Application of In-doped PbS thin film in preparation of cadmium telluride thin film battery

Abstract

The invention relates to the technical field of cadmium telluride thin film solar cells, in particular to application of an In-doped PbS thin film in preparation of a cadmium telluride thin film cell. An In-doped PbS thin film is used as a back contact layer of the cadmium telluride thin film cell, and in the In-doped PbS thin film, the mass percent of In is 5wt%-10wt%, and the balance is PbS. The problems of material stability and element diffusion of the back contact layer are mainly solved, the In-doped PbS thin film serves as the back contact layer, the problem that the stability of the cell is reduced due to copper diffusion generated by the back contact layer in a traditional process can be better solved, meanwhile, the In-doped PbS thin film and the cadmium telluride thin film can also form better energy band matching, and the performance of the cell is improved. Therefore, the defect of low photoelectric conversion efficiency of the cadmium telluride thin film cell due to the back contact layer in the prior art is overcome.

Description

Technical Field

[0001] This invention relates to the field of cadmium telluride thin-film solar cell technology, specifically the application of In-doped PbS thin films in the fabrication of cadmium telluride thin-film batteries. In this invention, an In-containing lead sulfide compound is used as the back contact layer of the cadmium telluride thin-film battery to improve the power generation efficiency of the cadmium telluride thin-film solar cell. Background Technology

[0002] With the continuous development and progress of society, the demand for clean energy is increasing. However, most of the world's energy still relies on fossil fuels. The extensive use of fossil fuels has brought about many social problems, such as global warming, air pollution, and an increased risk of cancer in humans. Therefore, the development of clean energy has become an urgent issue to be addressed.

[0003] Solar energy, as an inexhaustible resource, is the preferred choice for developing clean energy. Cadmium telluride thin-film solar cells possess advantages such as low cost, high theoretical efficiency, stable performance, good performance in low light conditions, and a uniform appearance suitable for building-integrated applications. Therefore, research on cadmium telluride thin-film solar cells is of great significance. However, current technologies for preparing the back contact layer still suffer from defects such as material stability and element diffusion limitations, electrical performance constraints, complex processes, and mismatch between the interface and energy band, resulting in low photoelectric conversion efficiency. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides the application of In-doped PbS thin films in the fabrication of cadmium telluride thin-film batteries. This invention primarily solves the problems of back contact layer material stability and element diffusion. Specifically, the In-doped PbS thin film, acting as the back contact layer, better avoids the problem of copper diffusion in the back contact layer, which leads to decreased battery stability in traditional processes. Furthermore, the In-doped PbS thin film of this invention can form a better bandgap match with the cadmium telluride thin film, reducing the contact barrier and thus overcoming the deficiency of low photoelectric conversion efficiency in cadmium telluride thin-film batteries caused by the back contact layer in existing technologies.

[0005] Based on the above technical objectives, the present invention adopts the following technical solution: This invention protects the application of In-doped PbS thin films in the fabrication of cadmium telluride thin-film solar cells. The In-doped PbS thin film is used as the back contact layer of the cadmium telluride thin-film solar cell. In the In-doped PbS thin film, the mass percentage of In is 5wt% to 10wt%, with the balance being PbS. If the mass percentage of In is outside this range, the back contact layer interface of the cadmium telluride thin-film solar cell cannot form an efficient and stable ohmic contact, thereby reducing the efficiency of the cadmium telluride thin-film solar cell.

[0006] Preferably, in the In-doped PbS film, the mass percentage of In is 8 wt%.

[0007] Preferably, the thickness of the In-doped PbS film is 10 nm to 50 nm.

[0008] Preferably, the In-doped PbS thin film is prepared according to the following steps: the magnetron sputtering equipment is pumped to 1×10⁻⁶. -1 Pa~5×10 -4 Indium-doped lead sulfide targets were sputtered using magnetron sputtering at power of 80W~300W, pressure of 0.2Pa~5Pa, and gas flow rate of 1sccm~500sccm to obtain In-doped PbS thin films.

[0009] Preferably, the cadmium telluride thin-film battery consists of a substrate layer, a transparent conductive oxide thin film layer, a high-resistivity buffer layer, a battery window layer, a battery layer, a back contact layer, and a back electrode, which are stacked sequentially from bottom to top. The battery layer is a CdTe layer, and the back contact layer is an In-doped PbS thin film.

