Preparation method of surface-sulfurized copper indium gallium selenide thin film and solar cell

Abstract

The present invention discloses a method for preparing a surface-sulfurized copper indium gallium selenide thin film and a solar cell. The method for preparing the surface-sulfurized copper indium gallium selenide thin film comprises the following steps: providing a substrate having a metal bottom electrode layer on its surface; preparing a copper indium gallium selenide thin film on the metal bottom electrode layer to obtain a substrate having a copper indium gallium selenide thin film on its surface; placing the substrate having the copper indium gallium selenide thin film on its surface in an electrolyte containing elemental sulfur, and using an electrochemical ion extraction process to diffuse the elemental sulfur in the electrolyte to the surface of the copper indium gallium selenide thin film to obtain a surface-sulfurized copper indium gallium selenide thin film. The present invention uses an electrochemical ion extraction process to surface-sulfurize a CIGS thin film, allowing the elemental sulfur in the electrolyte to diffuse to the surface layer of the CIGS thin film. The electrochemical ion extraction process can be performed under low-temperature conditions, which is less difficult than existing high-temperature sulfurization processes and can avoid adverse effects on the structure of the CIGS thin film that may be caused by high temperatures.

Description

Technical Field

[0001] The present invention relates to the field of thin-film solar cells, and in particular to a surface-sulfurized copper indium gallium selenide thin film and a method for preparing a solar cell. Background Art

[0002] Copper indium gallium selenide (CIGS) thin-film solar cells are highly efficient and one of the most promising solar cells currently. They offer advantages such as high power generation, extended daytime power generation, stable power generation, strong light absorption, and high conversion efficiency. The basic structure of a CIGS thin-film solar cell consists of a substrate, back electrode, light absorption layer, buffer layer, window layer, and metal electrode layer stacked in sequence. The light absorption layer is a compound semiconductor thin film composed of four elements: copper, indium, gallium, and selenium.

[0003] Copper indium gallium selenide (CIGS) thin-film solar cells are currently one of the most promising solar cells, but further improvements in cell efficiency are limited by the device's open-circuit voltage. Increasing the band gap of the CIGS absorber layer can improve the open-circuit voltage, but this comes with a corresponding loss of current. Theoretical models and analysis of CIGS cell devices indicate that recombination in the space charge region limits the device's open-circuit voltage. Numerous interface states and defect states exist at the CdS / CIGS interface and near the CIGS surface, serving as primary carrier recombination centers. Increasing the valence band gap near the film and the surface creates a barrier for holes, effectively reducing carrier recombination at the CdS / CIGS interface and near the surface, thereby increasing the open-circuit voltage without photocurrent loss. Therefore, the band structure of the film surface significantly influences cell performance. Surface sulfurization not only increases the surface conduction band, facilitating electron transport, but also reduces the valence band gap, forming a hole barrier, thereby improving device performance. Existing research has shown that sulfur doping (surface sulfurization) of the CIGS light-absorbing layer is an effective method for increasing the surface band gap and improving cell performance, significantly enhancing the conversion efficiency of CIGS thin-film solar cells. S doping can adjust the CIGS band gap from 1.0-1.68eV to 1.0-2.43eV, thereby changing the band gap on the CIGS absorber surface and improving solar light utilization and cell efficiency. (X is [Ga] / ([Ga]+[In]) and Y is [S] / ([S]+[Se]).

[0004]

[0005] The main methods for doping the CIGS light-absorbing layer with sulfur are: (1) annealing the CIGS thin film at high temperature in an H2S atmosphere or sulfur vapor; (2) directly evaporating In2S3 after CIGS thin film deposition; and (3) wet deposition of Group III (In, Ga, Al, Y) sulfides via CBD. All of the above surface methods require doping under high-temperature process conditions or water bath conditions to achieve sufficient surface sulfurization. High-temperature process conditions require precise control of process parameters, increasing the process difficulty. Otherwise, the high temperature may adversely affect the structure of the CIGS light-absorbing layer (especially the lattice structure), failing to achieve the goal of improving the efficiency of CIGS thin-film solar cells.

[0006] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0007] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a surface-sulfurized copper indium gallium selenide film and a solar cell, aiming to solve the problem that the surface sulfurization method of the existing CIGS film needs to be carried out under high-temperature process conditions, resulting in greater process difficulty.

