Preparation method of copper-indium-gallium-sulfur-selenium solar cell and solar cell

Abstract

The invention provides a preparation method of a copper-indium-gallium-sulfur-selenium solar cell, which belongs to the technical field of solar cells, and comprises the following steps of: after a copper-indium-gallium-sulfur-selenium absorption layer is prepared, introducing a gallium-rich layer on a front interface of the absorption layer to modify the copper-indium-gallium-sulfur-selenium absorption layer, preparing a copper-indium-gallium-sulfur precursor solution, and preparing a semi-finished cell product; the battery semi-finished product comprises a copper indium gallium sulfur selenium absorption layer; preparing a gallium-rich solution, and inserting a gallium-rich layer on the copper-indium-gallium-sulfur-selenium absorption layer; a buffer layer, an intrinsic zinc oxide layer and a window layer are sequentially deposited on the gallium-rich layer, a top electrode is configured, and then the CIGS thin film solar cell is prepared. According to the preparation method of the copper-indium-gallium-sulfur-selenium solar cell provided by the invention, the Fermi level is increased due to the introduction of the Ga-rich layer, the VBO is favorably expanded, the CBO is favorably reduced, and the condition of a front interface of the absorption layer is optimized. The invention also provides a solar cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and specifically relates to a method for preparing a copper indium gallium sulfide selenide solar cell and a solar cell. More specifically, it relates to a method for preparing a copper indium gallium sulfide selenide solar cell and a solar cell prepared using the preparation method. Background Art

[0002] Among renewable energy technologies, solar cells, as a technology that directly converts solar energy into electricity, have received widespread attention worldwide. Among them, copper indium gallium sulfide selenide (CIGSSe) solar cells offer excellent properties, including high photoelectric conversion efficiency, lightweight, flexible, easy-to-process, high stability, long lifespan, abundant materials, and environmental friendliness. CIGSSe solar cells are a promising thin-film solar cell.

[0003] The preparation methods of copper indium gallium sulfide selenide (CIGSSe) solar cells include vacuum preparation process and solution preparation process. Compared with the vacuum preparation process, the solution preparation process has the advantages of relatively simple equipment, low cost, and can be carried out at room temperature and pressure. It can achieve accurate measurement and efficient utilization of raw materials, reduce material waste, and greatly reduce energy consumption and equipment production costs. It can make CIGSSe cells more price-competitive and help promote their commercial application. However, the solution method has the following problems: the prepared absorption layer is difficult to achieve a "V"-shaped gradient band gap, making it difficult to solve the interface energy level mismatch between the CIGSSe absorption layer and the CdS buffer layer. If the band gap is not matched properly, it will lead to an increase in the probability of recombination of photogenerated carriers at the interface, reducing the carrier collection efficiency of the battery, which limits the improvement of battery performance.

[0004] Therefore, developing a new preparation method for copper indium gallium sulfur selenide solar cells is of great significance to breaking through the existing performance bottleneck. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a copper indium gallium sulfide selenide solar cell and a solar cell, aiming to solve the technical problems existing in the existing solution method: the interface energy level mismatch between the CIGSSe absorption layer and the CdS buffer layer is difficult to solve, and the cell performance is poor.

[0006] To achieve the above object, the technical solution adopted by the present invention is to provide a method for preparing a copper indium gallium sulfur selenide solar cell, comprising the following steps:

[0007] After preparing the copper indium gallium sulfide selenide absorber layer, a gallium-rich layer is introduced at the front interface of the absorber layer to modify the copper indium gallium sulfide selenide absorber layer, including the following steps:

[0008] Prepare a copper indium gallium sulfide precursor solution and prepare a semi-finished battery product, which includes a copper indium gallium sulfide selenide absorber layer;

[0009] A gallium-rich solution is prepared, and a gallium-rich layer is inserted on the copper indium gallium sulfur selenide absorber layer;

[0010] A buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode are sequentially deposited on the gallium-rich layer to prepare a copper indium gallium sulfur selenide thin film solar cell.

[0011] Preferably, the copper indium gallium sulfide precursor solution is prepared and a semi-finished battery product is prepared, wherein the semi-finished battery product includes a copper indium gallium sulfide selenide absorber layer, including:

[0012] Selecting a substrate type and a back electrode type, and depositing the back electrode on the upper surface of the substrate;

[0013] Thiourea, copper acetate, indium trichloride tetrahydrate, and anhydrous gallium chloride are added to an N,N-dimethylformamide solvent in order and stirred to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution; wherein the molar ratio of each substance in the precursor solution satisfies: Cu / (In+Ga)=0.8-1.1, Ga / (In+Ga)=0.2-0.4, and Tu / (Cu+In+Ga)=2.5-4.5;

[0014] A copper indium gallium sulfide selenide absorption layer is deposited on the back electrode.

