Novel solvent-assisted hydrothermal deposition method for preparing selenium antimony sulfide solar cell

Abstract

According to the method, an auxiliary solvent N, N-dimethylformamide (DMF) is added into a precursor solution for hydrothermal deposition of the selenium antimony sulfide thin film to adjust the deposition rate, so that the thickness of the thin film is optimized, the morphology of the thin film is improved, the crystallinity is improved, the defect density of the thin film is reduced, and the performance of a device is improved. The selenium antimony sulfide solar cell comprises a conductive substrate (including FTO and the like), an electron transport layer, a selenium antimony sulfide solar cell absorption layer and a counter electrode. The DMF can promote grain polymerization of the selenium antimony sulfide thin film, increase the grain size and reduce electric leakage channels of the solar cell. And the DMF has the effect of adjusting the deposition rate, so that the reaction is slower, and a more appropriate thickness of the absorption layer is obtained. By constructing an effective selenium antimony sulfide thin film solar cell structure, the device performance of the selenium antimony sulfide solar cell is improved.

Description

Technical Field

[0001] The invention belongs to the field of antimony selenide sulfide solar cells, and specifically relates to a method for using a new solvent to assist in regulating the deposition rate of antimony selenide sulfide in a hydrothermal deposition process, thereby improving film quality and film thickness. Background Art

[0002] In today's society where environmental awareness is increasing, solar cells, as a new energy source, have received more and more attention. Solar cells are devices that convert solar energy into electrical energy and are widely used in household, industrial and agricultural fields. Antimony selenide sulfide thin film solar cells have excellent photoelectric properties and excellent absorption coefficient (10 5 cm -1 ), rich element reserves (Se storage is 0.05ppm, S storage is 260ppm), and excellent stability have attracted much attention. Its unique one-dimensional crystal structure is conducive to reducing the main defects in typical thin-film solar cells. In addition, antimony selenide sulfide solar cells also have the advantage of adjustable band gap. Since Sb2S3 and Sb2Se3 have the same crystal structure, the band gap (1.7-1.7eV) can be adjusted by changing the atomic ratio of Se to S. According to the Shockley-Queisser theory, Sb2(S 1-x , Se x )3 Single-junction solar cells can achieve a theoretical power conversion efficiency (PCE) of 33.7%. Based on these unique properties of antimony selenide sulfide thin-film solar cells, they have the potential to be developed into a new generation of solar cells and applied on a large scale. However, the actual efficiency of antimony selenide sulfide solar cells is still far from the theoretical efficiency. Therefore, it is still crucial to improve the performance of antimony selenide sulfide solar cells.

[0003] For heterojunction thin-film solar cells, the film quality of the absorption layer and the contact between the interfaces jointly determine the performance of the cell. The absorption layer should have a suitable band gap, a large grain size, a high degree of crystallinity, and excellent carrier transport properties. The film quality of antimony selenide sulfide thin films depends largely on the preparation method, deposition formula, and post-processing. In addition, the thickness of the antimony selenide sulfide film cannot be too thick, otherwise it will increase its series resistance and seriously reduce the performance of the device. Therefore, the thickness of the antimony selenide sulfide film should be controlled within the optimization range of 100-200nm.

[0004] The current method for preparing the most efficient devices is hydrothermal deposition, but the hydrothermal deposition method also has disadvantages that cannot be ignored, that is, the deposition process of antimony selenide sulfide film cannot be observed and controlled in a sealed autoclave. Therefore, the reaction process depends entirely on the state of the precursor solution. In the hydrothermal deposition process, deionized water is usually selected as the solvent, and a large number of studies have shown that antimony selenide sulfide films prepared by hydrothermal deposition using deionized water contain oxide impurities. These oxide impurities may introduce more defects and increase the recombination rate of electron-hole pairs, thereby affecting the transport of carriers and their lifetime. The idea of ​​adding auxiliary solvents is essentially to adjust the Sb by adding other ions. 3+ The concentration of Sb can be adjusted to adjust the reaction kinetics, and N, N-dimethylformamide (DMF), known as a universal solvent, can dissolve selenium, sulfur and antimony sources, and can also adjust the concentration of Sb 3+ The concentration of antimony selenide sulfide can be adjusted to adjust the deposition rate. There is no report on improving the hydrothermal deposition rate of antimony selenide sulfide film by adding N, N-dimethylformamide (DMF) as an auxiliary solvent. This project intends to add N, N-dimethylformamide (DMF) as an auxiliary solvent to the precursor solution of hydrothermal deposition of antimony selenide sulfide film to adjust the deposition rate, thereby optimizing the film thickness, improving the film morphology, increasing the crystallinity and reducing the defect density of the film, thereby improving the device performance.

