In-situ coating process for thin-film solar cells and thin-film solar cells

Abstract

The application provides an in-situ coating process for a thin-film solar cell and the thin-film solar cell, and belongs to the technical field of thin-film solar cells, which is used for continuously attaching a metal back electrode layer and a copper-nickel alloy layer to the surface of a semiconductor junction functional layer of a semi-finished product cell, and comprises the following steps: S1, sputtering deposition of the semi-finished product cell in a cavity of a magnetron sputtering device to form a metal back electrode layer; S2, continuously sputtering deposition of a copper-nickel alloy layer on the surface of the metal back electrode layer under the condition that the gas pressure, temperature and argon atmosphere in the cavity of the magnetron sputtering device remain unchanged; and S3, vacuum gradient cooling in the cavity of the magnetron sputtering device, and packaging after discharging. After the deposition of the metal back electrode layer is completed, the copper-nickel alloy layer can be deposited without transferring the equipment and changing the environmental state, the oxidation and interface pollution caused by the environmental transfer are avoided, and the bonding force between the metal back electrode layer and the copper-nickel alloy layer is improved. Moreover, the production process can be simplified, the mass production efficiency is improved, and the cost is reduced.

Description

Technical Field

[0001] This application belongs to the field of thin-film solar cell technology, and more specifically, relates to an in-situ coating process for thin-film solar cells and a thin-film solar cell. Background Technology

[0002] Thin-film solar cells are a new type of photovoltaic device that is thin, lightweight, and flexible. They generate electricity by depositing a very thin layer of photoelectric material onto a substrate. A typical thin-film solar cell consists of a transparent substrate, a transparent front electrode layer, a semiconductor junction functional layer composed of a window layer and a light-absorbing layer, and a back electrode layer, arranged sequentially. Compared to traditional crystalline silicon cells, they offer significant advantages such as lower cost, better low-light power generation performance, and ease of integration with buildings. The back electrode layer often uses metals such as molybdenum, aluminum, and chromium, deposited on the surface of the semiconductor junction functional layer using magnetron sputtering equipment, serving as the back electrode of the thin-film solar cell. However, in practical applications, due to the poor wettability of the back electrode layer material with solder, conventional photovoltaic soldering processes cannot be used to directly solder wires or terminals.

[0003] In the prior art, Chinese utility model patent CN203103327U discloses a novel amorphous silicon thin-film solar cell module, which prepares a copper-nickel alloy layer on the back electrode. Because the copper-nickel alloy layer has good wettability with solder, direct soldering connection between the wires and the back electrode can be achieved. However, in actual production, after the back electrode layer is deposited, an offline secondary coating process is required to add the copper-nickel alloy layer. That is, after the overall thin-film solar cell is fabricated, it needs to be transferred to other equipment for copper-nickel alloy coating. The vacuum breaking process during cell transfer can easily introduce impurities and cause film oxidation, resulting in poor adhesion of the newly added copper-nickel alloy layer, making it prone to delamination and peeling. Furthermore, the segmentation process complicates the process and increases costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides an in-situ coating process for thin-film solar cells and a thin-film solar cell. Through integrated vacuum in-situ continuous coating, the continuous forming of the metal back electrode and the copper-nickel alloy layer is achieved, thereby improving the adhesion of the copper-nickel alloy layer, product yield, and mass production efficiency.

[0005] To achieve the above objectives, the technical solution of this application provides an in-situ coating process for thin-film solar cells, used to continuously attach a metal back electrode layer and a copper-nickel alloy layer to the surface of the semiconductor junction functional layer of a semi-finished cell; wherein, the semi-finished cell includes a transparent substrate, a transparent front electrode layer, and a semiconductor junction functional layer stacked sequentially, and has been grooved, specifically including: Step S1: The semi-finished battery is fed into the cavity of the magnetron sputtering equipment. A back electrode target with a back electrode target material is set in the cavity of the magnetron sputtering equipment. Under the condition that the inner cavity of the magnetron sputtering equipment is kept at a set vacuum level, a set temperature and an argon atmosphere, a metal back electrode layer is formed by sputtering and depositing on the surface of the semiconductor junction functional layer of the semi-finished battery through the back electrode target. Step S2: A copper-nickel alloy target with a copper-nickel alloy target material is placed in the cavity of the magnetron sputtering equipment. Under the condition of keeping the gas pressure, temperature and argon atmosphere in the cavity of the magnetron sputtering equipment constant, a copper-nickel alloy layer is continuously sputtered and deposited on the surface of the metal back electrode layer through the copper-nickel alloy target to form an unencapsulated finished battery cell. Step S3: The finished solar cells are subjected to vacuum gradient cooling inside the magnetron sputtering equipment, and after discharge, they are encapsulated to form finished thin-film solar cells.