[0010] Preferably, the CdTe layer undergoes post-treatment. The post-treatment method involves coating the CdTe layer with a CdCl2 solution via impregnation, first evaporating the solvent to form a CdCl2 thin film, and then annealing at 400°C~500°C for 20min~40min. The purpose of annealing is to improve the interdiffusion between the CdCl2 thin film and the cadmium sulfide thin film layer, thereby forming a CdSTe composite film layer, reducing surface pinholes in the cadmium sulfide film layer, and further reducing surface defects in the cadmium telluride thin-film battery, thus improving battery efficiency.

[0011] Preferably, the concentration of the CdCl2 solution is 0.2 mol / L to 20 mol / L.

[0012] Preferably, the thickness of the high-resistivity buffer layer is 10nm~100nm, the thickness of the battery window layer is 10nm~50nm, the thickness of the battery layer is 1μm~5μm, and the thickness of the back electrode is 5nm~100nm.

[0013] Preferably, the transparent conductive oxide thin film layer is a fluorine-doped tin oxide layer, the high-resistivity buffer layer is a SnO2 layer, the battery window layer is a CdS window layer, and the back electrode is an Au electrode.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention is the first to apply In-doped PbS thin film as a back contact layer in cadmium telluride thin-film solar cells. The reason is that, compared with traditional copper-doped zinc telluride, In-doped PbS thin film as a back contact layer can better avoid the copper diffusion problem in the traditional copper-doped zinc telluride process. While improving the stability of the cell, In-doped PbS thin film and cadmium telluride thin film form a better band match, reduce the contact barrier, and thus improve the power generation efficiency of cadmium telluride thin-film solar cells. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a cadmium telluride thin-film battery.

[0016] Explanation of reference numerals in the attached figures: 1-substrate layer, 2-transparent conductive oxide thin film layer, 3-high resistance buffer layer, 4-cell window layer, 5-cell layer, 6-back contact layer, 7-back electrode. Detailed Implementation

[0017] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0018] Considering that existing technologies use copper-doped zinc telluride thin films as back contact layers, but these suffer from Cu diffusion problems, resulting in poor stability of the back contact layer material and consequently affecting the performance of cadmium telluride thin-film solar cells, this invention provides a novel back contact layer, namely an In-doped PbS thin film, and applies it to cadmium telluride thin-film solar cells. This effectively improves the stability of the back contact layer material while solving the Cu diffusion problem.

[0019] In this invention, the indium-doped lead sulfide target, zinc-doped lead sulfide target, aluminum-doped lead sulfide target, and copper-doped lead sulfide target were all custom-made from Jiangsu Pioneer Microelectronics Technology Co., Ltd. according to requirements.

[0020] The technical solution of the present invention will be studied below using examples and comparative examples. The specific research methods and results are shown below: Example 1 A method for preparing a cadmium telluride thin-film battery includes the following steps: Step 1: Cleaning the TCO conductive glass: Place the TCO conductive glass in a beaker, add glass cleaning solution to the beaker, and clean it with a small brush. After cleaning 3 times, pour out the glass cleaning solution and clean the foam off the surface of the TCO conductive glass with ultrapure water. Then, pour acetone solution and toluene solution into the beaker, place the TCO conductive glass in the beaker and put it into an ultrasonic glass cleaning device for ultrasonic cleaning. After cleaning for 30 minutes, clean the surface of the TCO conductive glass with ultrapure water. Then, spray a layer of alcohol on the surface of the TCO conductive glass, blow off the alcohol on the surface of the TCO conductive glass with nitrogen, and then put it in a drying oven to dry. The cleaned TCO conductive glass substrate is composed of glass and fluorine-doped tin oxide (FTO), that is, it is composed of substrate layer 1 and transparent conductive oxide thin film layer 2.

[0021] Step 2: Sputtering SnO2 thin film using magnetron sputtering equipment: Place the SnO2 target in the magnetron sputtering equipment and sputter a 40nm thick SnO2 thin film on the transparent conductive oxide thin film layer 2 using the magnetron sputtering equipment. The magnetron sputtering conditions are: sputtering power 100W, sputtering atmosphere 100% argon, TCO conductive glass substrate temperature 150℃, and chamber pressure 2Pa. A high-resistivity buffer layer 3 is obtained on the transparent conductive oxide thin film layer 2.