[0015] Preferably, the gallium-rich solution is prepared and a gallium-rich layer is inserted on the copper indium gallium sulfide selenide absorption layer, comprising: sequentially adding Tu and gallium chloride to an N,N-dimethylformamide solvent, stirring and dissolving, thereby obtaining a gallium-rich solution; wherein the molar ratio of each substance in the gallium-rich solution satisfies: Tu / Ga=2-4; and the molar concentration of Ga is 0%-50% of the molar concentration in the precursor solution.

[0016] Preferably, the step of preparing a gallium-rich solution and inserting a gallium-rich layer on the CIGS absorption layer comprises: the molar concentration of Ga is 5% of the molar concentration in the precursor solution.

[0017] Preferably, the step of preparing a gallium-rich solution and inserting a gallium-rich layer on the copper indium gallium sulfide selenide absorption layer comprises: a molar ratio of each substance in the gallium-rich solution satisfies: Tu / Ga=3.

[0018] Preferably, the method of preparing a gallium-rich solution and inserting a gallium-rich layer on the copper indium gallium sulfide selenide absorption layer further includes: spin coating 1-3 layers of gallium-rich solution on the surface of the copper indium gallium sulfide selenide absorption layer at a rotation speed of 1000-3000 rpm for 10-40 seconds, and then annealing on a hot stage at a temperature of 180-250°C for 1-4 minutes to prepare a gallium-rich layer.

[0019] Preferably, thiourea, copper acetate, indium trichloride tetrahydrate, and anhydrous gallium chloride are added to an N,N-dimethylformamide solvent in that order, and stirred to dissolve, thereby obtaining a copper indium gallium sulfur precursor solution, including: the molar ratio of each substance in the precursor solution satisfies: Cu / (In+Ga)=0.93, Ga / (In+Ga)=0.3, Tu / (Cu+In+Ga)=3.5.

[0020] Preferably, the depositing of the copper indium gallium sulfide selenide absorption layer on the back electrode comprises: spin coating a copper indium gallium sulfide precursor solution on the back electrode at a rotation speed of 1000-3000 rpm for 30-90s, then annealing on a hot stage at a temperature of 250-350°C for 1-3min, and repeating this process 10-14 times; and performing high-temperature selenization on the precursor film obtained by spin coating using a rapid annealing furnace, the selenization temperature being 500-600°C and the time being 15-25min.

[0021] A solar cell, characterized in that it comprises a product prepared by the method for preparing a copper indium gallium sulfide selenide solar cell according to any one of the above

[0022] Preferably, it comprises: a substrate, a back electrode layer, a copper indium gallium sulfide selenide absorption layer, a gallium-rich layer, a buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode layer stacked in sequence from one end to the other.

[0023] The present invention provides a method for preparing a copper indium gallium sulfide selenide solar cell and a solar cell thereof. Compared to the prior art, the present invention utilizes dimethylformamide as a solvent and copper acetate, silver chloride, indium trichloride tetrahydrate, anhydrous gallium chloride, and thiourea as solutes to prepare a copper indium gallium sulfide precursor solution and a gallium-rich solution. Selenization annealing and other methods are then used to obtain a copper indium gallium sulfide selenide absorber layer having a copper-poor, gallium-rich front interface. The introduction of the Ga-rich layer increases the Fermi level, helps increase VBO, reduces CBO, and optimizes the front interface of the absorber layer. Consequently, a high-efficiency CIGSSe thin-film solar cell is produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Shows the battery parameter box plots of each device;

[0026] Figure 2A schematic diagram of the process for preparing a gallium-rich thin film at the front interface of the absorption layer is shown;

[0027] Figure 3 The energy band diagrams obtained from the UPS data analysis of CW / O and CG-5 are shown respectively;

[0028] Figure 4 The current-voltage parameters of CW / O and CG-5 are shown respectively. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] Please also refer to Figures 1 to 4 The present invention now provides a solar cell, specifically a copper indium gallium sulfide selenide solar cell. The copper indium gallium sulfide selenide solar cell comprises: a substrate, a back electrode layer, a copper indium gallium sulfide selenide absorber layer, a gallium-rich layer, a buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode layer, stacked in sequence from one end to the other.

[0031] As a specific implementation of an embodiment of the present invention, the substrate includes, but is not limited to, a molybdenum foil substrate, a molybdenum glass substrate, an ITO (Indium Tin Oxide) glass substrate, and an FTO (Fluorine-doped Tin Oxide) glass substrate. In any feasible embodiment, the substrate is a molybdenum glass substrate. A back electrode layer is deposited on the molybdenum glass substrate, and the back electrode layer is a Mo back electrode.

[0032] As a specific implementation of the embodiment of the present invention, the buffer layer is a CdS buffer layer.

[0033] As a specific implementation of the embodiment of the present invention, the window layer is an aluminum-doped zinc oxide layer.

[0034] As a specific implementation of the embodiment of the present invention, the top electrode is one or more of a nickel / aluminum electrode, a silver electrode, and a gold electrode.

[0035] In any feasible embodiment, the structure of the CIGS solar cell may be as follows:

[0036] SLG / Mo / CIGSSe / CdS / i-ZnO / ZnO:Al / Ag.