[0005] In summary, antimony selenide sulfide thin-film solar cells are still facing the problem of improving power conversion efficiency. Poor film quality of the absorption layer and inappropriate thickness of the absorption layer will greatly reduce device performance. These challenges limit the development of antimony selenide sulfide thin-film solar cells. Summary of the invention

[0006] In order to improve the film-forming quality of the absorption layer and thus enhance the performance of antimony selenide sulfide solar cells, the present invention adjusts the deposition rate by a hydrothermal deposition method with the addition of N,N-dimethylformamide (DMF) as an auxiliary solvent, so that the absorption layer has a larger grain size, a flatter film surface and a more appropriate thickness, thereby improving the device performance of antimony selenide sulfide solar cells.

[0007] The first object of the present invention is to obtain antimony selenide sulfide thin films with higher quality so as to make them very suitable for solar cells.

[0008] The second purpose of the present invention is to improve the device performance of antimony selenide sulfide thin film solar cells by using a hydrothermal deposition method with the addition of N,N-dimethylformamide (DMF) as an auxiliary solvent, so that the short-circuit current density is higher and the power conversion efficiency is higher.

[0009] In a first aspect of the present invention, there is provided a method for preparing an antimony selenide sulfide film by hydrothermal deposition by adding N,N-dimethylformamide (DMF) as an auxiliary solvent, the steps comprising:

[0010] (1) Cleaning of substrate materials;

[0011] (2) preparing a precursor solution for growing antimony selenide sulfide thin film;

[0012] (3) preparing the absorption layer by hydrothermal deposition;

[0013] (4) fixing the substrate in a closed container containing a precursor solution;

[0014] (5) placing the sealed container of step (4) in a constant temperature device and growing for a specific time;

[0015] (6) After the growth in step (5) is completed, the substrate is taken out and cleaned to obtain an antimony selenide sulfide film.

[0016] The second aspect of the present invention provides a solar cell based on DMF-modified antimony selenide sulfide absorption layer, the device comprising:

[0017] substrate;

[0018] Electron transport layer;

[0019] Antimony selenide sulfide absorber layer;

[0020] Carbon electrode.

[0021] Base The substrate of the present invention is not specifically limited, as long as it does not limit the purpose of the present invention. It can be conductive glass, plastic flexible substrate and stainless steel, etc. Preferably, FTO glass is used.

[0022] Electron transport layer The electron transport layer of the present invention is not specifically limited as long as it does not limit the purpose of the present invention. For example, cadmium sulfide, zinc oxide, and tin dioxide with good electron transport effect can be used.

[0023] Antimony selenide sulfide absorber There is no specific limitation on the material of the antimony selenide sulfide light absorption layer, as long as it does not limit the purpose of the present invention. For example, a direct carrier transport path and an antimony selenide sulfide material matching the upper and lower layer energy bands can be used, preferably a material with potassium antimony tartrate as the antimony source.

[0024] Carbon Electrode The counter electrode (or back electrode) of the present invention is not specifically limited, as long as it does not limit the purpose of the present invention. Aluminum paste, gold and carbon can be selected. Preferably, carbon paste is selected. Preferably, the thickness of the counter electrode is 200nm.

[0025] Compared with the prior art, the present invention has the following advantages and positive effects:

[0026] (1) The present invention prepares an antimony selenide sulfide thin film structure with larger grain size and better crystallinity, which can improve the performance of antimony selenide sulfide solar cell devices;

[0027] (2) With fewer interface defects, DMF can regulate the deposition reaction rate, making the hydrothermal deposition of antimony selenide sulfide thin films slower, which is more conducive to obtaining the ideal film thickness;

[0028] (3) DMF has good solubility and can dissolve antimony source, selenium source, and sulfur source without reacting with them, which is conducive to a more complete hydrothermal deposition reaction;

[0029] (4) DMF has a tendency to aggregate the grains of antimony selenide sulfide film into larger grains, and a larger grain size is beneficial to reducing leakage loss;

[0030] (5) The method of the present invention is simple, low-cost and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to make the purpose, 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, wherein:

[0032] Figure 1 It is a schematic diagram of antimony selenide sulfide thin film solar cell with hydrothermal deposition by adding DMF as an auxiliary solvent; DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually carried out under normal conditions. Unless otherwise defined or specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention.

