Method for regulating and controlling crystallization orientation and defects of selenium antimony sulfide thin film and application

Abstract

The invention relates to the technical field of solar cells, in particular to a method for regulating and controlling crystallization orientation and defects of a selenium antimony sulfide thin film and application. The crystallization orientation and defect characteristics of the selenium antimony sulfide thin film are regulated and controlled by adding a weak acid-base additive composed of polyhedral anions, the pH value in a hydrothermal solution is regulated through weak acid-base, the decomposition rate of a selenium source and a sulfur source is regulated and controlled, meanwhile, formation of antimony oxide is hindered, and heterogeneous nucleation of the selenium antimony sulfide thin film is accelerated; besides, polyhedral anions coordinate with antimony or antimony oxide ions in a solution by utilizing a unique local electronic structure, a reaction path is changed, a large-size effect is combined, selenium antimony sulfide clusters are induced to nucleate at vertexes of a polyhedron and crystallize along a specific [hk1] direction, body defects are finally passivated, and preparation of a high-quality thin film is realized. The method for regulating and controlling crystallization orientation and defects of the selenium antimony sulfide thin film is safe, reliable and easy to operate. According to the invention, the weak acid-base additive composed of polyhedral anions is used for regulating and controlling the crystallization orientation and defect characteristics of the selenium antimony sulfide thin film for the first time.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a method for regulating the crystallization orientation and defects of an antimony selenide sulfide film and its application. Background Art

[0002] As a representative clean energy, the effective use of solar energy can significantly alleviate the current energy and environmental problems. Photovoltaic power generation is one of the most important ways of utilization. At present, commercial solar cells are still mainly silicon-based solar cells, and the silicon absorption layer used is several hundred microns thick and the manufacturing process is complex. Thin-film solar cells occupy an important position in the global photovoltaic market due to their advantages of low attenuation, light weight, less consumables and low energy consumption in preparation, such as cadmium telluride and copper indium gallium selenide cells. Due to the scarcity of toxic elements cadmium and indium gallium, further development in the future is limited. It is urgent to seek a low-cost, environmentally friendly, stable and efficient photovoltaic absorption layer.

[0003] In recent years, an emerging antimony-based chalcogenide semiconductor material, antimony selenide, has been developed, which has an adjustable band gap (1.1-1.7 eV), a high visible light absorption coefficient (>10 5 cm -1 ), excellent physical and chemical stability, rich composition elements and low toxicity, giving it a theoretical photoelectric conversion efficiency of more than 32%, making it a very promising battery absorption layer material. In addition, the quasi-one-dimensional crystal structure also makes this material potentially applicable to flexible wearable devices. However, the low-dimensional crystal structure gives this material the disadvantages of carrier migration anisotropy and complex deep defects. Although the current laboratory efficiency has gradually broken through to more than 10%, there is still a huge gap from the theoretical efficiency. Therefore, it is of great significance to regulate the crystallization orientation and deep defects of antimony selenide sulfide films in order to improve the performance of solar cells. . Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for regulating the crystallization orientation and deep defects of antimony selenide sulfide thin films, so as to solve the technical problem of how to improve the quality of thin films and the performance of solar cells.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a method for regulating the crystallization orientation and deep defects of antimony selenide sulfide thin films, comprising the following steps: A precursor solution is prepared and poured into a hydrothermal reactor, and then a weak acid-base additive composed of polyhedral anions is added, and then the FTO conductive glass deposited with a CdS film is immersed in the reaction precursor solution, the reactor is sealed and placed in a drying oven for hydrothermal reaction, and after the reaction is completed, the film is taken out, washed with deionized water and dried to obtain an amorphous antimony selenide sulfide film; the amorphous antimony selenide sulfide film is subjected to high-temperature annealing treatment to obtain a crystalline antimony selenide sulfide film; the precursor solution contains potassium antimony tartrate, selenourea, sodium selenosulfate and sodium thiosulfate; the weak acid-base additive composed of polyhedral anions is a water-soluble material.

[0006] The anions contained in the weak acid and alkaline additive composed of the polyhedral anions are one or more of pyrophosphate, orthosilicate, hypophosphate, tetrametaphosphate, tripolyphosphate, periodate, tetrapolyphosphate, heptamolybdate, decavanadate and dodecamolybdate; the cations contained in the weak acid and alkaline additive composed of the polyhedral anions are one or more of ammonium ions, hydrogen ions, alkali metal ions, alkaline earth metal ions, chromium ions and aluminum ions.