[0037] The present invention also provides a method for preparing a copper indium gallium sulfide selenide solar cell based on a solution process, which is used to prepare a solar cell as described in any of the above items. After preparing the copper indium gallium sulfide selenide absorber layer, a gallium-rich layer of appropriate concentration is introduced at the front interface of the absorber layer to achieve the purpose of modifying the interface, thereby obtaining a high-quality CIGSSe thin film solar cell. For details, please refer to Figures 1 to 4 , including the following steps:

[0038] Step S1: prepare a copper indium gallium sulfide precursor solution and prepare a semi-finished battery product, wherein the semi-finished battery product includes a copper indium gallium sulfide selenide absorption layer.

[0039] The specific implementation process of this step can be:

[0040] Step S1.1: Select a substrate type and a back electrode type, and deposit a back electrode on the top surface of the substrate. Specifically, the substrate includes, but is not limited to, a molybdenum foil substrate and a glass substrate. The top surface of the substrate is coated with a functional layer (i.e., the back electrode), which is one or more of molybdenum (Mo), ITO (Indium Tin Oxide) thin film, and FTO (Fluorine-doped Tin Oxide).

[0041] Step S1.2: Prepare a copper indium gallium sulfide precursor solution. Specifically, add thiourea (CH4N2S, Tu), copper acetate (Cu(CH3COO)2·H2O), indium trichloride tetrahydrate (InCl3·4H2O), and anhydrous gallium chloride (GaCl3) to an N,N-dimethylformamide (C3H7NO, DMF) solvent in this order, and stir to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution. The molar ratios of the substances in the precursor solution satisfy the following: Cu / (In+Ga)=0.8-1.1, Ga / (In+Ga)=0.2-0.4, and Tu / (Cu+In+Ga)=2.5-4.5.

[0042] Step S1.3: Deposit a copper indium gallium sulfide selenide absorber layer on the back electrode. Specifically, the precursor solution is deposited on a molybdenum glass substrate using existing processes such as spin coating to obtain a copper indium gallium sulfide precursor film. Spin coating is preferred. More specifically, the copper indium gallium sulfide precursor solution is spin-coated on the back electrode at a speed of 1000-3000 rpm for 30-90 seconds, then annealed on a hot plate at a temperature of 250-350°C for 1-3 minutes, and repeated 10-14 times.

[0043] The spin-coated precursor film undergoes high-temperature selenization in a rapid annealing furnace at a temperature of 500-600°C for 15-25 minutes. More specifically, the selenization annealing process involves placing selenium particles in a graphite box, placing the copper indium gallium sulfide precursor film obtained above into the box, and then heating the container in a nitrogen atmosphere for selenization annealing.

[0044] Step S2: preparing a gallium-rich solution and inserting a gallium-rich layer on the CIGS absorption layer.

[0045] In this step, the gallium-rich film is prepared by one or more methods including spin coating, blade coating, and spray annealing.

[0046] The specific implementation process of this step can be:

[0047] Step S2.1: Tu and GaCl3 are sequentially added to a DMF solvent and stirred to dissolve, thereby obtaining a gallium-rich solution. The molar ratio of the substances in the gallium-rich solution satisfies: Tu / Ga = 2-4. The molar concentration of Ga is 0%-50% of the molar concentration in the copper indium gallium sulfide precursor solution. Preferably, the molar concentration of Ga is 5% of the molar concentration in the precursor solution.

[0048] Step S2.2: Spin-coat 1-3 layers of gallium-rich solution on the surface of the CIGS absorber layer at a rotation speed of 1000-3000 rpm for 10-40 seconds, and then anneal on a hot plate at a temperature of 180-250° C. for 1-4 minutes to prepare a gallium-rich layer.

[0049] Step S3: depositing a buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode in sequence on the gallium-rich layer, thereby preparing a copper indium gallium sulfur selenide thin film solar cell.

[0050] In this step, the buffer layer is a CdS (cadmium sulfide) buffer layer. The thickness of the CdS (cadmium sulfide) buffer layer is 30-60 nm. The CdS (cadmium sulfide) buffer layer is deposited using a chemical water bath method.

[0051] In this step, the intrinsic zinc oxide layer has a thickness of 40-60 nm and is deposited by DC magnetron sputtering.

[0052] In this step, the window layer is an aluminum-doped zinc oxide layer with a thickness of 200-300 nm. The aluminum-doped zinc oxide layer is deposited by DC magnetron sputtering.

[0053] The specific implementation process of this step can be:

[0054] Step S3.1: Depositing a cadmium sulfide buffer layer on the treated absorber layer. Specifically, depositing an N-type buffer layer cadmium sulfide thin film on the surface of the P-type gallium-rich absorber layer; wherein the thickness of the cadmium sulfide film is 30-60 nm, preferably 40-50 nm.

[0055] Step S3.2: Then, an intrinsic zinc oxide layer and an aluminum-doped zinc oxide window layer are configured on the surface of the buffer layer film by using a DC magnetron sputtering method.