[0022] Step 3: Preparation of the CdS window layer (i.e., battery window layer 4): Using cadmium sulfate as the cadmium source, thiourea as the sulfur source, ammonia as the complexing agent, and ammonium acetate as the pH adjuster, cadmium sulfate, ammonium acetate, thiourea, and ammonia are added sequentially to 500 mL of deionized water, where the ratio of cadmium sulfate:ammonium acetate:thiourea:ammonia is 0.171 g:5.78 g:5.71 g:28 mL. Cadmium sulfate undergoes a complexation reaction with the ammonium salt to generate Cd(NH3)4. 2+ Thiourea decomposes in alkaline solution to form HS. - Further dissociation forms S 2- Then, the TCO conductive glass with the high-resistivity buffer layer 3 deposited on it was placed in the prepared solution for deposition. The deposition time was 20 min and the temperature was 60 °C. The battery window layer 4 was deposited on the high-resistivity buffer layer 3. The thickness of the battery window layer 4 was 50 nm.

[0023] Step 4: Deposit CdTe thin film (i.e., battery layer 5) using CSS equipment: Place the TCO conductive glass with battery window layer 4 into the CSS equipment and heat it to 450°C. Heat the CdTe source to 600°C and hold it for 6 minutes to deposit a 4μm battery layer 5 on the battery window layer 4.

[0024] Post-treatment using cadmium chloride solution: A CdCl2 solution (the solvent of the CdCl2 solution is methanol or water, and the concentration is 0.2 mol / L) is uniformly coated on the surface of battery layer 5 by impregnation. Then the solvent is removed to form a CdCl2 film on battery layer 5. The film is then annealed at 450°C for 30 min to obtain TCO conductive glass post-treated with cadmium chloride.

[0025] Step 5: Preparation of In-doped PbS thin film (back contact layer 6): The pre-customized indium-doped lead sulfide target (wherein, In:PbS=5wt%:95wt%) is placed in the magnetron sputtering equipment, and the magnetron sputtering equipment is pulled to 1×10 -1Pa, then open the argon valve and pre-sputter with the target baffle for 5 min, then open the baffle and perform formal sputtering on cadmium chloride for 10 min under the conditions of power 200W, pressure 3Pa, and gas flow rate 300sccm, and then stop sputtering to obtain a back contact layer 6 with a thickness of 20nm, namely an In-doped PbS film.

[0026] Step 6: Deposit a layer of Au on the back contact layer 6 to form the back electrode 7, thus obtaining a cadmium telluride thin film battery.

[0027] Example 2 A method for preparing an In-doped PbS thin film is the same as the preparation steps in Example 1, except that the indium content is replaced by 8wt% instead of 5wt%.

[0028] Example 3 A method for preparing an In-doped PbS thin film is the same as the preparation steps in Example 1, except that the indium percentage is replaced by 10 wt% instead of 5 wt%.

[0029] Example 4 A method for preparing a cadmium telluride thin-film battery includes the following steps: Step 1: Cleaning the TCO conductive glass: Place the TCO conductive glass in a beaker, add glass cleaning solution to the beaker, and clean it with a small brush. After cleaning 3 times, pour out the glass cleaning solution and clean the foam off the surface of the TCO conductive glass with ultrapure water. Then, pour acetone solution and toluene solution into the beaker, place the TCO conductive glass in the beaker and put it into an ultrasonic glass cleaning device for ultrasonic cleaning. After cleaning for 30 minutes, clean the surface of the TCO conductive glass with ultrapure water. Then, spray a layer of alcohol on the surface of the TCO conductive glass, blow off the alcohol on the surface of the TCO conductive glass with nitrogen, and then put it in a drying oven to dry. The cleaned TCO conductive glass substrate is composed of glass and fluorine-doped tin oxide (FTO), that is, it is composed of substrate layer 1 and transparent conductive oxide thin film layer 2.

[0030] Step 2: Sputtering SnO2 thin film using magnetron sputtering equipment: Place the SnO2 target in the magnetron sputtering equipment and sputter a 10nm thick SnO2 thin film on the transparent conductive oxide thin film layer 2 using the magnetron sputtering equipment. The magnetron sputtering conditions are: sputtering power 100W, sputtering atmosphere 100% argon, TCO conductive glass substrate temperature 150℃, and chamber pressure 2Pa. A high-resistivity buffer layer 3 is obtained on the transparent conductive oxide thin film layer 2.