[0008] The technical solutions of the present invention are as follows:

[0009] A method for preparing a surface-sulfurized copper indium gallium selenide thin film, comprising the steps of:

[0010] Providing a substrate having a metal bottom electrode layer on its surface;

[0011] preparing a copper indium gallium selenide thin film on the metal bottom electrode layer to obtain a substrate having the copper indium gallium selenide thin film on the surface;

[0012] The substrate with the copper indium gallium selenide thin film on its surface is placed in an electrolyte containing sulfur, and the sulfur element in the electrolyte is diffused to the surface of the copper indium gallium selenide thin film through an electrochemical ion extraction process to obtain a surface-sulfurized copper indium gallium selenide thin film.

[0013] Optionally, the electrochemical ion extraction process includes: using the substrate having the copper indium gallium selenide thin film on the surface as the positive electrode, providing a conductive electrode as the negative electrode, discharging the copper indium gallium selenide thin film in the electrolyte, so that the sulfur element in the electrolyte diffuses to the surface of the copper indium gallium selenide thin film.

[0014] Optionally, the discharge current of the copper indium gallium selenide film is 80-120 μA, and the discharge time T is T=S×t; wherein S is the area of ​​the copper indium gallium selenide film immersed in the electrolyte, and t is the charging time per unit area, t=17.6s.

[0015] Optionally, the electrolyte includes a solvent and a compound containing elemental sulfur dissolved in the solvent, and the compound containing elemental sulfur is at least one of Na2S, K2S, and Na2S4.

[0016] Optionally, the concentration of the compound containing elemental sulfur in the electrolyte is 0.01-0.5 mol / L.

[0017] Optionally, the solvent is a mixed solvent consisting of EC, DMC, EMC and DEC, and the volume ratio of EC, DMC, EMC and DEC is 1:1:1:1.

[0018] A method for preparing a solar cell based on a surface-sulfurized copper indium gallium selenide thin film, comprising the step of preparing the surface-sulfurized copper indium gallium selenide thin film. The method for preparing the surface-sulfurized copper indium gallium selenide thin film is the method for preparing the surface-sulfurized copper indium gallium selenide thin film described in the present invention.

[0019] Optionally, the method for preparing the solar cell specifically comprises the steps of:

[0020] Providing a substrate, and preparing a metal bottom electrode layer on the substrate;

[0021] Preparing a copper indium gallium selenide thin film on the metal bottom electrode layer to obtain the substrate having the copper indium gallium selenide thin film on the surface;

[0022] placing the substrate having the copper indium gallium selenide thin film on the surface thereof in an electrolyte containing elemental sulfur, and diffusing the elemental sulfur in the electrolyte to the surface of the copper indium gallium selenide absorption layer through an electrochemical ion extraction process to obtain a surface-sulfurized copper indium gallium selenide thin film;

[0023] preparing a buffer layer on the surface-sulfurized copper indium gallium selenide film;

[0024] preparing a window layer on the buffer layer;

[0025] A metal top electrode layer is prepared on the window layer to obtain the solar cell.

[0026] Optionally, the metal bottom electrode layer includes a first Mo thin film layer and a second Mo thin film layer stacked sequentially on the substrate; the metal top electrode layer includes a first Ni thin film layer, an Al thin film layer and a second Ni thin film layer stacked sequentially on the window layer.

[0027] Optionally, the buffer layer is a CdS buffer layer;

[0028] The window layer includes an i-ZnO thin film layer and an AZO thin film layer sequentially stacked on the buffer layer.

[0029] Beneficial Effects: The method for preparing a surface-sulfurized copper indium gallium selenide thin film provided by the present invention involves preparing a CIGS thin film on a substrate and then surface-sulfurizing the CIGS thin film through an electrochemical ion extraction process, allowing sulfur in the electrolyte to diffuse into the surface layer of the CIGS thin film. This electrochemical ion extraction process can be performed at low temperatures (e.g., room temperature), making it less complex than existing high-temperature sulfurization processes and avoiding potential adverse effects on the CIGS thin film structure caused by high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of an electrochemical device for preparing a surface-sulfurized copper indium gallium selenide thin film according to an embodiment of the present invention.

