Buffer layer, copper indium gallium selenide thin film solar cell and preparation method thereof

Abstract

The buffer layer, copper indium gallium selenide thin film solar cell and preparation method provided in the present application are to deposit Zn on the CIGS absorption layer by radio frequency magnetron sputtering. 1‑x Al x (O, S) buffer layer; wherein: in the RF magnetron sputtering method, the working gas is argon and H2S, the argon and H2S flow rate control ratio is in the range of 15:1-30:1, and the S / (S+O) is adjusted by controlling the flow rate of argon and H2S, so that Zn 1‑ x Al x The (O,S) buffer layer and the absorption layer can have a better match, the transmittance of the buffer layer in the visible light region can reach more than 90%, and the optical band gap width of the prepared copper indium gallium selenide thin-film solar cell is between 2.6 and 3.8 eV.

Description

Technical Field

[0001] The present application relates to the technical field of thin-film solar cells, and in particular to a buffer layer, a copper indium gallium selenide thin-film solar cell, and a preparation method thereof. Background Art

[0002] In the 21st century, photovoltaic power generation is an indispensable component of sustainable development as a new energy source. Over the past decade or so, global solar power supply has maintained a robust annual growth rate of 20% to 30%. Although thin-film solar modules hold a relatively small market share, their absolute growth has significantly increased. A-Si, CdTe, and CIGS solar modules have achieved commercial mass production. Over the past decade or so, thanks to a series of innovative research results, small-area CdTe, CIGS, and PSC thin-film solar cells have achieved conversion efficiencies exceeding 22%.

[0003] Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells have long been considered one of the most promising renewable energy technologies due to their excellent optoelectronic performance, potential low cost, and great flexibility for large-scale production. The highest efficiency achieved to date for CIGSSe solar cells is 23.35%. CdS is the most widely studied and used buffer layer in conventional high-efficiency CIGSSe solar cells, but CdS poses a potential environmental threat. Over the past few decades, many researchers have shown significant interest in developing environmentally friendly buffer layers to replace CdS. Zinc-based semiconductors, including ZnS, Zn(O,S), and ZnMgO, are important alternative candidates. To date, Zn(O,S) layers grown via chemical bath deposition (CBD) appear to be the most successful competitor to CdS. Zn(O,S) is non-toxic and has a tunable band gap (Eg) between 2.6 and 3.8 eV. Therefore, Zn(O,S) should offer higher transparency to the solar spectrum than CdS, thereby reducing optical losses, particularly in the blue wavelength region. Impressively, SolarFrontier reported a single-junction CIGSSe device that demonstrated world-record conversion efficiency using a CBD-Zn(O,S) buffer.

[0004] The disadvantages of the chemical bath deposition (CBD) method are that the obtained film has poor wettability with the coated surface, it is difficult to maintain integrity in a wet state, and it is difficult to form; secondly, a large amount of reactor space is required to place the solution; thirdly, its anti-corrosion effect is poor, especially the dielectric solvent is easy to corrode the hot furnace tube, and there are safety hazards such as increasing the additional maintenance frequency.

[0005] Radio frequency magnetron sputtering is a process for preparing thin films. Especially when using non-conductive materials, the thin film is grown on a substrate placed in a vacuum chamber. Radio frequency magnetron sputtering ionizes the target material, generating a more stable plasma. The bombardment energy of ions is higher than that of medium-frequency sputtering, enabling the preparation of more uniform and dense thin films, which is suitable for preparing some thin films that require high quality and high uniformity, such as metal films, alloy films, piezoelectric films, ferroelectric films, high-temperature superconducting thin films, etc.

[0006] Patent application 202211156879.X provides a copper indium gallium selenide thin film solar cell and its preparation method, depositing Zn by medium-frequency magnetron sputtering , , x , , , , ,

[0014] , <00 ... In 1-x S (0 < x < 1) buffer layer, which not only overcomes the disadvantages of heavy metal cadmium harming human and environmental health and safety, but indium doping also increases the donor concentration of ZnS and promotes carrier transport. However, its light transmittance and energy band width need to be improved. Summary of the Invention

[0007] In view of this, it is necessary to provide a buffer layer, a copper indium gallium selenide thin film solar cell and its preparation method with higher light transmittance and energy band width for the technical problems of lower light transmittance and energy band width existing in the current copper indium gallium selenide thin film solar cell.