[0056] Step S3.3: Deposit an electrode on the window layer using a thermal evaporation method to obtain a copper indium gallium sulfide selenide thin film solar cell. The thickness of the top electrode is 1-1.5 μm.

[0057] Example 1

[0058] A method for preparing a copper indium gallium sulfur selenide solar cell comprises the following steps:

[0059] A copper indium gallium sulfide precursor solution is prepared and a semi-finished battery product is prepared. The semi-finished battery product includes a copper indium gallium sulfide selenide absorption layer.

[0060] The specific implementation process of this step can be:

[0061] The substrate type and the back electrode type are selected, and the back electrode is deposited on the upper surface of the substrate. Specifically, the substrate is a glass substrate. The upper surface of the substrate is plated with molybdenum.

[0062] Thiourea (CH4N2S, Tu), copper acetate (Cu(CH3COO)2·H2O), indium trichloride tetrahydrate (InCl3·4H2O), and anhydrous gallium chloride (GaCl3) were added to N,N-dimethylformamide (C3H7NO, DMF) solvent in order and stirred to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution. The molar ratios of the substances in the precursor solution satisfy the following requirements: Cu / (In+Ga)=0.93, Ga / (In+Ga)=0.3, and Tu / (Cu+In+Ga)=3.5.

[0063] The precursor solution was spin-coated onto a molybdenum glass substrate at 2000 rpm for 60 seconds. The solution was then annealed on a hot plate at 300°C for 2 minutes, a process repeated 12 times to produce a precursor film of sufficient thickness. The precursor film was then selenized in a rapid annealing furnace at 580°C for 20 minutes to form a copper indium gallium sulfide selenide absorber layer.

[0064] A cadmium sulfide buffer layer, an intrinsic zinc oxide layer, an aluminum-doped zinc oxide window layer, and a silver electrode are sequentially deposited on the gallium-rich layer to prepare a copper indium gallium sulfur selenide thin film solar cell.

[0065] The specific implementation process of this step can be as follows: depositing a cadmium sulfide buffer layer on the absorption layer. The thickness of the cadmium sulfide film is 50nm. Then, using DC magnetron sputtering, an intrinsic zinc oxide layer and an aluminum-doped zinc oxide window layer are configured on the surface of the buffer layer. The thickness of the intrinsic zinc oxide layer is 60nm. The thickness of the aluminum-doped zinc oxide window layer is 300nm. Finally, using thermal evaporation to deposit a silver electrode with a thickness of 1-1.5μm on the window layer, copper indium gallium sulfide selenide thin film solar cell CW / O.

[0066] Example 2

[0067] A method for preparing a copper indium gallium sulfide selenide solar cell, please refer to Figure 2 , Figure 2 A schematic diagram of the process for preparing a gallium-rich thin film at the front interface of the absorption layer is shown, including the following steps:

[0068] Step S1: prepare a copper indium gallium sulfide precursor solution and prepare a semi-finished battery product, wherein the semi-finished battery product includes a copper indium gallium sulfide selenide absorption layer.

[0069] The specific implementation process of this step can be:

[0070] Step S1.1: Select the substrate type and the back electrode type, and deposit the back electrode on the upper surface of the substrate. Specifically, the substrate is a glass substrate, and the upper surface of the substrate is plated with molybdenum.

[0071] Step S1.2: Add thiourea (CH4N2S, Tu), copper acetate (Cu(CH3COO)2·H2O), indium trichloride tetrahydrate (InCl3·4H2O), and anhydrous gallium chloride (GaCl3) to N,N-dimethylformamide (C3H7NO, DMF) solvent in this order, and stir to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution. The molar ratios of the substances in the precursor solution satisfy: Cu / (In+Ga)=0.93, Ga / (In+Ga)=0.3, and Tu / (Cu+In+Ga)=3.5.

[0072] Step S1.3: Spin-coat the precursor solution onto a molybdenum glass substrate at 2000 rpm for 60 seconds. Then, anneal on a hot plate at 300°C for 2 minutes. Repeat this process 12 times to obtain a precursor film of sufficient thickness. The precursor film is then selenized in a rapid annealing furnace at 580°C for 20 minutes to obtain a copper indium gallium sulfide selenide absorber layer.

[0073] Step S2: Prepare a gallium-rich solution and insert a gallium-rich layer on the absorption layer. The specific implementation process of this step can be:

[0074] Step S2.1: Tu and GaCl3 are sequentially added to a DMF solvent and stirred to dissolve, thereby obtaining a gallium-rich solution. The molar ratio of the substances in the gallium-rich solution satisfies: Tu / Ga = 3. The molar concentration of Ga is 2% of the molar concentration of the copper indium gallium sulfide precursor solution (i.e., the copper indium gallium sulfide precursor solution prepared in step S1.2).

[0075] Step S2.2: Spin-coat a layer of gallium-rich solution on the surface of the CIGS absorber layer at a rotation speed of 2000 rpm for 30 seconds, and then anneal on a hot plate at a temperature of 220° C. for 2 minutes to prepare a gallium-rich layer.