[0031] Figure 2 Schematic diagram of preparing a surface-sulfurized copper indium gallium selenide thin film using an electrochemical ion extraction process according to an embodiment of the present invention.

[0032] Figure 3 JV curves of solar cells of Example and Comparative Example. DETAILED DESCRIPTION

[0033] The present invention provides a method for preparing a surface-sulfurized copper indium gallium selenide thin film and a solar cell. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0034] An embodiment of the present invention provides a method for preparing a surface-sulfurized copper indium gallium selenide thin film, comprising the steps of:

[0035] Providing a substrate having a metal bottom electrode layer on its surface;

[0036] preparing a copper indium gallium selenide thin film on the metal bottom electrode layer to obtain a substrate having the copper indium gallium selenide thin film on the surface;

[0037] The substrate with the copper indium gallium selenide thin film on its surface is placed in an electrolyte containing sulfur, and the sulfur element in the electrolyte is diffused to the surface of the copper indium gallium selenide thin film through an electrochemical ion extraction process to obtain a surface-sulfurized copper indium gallium selenide thin film.

[0038] This embodiment provides a method for preparing a surface-sulfurized copper indium gallium selenide thin film. After a CIGS thin film is formed on a substrate, the CIGS thin film is surface-sulfurized using an electrochemical ion extraction process, allowing sulfur in the electrolyte to diffuse into the surface layer of the CIGS film. This electrochemical ion extraction process can be performed at low temperatures (e.g., room temperature), making it less complex than existing high-temperature sulfurization processes and avoiding potential structural damage to the CIGS film caused by high temperatures.

[0039] In some embodiments, the electrochemical ion extraction process includes: using the substrate having the copper indium gallium selenide thin film on the surface as the positive electrode, providing a conductive electrode as the negative electrode, discharging the copper indium gallium selenide thin film in the electrolyte, so that the sulfur element in the electrolyte diffuses to the surface of the copper indium gallium selenide thin film.

[0040] It should be noted that the voltage is applied between the conductive electrode as the negative electrode and the metal bottom electrode layer on the substrate as the positive electrode. In a preferred embodiment, the conductive electrode as the negative electrode is graphite.

[0041] In some embodiments, the discharge current of the CIGS film is 80-120 μA (preferably 100 μA), and the discharge time T is T=S×t; wherein S is the area of ​​the CIGS film immersed in the electrolyte, and t is the charging time per unit area, t=17.6s.

[0042] In some embodiments, the electrolyte includes a solvent and a compound containing elemental sulfur dissolved in the solvent, and the compound containing elemental sulfur is at least one of Na2S, K2S, and Na2S4.

[0043] In some embodiments, the concentration of the compound containing elemental sulfur in the electrolyte is 0.01-0.5 mol / L.

[0044] In some embodiments, the solvent is a mixed solvent consisting of EC, DMC, EMC and DEC, and the volume ratio of EC, DMC, EMC and DEC is 1:1:1:1.

[0045] In some embodiments, after the electrochemical ion extraction process is completed, the substrate is removed and the surface of the surface-sulfurized copper indium gallium selenide thin film is cleaned with dimethyl carbonate to remove residual electrolyte.

[0046] An embodiment of the present invention provides a method for preparing a solar cell based on a surface-sulfurized copper indium gallium selenide thin film, which includes a step of preparing a surface-sulfurized copper indium gallium selenide thin film. The method for preparing the surface-sulfurized copper indium gallium selenide thin film is the method for preparing the surface-sulfurized copper indium gallium selenide thin film described in an embodiment of the present invention.

[0047] In some embodiments, the method for preparing a solar cell specifically comprises the steps of:

[0048] Providing a substrate, and preparing a metal bottom electrode layer on the substrate;

[0049] Preparing a copper indium gallium selenide thin film on the metal bottom electrode layer to obtain the substrate having the copper indium gallium selenide thin film on the surface;

[0050] placing the substrate having the copper indium gallium selenide thin film on the surface thereof in an electrolyte containing elemental sulfur, and diffusing the elemental sulfur in the electrolyte to the surface of the copper indium gallium selenide absorption layer through an electrochemical ion extraction process to obtain a surface-sulfurized copper indium gallium selenide thin film;

[0051] preparing a buffer layer on the surface-sulfurized copper indium gallium selenide film;

[0052] preparing a window layer on the buffer layer;

[0053] A metal top electrode layer is prepared on the window layer to obtain the solar cell.