[0008] To solve the above problems, the present application adopts the following technical solutions:

[0009] One of the purposes of the present application is to provide a preparation method of a buffer layer, including the following steps:

[0010] Depositing Zn 1-x Al x (O,S) buffer layer on the CIGS absorption layer; where:

[0011] In the radio frequency magnetron sputtering method, the working gas is argon and H2S, and the regulated ratio of the argon to H2S flow rate is in the range of 15:1 - 30:1.

[0012] In some embodiments, the regulated ratio of the argon to H2S flow rate is 60:2.75.

[0013] In some embodiments, the target material for radio frequency magnetron sputtering in the radio frequency magnetron sputtering method is a zinc oxide target doped with alumina, ZnO:Al2O3 = 99:1 wt%.

[0014] In some embodiments, the working temperature in the radio frequency magnetron sputtering method is 25 - 100 degrees Celsius. During the radio frequency sputtering process, first sputter at a low frequency of 120 w for 2 - 3 minutes, and then sputter at a high frequency of 300 w for 3 - 8 minutes.

[0015] In some embodiments, the Zn 1-x Al x The thickness of the (O,S) buffer layer is 40 to 60 nm.

[0016] The second purpose of this application is to provide a buffer layer prepared by the preparation method.

[0017] The third object of the present application is to provide a method for preparing a copper indium gallium selenide thin film solar cell, comprising the following steps:

[0018] providing a substrate;

[0019] Depositing a Mo back electrode on the substrate;

[0020] depositing a CIGS absorption layer on the Mo back electrode;

[0021] Zn was deposited on the CIGS absorber layer by radio frequency magnetron sputtering. 1-x Al x (O, S) buffer layer; wherein: the working gas in the RF magnetron sputtering method is argon and H2S, and the flow rate of argon and H2S is controlled in the range of 15:1-30:1;

[0022] In the Zn 1-x Al x AZO is sputtered on the surface of (O,S) buffer layer;

[0023] An electrode layer is evaporated on the surface of the AZO.

[0024] In some embodiments, the flow rate of argon and H2S is controlled at a ratio of 60:2.75.

[0025] In some embodiments, the target material of the RF magnetron sputtering method is an aluminum oxide-doped zinc oxide target material, ZnO:Al2O3=99:1wt%.

[0026] In some embodiments, in the RF magnetron sputtering method, the operating temperature is 25-100 degrees Celsius, and the RF sputtering process is first performed with a low frequency of 120W for 2-3 minutes, and then with a high frequency of 300W for 3-8 minutes.

[0027] The fourth object of the present application is to provide a copper indium gallium selenide thin film solar cell, which is prepared by the copper indium gallium selenide thin film solar cell preparation method.

[0028] This application adopts the above technical solution, and its beneficial effects are as follows:

[0029] The buffer layer, copper indium gallium selenide thin film solar cell and preparation method provided in the present application are to deposit Zn on the CIGS absorption layer by radio frequency magnetron sputtering.1-x Al x (O, S) buffer layer; wherein: in the RF magnetron sputtering method, the working gas is argon and H2S, the argon and H2S flow rate control ratio is in the range of 15:1-30:1, and the S / (S+O) is adjusted by controlling the flow rate of argon and H2S, so that Zn 1-x Al x The (O,S) buffer layer and the absorption layer can have a better match, the transmittance of the buffer layer in the visible light region can reach more than 90%, and the optical band gap width of the prepared copper indium gallium selenide thin-film solar cell is between 2.6 and 3.8 eV.

[0030] In addition, the buffer layer, copper indium gallium selenide thin-film solar cell and preparation method provided in the present application use Al doping to increase the donor concentration of Zn(O,S) and promote carrier transport; and eliminate the environmental pollution risks of the cadmium-containing buffer layer, which can broaden the response range of the battery to the solar spectrum and become a more ideal material to replace the CdS buffer layer film; in addition, the radio frequency magnetron sputtering process effectively improves the consistency of the preparation process of CIGSSe thin-film solar cell modules, is more convenient for assembly line production, one-time molding, reduces the contamination of samples during transfer between different processes, and improves production efficiency and yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 A flow chart of the steps of a method for preparing a copper indium gallium selenide thin-film solar cell provided in one embodiment of the present invention.