[0031] Step 3: Preparation of the CdS window layer (i.e., battery window layer 4): Using cadmium sulfate as the cadmium source, thiourea as the sulfur source, ammonia as the complexing agent, and ammonium acetate as the pH adjuster, cadmium sulfate, ammonium acetate, thiourea, and ammonia are added sequentially to 500 mL of deionized water, where the ratio of cadmium sulfate:ammonium acetate:thiourea:ammonia is 0.171 g:5.78 g:5.71 g:28 mL. Cadmium sulfate undergoes a complexation reaction with the ammonium salt to generate Cd(NH3)4. 2+ Thiourea decomposes in alkaline solution to form HS. - Further dissociation forms S 2- Then, the TCO conductive glass with the high-resistivity buffer layer 3 deposited on it was placed in the prepared solution for deposition. The deposition time was 20 min and the temperature was 60 °C. The battery window layer 4 was deposited on the high-resistivity buffer layer 3. The thickness of the battery window layer 4 was 30 nm.

[0032] Step 4: Deposit CdTe thin film (i.e., battery layer 5) using CSS equipment: Place the TCO conductive glass with battery window layer 4 into the CSS equipment and heat it to 450°C. Heat the CdTe source to 600°C and hold it for 6 minutes to deposit a 3.5μm battery layer 5 on the battery window layer 4.

[0033] Post-treatment using cadmium chloride solution: A CdCl2 solution (the solvent of the CdCl2 solution is methanol or water, and the concentration is 10 mol / L) is uniformly coated on the surface of battery layer 5 by impregnation. Then the solvent is removed to form a CdCl2 film on battery layer 5. The film is then annealed at 450°C for 30 min to obtain TCO conductive glass post-treated with cadmium chloride.

[0034] Step 5: Preparation of In-doped PbS thin film (back contact layer 6): The pre-customized indium-doped lead sulfide target (wherein, In:PbS=5wt%:95wt%) is placed in the magnetron sputtering equipment, and the magnetron sputtering equipment is evacuated to a vacuum of 5×10⁻⁶. -4 Pa, then open the argon valve and pre-sputter with the target baffle for 5 min, then open the baffle and perform formal sputtering on cadmium chloride for 10 min under the conditions of power 300W, pressure 0.2Pa, and gas flow rate 1sccm, and then stop sputtering to obtain a back contact layer 6 with a thickness of 5nm, namely an In-doped PbS film.

[0035] Step 6: Deposit a layer of Au on the back contact layer 6 to form the back electrode 7, thus obtaining a cadmium telluride thin film battery.

[0036] Example 5 A method for preparing a cadmium telluride thin-film battery includes the following steps: Step 1: Cleaning the TCO conductive glass: Place the TCO conductive glass in a beaker, add glass cleaning solution to the beaker, and clean it with a small brush. After cleaning 3 times, pour out the glass cleaning solution and clean the foam off the surface of the TCO conductive glass with ultrapure water. Then, pour acetone solution and toluene solution into the beaker, place the TCO conductive glass in the beaker and put it into an ultrasonic glass cleaning device for ultrasonic cleaning. After cleaning for 30 minutes, clean the surface of the TCO conductive glass with ultrapure water. Then, spray a layer of alcohol on the surface of the TCO conductive glass, blow off the alcohol on the surface of the TCO conductive glass with nitrogen, and then put it in a drying oven to dry. The cleaned TCO conductive glass substrate is composed of glass and fluorine-doped tin oxide (FTO), that is, it is composed of substrate layer 1 and transparent conductive oxide thin film layer 2.

[0037] Step 2: Sputtering SnO2 thin film using magnetron sputtering equipment: Place the SnO2 target in the magnetron sputtering equipment and sputter a 100nm thick SnO2 thin film on the transparent conductive oxide thin film layer 2 using the magnetron sputtering equipment. The magnetron sputtering conditions are: sputtering power 100W, sputtering atmosphere 100% argon, TCO conductive glass substrate temperature 150℃, and chamber pressure 2Pa. A high-resistivity buffer layer 3 is obtained on the transparent conductive oxide thin film layer 2.