[0007] The addition amount of the weak acid and alkaline additive composed of the polyhedral anions is (0.001~20) mg / 40 mL; the molar ratio of the potassium antimony tartrate, selenourea, sodium selenosulfate and sodium thiosulfate is 1:0.3~0.5:0.05~0.3:4~8; the amount of the potassium antimony tartrate is 0.2~0.4 g / 40 mL; the sodium selenosulfate is an aqueous solution with a concentration of (0.01~0.3)mmol / (0.2~3)mL.

[0008] The temperature of the hydrothermal reaction is 110 ~ 160 ° C, the hydrothermal reaction time is 1 ~ 24 h, and the heating and cooling rate is 1 ~ 10 ° C / min; the annealing process is carried out in a nitrogen atmosphere, the annealing temperature is 330 ~ 410 ° C, and the annealing time is 5 ~ 10 min.

[0009] Furthermore, the thickness of the CdS film is 60 to 80 nm, the thickness of the FTO conductive layer is 400 to 600 nm, and the thickness of the antimony selenide sulfide film is 150 to 300 nm.

[0010] The invention also provides an antimony selenide sulfide film.

[0011] The present invention also provides an application of an antimony selenide sulfide film in a solar cell. The solar cell device is in a flat plate shape, with FTO as a cathode, CdS as an electron transport layer, 60 to 80 nm thick Spiro-OMeTAD as a hole transport layer, 60 to 100 nm thick gold as an anode, and the antimony selenide sulfide film as a light absorption layer.

[0012] Further, the CdS electron transport layer is chemically bath deposited on the FTO cathode, the Spiro-OMeTAD hole transport layer is spin-coated on the antimony selenide sulfide thin film absorption layer, and the gold anode is thermally evaporated on the Spiro-OMeTAD layer.

[0013] Beneficial effects of the present invention: The present invention prepares antimony selenide sulfide thin film based on the hydrothermal method, and uses weak acid and alkaline additives composed of polyhedral anions to regulate the deposition and subsequent crystallization process of the thin film. The size effect of the polyhedral anions inhibits the lateral growth of the ribbon in the antimony selenide sulfide, strengthens the [hk1] oriented growth of the film, and significantly improves the crystallinity of the film. In addition, the weak acid and alkalinity can adjust the decomposition rate of the selenium source and the sulfur source, regulate the Se / S ratio of the film, and the polyhedral anions are located in the ribbon gaps, which synergistically reduces the body defects in the film. The method provided by the present invention is simple to operate, safe and controllable. The present invention uses weak acid and alkaline additives composed of polyhedral anions for the first time to regulate the quality of antimony selenide sulfide thin films and use them in solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of substrate placement and ribbon growth.

[0015] Figure 2 This is the SEM image of the device obtained in comparative application example 1.

[0016] Figure 3 This is the SEM image of the device obtained in Application Example 1.

[0017] Figure 4 This is the SEM image of the device obtained in Application Example 2.

[0018] Figure 5 This is the SEM image of the device obtained in Application Example 3.

[0019] Figure 6 This is the SEM image of the device obtained in Application Example 4.

[0020] Figure 7 This is the SEM image of the device obtained in Application Example 5.

[0021] Figure 8 The XRD diagrams of the devices obtained in Application Example 1 and Application Example 3 are compared.

[0022] Fig. 9 The defect density calculation diagram of the devices obtained by comparing Application Example 1 and Application Example 3 is shown.

[0023] Fig.10 This is the current density-voltage curve of the solar cell device obtained in Application Example 3.

[0024] Table 1 shows the EDS element composition of the devices obtained by comparing Application Example 1 and Application Example 3. DETAILED DESCRIPTION

[0025] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0026] In view of the current development status of antimony selenide sulfide thin films, the present invention provides a method for regulating the crystallization orientation and deep defects of antimony selenide sulfide thin films, which can achieve the preferred [hk1] orientation growth and defect passivation of the film, improve the quality of the film, and the method is safe and reliable. It includes the following steps: A precursor solution is prepared and poured into a hydrothermal reactor, and then a weak acid-base additive composed of polyhedral anions is added, and then the FTO conductive glass deposited with a CdS film is immersed in the reaction precursor solution, the reactor is sealed and placed in a drying oven for hydrothermal reaction, and after the reaction is completed, the film is taken out, washed with deionized water and dried to obtain an amorphous antimony selenide sulfide film; the amorphous antimony selenide sulfide film is subjected to high-temperature annealing treatment to obtain a crystalline antimony selenide sulfide film; the precursor solution contains potassium antimony tartrate, selenourea, sodium selenosulfate and sodium thiosulfate; the weak acid-base additive composed of polyhedral anions is a water-soluble material.

