Perovskite solar cell based on tin oxide electron transport layer prepared by chemical bath deposition method and preparation method thereof

Abstract

The application relates to a perovskite solar cell based on a tin oxide electronic transmission layer prepared by a chemical bath deposition method and a preparation method thereof. The cell is composed of an Au electrode, a spiro-OMeTAD hole transmission layer, a perovskite light absorption layer, a SnO2 electronic transmission layer and an FTO substrate from top to bottom. Mercaptoacetic acid TGA as a complexing agent in a traditional process is replaced by a strong action between citric acid and tin oxide, an effect of improving the tin oxide interface is achieved, and the tin oxide layer has better electronic transmission capacity. The solar cell improves the open circuit voltage of the perovskite solar cell device, thereby improving the device performance.

Description

Technical Field

[0001] This invention belongs to the field of thin-film solar cells, specifically relating to a perovskite solar cell based on chemical bath deposition to prepare a tin oxide electron transport layer and its preparation method. Background Technology

[0002] Compared to other thin-film solar cell absorber layer materials, such as gallium arsenide (GaAs), cadmium telluride (CdTe), and copper indium gallium selenide (CIGS), perovskite solar cells are among the most promising materials in the field of thin-film solar cells due to their superior photoelectric conversion efficiency, lower economic cost, high light absorption coefficient, and tunable bandgap. In recent years, the perovskite solar cell field has achieved remarkable success, with single-cell efficiency exceeding 25.7%, which has greatly promoted the industrialization and commercialization of perovskite solar cells, making them an ideal candidate to replace traditional energy sources.

[0003] Perovskite solar cells typically consist of a glass substrate, a transparent conductive electrode, an electron transport layer (ETL), a perovskite light-absorbing layer, a hole transport layer, and a back electrode. Among these layers, the ETL is crucial for the transport of photogenerated electrons and the blocking of holes in perovskite solar cells. In nip-type perovskite solar cells, tin oxide (SnO2) is the most widely used ETL material due to its excellent electron mobility, UV stability, and low-temperature processability. Currently, in most high-efficiency nip devices, SnO2 is prepared using a chemical bath deposition (CBD) method. However, the traditional process requires SnCl2·2H2O as the source of Sn in SnO2 and TGA (thioglycolic acid) as a complexing agent to carry SnO2 to the FTO substrate surface. TGA, as a chemical linker in the bath deposition process, carries thiol groups that can cause surface defects in tin oxide, leading to recombination during electron transport and thus affecting the overall device performance. Summary of the Invention

[0004] To address the problems existing in current technologies, this invention provides a perovskite solar cell and its preparation method for fabricating a tin oxide electron transport layer using a chemical bath deposition method. This invention uses citric acid, which is mercapto-free, as a chemical linker, avoiding the additional defects introduced by the complexing agent step. Furthermore, as a complexing agent, the binding energy between tin and sulfur is significantly weaker than that between tin and oxygen; therefore, we believe citric acid is a superior complexing agent. Utilizing the strong interaction between citric acid and tin oxide, we believe it can replace TGA as a complexing agent in traditional processes, improving the tin oxide interface and giving the tin oxide layer better electron transport capabilities. In addition, SnCl2·2H2O is used as the tin source in Sn... 2+ Sn is converted into the target product SnO2. 4+During the process, incomplete conversion may occur. Therefore, after the CBD process, we use a KIO3 aqueous solution as an interface modification step, utilizing the oxidizing properties of KIO3 to promote the conversion of residual Sn on the tin oxide surface. 2+ Convert to Sn 4+ This reduces surface oxygen vacancy defects and suppresses carrier recombination. Through the synergistic effect of citric acid and KIO3, a tin oxide electron transport layer with better crystallinity was obtained, reducing surface defects, enhancing the electron transport capacity of the layer, and significantly improving device performance.

[0005] The purpose of this invention is to provide a method for preparing a perovskite solar cell based on a chemical bath deposition method for preparing a tin oxide electron transport layer. This method improves the open-circuit voltage of the perovskite solar cell device and thus improves the device performance.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A perovskite solar cell based on chemical bath deposition to prepare a tin oxide electron transport layer consists of an Au electrode, a Spiro-OMeTAD hole transport layer, a perovskite light-absorbing layer, a SnO2 electron transport layer, and an FTO substrate, arranged sequentially from top to bottom.