[0006] Optionally, the back electrode target includes a molybdenum target, an aluminum target, and a chromium target, wherein a molybdenum metal target is disposed inside the molybdenum target, an aluminum metal target is disposed inside the aluminum target, and a chromium metal target is disposed inside the chromium target. In step S1, during the process of sputtering and depositing a metal back electrode layer on the surface of the semiconductor junction functional layer of the semi-finished battery, a molybdenum target, an aluminum target, and a chromium target are sputtered and deposited in sequence to form a three-layer metal back electrode layer structure in which molybdenum metal, aluminum metal, and chromium metal are stacked sequentially on the surface of the semiconductor junction functional layer. The steps between S1 and S2 also include: Step S1.5: Under the condition of keeping the gas pressure, temperature and argon atmosphere of the inner cavity of the magnetron sputtering equipment constant, the deposition rate of the chromium metal target decreases linearly until it reaches zero. Simultaneously, the deposition rate of the copper-nickel alloy target gradually increases linearly from zero until the set rate, so as to form a copper-nickel-chromium composite transition layer between the metal back electrode layer and the copper-nickel alloy layer. In step S2, the copper-nickel alloy layer is continuously sputtered and deposited on the surface of the metal back electrode layer using a copper-nickel alloy target.

[0007] Optionally, the total thickness of the three-layer metal back electrode structure ranges from 500 nm to 1200 nm, wherein the thickness of the molybdenum metal layer ranges from 50 nm to 150 nm, the thickness of the aluminum metal layer ranges from 400 nm to 1000 nm, and the thickness of the chromium metal layer ranges from 10 nm to 50 nm; the thickness of the copper-nickel-chromium composite transition layer ranges from 10 nm to 95 nm, and the thickness of the copper-nickel alloy layer ranges from 50 nm to 200 nm.

[0008] Optionally, in step S1, the deposition rate of the molybdenum metal layer is 200 nm / min to 800 nm / min, the deposition rate of the aluminum metal layer is 500 nm / min to 2000 nm / min, and the deposition rate of the chromium metal layer is 150 nm / min to 600 nm / min. In step S1.5, the sputtering deposition time of chromium metal and the sputtering deposition time of copper-nickel alloy layer are both between 3 seconds and 10 seconds. When the copper-nickel-chromium composite transition layer is completed, the deposition rate of copper-nickel alloy reaches a steady-state rate in the range of 300 nm / min to 500 nm / min. In step S2, the copper-nickel alloy deposition rate is maintained at the steady-state rate to achieve sputter deposition of the copper-nickel alloy layer.

[0009] Optionally, the copper-nickel alloy target includes a copper target and a nickel target, with copper metal material located on the copper target and nickel metal material located on the nickel target; In step S2, the copper target and the nickel target are sputtered and deposited simultaneously to form the copper-nickel alloy layer. As the copper-nickel alloy layer is sputtered and deposited, the sputtering deposition rate of nickel metal decreases linearly, while the sputtering deposition rate of copper metal increases linearly, forming a copper-nickel alloy layer in which the copper-nickel ratio gradually increases along the direction away from the metal back electrode layer.

[0010] Optionally, the thickness of the metal back electrode layer ranges from 500 nm to 1200 nm, and the thickness of the copper-nickel alloy layer ranges from 50 nm to 200 nm.