[0027] In the process of preparing antimony selenide sulfide film, the present application first selects additives, wherein the anions contained in the weak acid and alkaline additive composed of polyhedral anions are one or more of pyrophosphate, orthosilicate, hypophosphate, tetrametaphosphate, tripolyphosphate, periodate, tetrapolyphosphate, heptamolybdate, decavanadate and dodecamolybdate; the cations contained in the weak acid and alkaline additive composed of polyhedral anions are one or more of ammonium ions, hydrogen ions, alkali metal ions, alkaline earth metal ions, chromium ions and aluminum ions.

[0028] In the present invention, the addition amount of the weak acid and alkaline additive composed of polyhedral anions is preferably (0.01-10) mg / 40 mL, and more preferably (0.01-2) mg / 40 mL.

[0029] In the present invention, the molar ratio of potassium antimony tartrate, selenourea, sodium selenosulfate and sodium thiosulfate is preferably 1:0.3 ~ 0.5:0.05 ~ 0.2:4 ~ 8, and more preferably 1:0.3 ~ 0.5:0.05 ~ 0.15:4 ~ 8.

[0030] In the present invention, the amount of potassium antimony tartrate is preferably 0.2 to 0.35 g / 40 mL, and more preferably 0.2 to 0.3 g / 40 mL.

[0031] In the present invention, the concentration of the sodium selenosulfate aqueous solution is preferably (0.01 ~ 0.2) mmol / (0.2 ~ 3) mL, and more preferably (0.01 ~ 0.1) mmol / (0.2 ~ 3) mL.

[0032] In the present invention, the temperature of the hydrothermal reaction is 110 to 160 ° C, preferably 120 to 150 ° C, and more preferably 130 ° C; the heating and cooling rate is 1 to 10 ° C / min, preferably 3 to 7 ° C / min, and more preferably 4 to 6 ° C / min; the hydrothermal reaction time is 1 to 24 h, preferably 2 to 12 h, and more preferably 2 to 4 h.

[0033] In the present invention, the annealing temperature in the annealing process is 330 to 410 ° C, preferably 350 ° C; the annealing time is 5 to 10 min, preferably 10 min.

[0034] In the present invention, the thickness of the CdS film is 60 to 80 nm, preferably 70 nm; the thickness of the FTO conductive layer is 400 to 600 nm, preferably 500 nm; the thickness of the antimony selenide sulfide film is 150 to 300 nm, preferably 150 to 250 nm.

[0035] The invention also provides an antimony selenide sulfide film.

[0036] The present invention also provides an application of an antimony selenide sulfide film in a solar cell. The solar cell device is in a flat plate shape, with FTO as a cathode and CdS as an electron transport layer; the Spiro-OMeTAD as a hole transport layer with a thickness of 60 to 80 nm, preferably 70 nm; the gold as an anode with a thickness of 60 to 100 nm, preferably 80 nm; and the antimony selenide sulfide film as a light absorption layer.

[0037] The solar cell device of the present invention is in a planar shape. The CdS electron transport layer is chemically bath deposited on the FTO cathode; the Spiro-OMeTAD hole transport layer is spin-coated on the antimony selenium sulfide film absorption layer; and the gold anode is thermally evaporated on the Spiro-OMeTAD layer.

[0038] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0039] Example 1 Take 40 mL of deionized water as solvent, add 1 mmol potassium antimony tartrate, 0.4 mmol selenourea, 6 mmol sodium thiosulfate, 0.1 mmol sodium selenosulfate and 0.5 mg disodium dihydrogen pyrophosphate, stir until all dissolved to form a precursor solution, and pour it into a polytetrafluoroethylene liner. Then, soak the FTO conductive glass deposited with CdS film in the reaction precursor solution, put the liner into a stainless steel reactor, tighten the seal, and then put the reactor into a drying oven for hydrothermal reaction. Set the heating and cooling rate to 5 °C / min, the hydrothermal temperature to 130 °C, and the reaction time to 140 min. After the reaction is completed, take out the film, wash it with deionized water and dry it to obtain an amorphous antimony selenide sulfide film. Then, in a nitrogen-filled glove box, anneal the film on a hot plate at 350 °C for 10 min to form a crystalline antimony selenide sulfide film.