[0038] Step 3: Preparation of the CdS window layer (i.e., battery window layer 4): Using cadmium sulfate as the cadmium source, thiourea as the sulfur source, ammonia as the complexing agent, and ammonium acetate as the pH adjuster, cadmium sulfate, ammonium acetate, thiourea, and ammonia are added sequentially to 500 mL of deionized water, where the ratio of cadmium sulfate:ammonium acetate:thiourea:ammonia is 0.171 g:5.78 g:5.71 g:28 mL. Cadmium sulfate undergoes a complexation reaction with the ammonium salt to generate Cd(NH3)4. 2+ Thiourea decomposes in alkaline solution to form HS. - Further dissociation forms S 2- Then, the TCO conductive glass with the high-resistivity buffer layer 3 deposited on it was placed in the prepared solution for deposition. The deposition time was 20 min and the temperature was 60 °C. The battery window layer 4 was deposited on the high-resistivity buffer layer 3. The thickness of the battery window layer 4 was 50 nm.

[0039] Step 4: Deposit CdTe thin film (i.e., battery layer 5) using CSS equipment: Place the TCO conductive glass with battery window layer 4 into the CSS equipment and heat it to 450°C. Heat the CdTe source to 600°C and hold it for 6 minutes to deposit a 3μm battery layer 5 on the battery window layer 4.

[0040] Post-treatment using cadmium chloride solution: A CdCl2 solution (the solvent of the CdCl2 solution is methanol or water, and the concentration is 10 mol / L) is uniformly coated on the surface of battery layer 5 by impregnation. Then the solvent is removed to form a CdCl2 film on battery layer 5. The film is then annealed at 450°C for 30 min to obtain TCO conductive glass post-treated with cadmium chloride.

[0041] Step 5: Preparation of In-doped PbS thin film (back contact layer 6): The pre-customized indium-doped lead sulfide target (wherein, In:PbS=5wt%:95wt%) is placed in the magnetron sputtering equipment, and the magnetron sputtering equipment is evacuated to a vacuum of 5×10⁻⁶. -4 Pa, then open the argon valve and pre-sputter with the target baffle for 5 min, then open the baffle and perform formal sputtering on cadmium chloride for 10 min under the conditions of power 80 W, pressure 5 Pa, and gas flow rate 500 sccm, and then stop sputtering to obtain a back contact layer 6 with a thickness of 100 nm, namely an In-doped PbS film.

[0042] Step 6: Deposit a layer of Au on the back contact layer 6 to form the back electrode 7, thus obtaining a cadmium telluride thin film battery.

[0043] Comparative Example 1 A method for preparing a cadmium telluride thin-film battery is the same as that in Example 2, except that in step S6, the In-doped PbS film is replaced with a Zn-doped PbS film. The Zn-doped PbS film is prepared according to the following steps: The pre-customized zinc-doped lead sulfide target (Zn:PbS=8wt%:92wt%) was placed into the magnetron sputtering equipment, and the magnetron sputtering equipment was pulled to 1×10 -1 Pa, then open the argon valve to pre-sputter the target baffle for 5 minutes, then open the baffle again and perform formal sputtering on cadmium chloride for 10 minutes before stopping sputtering to obtain a 20 nm Zn-doped PbS thin film.

[0044] Comparative Example 2 A method for preparing a cadmium telluride thin-film battery is the same as that in Example 2, except that in step S6, the In-doped PbS film is replaced with a Cu-doped PbS film. The Cu-doped PbS film is prepared according to the following steps: The pre-customized copper-doped lead sulfide target (Cu:PbS=8wt%:92wt%) was placed into the magnetron sputtering equipment, and the magnetron sputtering equipment was pumped to 1×10 -1 Pa, then open the argon valve to pre-sputter the target baffle for 5 minutes, then open the baffle again and perform formal sputtering on cadmium chloride for 10 minutes before stopping sputtering to obtain a 20 nm Cu-doped PbS thin film.

[0045] Comparative Example 3 A method for preparing a cadmium telluride thin-film battery is the same as that in Example 2, except that in step S6, the In-doped PbS film is replaced with an Al-doped PbS film. The Al-doped PbS film is prepared according to the following steps: The pre-customized aluminum-doped lead sulfide target (Al:PbS=8wt%:92wt%) was placed into the magnetron sputtering equipment, and the magnetron sputtering equipment was pulled to 1×10 -1 Pa, then open the argon valve to pre-sputter the target baffle for 5 min, then open the baffle again and perform formal sputtering on cadmium chloride for 10 min before stopping sputtering to obtain a 20 nm Al-doped PbS thin film.