[0008] Furthermore, the thickness of the Au electrode is 80~100nm.

[0009] Furthermore, the Spiro-OMeTAD layer is composed of Spiro-OMeTAD, Li salt, Co salt, and tributyl phosphate (TBP), and its thickness is 70~100 nm.

[0010] Furthermore, the perovskite light-absorbing layer is FA. 0.9 MA 0.05 Cs 0.05 PbI 2.94 Cl 0.06 The thin film has a thickness of 450~550nm.

[0011] Furthermore, the tin oxide electron transport layer is prepared using a chemical bath deposition method, and its thickness is 50~100nm.

[0012] Furthermore, the thickness of the FTO substrate is 350~400nm.

[0013] This invention also provides a method for preparing the above-mentioned perovskite solar cell based on the chemical bath deposition method for preparing the electron transport layer, comprising the following steps:

[0014] (1) Clean the FTO substrate and then dry it with nitrogen to obtain a clean substrate;

[0015] (2) After preparing the precursor solution, a tin oxide layer was prepared by chemical bath deposition. Then, a SnO2 electron transport layer with suitable grain size was obtained by solution immersion treatment followed by annealing.

[0016] (3) A perovskite layer was prepared on a SnO2 thin film, and a perovskite precursor film was prepared by anti-solvent method. After annealing, a perovskite light-absorbing layer with good crystallinity was obtained.

[0017] (4) A Spiro-OMeTAD hole transport layer was prepared on the perovskite layer by spin coating;

[0018] (5) Au electrodes were deposited on the Spiro-OMeTAD hole transport layer using vacuum evaporation technology.

[0019] Further, in step (2), the precursor solution includes SnCl2·2H2O, citric acid, urea and HCl.

[0020] Furthermore, in step (2), the solution used in the solution soaking method is an aqueous solution of KIO3.

[0021] Furthermore, in step (2), the annealing temperature is 180°C and the annealing time is 1 hour.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention relates to a perovskite solar cell with a tin oxide electron transport layer prepared by a chemical bath deposition method. This cell achieves an efficiency exceeding 24.9%, thus accelerating the application of perovskite solar cells. Furthermore, it utilizes citric acid as a complexing agent in the electron transport layer synthesis step and KIO3 aqueous solution as a surface modifier after the reaction. Through the synergistic effect of citric acid and KIO3, a tin oxide electron transport layer with better crystallinity is obtained, surface defects are reduced, and the electron transport capacity of the layer is enhanced, resulting in a significant improvement in device performance. Simultaneously, the preparation method of this invention is simple and easily industrialized. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a perovskite solar cell with a tin oxide electron transport layer prepared by chemical bath deposition according to an embodiment of the present invention.

[0025] Figure 2 This describes the preparation process of the tin oxide electron transport layer in this embodiment of the invention.

[0026] Figure 3 This is a SEM surface image of the tin oxide electron transport layer in an embodiment of the present invention.

[0027] Figure 4 FA in this invention0.9 MA 0.05 Cs 0.05 PbI 2.94 Cl 0.06 SEM image of the perovskite film.

[0028] Figure 5 FA in this invention 0.9 MA 0.05 Cs 0.05 PbI 2.94 Cl 0.06 XRD pattern of the thin film.

[0029] Figure 6 The embodiments of this invention include perovskite solar cells with citric acid and KIO3 synergistically acting on the tin oxide electron transport layer, perovskite solar cells using citric acid but without KIO3 modification on the tin oxide electron transport layer, and conventional perovskite solar cells using TGA to act on the tin oxide electron transport layer. JV curve. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] like Figure 1 As shown, this example provides a perovskite solar cell based on the chemical bath deposition method for preparing a tin oxide electron transport layer.