[0011] Optionally, in step S2, the initial sputtering deposition rate of nickel metal is 400 nm / min to 630 nm / min, and the final sputtering deposition rate is 70 nm / min to 100 nm / min; the initial sputtering deposition rate of copper metal is 400 nm / min to 500 nm / min, and the final sputtering deposition rate is 600 nm / min to 800 nm / min; the sputtering deposition time of nickel metal and copper metal is the same and is between 3 seconds and 16 seconds.

[0012] Optionally, in step S1, the gas pressure in the inner chamber of the magnetron sputtering equipment before argon is introduced is not higher than 5 × 10⁻⁶. -3 Pa, the pressure range after filling with argon is 0.3 Pa to 0.8 Pa, and the set temperature is maintained between 80°C and 120°C.

[0013] Optionally, the following may be included between step S2 and step S3: Step S2.5: While maintaining the gas pressure, temperature and argon atmosphere inside the magnetron sputtering equipment, turn off the sputtering power supply and the target baffle, and keep it at that temperature for 2 to 5 minutes. In step S3, the vacuum gradient cooling includes the following steps: Step S3-1: While keeping the gas pressure inside the magnetron sputtering equipment constant, reduce the temperature inside the magnetron sputtering equipment at a rate of 5-8℃ / min until the temperature inside the cavity is below 80℃. Step S3-2: Continue to lower the temperature of the inner cavity of the magnetron sputtering equipment at a rate of 5-8℃ / min until the temperature inside the cavity is below 50℃, and at the same time, linearly increase the gas pressure inside the cavity to 10Pa to 50Pa by filling the cavity with argon gas, and then stop filling the cavity with argon gas. Step S3-3: Continue to reduce the temperature of the inner cavity of the magnetron sputtering equipment at a rate of 5-8℃ / min until the temperature inside the cavity is below 40℃; Step S3-4: Introduce nitrogen to increase the chamber pressure to 0.8 × 10⁻⁶. 4 Pa up to 1.2 × 10 4 Hold the pressure at 100 to 140 seconds after applying 100 Pa, then continue filling with nitrogen to increase the chamber pressure to 4 × 10⁻⁶. 4 Pa to 6×10 4 After pressing the pressure (Pa) for 50 to 70 seconds, continue filling with nitrogen until atmospheric pressure is reached before opening the cavity to remove the film.

[0014] A thin-film solar cell is manufactured using the aforementioned in-situ coating process for thin-film solar cells.

[0015] The advantages of the technical solution in this application compared to the prior art are as follows: After the metal back electrode layer is deposited by magnetron sputtering, it can be directly sputtered and deposited in situ with a copper-nickel alloy layer without being removed and transferred to other equipment. This achieves continuous forming of the metal back electrode and the copper-nickel alloy layer. This method can fundamentally avoid oxidation and interface contamination caused by environmental transfer. At the same time, since the metal back electrode layer does not need to be removed and transferred to other equipment for copper-nickel alloy layer coating after sputtering deposition, the production process can be simplified, mass production efficiency can be improved, and production costs can be reduced. Because the metal back electrode layer must undergo a process of cooling and pressurizing followed by heating and pressurizing during equipment transfer, the bonding force between the metal back electrode layer and the copper-nickel alloy layer is lower than that of directly depositing the copper-nickel alloy layer while maintaining environmental conditions. Therefore, the technical solution itself can improve the bonding force between the metal back electrode layer and the copper-nickel alloy layer, and avoid delamination. The contact surfaces of the metal back electrode layer and the copper-nickel alloy layer can be sputtered and deposited simultaneously to form a composite structure, which allows the two surfaces to fuse together, further enhancing the bonding force and making the product stable and reliable. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the in-situ coating process for thin-film solar cells. Figure 2 This is a schematic diagram of the first type of thin-film solar cell structure; Figure 3 This is a schematic diagram of the second type of thin-film solar cell structure.

[0018] Icons: 11. Transparent substrate; 12. Transparent front electrode layer; 13. Semiconductor junction functional layer; 14. Metal back electrode layer; 15. Molybdenum metal layer; 16. Aluminum metal layer; 17. Chromium metal layer; 18. Copper-nickel-chromium composite transition layer; 19. Copper-nickel alloy layer. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0020] Example 1: based on Figure 1 and Figure 2 As shown, this embodiment provides an in-situ coating process for thin-film solar cells, used in the production of thin-film solar cells, for continuously attaching a metal back electrode layer 14 and a copper-nickel alloy layer 19 to the surface of the semiconductor junction functional layer 13 of a semi-finished cell. The semi-finished cell includes a transparent substrate 11, a transparent front electrode layer 12, and a semiconductor junction functional layer 13 stacked sequentially, and grooves have been etched.