[0054] The method for fabricating a solar cell based on a surface-sulfurized CIGS thin film provided in this embodiment comprises: after forming a CIGS thin film (serving as a light-absorbing layer) on a substrate, the CIGS thin film is surface-sulfurized using an electrochemical ion extraction process. This allows sulfur in the electrolyte to diffuse into the surface layer of the CIGS film, increasing the surface band gap, improving the device's open-circuit voltage (Voc) and fill factor (FF), and thereby enhancing the efficiency of the solar cell based on the surface-sulfurized CIGS thin film. The electrochemical ion extraction process can be performed at low temperatures (e.g., room temperature), making it less complex than existing high-temperature sulfurization processes and avoiding potential adverse effects on the CIGS thin film structure caused by high temperatures.

[0055] In some embodiments, the metal bottom electrode layer includes a first Mo thin film layer and a second Mo thin film layer sequentially stacked on the substrate. Providing the first Mo thin film layer first can improve adhesion between the Mo film and the substrate. Providing the second Mo thin film layer later can improve the conductivity of the Mo electrode.

[0056] In some embodiments, the metal bottom electrode layer may be formed on the substrate by a magnetron sputtering process.

[0057] In some embodiments, the copper indium gallium selenide thin film may be formed on the metal bottom electrode layer by using a co-evaporation process.

[0058] In some embodiments, the buffer layer is a CdS buffer layer.

[0059] In some embodiments, the buffer layer may be formed on the surface-sulfurized copper indium gallium selenide film by using a chemical water bath deposition process.

[0060] In some embodiments, the window layer includes an i-ZnO thin film layer and an AZO thin film layer sequentially stacked on the buffer layer.

[0061] In some embodiments, the window layer may be formed on the buffer layer by using a magnetron sputtering process.

[0062] In some embodiments, the metal top electrode layer includes a first Ni thin film layer, an Al thin film layer, and a second Ni thin film layer sequentially stacked on the window layer, wherein Ni may be replaced by Au or Ag, etc. without limitation.

[0063] In some embodiments, the metal top electrode layer may be formed on the window layer by using an electron beam thermal evaporation process.

[0064] In some embodiments, the metal top electrode layer may be formed on the window layer by using an electron beam thermal evaporation process.

[0065] The present invention will be further described below with reference to specific examples.

[0066] Example

[0067] Combine Figure 1-2 As shown, the method for preparing a solar cell based on a copper indium gallium selenide thin film of this embodiment comprises the following specific steps:

[0068] 1. Select soda-lime glass with a size of 10 cm × 10 cm × 2 mm as the substrate. Rinse it with plenty of deionized water, wipe it with dust-free paper dampened with water, then wipe it with dust-free paper containing a solution of cleaning powder, rinse it with plenty of deionized water, blow dry it with nitrogen, place it in a high vacuum injection chamber, and bake it for 10 minutes to remove moisture.

[0069] 2. Using the DC magnetron sputtering process, first sputter 45 times at a working pressure of 1.0Pa and a sputtering power of 350W to deposit a loose layer to improve the adhesion between the Mo film and the substrate. Then, sputter 5 times at a working pressure of 0.3Pa and a sputtering power of 800W to deposit a dense layer to improve the conductivity of the Mo electrode.

[0070] 3. The substrate, after sputtering to form a metal bottom electrode layer, was placed in the chamber of an MBE (molecular beam epitaxy) instrument. A copper indium gallium selenide (CIGS) absorber layer (i.e., a CIGS thin film) was deposited on the metal bottom electrode layer using a three-step co-evaporation process. The specific process for this step was carried out according to existing techniques, resulting in a CIGS absorber layer with a thickness of 1 μm. The entire process was carried out in an atmosphere with a sufficient amount of Se.