[0034] In this embodiment, the Au electrode has a thickness of 80 nm. The Spiro-OMeTAD hole transport layer consists of 100 mg Spiro-OMeTAD, 24.5 μL of an acetonitrile solution of 520 mg / mL Li salt, 49 μL of an acetonitrile solution of 300 mg / mL Co salt, and 40 μL of TBP, with a thickness of 70 nm. The perovskite light-absorbing layer is FA. 0.9 MA 0.05 Cs0.05 PbI 2.94 Cl 0.06 The thin film has a thickness of 500 nm, the tin oxide electron transport layer is prepared by chemical bath deposition and has a thickness of 80 nm, and the FTO substrate has a thickness of 400 nm.

[0035] In this embodiment, the perovskite solar cell fabrication process for preparing the electron transport layer using the chemical bath deposition method is as follows:

[0036] (1) Cleaning the FTO substrate

[0037] The sample was ultrasonically cleaned sequentially with deionized water, acetone, and anhydrous ethanol for 20 minutes each, dried with nitrogen, and then treated with ultraviolet-ozone.

[0038] (2) Fabrication of electron transport layer

[0039] Tin oxide layers were prepared using a chemical bath deposition method. Following solution immersion treatment and annealing, tin oxide layers with suitable grain sizes were obtained.

[0040] (201) Add 550mg SnCl2·2H2O, 20mg citric acid, and 1.2mg urea to 200mL of ultrapure water and stir. During stirring, add 1.2mL of concentrated hydrochloric acid with a concentration of 37wt% until the solution is completely transparent.

[0041] (202) Place the clean FTO substrate into the above solution, transfer it to an oil bath, heat it at 90°C for 5.5 hours, and then remove it and cool it to room temperature.

[0042] (203) The substrate with the above deposition completed is transferred into a KIO3 aqueous solution, then transferred to an oven for heating, and then the FTO is placed on an annealing table for annealing. Process parameters: KIO3 aqueous solution concentration is 2mM; oven temperature is 60℃, heating time is 10 minutes; annealing temperature is 180℃, time is 1 hour, and the process is carried out in an environment with relative humidity below 40%.

[0043] Figure 2 This is a schematic diagram of the process for preparing the tin oxide electron transport layer using the above chemical bath deposition method. Figure 3 This is a SEM image of the tin oxide electron transport layer surface after preparation.

[0044] (3) Preparation of FA by antisolvent method 0.9 MA 0.05 Cs 0.05 PbI 2.94 Cl 0.06 Perovskite light-absorbing layer, Figure 4 This is a SEM image of the thin film; Figure 5 The XRD pattern of this thin film.

[0045] (301) Weigh 8.9 mg of RbI, 11.1 mg of MAI, 645.4 mg of PbI2, 215.7 mg of FAI, and 11.8 mg of CsCl and dissolve them in a mixed solution of 800 μL of N,N-dimethylformamide (DMF) and 200 μL of dimethyl sulfoxide (DMSO). Stir and filter before use. Process parameters: DMF to DMSO volume ratio 4:1; stirring time 3~5 h; filter radius 0.22 μm.

[0046] (302) Transfer the FTO substrate, after the reaction in step (2), to a spin coater. Take 45 μL of the above solution to cover the surface and spin coat to prepare a perovskite light-absorbing layer precursor film. After adding the anti-solvent, transfer the precursor film to an annealing station for annealing. Process parameters: The spin coating process includes a. a low-speed stage, with a rotation speed of 1000 rpm, an acceleration of 200 rapm, and a time of 10 seconds; b. a high-speed stage, with a rotation speed of 4000 rpm, an acceleration of 2000 rapm, and a time of 30 seconds, and add 110 μL of the anti-solvent chlorobenzene at the 25th second. The annealing temperature is 110℃ and the time is 60 minutes.

[0047] (4) Preparation of Spiro-OMeTAD layer

[0048] Weigh 100 mg of Spiro-OMeTAD powder, 24.5 μL of acetonitrile solution of 520 mg / mL lithium bis(fluorosulfonyl)imide, 49 μL of acetonitrile solution of 300 mg / mL tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethane)sulfonylimide], and 40 μL of TBP. Mix the mixture, stir, and then transfer 20 μL of the solution to a perovskite surface for spin coating. Process parameters: rotation speed 4000 rpm; acceleration 3000 rpm; time 30 seconds.