[0021] For cadmium telluride thin-film solar cells, the semiconductor junction functional layer 13 includes a CdS window layer and a CdTe absorber layer. For perovskite thin-film solar cells, the semiconductor junction functional layer 13 includes a formal nip structure of an electron transport layer, a perovskite absorber layer, and a hole transport layer, or it can be an inverse pin structure of a hole transport layer, a perovskite absorber layer, and an electron transport layer. The manufacturing processes for each layer, including the grooving process, all utilize existing technologies, and the magnetron sputtering equipment is also existing equipment, which will not be described in detail. These are intermediate products in the production process of semi-finished cells and thin-film solar cells. The technical solution of this application is used to deposit a metal back electrode layer 14 and a copper-nickel alloy layer 19 in situ on a semi-finished cell using magnetron sputtering equipment to continue manufacturing a finished thin-film solar cell.

[0022] In this embodiment, the magnetron sputtering apparatus includes a back electrode target and a copper-nickel alloy target. The back electrode target is disposed on the back electrode target and is used to deposit a metal back electrode layer 14 on the surface of the semiconductor junction functional layer 13. The copper-nickel alloy target is made of copper-nickel alloy and is disposed on the copper-nickel alloy target for depositing a copper-nickel alloy layer 19. Specifically, it includes: Step S1: The semi-finished battery is fed into the cavity of the magnetron sputtering equipment. A back electrode target with a back electrode target material is set in the cavity of the magnetron sputtering equipment. Under the condition that the inner cavity of the magnetron sputtering equipment is kept at a set vacuum level, a set temperature and an argon atmosphere, a metal back electrode layer 14 is formed by sputtering and depositing on the surface of the semiconductor junction functional layer 13 of the semi-finished battery through the back electrode target.

[0023] Among them, the set vacuum level refers to the gas pressure in the inner chamber of the magnetron sputtering equipment before argon is filled, which is no higher than 5 × 10⁻⁶. -3 The pressure range after argon filling is 0.3 Pa to 0.8 Pa, and the set temperature is maintained between 80°C and 120°C. In this embodiment, after the semi-finished battery is placed into the chamber of the magnetron sputtering equipment, it is gradually evacuated until the pressure inside the chamber does not exceed 5 × 10⁻⁶ Pa. -3 Pa, then argon gas is introduced into the chamber until the pressure inside the chamber reaches 0.5 Pa, and the temperature inside the chamber is heated to 100°C. Throughout the production process, the pressure and temperature sensors inside the magnetron sputtering equipment monitor the pressure and temperature inside the chamber in real time, ensuring that the pressure is between 0.3 Pa and 0.8 Pa and the temperature is between 80°C and 120°C.

[0024] In step S1, the back electrode target includes a molybdenum target, an aluminum target, and a chromium target. The molybdenum target contains a molybdenum metal target, the aluminum target contains an aluminum metal target, and the chromium target contains a chromium metal target. During the sputtering deposition of the semiconductor junction functional layer 13 of the semi-finished battery to form a metal back electrode layer 14, the molybdenum target, the aluminum target, and the chromium target are sputtered and deposited in sequence to form a three-layer metal back electrode layer 14 structure of molybdenum metal, aluminum metal, and chromium metal stacked sequentially on the surface of the semiconductor junction functional layer 13.

[0025] In this embodiment, a molybdenum target is first sputtered to deposit molybdenum metal at a rate of 400 nm / min for 0.25 min, forming a 100 nm thick molybdenum metal layer 15. Then, sputtering on the molybdenum target stops, and an aluminum target begins to deposit aluminum metal. The aluminum metal deposition rate is 1200 nm / min, and it takes 0.5 min to form a 600 nm thick aluminum metal layer 16. Next, sputtering on the aluminum target stops, and a chromium target begins to deposit chromium metal. The chromium deposition rate is 400 nm / min, and it takes 0.05 min to form a 20 nm thick chromium metal layer 17. Finally, a metal back electrode layer 14 structure with a total thickness of 720 nm is formed.