[0033] Figure 2 This is the copper indium gallium selenide thin-film solar cell module structure provided by one embodiment of the present invention.

[0034] Figure 3 Zn prepared in Example 1 of the present invention 1-x Al x Schematic diagram of the transmittance of the (O,S) buffer layer.

[0035] Figure 4 Zn prepared in Example 2 of the present invention 1-x Al x Schematic diagram of the transmittance of the (O,S) buffer layer.

[0036] Figure 5The Zn prepared in Example 3 of the present invention 1-x Al x Schematic diagram of the transmittance of the (O,S) buffer layer.

[0037] Figure 6 The Zn provided in the comparative example of the present invention 1-x Al x Schematic diagram of the (O,S) buffer layer structure. DETAILED DESCRIPTION

[0038] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0039] In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0041] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application will be further described in detail below by taking the multifunctional detection of atherosclerosis in blood vessels as an example, in combination with the accompanying drawings and embodiments.

[0042] The present invention provides a method for preparing a buffer layer, which specifically comprises the following steps: depositing Zn on the CIGS absorption layer by radio frequency magnetron sputtering. 1-x Al x (O, S) buffer layer; in the radio frequency magnetron sputtering method, the working gases are argon and H2S, and the flow rate of the argon and H2S is controlled in the range of 15:1-30:1.

[0043] Specifically, the obtained sample coated with the CIGS absorption layer was placed in a radio frequency magnetron sputtering chamber, and the working gases were argon and H2S. The flow rate ratio of the argon and H2S was controlled in the range of 15:1-30:1.

[0044] It should be noted that: In this application, Zn is deposited on the CIGS absorption layer by radio frequency magnetron sputtering. 1-x Al x (O, S) buffer layer, the flow rate of argon and H2S is controlled in the range of 15:1-30:1, and the S / (S+O) is adjusted by controlling the flow rate of argon and H2S, so that Zn 1-x Al x The (O,S) buffer layer and the absorption layer can have a better match, the transmittance of the buffer layer in the visible light region can reach more than 90%, and the optical band gap width of the prepared copper indium gallium selenide thin-film solar cell is between 2.6 and 3.8 eV.

[0045] In some preferred embodiments, the control ratio of the flow rate of argon and H2S is 60:2.75. 1-x Al x The optical transmittance of the (O,S) buffer layer can reach up to 93%, and the energy band width is 3.1eV.

[0046] In some preferred embodiments, the RF magnetron sputtering target is an aluminum oxide-doped zinc oxide target with a purity of 99.99% zinc oxide: aluminum oxide, ZnO:Al2O3=99:1 wt%.

[0047] It can be understood that the use of the aluminum oxide-doped zinc oxide target in this embodiment increases the donor concentration of Zn(O, S) and promotes carrier transport.

[0048] In some preferred embodiments, in the radio frequency magnetron sputtering method, the operating temperature is 25-100 degrees Celsius, and during the radio frequency sputtering process, low frequency 120W sputtering is first used for 2-3 minutes, and then high frequency 300W sputtering is used for 3-8 minutes.

[0049] It can be understood that in the preparation method of the buffer layer provided in the present application, the temperature during the deposition of the buffer layer is 25-100 degrees Celsius, and no additional heating is required; in the RF sputtering process, low-power sputtering followed by high-power sputtering is beneficial to protecting the CIGS absorption layer and avoiding damage to the absorption layer due to excessive power.

[0050] In this embodiment, the Zn 1-x Al x The thickness of the (O,S) buffer layer is 40 to 60 nm.

[0051] The buffer layer provided in the above embodiment of the present application is deposited on the CIGS absorption layer by radio frequency magnetron sputtering. 1- x Al x(O, S) buffer layer; wherein: in the RF magnetron sputtering method, the working gas is argon and H2S, the argon and H2S flow rate control ratio is in the range of 15:1-30:1, and the S / (S+O) is adjusted by controlling the flow rate of argon and H2S, so that Zn 1-x Al x The (O,S) buffer layer and the absorption layer can have a better match, the transmittance of the buffer layer in the visible light region can reach more than 90%, and the optical band gap width of the prepared copper indium gallium selenide thin-film solar cell is between 2.6 and 3.8 eV.

[0052] See also Figure 1 The present application also provides a method for preparing a copper indium gallium selenide thin-film solar cell, including the following steps S110 to S160. The implementation method of each step is described in detail below.