[0034] Example 1: Preparation of antimony selenium sulfide solar cells using the present invention

[0035] (1) Clean the FTO conductive glass sheet with glass cleaner, deionized water, acetone, and anhydrous ethanol and blow dry.

[0036] (2) Place the FTO obtained in step (1) into the inner container of an autoclave, and pour in 40 ml of the prepared cadmium nitrate and thiourea precursor solution.

[0037] (3) placing the autoclave in step (2) in an oven and growing at 70° C. for 40 min, then taking out the FTO, rinsing it with deionized water and anhydrous ethanol, and drying it, thereby obtaining a cadmium sulfide electron transport layer.

[0038] (4) Annealing the cadmium sulfide electron transport layer obtained in step (3) on a hot plate at 350° C. for 10 min.

[0039] (5) The substrate obtained in step (4) is placed obliquely into the inner container of the autoclave, and 40 ml of the prepared precursor solution of potassium antimony tartrate, sodium thiosulfate, sodium selenium sulfite, and DMF is poured into it.

[0040] (6) The autoclave in step (5) is placed in an oven and grown at 120° C. for 120 min. The substrate is then taken out and rinsed with deionized water and anhydrous ethanol and dried to obtain an antimony selenide sulfide absorption layer.

[0041] (7) The antimony selenide sulfide absorption layer obtained in step (6) is annealed on a hot plate at 350° C. for 10 min.

[0042] (8) Prepare the back electrode (carbon or silver, etc.) on top of the absorption layer by scraping.

Claims

1. A novel solvent-assisted hydrothermal deposition method for preparing antimony selenide sulfide solar cells, characterized in that: The battery structure comprises: substrate; Electron transport layer; Antimony selenide sulfide absorber layer; Counter electrode.

2. The electron transport layer as claimed in claim 1 can be made of cadmium sulfide (CdS), zinc oxide (ZnO), tin dioxide (SnO2) and the like.

3. A novel solvent-assisted hydrothermal deposition method for preparing antimony selenide sulfide solar cells, characterized in that: The steps include: (1) Clean the FTO conductive glass sheet with glass cleaner, deionized water, acetone, and anhydrous ethanol and blow dry. (2) The FTO obtained in step (1) is placed in an autoclave, and the prepared cadmium nitrate and thiourea precursor solutions are poured in. (3) The autoclave in step (2) is placed in an oven for growth, and then the FTO is taken out, rinsed with deionized water and anhydrous ethanol, and dried to obtain a cadmium sulfide electron transport layer. (4) annealing the cadmium sulfide electron transport layer obtained in step (3) on a hot plate. (5) Place the substrate obtained in step (4) obliquely into the inner container of the autoclave, and pour in the prepared precursor solution of potassium antimony tartrate, sodium thiosulfate, sodium selenium sulfite, and 10-40 ml DMF. (6) The autoclave in step (5) is placed in an oven for growth, and then the substrate is taken out and rinsed with deionized water and anhydrous ethanol and dried to obtain an antimony selenide sulfide absorption layer. (7) The antimony selenide sulfide absorption layer obtained in step (6) is placed on a hot plate for annealing. (8) Prepare the back electrode (carbon or silver, etc.) on top of the absorption layer by scraping.

4. Step (2) as claimed in claim 3, characterized in that: The amount of the mixed solution poured into the inner container of the autoclave was 40 ml.

5. Step (3) as claimed in claim 3, characterized in that: The growth temperature for preparing the cadmium sulfide electron transport layer is 70°C and the time is 40 minutes.

6. Step (4) as claimed in claim 3, characterized in that: The annealing temperature of the cadmium sulfide electron transport layer is 350°C and the time is 10 min.

7. Step (5) as claimed in claim 3, characterized in that: The growth temperature for preparing the antimony selenide sulfide absorption layer is 120°C and the time is 120 minutes.

8. Step (6) as claimed in claim 3, characterized in that The annealing temperature of the antimony selenide sulfide absorption layer is 350°C and the time is 10 minutes.

9. Application of the hydrothermal deposition method using N,N-dimethylformamide (DMF) as an auxiliary solvent to improve the film quality of antimony selenide sulfide thin films in solar cells as claimed in claim 3.

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