[0026] Because aluminum has a lower resistivity than molybdenum and chromium, the aluminum metal layer 16, serving as the main conductive path, is the thickest, achieving conductivity superior to pure molybdenum or pure chromium electrodes. However, aluminum atoms tend to diffuse into the absorber layer at high temperatures, leading to reduced open-circuit voltage and conversion efficiency. Therefore, a molybdenum metal layer 15 is placed between the semiconductor junction functional layer 13 and the aluminum metal layer 16 to block aluminum atom diffusion. The chromium metal layer 17 enhances the electrode's resistance to oxidation and moisture corrosion. Taking a cadmium telluride thin-film solar cell as an example, the molybdenum, aluminum, and chromium three-layer metal back electrode layer 14 structure in this embodiment can improve efficiency by 1.85% compared to a device with a pure aluminum back electrode layer of the same thickness.

[0027] In other embodiments, the deposition rate of the molybdenum metal layer 15 can be set to any value between 200 nm / min and 800 nm / min, and the thickness of the formed molybdenum metal layer 15 is between 50 nm and 150 nm. The deposition rate of the aluminum metal layer 16 can be set to any value between 500 nm / min and 2000 nm / min, and the thickness of the formed aluminum metal layer 16 is between 400 nm and 1000 nm. The deposition rate of the chromium metal layer 17 can be set to any value between 150 nm / min and 600 nm / min, and the thickness of the formed chromium metal layer 17 is between 10 nm and 50 nm. Simultaneously, the total thickness of the three-layer metal back electrode layer 14 structure, i.e., the total thickness of the molybdenum metal layer 15, aluminum metal layer 16, and chromium metal layer 17, must be between 500 nm and 1200 nm.

[0028] Step S1.5: Under the conditions of maintaining the gas pressure in the inner cavity of the magnetron sputtering equipment at 0.5 Pa, the temperature in the cavity at 100 °C and the argon atmosphere at a constant level, the deposition rate of the chromium metal target decreases linearly until it reaches zero. Simultaneously, the deposition rate of the copper-nickel alloy target gradually increases linearly from zero until it reaches the set rate, so as to form a copper-nickel-chromium composite transition layer 18 between the metal back electrode layer 14 and the copper-nickel alloy layer 19.

[0029] In this embodiment, after the chromium metal layer 17 is deposited in step S1, the deposition of chromium metal on the chromium target is not directly interrupted, but the deposition rate decreases linearly until it reaches zero. A copper-nickel alloy target is simultaneously sputtered to form a copper-nickel-chromium composite transition layer 18, which combines chromium metal and copper-nickel alloy. In the copper-nickel alloy layer 19, the preferred mass ratio of copper metal to nickel metal is 3:7. The initial deposition rate of chromium is 400 nm / min, and the rate is reduced to -4800 nm / min. 2 Sputtering was performed at a rate of change of sputtering rate, with the velocity returning to zero after a total of 5 seconds of sputtering. Simultaneously, the copper-nickel alloy was sputtered at +4800 nm / min. 2Sputtering was performed at a rate of change of sputtering rate, reaching a steady-state deposition rate of 400 nm / min after 5 seconds, ultimately forming a 33.3 nm thick copper-nickel-chromium composite transition layer 18. When the deposition of the copper-nickel-chromium composite transition layer 18 was completed, the deposition rate of the copper-nickel alloy reached a steady-state rate of 400 nm / min.

[0030] Step S2: A copper-nickel alloy target with a copper-nickel alloy target is placed inside the cavity of the magnetron sputtering equipment. Under the conditions of maintaining the gas pressure inside the magnetron sputtering equipment at 0.5 Pa, the temperature inside the cavity at 100°C, and the argon atmosphere at a constant level, the copper-nickel alloy layer 19 is continuously sputtered and deposited on the surface of the metal back electrode layer 14 through the copper-nickel alloy target. The deposition rate of the copper-nickel alloy is maintained at the steady-state rate to achieve the sputtering deposition of the copper-nickel alloy layer 19. In this embodiment, the copper-nickel alloy is deposited at a steady-state rate of 400 nm / min for 0.25 min to form a copper-nickel alloy layer 19 with a thickness of 100 nm, forming an unencapsulated finished battery cell.