[0053] Step S110: providing a substrate.

[0054] In this embodiment, the substrate may be ordinary soda-lime glass, or a flexible substrate such as stainless steel foil or titanium foil.

[0055] Step S120: depositing a Mo back electrode layer on the substrate.

[0056] Step S130: depositing a CIGS absorption layer on the Mo back electrode.

[0057] In this embodiment, a CIGS absorption layer is deposited on the Mo back electrode of the substrate through a three-step co-evaporation process to form a light absorption layer with a thickness of about 2 μm.

[0058] Step S140: Depositing Zn on the CIGS absorption layer by RF magnetron sputtering 1-x Al x (O, S) buffer layer; wherein: the working gases in the radio frequency magnetron sputtering method are argon and H2S, and the flow rate control ratio of the argon and H2S is in the range of 15:1-30:1.

[0059] Specifically, the obtained sample coated with the CIGS absorption layer was placed in a radio frequency magnetron sputtering chamber, and the working gases were argon and H2S. The flow rate ratio of the argon and H2S was controlled in the range of 15:1-30:1.

[0060] It should be noted that: In this application, Zn is deposited on the CIGS absorption layer by radio frequency magnetron sputtering. 1-x Al x (O, S) buffer layer, the flow rate of argon and H2S is controlled in the range of 15:1-30:1, and the S / (S+O) is adjusted by controlling the flow rate of argon and H2S, so that Zn 1-x Al xThe (O,S) buffer layer and the absorption layer can have a better match, the transmittance of the buffer layer in the visible light region can reach more than 90%, and the optical band gap width of the prepared copper indium gallium selenide thin-film solar cell is between 2.6 and 3.8 eV.

[0061] In some preferred embodiments, the control ratio of the flow rate of argon and H2S is 60:2.75. 1-x Al x The optical transmittance of the (O,S) buffer layer can reach up to 93%, and the energy band width is 3.1eV.

[0062] In some preferred embodiments, the RF magnetron sputtering target is an aluminum oxide-doped zinc oxide target with a purity of 99.99% zinc oxide: aluminum oxide, ZnO:Al2O3=99:1 wt%.

[0063] It can be understood that the use of the aluminum oxide-doped zinc oxide target in this embodiment increases the donor concentration of Zn(O, S) and promotes carrier transport.

[0064] In some preferred embodiments, in the radio frequency magnetron sputtering method, the operating temperature is 25-100 degrees Celsius, and during the radio frequency sputtering process, low frequency 120W sputtering is first used for 2-3 minutes, and then high frequency 300W sputtering is used for 3-8 minutes.

[0065] It can be understood that in the preparation method of the buffer layer provided in the present application, the temperature during the deposition of the buffer layer is 25-100 degrees Celsius, and no additional heating is required; in the RF sputtering process, low-power sputtering followed by high-power sputtering is beneficial to protecting the CIGS absorption layer and avoiding damage to the absorption layer due to excessive power.

[0066] In this embodiment, the Zn 1-x Al x The thickness of the (O,S) buffer layer is 40 to 60 nm.

[0067] Step S150: In the Zn 1-x Al x An AZO layer is sputtered on the surface of the (O,S) buffer layer.

[0068] In this embodiment, the sample obtained in step S140 is placed in a radio frequency magnetron sputtering chamber, and filled with argon and hydrogen at a flow ratio of 20:1. 1-x Al x 200 nm of AZO was sputtered on the surface of the (O,S) buffer layer.

[0069] Step S160: evaporating an electrode layer on the surface of the AZO.

[0070] In this embodiment, 150 nm of Ni and 10,000 nm of Al were evaporated on the surface of the AZO sample by a thermal evaporation method as the cathode of the CIGSSe battery.

[0071] See also Figure 2 , which is the copper indium gallium selenide thin film solar cell module structure provided in another embodiment of the present application, can be divided into a substrate 110, a Mo back electrode layer 120, a light absorbing layer 130, a Zn 1-x Al x The (O, S) buffer layer 140, the AZO layer 150 and the electrode layer 160. The detailed implementation thereof can refer to the preparation method of the copper indium gallium selenide thin film solar cell provided in the above embodiment, which will not be described in detail here.