[0049] (5) Fabrication of the top Au electrode

[0050] The top electrode was fabricated using a vacuum evaporation method with a photomask. Process parameters: vacuum level less than 1×10⁻⁶. -4 The evaporation rate is 1 Å / s, and the deposition thickness is 80 nm. The Au electrode accounts for 10% of the total area of ​​the solar cell.

[0051] like Figure 6 As shown, in this embodiment, the open-circuit voltage of the perovskite solar cell with an electron transport layer prepared by chemical bath deposition is 1.17V, and the short-circuit current is 25.19mA / cm. 2The fill factor was 84.51%, and the photoelectric conversion efficiency was 24.91%. The open-circuit voltage of the perovskite solar cell using citric acid and without a KIO3-modified tin oxide electron transport layer was 1.14V, and the short-circuit current was 25.07mA / cm². 2 The fill factor is 83.24%, and the photoelectric conversion efficiency is 23.82%. The open-circuit voltage of a perovskite solar cell with an electron transport layer, prepared by a traditional chemical bath deposition method using TGA as a complexing agent, is 1.12V, and the short-circuit current is 24.87mA / cm². 2 The fill factor is 82.44%, and the photoelectric conversion efficiency is 22.96%. Compared with the traditional perovskite solar cell with electron transport layer prepared by chemical bath deposition method based on TGA as complexing agent, the open circuit voltage of the perovskite solar cell with electron transport layer prepared by chemical bath deposition method of the present invention is significantly improved, thereby significantly improving the photoelectric conversion efficiency of the device by 1.95%.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for fabricating a perovskite solar cell with a tin oxide electron transport layer based on chemical bath deposition, characterized in that, The perovskite solar cell consists of an Au electrode, a Spiro-OMeTAD hole transport layer, a perovskite light-absorbing layer, a SnO2 electron transport layer, and an FTO substrate, from top to bottom. The method for fabricating a perovskite solar cell with a tin oxide electron transport layer based on chemical bath deposition includes the following steps: (1) Clean the FTO substrate and then dry it with nitrogen to obtain a clean substrate; (2) After preparing the precursor solution, a tin oxide layer is prepared by chemical bath deposition, and then the SnO2 electron transport layer is obtained by solution immersion treatment and annealing. (3) A perovskite layer was prepared on a SnO2 thin film, and a perovskite precursor film was prepared by anti-solvent method. After annealing, a perovskite light-absorbing layer with good crystallinity was obtained. (4) A Spiro-OMeTAD hole transport layer was prepared on the perovskite layer by spin coating; (5) Au electrodes were deposited on the Spiro-OMeTAD hole transport layer using vacuum evaporation technology; In step (2), the precursor solution includes SnCl2·2H2O, citric acid, urea and HCl; In step (2), the solution used in the solution soaking method is an aqueous solution of KIO3.

2. The method for preparing a perovskite solar cell with a tin oxide electron transport layer based on chemical bath deposition according to claim 1, characterized in that, The thickness of the Au electrode is 80~100nm.

3. The method for preparing a perovskite solar cell with a tin oxide electron transport layer based on chemical bath deposition according to claim 1, characterized in that, The Spiro-OMeTAD hole transport layer consists of Spiro-OMeTAD, Li salt, Co salt, and tributyl phosphate (TBP), with a thickness of 70-100 nm.

4. The method for fabricating a perovskite solar cell with a tin oxide electron transport layer based on chemical bath deposition according to claim 1, characterized in that, The perovskite light-absorbing layer is FA. 0.9 MA 0.05 Cs 0.05 PbI 2.94 Cl 0.06 The thin film has a thickness of 450~550nm.

5. The method for preparing a perovskite solar cell with a tin oxide electron transport layer based on chemical bath deposition according to claim 1, characterized in that, The SnO2 electron transport layer was prepared using a chemical bath deposition method, and its thickness was 50~100nm.

6. The method for preparing a perovskite solar cell with a tin oxide electron transport layer based on chemical bath deposition according to claim 1, characterized in that, The thickness of the FTO substrate is 350~400nm.

7. The method for fabricating a perovskite solar cell based on chemical bath deposition of a tin oxide electron transport layer according to claim 1, characterized in that, In step (2), the annealing temperature is 180℃ and the annealing time is 1 hour.

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