[0031] Through steps S1.5 and S2 described above, a copper-nickel-chromium composite transition layer 18 and a copper-nickel alloy layer 19 are deposited on the surface of the metal back electrode layer 14. In the copper-nickel-chromium composite transition layer 18, the chromium content gradually decreases away from the chromium metal layer 17, while the copper-nickel alloy content gradually increases away from the chromium metal layer 17. Compared to directly depositing the copper-nickel alloy layer 19 on the surface of the metal back electrode layer 14, there is no abrupt interface change between the metal back electrode layer 14 and the copper-nickel alloy layer 19, which improves the bonding force between the metal back electrode layer 14 and the copper-nickel alloy layer 19 and ensures conductivity efficiency. This also ensures conductivity efficiency between the wires and the metal back electrode during subsequent soldering of the finished thin-film solar cell with external wires. The sputtering deposition of the copper-nickel-chromium composite transition layer 18 does not require additional process steps; it only requires simultaneous sputtering of chromium metal and copper-nickel alloy in a magnetron sputtering device, resulting in low cost and high production efficiency. Steps S1, S1.5, and S2 are all performed within the magnetron sputtering equipment cavity, without material transfer, maintaining a constant cavity environment, and without breaking the vacuum, thus achieving continuous forming of the metal back electrode and the copper-nickel alloy layer 19. This method can fundamentally avoid oxidation and interface contamination caused by environmental transfer.

[0032] In other embodiments, the thickness of the copper-nickel-chromium composite transition layer 18 can be set between 10 nm and 95 nm, the sputtering deposition time of chromium metal and the sputtering deposition time of copper-nickel alloy layer 19 are both between 1.5 seconds and 13 seconds, and when the copper-nickel-chromium composite transition layer 18 is deposited, the deposition rate of copper-nickel alloy reaches a steady-state rate between 300 nm / min and 500 nm / min.

[0033] For example, in step S1.5 of some embodiments, chromium is deposited at a rate ranging from 150 nm / min to 3000 nm / min.2 The sputtering rate change rate dropped to zero after 3 seconds of sputtering deposition, while the copper-nickel alloy sputtered at +6000 nm / min. 2 Sputtering was performed at a rate of change of sputtering rate, reaching a steady-state rate of 300 nm / min after 3 seconds, ultimately forming an 11.25 nm thick copper-nickel-chromium composite transition layer 18. When the deposition of the copper-nickel-chromium composite transition layer 18 was completed, the deposition rate of the copper-nickel alloy reached a steady-state rate of 300 nm / min. In step S2, the copper-nickel alloy was deposited at a steady-state rate of 300 nm / min for 10 seconds to form a copper-nickel alloy layer 19 with a thickness of 50 nm.

[0034] For example, in step S1.5 of some embodiments, chromium is deposited at a rate ranging from 600 nm / min to -3600 nm / min. 2 The sputtering rate change rate dropped to zero after 10 seconds of sputtering deposition, while the copper-nickel alloy sputtered at +3000 nm / min. 2 Sputtering was performed at a rate of change of sputtering rate, reaching a steady-state rate of 500 nm / min after 10 seconds, ultimately forming a 91.67 nm thick copper-nickel-chromium composite transition layer 18. When the deposition of the copper-nickel-chromium composite transition layer 18 was complete, the deposition rate of the copper-nickel alloy reached a steady-state rate of 500 nm / min. In step S2, the copper-nickel alloy was deposited at a steady-state rate of 500 nm / min for 24 seconds, forming a 200 nm thick copper-nickel alloy layer 19.

[0035] Step S2.5: While maintaining constant gas pressure, temperature, and argon atmosphere within the magnetron sputtering equipment cavity, turn off the sputtering power supply and target baffle, and hold the temperature for 2 to 5 minutes to homogenize the temperature of each layer and eliminate deposition stress. In this embodiment, the holding time is 3 minutes.