[0072] The above embodiment of the present application provides a copper indium gallium selenide thin film solar cell and a preparation method thereof, wherein Zn is deposited on the CIGS absorber layer by radio frequency magnetron sputtering. 1-x Al x (O, S) buffer layer; wherein: in the RF magnetron sputtering method, the working gas is argon and H2S, the argon and H2S flow rate control ratio is in the range of 15:1-30:1, and the S / (S+O) is adjusted by controlling the flow rate of argon and H2S, so that Zn 1-x Al x The (O,S) buffer layer and the absorption layer can have a better match, the transmittance of the buffer layer in the visible light region can reach more than 90%, and the optical band gap width of the prepared copper indium gallium selenide thin-film solar cell is between 2.6 and 3.8 eV.

[0073] In addition, the copper indium gallium selenide thin-film solar cell and preparation method provided in the present application use Al doping to increase the donor concentration of Zn(O,S) and promote carrier transport; and eliminate the environmental pollution risks of the cadmium-containing buffer layer, which can broaden the response range of the battery to the solar spectrum and become a more ideal material to replace the CdS buffer layer film; in addition, the radio frequency magnetron sputtering process effectively improves the consistency of the preparation process of CIGSSe thin-film solar cell modules, is more convenient for assembly line production, one-time molding, reduces the contamination of samples during transfer between different processes, and improves production efficiency and yield.

[0074] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0075] Example 1

[0076] Step 1: Deposit a CIGS absorption layer sample on the Mo back electrode of a glass substrate through a three-step co-evaporation process, with a light absorption layer thickness of about 2μm.

[0077] Step 2: Preparation of Zn 1-x Alx (O,S) buffer layer.

[0078] The sample coated with the CIGS absorption layer obtained in step 1 was placed in an RF magnetron sputtering chamber. The working gases were argon and H2S, with an argon flow rate of 60 sccm, an H2S flow rate of 2.75 sccm, an RF sputtering power of 120 W for 2 min, and an RF sputtering power of 300 W for 6 min to obtain a 50 nm Zn1-xAlx(O,S) buffer layer.

[0079] Step 3: Prepare the window layer and the transparent conductive layer.

[0080] The sample obtained in step 2 was placed in a radio frequency magnetron sputtering chamber and filled with argon and hydrogen at a flow ratio of 20:1. 1-x Al x 200 nm of AZO was sputtered on the surface of the (O,S) buffer layer.

[0081] Step 4: Prepare the gate by thermal evaporation on the surface of the AZO sample obtained in step 3 to deposit 150 nm of Ni and 10,000 nm of Al as the cathode of the CIGSSe battery.

[0082] See also Figure 3 , is the Zn prepared in step 2 of Example 1 1-x Al x From the transmittance of the (O, S) buffer layer, it can be clearly seen that the transmittance of the buffer layer prepared by the present invention in the visible light region can reach more than 90%.

[0083] Example 2

[0084] Step 1: A CIGS absorption layer sample was deposited on the Mo back electrode of a stainless steel foil substrate through a three-step co-evaporation process. The light absorption layer had a thickness of about 2 μm.

[0085] The sample coated with the CIGS absorption layer obtained in step 1 was placed in an RF magnetron sputtering chamber. The working gases were argon and H2S, with an argon flow rate of 15 sccm, an H2S flow rate of 1 sccm, an RF sputtering power of 120 W for 3 minutes, and an RF sputtering power of 300 W for 3 minutes to obtain a 40 nm Zn1-xAlx(O,S) buffer layer.

[0086] See also Figure 4 , which is a schematic diagram of the transmittance of the Zn1-xAlx(O,S) buffer layer prepared in Example 2. It can be clearly seen that the transmittance of the buffer layer prepared in the present invention in the visible light region can reach more than 80%.

[0087] Example 3

[0088] Step 1: Deposit a CIGS absorption layer sample on the Mo back electrode of the titanium foil substrate through a three-step co-evaporation process, with a light absorption layer thickness of about 2μm.

[0089] The sample coated with the CIGS absorption layer obtained in step 1 was placed in an RF magnetron sputtering chamber. The working gases were argon and H2S, with an argon flow rate of 30 sccm, an H2S flow rate of 1 sccm, an RF sputtering power of 120 W for 2.5 min, and an RF sputtering power of 300 W for 8 min to obtain a 60 nm Zn1-xAlx(O,S) buffer layer.