[0076] Step S3: depositing a buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode in sequence on the gallium-rich layer, thereby preparing a copper indium gallium sulfur selenide thin film solar cell.

[0077] The specific implementation process of this step can be as follows: depositing a cadmium sulfide buffer layer on the absorption layer. The thickness of the cadmium sulfide film is 50nm. Then, an intrinsic zinc oxide layer and an aluminum-doped zinc oxide window layer are configured on the surface of the buffer layer using DC magnetron sputtering. The thickness of the intrinsic zinc oxide layer is 60nm. The thickness of the aluminum-doped zinc oxide window layer is 300nm. Finally, a silver electrode with a thickness of 1-1.5μm is deposited on the window layer using thermal evaporation, forming a copper indium gallium sulfide selenide thin-film solar cell CG-2.

[0078] Example 3

[0079] A method for preparing a copper indium gallium sulfur selenide solar cell comprises the following steps:

[0080] Step S1: prepare a copper indium gallium sulfide precursor solution and prepare a semi-finished battery product, wherein the semi-finished battery product includes a copper indium gallium sulfide selenide absorption layer.

[0081] The specific implementation process of this step can be:

[0082] Step S1.1: Select the substrate type and the back electrode type, and deposit the back electrode on the upper surface of the substrate; specifically, the substrate is a glass substrate, and the upper surface of the glass substrate is plated with molybdenum.

[0083] Step S1.2: Add thiourea (CH4N2S, Tu), copper acetate (Cu(CH3COO)2·H2O), indium trichloride tetrahydrate (InCl3·4H2O), and anhydrous gallium chloride (GaCl3) to N,N-dimethylformamide (C3H7NO, DMF) solvent in this order, and stir to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution. The molar ratios of the substances in the precursor solution satisfy the following: Cu / (In+Ga)=0.93, Ga / (In+Ga)=0.3, and Tu / (Cu+In+Ga)=3.5.

[0084] Step S1.3: Spin-coat the precursor solution onto a molybdenum glass substrate at 2000 rpm for 60 seconds. Then, anneal on a hot plate at 300°C for 2 minutes. Repeat this process 12 times to obtain a precursor film of sufficient thickness. The precursor film is then selenized in a rapid annealing furnace at 580°C for 20 minutes to obtain a copper indium gallium sulfide selenide absorber layer.

[0085] Step S2: Prepare a gallium-rich solution and insert a gallium-rich layer on the absorption layer. The specific implementation process of this step can be:

[0086] Step S2.1: Tu and GaCl3 are sequentially added to a DMF solvent and stirred to dissolve, thereby obtaining a gallium-rich solution. The molar ratio of the substances in the gallium-rich solution satisfies: Tu / Ga = 3. The molar concentration of Ga is 5% of the molar concentration in the copper indium gallium sulfide precursor solution.

[0087] Step S2.2: Spin-coat a layer of gallium-rich solution on the surface of the CIGS absorber layer at a rotation speed of 2000 rpm for 30 seconds, and then anneal on a hot plate at a temperature of 220° C. for 2 minutes to prepare a gallium-rich layer.

[0088] Step S3: depositing a buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode in sequence on the gallium-rich layer, thereby preparing a copper indium gallium sulfur selenide thin film solar cell.

[0089] The specific implementation process of this step can be as follows: depositing a cadmium sulfide buffer layer on the absorption layer. The thickness of the cadmium sulfide film is 50nm. Then, an intrinsic zinc oxide layer and an aluminum-doped zinc oxide window layer are configured on the surface of the buffer layer using DC magnetron sputtering. The thickness of the intrinsic zinc oxide layer is 60nm. The thickness of the aluminum-doped zinc oxide window layer is 300nm. Finally, a silver electrode with a thickness of 1-1.5μm is deposited on the window layer using thermal evaporation, copper indium gallium sulfide selenide thin film solar cell CG-5.

[0090] Example 4

[0091] A method for preparing a copper indium gallium sulfur selenide solar cell comprises the following steps:

[0092] Step S1: prepare a copper indium gallium sulfide precursor solution and prepare a semi-finished battery product, wherein the semi-finished battery product includes a copper indium gallium sulfide selenide absorption layer.

[0093] The specific implementation process of this step can be:

[0094] Step S1.1: Select the substrate type and the back electrode type, and deposit the back electrode on the upper surface of the substrate. Specifically, the substrate is a glass substrate, and the upper surface of the substrate is plated with molybdenum.

[0095] Step S1.2: Add thiourea (CH4N2S, Tu), copper acetate (Cu(CH3COO)2·H2O), indium trichloride tetrahydrate (InCl3·4H2O), and anhydrous gallium chloride (GaCl3) to N,N-dimethylformamide (C3H7NO, DMF) solvent in this order, and stir to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution. The molar ratios of the substances in the precursor solution satisfy the following: Cu / (In+Ga)=0.93, Ga / (In+Ga)=0.3, and Tu / (Cu+In+Ga)=3.5.