[0071] 4. Placing the CIGS absorber layer in an electrolyte containing sulfur, and using an electrochemical ion extraction process to diffuse the sulfur in the electrolyte to the surface of the CIGS absorber layer. Specifically, the electrochemical ion extraction process includes: using the CIGS absorber layer as the positive electrode, providing a conductive electrode as the negative electrode, and discharging the CIGS absorber layer in the electrolyte to diffuse the sulfur in the electrolyte to the surface of the CIGS absorber layer. It should be noted that the CIGS absorber layer, specifically the substrate after the CIGS absorber layer is formed, serves as the positive electrode. A voltage is applied between the conductive electrode, serving as the negative electrode, and a metal bottom electrode layer on the substrate, serving as the positive electrode. The conductive electrode serving as the negative electrode is graphite. The discharge current for discharging the CIGS absorber layer is 100 μA, and the discharge time T is T = S × t, where S is the area of ​​the CIGS absorber layer immersed in the electrolyte, and t = 17.6 s.

[0072] The electrolyte comprises a solvent and a sulfur-containing compound dissolved in the solvent. The sulfur-containing compound is Na2S, and the concentration of the sulfur-containing compound in the electrolyte is 0.1 mol / L. The solvent is a mixed solvent of EC:DMC:EMC:DEC = 1:1:1:1 by volume, i.e., a mixed solvent with a volume ratio of EC, DMC, EMC, and DEC of 1:1:1:1.

[0073] After the electrochemical ion extraction process is completed, the substrate is removed and the surface of the CIGS absorber layer is cleaned with dimethyl carbonate to remove residual electrolyte.

[0074] 5. First, prepare the reaction solution. The reaction solution includes: cadmium sulfate (CdSO4) solution (CdSO4 mass 0.184g, CdSO4 solution volume 60mL), thiourea (CH4N2S) solution (CH4N2S mass 5.694g, CH4N2S solution volume 150mL), concentrated ammonia (NH3·H2O) (45mL), and deionized water (450mL). Heat the external water bath to 69°C and maintain this temperature. Place the CIGS sample prepared in step 4 in a large beaker and then pour the reaction solution into it. Next, place the beaker in the external water bath, turn on the magnetic stirrer, and time the reaction with a stopwatch. The reaction time is 9 minutes, and the deposited CdS film thickness is approximately 50nm. Rinse the sample surface with deionized water and blow dry with high-pressure N2 gas. Then, quickly place the sample in a 150°C oven and anneal for 2 minutes before removing it.

[0075] 6. Use radio frequency magnetron sputtering technology to prepare i-ZnO thin film layers and AZO thin film layers. Use intrinsic ZnO target (purity is 99.99%) to prepare i-ZnO, and use ZnO:Al2O3 target (doped with 2wt% Al2O3) to prepare AZO.-5 Under a vacuum of 1.5 Pa, the sample is placed on a heating furnace plate. After adjusting the process parameters, the carriage performs a periodic back-and-forth motion over the target. After sputtering is complete, a combined i-ZnO and AZO window layer with a thickness of approximately 450 nm is obtained.

[0076] 7. Cover the prepared mask on the sample surface, and evaporate the metal in the crucible by adjusting the beam position and electron beam current, and deposit Ni, Al, and Ni metal sources in sequence. The thickness of the first layer of Ni electrode is The thickness of the Al electrode is The thickness of the final evaporated Ni electrode is Complete the preparation of solar cells based on copper indium gallium selenide thin films.

[0077] Comparative Example

[0078] The method is basically the same as the embodiment, except that step 4 is not performed (ie, the copper indium gallium selenide absorber layer is not sulfurized).

[0079] The solar cells of the embodiment and the comparative example were tested for performance. The test results are shown in FIG. Figure 3 As shown, from Figure 3 It can be seen that the performance of CIGS solar cells after surface sulfurization treatment is significantly improved. Specifically, the device's open-circuit voltage (Voc) and fill factor (FF) are increased, thereby improving device performance. This is because surface sulfurization changes the surface band gap and surface structure, increasing the CIGS surface conduction band, thereby enhancing electron transport, and reducing the hole barrier formed in the valence band, thereby increasing the open-circuit voltage without losing photocurrent.