[0040] Example 2 The difference from Example 1 is that the additive is 0.05 mg of periodic acid, and the other conditions are the same as those in Example 1.

[0041] Example 3 The difference from Example 1 is that the additive is 0.1 mg of ammonium molybdate tetrahydrate, and the other conditions are the same as those in Example 1.

[0042] Example 4 The difference from Example 1 is that the additive is 1 mg of sodium tripolyphosphate, and the other conditions are the same as those in Example 1.

[0043] Example 5 The difference from Example 1 is that the additive is 0.03 mg of hexaammonium dodecamolybdate dichromate, and the other conditions are the same as those in Example 1.

[0044] Comparative Example 1 The difference from Example 1 is that no weak acid or alkaline additive composed of polyhedral anions is added, and other conditions are the same as those in Example 1.

[0045] Application Example 1 Preparation of solar cells: (1) FTO pretreatment: FTO was ultrasonically cleaned for 15 min using glass cleaner, deionized water, isopropanol, acetone, and anhydrous ethanol in sequence, dried with nitrogen, and then cleaned with a UV-ozone cleaner for 15 min; (2) CdS thin film was deposited on FTO by chemical water bath method with a film thickness of 70 nm; (3) Using the method of Example 1, an antimony selenide sulfide film was grown on a substrate on which a CdS film was deposited, and the film thickness was 190 nm; (4) Spin-coating a Spiro-OMeTAD layer on the antimony selenide sulfide film at a speed of 3500 r / min, a spin-coating time of 30 s, and a thickness of 70 nm, followed by heating and oxidation at 100 °C in air for 10 min; (5) Gold electrodes were deposited on the Spiro-OMeTAD layer using thermal evaporation technology with a vacuum degree of 2×10 -5 Pa, thickness is 80 nm.

[0046] Application Example 2 The difference from Application Example 1 is that the method of Example 2 is adopted to prepare an antimony selenide sulfide film, and the film thickness is 210 nm.

[0047] Application Example 3 The difference from Application Example 1 is that the method of Example 3 is adopted to prepare an antimony selenide sulfide film, and the film thickness is 230 nm.

[0048] Application Example 4 The difference from Application Example 1 is that the method of Example 4 is adopted to prepare an antimony selenide sulfide film with a film thickness of 250 nm.

[0049] Application Example 5 The difference from Application Example 1 is that the method of Example 5 is adopted to prepare an antimony selenide sulfide film, and the film thickness is 230 nm.

[0050] Comparative application example 1 The difference from Application Example 1 is that: the method of Comparative Example 1 is adopted to prepare an antimony selenide sulfide film, and the film thickness is 200 nm.

[0051] It can be seen from the above embodiments that the present invention provides a method and application for regulating the crystallization orientation and defects of antimony selenide sulfide thin films. The present invention regulates the deposition and subsequent crystallization process of hydrothermal antimony selenide sulfide thin films by adding weak acid-base additives composed of polyhedral anions. The size effect of the polyhedral anions inhibits the lateral growth of the ribbons in antimony selenide sulfide, strengthens the [hk1] oriented growth of the film, and significantly improves the crystallinity of the film. In addition, the weak acid and alkalinity can regulate the decomposition rate of the selenium source and the sulfur source, regulate the Se / S ratio of the film, and the polyhedral anions are located in the ribbon gaps, which synergistically reduces the body defects in the film. The method provided by the present invention is simple to operate, safe and controllable. The present invention uses weak acid-base additives composed of polyhedral anions for the first time to regulate the quality of antimony selenide sulfide thin films and use them in solar cells.