[0096] Step S1.3: Spin-coat the precursor solution onto a molybdenum glass substrate at 2000 rpm for 60 seconds. Then, anneal on a hot plate at 300°C for 2 minutes. Repeat this process 12 times to obtain a precursor film of sufficient thickness. The precursor film is then selenized in a rapid annealing furnace at 580°C for 20 minutes to obtain a copper indium gallium sulfide selenide absorber layer.

[0097] Step S2: Prepare a gallium-rich solution and insert a gallium-rich layer on the absorption layer. The specific implementation process of this step can be:

[0098] Step S2.1: Tu and GaCl3 are sequentially added to a DMF solvent and stirred to dissolve, thereby obtaining a gallium-rich solution. The molar ratio of the substances in the gallium-rich solution satisfies: Tu / Ga = 3. The molar concentration of Ga is 10% of the molar concentration in the copper indium gallium sulfide selenide precursor solution.

[0099] Step S2.2: Spin-coat a layer of gallium-rich solution on the surface of the CIGS absorber layer at a rotation speed of 2000 rpm for 30 seconds, and then anneal on a hot plate at a temperature of 220° C. for 2 minutes to prepare a gallium-rich layer.

[0100] Step S3: depositing a buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode in sequence on the gallium-rich layer, thereby preparing a copper indium gallium sulfur selenide thin film solar cell.

[0101] The specific implementation process of this step can be as follows: depositing a cadmium sulfide buffer layer on the absorption layer. The thickness of the cadmium sulfide film is 50nm. Then, using DC magnetron sputtering, an intrinsic zinc oxide layer and an aluminum-doped zinc oxide window layer are configured on the surface of the buffer layer. The thickness of the intrinsic zinc oxide layer is 60nm. The thickness of the aluminum-doped zinc oxide window layer is 300nm. Finally, using thermal evaporation, a silver electrode with a thickness of 1-1.5μm is deposited on the window layer. This is the copper indium gallium sulfide selenide thin-film solar cell CG-10.

[0102] Example 5

[0103] A method for preparing a copper indium gallium sulfur selenide solar cell comprises the following steps:

[0104] Step S1: prepare a copper indium gallium sulfide precursor solution and prepare a semi-finished battery product, wherein the semi-finished battery product includes a copper indium gallium sulfide selenide absorption layer.

[0105] The specific implementation process of this step can be:

[0106] Step S1.1: Select the substrate type and the back electrode type, and deposit the back electrode on the upper surface of the substrate. Specifically, the substrate is a glass substrate, and the upper surface of the substrate is plated with molybdenum.

[0107] Step S1.2: Add thiourea (CH4N2S, Tu), copper acetate (Cu(CH3COO)2·H2O), indium trichloride tetrahydrate (InCl3·4H2O), and anhydrous gallium chloride (GaCl3) to N,N-dimethylformamide (C3H7NO, DMF) solvent in this order, and stir to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution. The molar ratios of the substances in the precursor solution satisfy the following: Cu / (In+Ga)=0.93, Ga / (In+Ga)=0.3, and Tu / (Cu+In+Ga)=3.5.

[0108] Step S1.3: Spin-coat the precursor solution onto a molybdenum glass substrate at 2000 rpm for 60 seconds. Then, anneal on a hot plate at 300°C for 2 minutes. Repeat this process 12 times to obtain a precursor film of sufficient thickness. The precursor film is then selenized in a rapid annealing furnace at 580°C for 20 minutes to obtain a copper indium gallium sulfide selenide absorber layer.

[0109] Step S2: Prepare a gallium-rich solution and insert a gallium-rich layer on the absorption layer. The specific implementation process of this step can be:

[0110] Step S2.1: Tu and GaCl3 are sequentially added to a DMF solvent and stirred to dissolve, thereby obtaining a gallium-rich solution. The molar ratio of the substances in the gallium-rich solution satisfies: Tu / Ga = 3. The molar concentration of Ga is 20% of the molar concentration in the copper indium gallium sulfide precursor solution.

[0111] Step S2.2: Spin-coat a layer of gallium-rich solution on the surface of the CIGS absorber layer at a rotation speed of 2000 rpm for 30 seconds, and then anneal on a hot plate at a temperature of 220° C. for 2 minutes to prepare a gallium-rich layer.

[0112] Step S3: depositing a buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode in sequence on the gallium-rich layer, thereby preparing a copper indium gallium sulfur selenide thin film solar cell.

[0113] The specific implementation process of this step can be as follows: depositing a cadmium sulfide buffer layer on the absorption layer. The thickness of the cadmium sulfide film is 50nm. Then, an intrinsic zinc oxide layer and an aluminum-doped zinc oxide window layer are configured on the surface of the buffer layer using DC magnetron sputtering. The thickness of the intrinsic zinc oxide layer is 60nm. The thickness of the aluminum-doped zinc oxide window layer is 300nm. Finally, a silver electrode with a thickness of 1-1.5μm is deposited on the window layer using thermal evaporation. The copper indium gallium sulfide selenide thin film solar cell CG-20.