[0080] In summary, the present invention discloses a method for preparing a solar cell based on a surface-sulfurized CIGS thin film. After preparing a CIGS thin film on a substrate, the CIGS thin film is surface-sulfurized using an electrochemical ion extraction process. This allows sulfur in the electrolyte to diffuse into the surface layer of the CIGS film, increasing the surface band gap and improving the device's open-circuit voltage (Voc) and fill factor (FF), thereby enhancing the efficiency of the solar cell based on the surface-sulfurized CIGS thin film. The electrochemical ion extraction process can be performed at low temperatures (e.g., room temperature), making it less complex than existing high-temperature sulfurization processes and avoiding potential adverse effects on the CIGS thin film structure caused by high temperatures.

[0081] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a surface-sulfurized copper indium gallium selenide thin film, characterized in that: Including steps: Providing a substrate having a metal bottom electrode layer on its surface; preparing a copper indium gallium selenide thin film on the metal bottom electrode layer to obtain a substrate having the copper indium gallium selenide thin film on the surface; placing the substrate having the copper indium gallium selenide thin film on the surface thereof in an electrolyte containing elemental sulfur, and diffusing the elemental sulfur in the electrolyte to the surface of the copper indium gallium selenide thin film through an electrochemical ion extraction process to obtain a surface-sulfurized copper indium gallium selenide thin film; The electrochemical ion extraction process includes: using the substrate having the copper indium gallium selenide film on the surface as the positive electrode, providing a conductive electrode as the negative electrode, discharging the copper indium gallium selenide film in the electrolyte, so that the sulfur element in the electrolyte diffuses to the surface of the copper indium gallium selenide film.

2. The method for preparing a surface-sulfurized copper indium gallium selenide thin film according to claim 1, characterized in that: The discharge current of the CIGS film is 80-120 μA, and the discharge time T is T=S×t; wherein S is the area of ​​the CIGS film immersed in the electrolyte, and t is the charging time per unit area, t=17.6 s.

3. The method for preparing a surface-sulfurized copper indium gallium selenide thin film according to claim 1, wherein: The electrolyte includes a solvent and a compound containing sulfur dissolved in the solvent, and the compound containing sulfur is at least one of Na2S, K2S, and Na2S4.

4. The method for preparing a surface-sulfurized copper indium gallium selenide thin film according to claim 3, wherein: The concentration of the compound containing elemental sulfur in the electrolyte is 0.01-0.5 mol / L.

5. The method for preparing a surface-sulfurized copper indium gallium selenide thin film according to claim 3, characterized in that: The solvent is a mixed solvent consisting of EC, DMC, EMC and DEC, and the volume ratio of EC, DMC, EMC and DEC is 1:1:1:

1.

6. A method for preparing a solar cell based on a surface-sulfurized copper indium gallium selenide thin film, characterized in that: The method comprises the steps of preparing a surface-sulfurized copper indium gallium selenide film, wherein the preparation method of the surface-sulfurized copper indium gallium selenide film is the preparation method according to any one of claims 1 to 5.

7. The method for preparing a solar cell based on a surface-sulfurized copper indium gallium selenide thin film according to claim 6, characterized in that: The method for preparing the solar cell specifically comprises the steps of: Providing a substrate, and preparing a metal bottom electrode layer on the substrate; Preparing a copper indium gallium selenide thin film on the metal bottom electrode layer to obtain the substrate having the copper indium gallium selenide thin film on the surface; placing the substrate having the copper indium gallium selenide thin film on the surface thereof in an electrolyte containing elemental sulfur, and diffusing the elemental sulfur in the electrolyte to the surface of the copper indium gallium selenide absorption layer through an electrochemical ion extraction process to obtain a surface-sulfurized copper indium gallium selenide thin film; preparing a buffer layer on the surface-sulfurized copper indium gallium selenide film; preparing a window layer on the buffer layer; A metal top electrode layer is prepared on the window layer to obtain the solar cell.

8. The method for preparing a solar cell based on surface sulfided copper indium gallium selenide thin film according to claim 7, characterized in that: The metal bottom electrode layer includes a first Mo thin film layer and a second Mo thin film layer sequentially stacked on the substrate; the metal top electrode layer includes a first Ni thin film layer, an Al thin film layer and a second Ni thin film layer sequentially stacked on the window layer.

9. The method for preparing a solar cell based on surface sulfided copper indium gallium selenide thin film according to claim 7, characterized in that: The buffer layer is a CdS buffer layer; The window layer includes an i-ZnO thin film layer and an AZO thin film layer sequentially stacked on the buffer layer.

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