solar cell and significantly extend the service life of the perovskite solar cell.

[0093] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. An electron transport layer, characterized in that, The electron transport layer comprises carbon-coated tin oxide nanoparticles.

2. A method for preparing an electron transport layer as described in claim 1, characterized in that, The preparation method of the electron transport layer comprises the following steps: Mix tin oxide nanoparticles with an organic carbon source, and obtain carbon-coated tin oxide nanoparticles through a hydrothermal reaction; the carbon-coated tin oxide nanoparticles are washed, dispersed, and coated to obtain the electron transport layer.

3. The preparation method according to claim 2, wherein The organic carbon source comprises organic small molecules having a benzene ring or pyridine structure and amino and / or carboxyl substituents; Preferably, the organic small molecules having a benzene ring or pyridine structure and amino and / or carboxyl substituents comprise any one or a combination of at least two of o-, m-, p-phenylenediamine and its derivatives, or o-, m-, p-phthalic acid and its derivatives, or trimesic acid, or 3-aminopyridine-2-carboxylic acid, or 4-aminopyridine-3-carboxylic acid; Preferably, the mass ratio of the tin oxide nanoparticles to the organic carbon source is 1:(0.3-1).

4. The preparation method according to claim 2 or 3, characterized in that, The temperature of the hydrothermal reaction is 150°C - 220°C; Preferably, the time of the hydrothermal reaction is 1h - 5h.

5. The preparation method according to any one of claims 2-4, characterized in that, The solvent used for washing comprises water and / or ethanol; Preferably, the dispersion method comprises ultrasonic dispersion in water.

6. The preparation method according to any one of claims 2-5, characterized in that, The average particle size of the carbon-coated tin oxide nanoparticles is 1nm - 10nm; Preferably, the mass concentration of the slurry obtained by dispersion is 5mg / mL - 20mg / mL.

7. A perovskite solar cell, characterized in that, The perovskite solar cell comprises the electron transport layer as claimed in claim 1.

8. The perovskite solar cell according to claim 7, wherein, The structure of the perovskite solar cell is successively a transparent conductive layer, an electron transport layer, a perovskite absorption layer, a hole transport layer, and an electrode; Preferably, the thickness of the electron transport layer is 10nm - 300nm.

9. The perovskite solar cell according to claim 7 or 8, characterized in that, The material of the transparent conductive layer comprises any one or a combination of at least two of FTO, ITO, IZO, or AZO; Preferably, the material of the perovskite absorption layer includes MA 0.05 Cs 0.05 FA 0.9 Pb(I 0.95 Br 0.05 )3, CH3NH3PbI3, CsPbI3, FAPbI3, or any combination of at least two of CsPbI2Br; Preferably, the material of the hole transport layer comprises any one or a combination of at least two of Spiro-OMeTAD, PTAA, CuSCN, or nickel oxide; Preferably, the electrode comprises any one or a combination of at least two of Cu, Au, Ag, or Al.

10. A method for preparing a perovskite solar cell according to any one of claims 7-9, characterized in that, The preparation method comprises the following steps: (1) Provide the electron transport layer as claimed in claim 1 on the surface of the transparent conductive layer; (2) Provide the perovskite absorption layer on the surface of the electron transport layer away from the transparent conductive layer; (3) Provide the hole transport layer on the surface of the perovskite absorption layer away from the electron layer; (4) Provide the electrode on the surface of the hole transport layer away from the perovskite absorption layer.

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