[0114] Data Analysis, please also refer to Figures 1 to 4 ,in, Figure 1 The box plot of battery parameters of each device shows that the open circuit voltage (V OC ) have been improved. The average open circuit voltage of CG-5 and CG-10 is relatively high, indicating that the insertion of an appropriate concentration of Ga-rich layer has a positive effect on improving the open circuit voltage. Compared with the CW / O sample, the average short circuit current density (J SC ), indicating that the insertion of the Ga-rich layer is somewhat detrimental to improving the short-circuit current density. This may be related to the deposition of the cadmium sulfide buffer layer. The insertion of a moderate concentration of Ga-rich layer, particularly 5%, has a positive effect on improving the performance of CIGSSe solar cells, but excessive concentrations (20%) may not achieve further improvement and may even have a negative effect. Figure 4 The JV diagram of the champion device of CW / O and CG-5 is given, and the performance parameters are given. It can be seen that by optimizing the concentration of GaCl3, a cell efficiency of 16.65% is achieved, V OC The open circuit voltage is 0.692 V, which is the highest open circuit voltage based on the dimethylformamide solvent system.

[0115] Figure 3 This energy band diagram is obtained by combining ultraviolet photoelectron spectroscopy (UPS) data with absorption and transmission spectra. The Fermi level positions of W / O and G-5 obtained from UPS data are calculated to be -4.62 and -4.56 eV, respectively. Raising the Fermi level can optimize the band bending of the PN junction, reduce carrier recombination, and increase the open circuit voltage V OCProvides the basis of electronic structure. It was determined that the distances between the VBE and the corresponding Fermi level of W / O and G-5 are 0.40 and 0.52 eV, respectively. The data of the W / O structure mainly reflects the characteristics of the CIGSSe absorption layer, G-5 mainly reflects the characteristics of the Ga-rich layer + GIGS absorption layer, and the data of the W / O / H (after CdS deposition) and G-5 / H (after CdS deposition) structures mainly reflect the surface characteristics of sulfur CdS. It can be clearly observed that when the Ga-rich layer is added, the bottom energy level difference (CBO) of the conduction band at the interface between CdS and CIGSSe is reduced from 0.32 eV to 0.1 eV, achieving almost seamless docking. This extremely small energy level difference greatly reduces the barrier for carrier (electron) transmission from CIGSSe to CdS, reduces carrier recombination at the interface, and is beneficial to improving the short-circuit current J SC . In addition, the valence band top energy level difference (VBO) increases from 0.95eV to 1.13eV, making it difficult for holes to transmit at the interface between CIGSSe and CdS. A larger VBO can effectively restrict the entry of holes into CdS, preventing holes from inducing recombination at the interface, thereby maintaining the effective separation of holes in CIGSSe, indirectly improving the utilization efficiency of carriers, and playing a positive role in the photoelectric conversion efficiency of the device. These results show that the introduction of the Ga-rich layer increases the Fermi level, helps to expand VBO, reduce CBO, and optimize the interface before the absorption layer.

[0116] The present invention provides a solution-based method for preparing copper indium gallium sulfide selenide solar cells. This method modifies the front interface of the absorber layer of a copper indium gallium sulfide selenide thin-film solar cell. Compared to the prior art, a copper indium gallium sulfide precursor solution and a gallium-rich solution are prepared using dimethylformamide as a solvent and copper acetate, silver chloride, indium trichloride tetrahydrate, anhydrous gallium chloride, and thiourea as solutes. A copper indium gallium sulfide selenide absorber layer with a copper-poor, gallium-rich front interface is then obtained through methods such as selenization annealing. The introduction of the Ga-rich layer raises the Fermi level, helps expand VBO, reduces CBO, and optimizes the front interface of the absorber layer. Finally, a high-efficiency CIGSSe thin-film solar cell is prepared. The CIGSSe device obtained using this method can achieve an efficiency of 16.65% and an open-circuit voltage of 0.692V.

[0117] It should be pointed out that this invention can obtain the currently highest open circuit voltage based on the dimethylformamide solvent system, which opens up a simple and feasible method for preparing high-efficiency CIGSSe thin-film solar cells based on the solution method.

[0118] This invention, through research and development, introduces a gallium-rich layer of appropriate concentration at the front interface of the copper indium gallium sulfide selenide absorber layer to produce high-quality CIGSSe thin-film solar cells, significantly improving cell performance. This invention effectively addresses the difficulty of obtaining CIGSSe thin films with copper-poor, gallium-rich surfaces using solution methods. Furthermore, the solution method achieves a more precise match between the absorber layer band gap and the buffer layer band gap, simplifying the preparation process and further leveraging the advantages of the solution method, potentially increasing the potential for large-scale solution-based production of CIGSSe photovoltaic modules.