[0090] See also Figure 5 , which is a schematic diagram of the transmittance of the Zn1-xAlx(O,S) buffer layer prepared in Example 3. It can be clearly seen that the transmittance of the buffer layer prepared in the present invention in the visible light region can reach more than 80%.

[0091] Comparative Example

[0092] Step 1: Deposit a CIGS absorption layer sample on the Mo back electrode of a glass substrate through a three-step co-evaporation process, with a light absorption layer thickness of about 2μm.

[0093] The sample coated with the CIGS absorption layer obtained in step 1 was placed in an RF magnetron sputtering chamber. The working gases were argon and H2S, with an argon flow rate of 60 sccm, an H2S flow rate of 2.75 sccm, an RF sputtering power of 300 W for 2 minutes, and an RF sputtering power of 200 W for 8 minutes to obtain a 50 nm Zn1-xAlx(O,S) buffer layer.

[0094] See also Figure 6 , which is the Zn1-xAlx(O,S) buffer layer prepared in the comparative example, it can be seen that the absorption layer has been greatly damaged.

[0095] It can be understood that the various technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above are merely preferred embodiments of the present application and only specifically describe the technical principles of the present application. These descriptions are intended only to explain the principles of the present application and should not be construed in any way as limiting the scope of protection of the present application. Based on the explanations herein, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application, as well as other specific implementations of the present application that can be conceived by those skilled in the art without inventive effort, shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a buffer layer, characterized in that: The steps include: Deposition of Zn on CIGS absorber layer by RF magnetron sputtering 1-x Al x (O,S) buffer layer; wherein: In the radio frequency magnetron sputtering method, the working gases are argon and H2S, and the flow rate ratio of the argon and H2S is controlled in the range of 15:1-30:

1.

2. The method for preparing a buffer layer according to claim 1, wherein: The control ratio of the argon gas and H2S flow rates is 60:2.

75.

3. The method for preparing a buffer layer according to claim 1, wherein: In the radio frequency magnetron sputtering method, the target material of the radio frequency magnetron sputtering is a zinc oxide target material doped with aluminum oxide, ZnO:Al2O3=99:1wt%.

4. The method for preparing a buffer layer according to claim 1, wherein: In the radio frequency magnetron sputtering method, the working temperature is 25-100 degrees Celsius. During the radio frequency sputtering process, low frequency 120W sputtering is first used for 2-3 minutes, and then high frequency 300W sputtering is used for 3-8 minutes.

5. The method for preparing a buffer layer according to claim 1, wherein: The Zn 1-x Al x The thickness of the (O,S) buffer layer is 40 to 60 nm.

6. A buffer layer, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 5.

7. A method for preparing a copper indium gallium selenide thin film solar cell, characterized in that: The following steps are involved: providing a substrate; Depositing a Mo back electrode on the substrate; depositing a CIGS absorption layer on the Mo back electrode; Zn was deposited on the CIGS absorber layer by radio frequency magnetron sputtering. 1-x Al x (O, S) buffer layer; wherein: the working gas in the RF magnetron sputtering method is argon and H2S, and the flow rate of argon and H2S is controlled in the range of 15:1-30:1; In the Zn 1-x Al x AZO is sputtered on the surface of (O,S) buffer layer; An electrode layer is evaporated on the surface of the AZO.

8. The method for preparing a copper indium gallium selenide thin film solar cell according to claim 7, wherein: The control ratio of the argon gas and H2S flow rates is 60:2.

75.

9. The method for preparing a copper indium gallium selenide thin film solar cell according to claim 7, wherein: In the radio frequency magnetron sputtering method, the target material of the radio frequency magnetron sputtering is a zinc oxide target material doped with aluminum oxide, ZnO:Al2O3=99:1wt%.

10. The method for preparing a copper indium gallium selenide thin film solar cell according to claim 7, wherein: In the radio frequency magnetron sputtering method, the working temperature is 25-100 degrees Celsius. During the radio frequency sputtering process, low frequency 120W sputtering is first used for 2-3 minutes, and then high frequency 300W sputtering is used for 3-8 minutes.

11. A copper indium gallium selenide thin film solar cell, characterized in that: The copper indium gallium selenide thin film solar cell is prepared by the preparation method of any one of claims 7 to 8.

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