[0052] Depend on Figure 1 ~ 10 It can be seen that Figure 1To deposit CdS, the FTO conductive glass was placed in the precursor solution at an angle of about 70°. The reactor was then sealed and placed in a drying oven. The antimony selenide sulfide film was deposited by hydrothermal reaction at 130 °C and kept warm for 140 min. The film was then crystallized and annealed at 350 °C for 10 min. The polyhedral anions were located in the ribbon gaps to regulate the [hk1] oriented growth. Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 As the control group, it is shown that the addition of weakly acidic and alkaline additives with different polyhedral anion compositions can significantly change the growth morphology, grain size and crystallinity of the film. Figure 8 This is the XRD pattern of the control group, which shows that after adding the weak acid-base additive composed of polyhedral anions, strong [hk1] oriented growth is exhibited and the crystallinity is improved. Fig. 9 The defect density calculation diagram of the control group shows that the defect density is significantly reduced after adding weak acid-base additives composed of polyhedral anions. Fig.10 Table 1 shows the JV curve and performance parameters of the champion device. Table 1 shows the EDS elemental composition analysis, which shows that the weak acid-base additive composed of polyhedral anions can adjust the Se / S ratio and control the decomposition rate of the selenium source and sulfur source.

[0053] Table 1 Examples Sb (%) S (%) Se (%) Mo (%) Se / S Comparative application example 1 39.55 43.39 17.06 - 0.39 Application Example 3 39.95 42.83 17.22 - 0.40 The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method and application for regulating the crystallization orientation and defects of antimony selenide sulfide thin films, characterized in that: The following steps are involved: The prepared precursor solution is poured into a hydrothermal reactor, and then a weak acid-base additive composed of polyhedral anions is added, and then the FTO conductive glass deposited with a CdS film is immersed in the reaction precursor solution, the reactor is sealed and placed in a drying oven for hydrothermal reaction, and after the reaction is completed, the film is taken out, washed with deionized water and dried to obtain an amorphous antimony selenide sulfide film; the amorphous antimony selenide sulfide film is subjected to high-temperature annealing treatment to obtain a crystalline antimony selenide sulfide film; the precursor solution contains potassium antimony tartrate, selenourea, sodium selenosulfate and sodium thiosulfate; the weak acid-base additive composed of polyhedral anions is a water-soluble material.

2. The method and application of controlling the crystallization orientation and defects of antimony selenide sulfide thin film according to claim 1, characterized in that: The anions contained in the weak acid and alkaline additive composed of the polyhedral anions are one or more of pyrophosphate, orthosilicate, hypophosphate, tetrametaphosphate, tripolyphosphate, periodate, tetrapolyphosphate, heptamolybdate, decavanadate and dodecamolybdate; the cations contained in the weak acid and alkaline additive composed of the polyhedral anions are one or more of ammonium ions, hydrogen ions, alkali metal ions, alkaline earth metal ions, chromium ions and aluminum ions.

3. The method and application of controlling the crystallization orientation and defects of antimony selenide sulfide thin film according to claim 1, characterized in that: The addition amount of the weak acid and alkaline additive composed of the polyhedral anions is (0.001~20) mg / 40 mL; the molar ratio of the potassium antimony tartrate, selenourea, sodium selenosulfate and sodium thiosulfate is 1:0.3~0.5:0.05~0.3:4~8; the amount of the potassium antimony tartrate is 0.2~0.4 g / 40 mL; the sodium selenosulfate is an aqueous solution with a concentration of (0.01~0.3)mmol / (0.2~3)mL.

4. The method and application of controlling the crystallization orientation and defects of antimony selenide sulfide thin film according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 110 ~ 160 ° C, the hydrothermal reaction time is 1 ~ 24 h, and the heating and cooling rate is 1 ~ 10 ° C / min; the annealing process is carried out in a nitrogen atmosphere, the annealing temperature is 330 ~ 410 ° C, and the annealing time is 5 ~ 10 min.

5. The method and application of controlling the crystallization orientation and defects of antimony selenide sulfide thin film according to claim 1, characterized in that: The thickness of the CdS film is 60 to 80 nm, the thickness of the FTO conductive layer is 400 to 600 nm, and the thickness of the antimony selenide sulfide film is 150 to 300 nm.

6. Antimony selenide sulfide thin film prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the antimony selenide sulfide film according to claim 6 in a solar cell, characterized in that: The solar cell device is in a flat plate shape, with FTO as a cathode, CdS as an electron transport layer, 60-80 nm thick Spiro-OMeTAD as a hole transport layer, 60-100 nm thick gold as an anode, and an antimony selenide sulfide film as a light absorption layer.

8. The use of the antimony selenide sulfide film in a solar cell according to claim 7, characterized in that: The CdS electron transport layer was chemically bath deposited on the FTO cathode, the Spiro-OMeTAD hole transport layer was spin-coated on the antimony selenide sulfide thin film absorption layer, and the gold anode was thermally evaporated on the Spiro-OMeTAD layer.

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