[0119] The technical solutions disclosed and proposed by the present invention can be realized by those skilled in the art by drawing on the contents of this article and appropriately changing the conditions, routes and other links. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, relevant technical personnel can obviously modify or re-combine the methods and technical routes described herein without departing from the content, spirit and scope of the present invention to achieve the final preparation technology. It should be pointed out in particular that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the spirit, scope and content of the present invention. That is, the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a copper indium gallium sulfur selenide solar cell, characterized in that: After preparing the copper indium gallium sulfide selenide absorber layer, a gallium-rich layer is introduced at the front interface of the absorber layer to modify the copper indium gallium sulfide selenide absorber layer, including the following steps: Prepare a copper indium gallium sulfide precursor solution and prepare a semi-finished battery product, which includes a copper indium gallium sulfide selenide absorber layer; A gallium-rich solution is prepared, and a gallium-rich layer is inserted on the copper indium gallium sulfur selenide absorber layer; A buffer layer, an intrinsic zinc oxide layer, a window layer, and a top electrode are sequentially deposited on the gallium-rich layer to prepare a copper indium gallium sulfur selenide thin film solar cell.

2. The method for preparing a copper indium gallium sulfur selenide solar cell according to claim 1, characterized in that: The copper indium gallium sulfide precursor solution is prepared and a semi-finished battery product is prepared. The semi-finished battery product includes a copper indium gallium sulfide selenide absorption layer, including: Selecting a substrate type and a back electrode type, and depositing the back electrode on the upper surface of the substrate; Thiourea, copper acetate, indium trichloride tetrahydrate, and anhydrous gallium chloride are added to an N,N-dimethylformamide solvent in order and stirred to dissolve, thereby obtaining a copper indium gallium sulfide precursor solution; wherein the molar ratio of each substance in the precursor solution satisfies: Cu / (In+Ga)=0.8-1.1, Ga / (In+Ga)=0.2-0.4, and Tu / (Cu+In+Ga)=2.5-4.5; A copper indium gallium sulfide selenide absorption layer is deposited on the back electrode.

3. The method for preparing a copper indium gallium sulfur selenide solar cell according to any one of claims 1 or 2, characterized in that: The method of preparing a gallium-rich solution and inserting a gallium-rich layer on the copper indium gallium sulfur selenide absorption layer includes: Tu and gallium chloride are sequentially added to an N,N-dimethylformamide solvent and stirred to dissolve, thereby obtaining a gallium-rich solution; wherein the molar ratio of each substance in the gallium-rich solution satisfies: Tu / Ga=2-4; and the molar concentration of Ga is 0%-50% of the molar concentration in the precursor solution.

4. The method for preparing a copper indium gallium sulfur selenide solar cell according to claim 3, characterized in that: The gallium-rich solution is prepared and a gallium-rich layer is inserted on the copper indium gallium sulfur selenide absorption layer, including: the molar concentration of Ga is 5% of the molar concentration in the precursor solution.

5. The method for preparing a copper indium gallium sulfur selenide solar cell according to claim 3, characterized in that: The gallium-rich solution is prepared, and a gallium-rich layer is inserted on the copper indium gallium sulfur selenide absorption layer, including: the molar ratio of each substance in the gallium-rich solution satisfies: Tu / Ga=3.

6. The method for preparing a copper indium gallium sulfur selenide solar cell according to claim 3, characterized in that: The method of preparing a gallium-rich solution and inserting a gallium-rich layer on the copper indium gallium sulfide selenide absorption layer further includes: spin coating 1-3 layers of the gallium-rich solution on the surface of the copper indium gallium sulfide selenide absorption layer at a rotation speed of 1000-3000 rpm for 10-40 seconds, and then annealing on a hot plate at a temperature of 180-250° C. for 1-4 minutes to prepare the gallium-rich layer.

7. The method for preparing a copper indium gallium sulfur selenide solar cell according to claim 5, characterized in that: The method comprises adding thiourea, copper acetate, indium trichloride tetrahydrate, and anhydrous gallium chloride to an N,N-dimethylformamide solvent in sequence and stirring to dissolve, thereby obtaining a copper indium gallium sulfur precursor solution, wherein the molar ratio of each substance in the precursor solution satisfies: Cu / (In+Ga)=0.93, Ga / (In+Ga)=0.3, and Tu / (Cu+In+Ga)=3.

5.

8. The method for preparing a copper indium gallium sulfur selenide solar cell according to claim 7, characterized in that: The method of depositing a copper indium gallium sulfide selenide absorption layer on the back electrode includes: spin-coating a copper indium gallium sulfide precursor solution on the back electrode at a rotation speed of 1000-3000 rpm for 30-90 seconds, then annealing on a hot plate at a temperature of 250-350°C for 1-3 minutes, and repeating the process 10-14 times; and performing high-temperature selenization on the precursor film obtained by spin coating in a rapid annealing furnace, at a selenization temperature of 500-600°C for 15-25 minutes.

9. A solar cell, characterized in that: The invention comprises a product prepared by the method for preparing a copper indium gallium sulfur selenide solar cell according to any one of claims 1 to 8.

10. A solar cell according to claim 9, characterized in that: include: The substrate, the back electrode layer, the copper indium gallium sulfide selenide absorption layer, the gallium-rich layer, the buffer layer, the intrinsic zinc oxide layer, the window layer, and the top electrode layer are stacked in sequence from one end to the other.

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