[0046] In Examples 1-3 of this invention, In-doped PbS thin films were prepared under different conditions, and cadmium telluride thin-film batteries with an efficiency of 16.18% were fabricated using the In-doped PbS thin films. The cadmium telluride thin-film batteries of Examples 1-3 are used as examples below, and compared with those of Comparative Examples 1-3. The specific research methods and results are shown below: Table 1 Performance parameters of cadmium telluride thin-film batteries Table 1 shows that using an In-doped PbS thin film as the back contact layer of a cadmium telluride thin-film solar cell can reduce interfacial recombination, improve carrier collection efficiency, and reduce copper diffusion, thereby improving the fill power of the cadmium telluride thin-film solar cell. In the cadmium telluride solar cell and its fabrication method of the present invention, an In-doped lead sulfide compound is added to the back contact layer to optimize the surface properties of the back contact layer and effectively improve the conversion efficiency of the cell.

[0047] Furthermore, a comparison between the examples and the comparative examples shows that the fill factor of the examples is significantly improved, while the improvement of open-circuit voltage and current density is relatively difficult.

[0048] Various materials have their own suitability (for example, compared with Examples 1 to 3 of this application). A suitable doping ratio can improve the fill factor, thereby improving the photoelectric conversion efficiency of the battery. Therefore, the doping ratio is not necessarily better the more it is. Under the same conditions, the higher the fill factor, the higher the efficiency. Under the same doping ratio, the photoelectric conversion efficiency of Comparative Examples 1 to 3 (optimal doping ratio) is inferior to that of the Examples.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. Use of In-doped PbS thin films in the preparation of cadmium telluride thin film batteries, characterized in that, The In-doped PbS film is used as the back contact layer of the CdTe thin film cell, and the mass percentage of In in the In-doped PbS film is 5wt%-10wt%, and the rest is PbS.

2. Use of the In-doped PbS thin film according to claim 1 for the production of a cadmium telluride thin film cell, characterized in that, The mass percentage of In in the In-doped PbS film is 8wt%.

3. Use of the In-doped PbS thin film according to claim 1 for the production of a cadmium telluride thin film cell, characterized in that, The thickness of the In-doped PbS film is 10nm-50nm.

4. Use of the In-doped PbS thin film according to claim 1 for the production of a cadmium telluride thin film cell, characterized in that, The In-doped PbS film is prepared according to the following steps: A magnetron sputtering device was pumped to 1×10 -1 Pa~5×10 -4 Pa, using a magnetron sputtering method, under the conditions of power 80W~300W, pressure 0.2Pa~5Pa, and gas flow 1sccm~500sccm, an indium-doped lead sulfide target was magnetron sputtered to obtain an In-doped PbS thin film.

5. Use of the In-doped PbS thin film according to claim 1 for the preparation of a cadmium telluride thin film cell, characterized in that, The CdTe thin film cell is composed of a substrate layer (1), a transparent conductive oxide film layer (2), a high resistance buffer layer (3), a cell window layer (4), a cell layer (5), a back contact layer (6) and a back electrode (7) which are sequentially stacked from bottom to top, wherein the cell layer (5) is a CdTe layer, and the back contact layer (6) is an In-doped PbS film.

6. Use of the In-doped PbS thin film according to claim 5 for the production of a cadmium telluride thin film cell, characterized in that, The CdTe layer is also subjected to post-treatment, and the post-treatment method is as follows: CdCl2 solution is covered on the CdTe layer by immersion, the solvent is evaporated first to form a CdCl2 film, and then annealing is performed at 400°C-500°C for 20min-40min.

7. Use of the In-doped PbS thin film according to claim 5 for the production of a cadmium telluride thin film cell, characterized in that, The thickness of the high resistance buffer layer (3) is 10nm-100nm, the thickness of the cell window layer (4) is 10nm-50nm, the thickness of the cell layer (5) is 1μm-5μm, and the thickness of the back electrode (7) is 5nm-100nm.

8. Use of the In-doped PbS thin film according to claim 5 for the production of a cadmium telluride thin film cell, characterized in that, The transparent conductive oxide film layer (2) is a fluorine-doped tin oxide layer, the high resistance buffer layer (3) is a SnO2 layer, the cell window layer (4) is a CdS window layer, and the back electrode (7) is an Au electrode.

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