[0036] Step S3: The finished solar cells are subjected to vacuum gradient cooling inside the magnetron sputtering equipment, and after discharge, they are encapsulated to form finished thin-film solar cells.

[0037] In step S3, the vacuum gradient cooling includes the following steps: Step S3-1: While maintaining a constant gas pressure inside the magnetron sputtering equipment cavity, reduce the temperature of the cavity at a rate of 5-8°C / min until the cavity temperature is below 80°C. In this embodiment, the temperature decrease rate is 5°C / min, and the cooling process takes 4.5 minutes until the cavity temperature drops from 100°C to 75°C.

[0038] Step S3-2: Continue to decrease the temperature of the magnetron sputtering equipment cavity at a rate of 5-8℃ / min until the cavity temperature is below 50℃. Simultaneously, linearly increase the cavity pressure to 10Pa to 50Pa by introducing argon gas, then stop introducing argon gas. The pressure increase must be linear and slow to avoid stress abrupt changes caused by gas flow impacting the film layer. In this embodiment, the temperature decrease rate remains at 5℃ / min, and after 5.4 minutes of cooling, the cavity temperature drops from 75℃ to 48℃. During cooling, argon gas is introduced into the cavity until the cavity pressure reaches 35Pa. The introduction time is the same as the cooling time, both 5.4 minutes, and the introduction rate is uniform.

[0039] Step S3-3: Continue to reduce the temperature of the inner cavity of the magnetron sputtering equipment at a rate of 5-8℃ / min until the cavity temperature is below 40℃. In this embodiment, the temperature reduction rate is maintained at 5℃ / min, and after 2 minutes of cooling, the cavity temperature is reduced from 48℃ to 38℃.

[0040] Step S3-4: Introduce nitrogen to increase the chamber pressure to 0.8 × 10⁻⁶. 4 Pa up to 1.2 × 10 4 Hold the pressure at 100 to 140 seconds after applying 100 Pa, then continue filling with nitrogen to increase the chamber pressure to 4 × 10⁻⁶. 4 Pa to 6×10 4 After pressing the pressure at 1000 MPa, maintain the pressure for 50 to 70 seconds, then continue filling with nitrogen until atmospheric pressure is reached before opening the cavity to remove the film. In this embodiment, nitrogen is first introduced to raise the cavity pressure to 1 × 10⁻⁶ MPa. 4 Maintain the pressure at 120 Pa for 120 seconds, inflating at a constant rate for at least 3 minutes. Then continue inflating with nitrogen to raise the chamber pressure to 5 × 10⁻⁶. 4 After Pa, maintain for 60 seconds, inflate at a constant rate for at least 3 minutes, and finally continue inflating with nitrogen to atmospheric pressure for at least 2 minutes before opening the cavity to remove the film.

[0041] Vacuum gradient cooling, while maintaining an oxygen-free environment during pressurization, prevents oxidation of the semiconductor junction functional layer 13 and the metal back electrode layer 14. A slow cooling rate of 5-8℃ / min gradually releases the thermal stress concentrated during cooling, preventing cracking of the metal back electrode and avoiding increased contact resistance. A faster cooling rate results in higher production efficiency, while a slower cooling rate provides better stress release. The chamber can only be opened and the material removed when the internal temperature is below 40℃ and the internal pressure is restored to atmospheric pressure by filling with nitrogen. After unloading, the material is encapsulated to produce a finished thin-film solar cell. The encapsulation process uses EVA film lamination at a lamination temperature of 140℃ and a pressure of 0.1MPa, followed by a 20-minute holding period to produce the finished thin-film solar cell.

[0042] Comparative Example 1: The technical solution of Comparative Example 1 uses two magnetron sputtering devices identical to those in Example 1, and includes the following steps: Step 1: The semi-finished battery with the same specifications as in Example 1 is fed into the cavity of the first magnetron sputtering equipment, and a vacuum is drawn until the gas pressure in the cavity does not exceed 5 × 10⁻⁶. -3 Argon gas was introduced until the pressure stabilized at 0.5 Pa, and the chamber temperature was heated to 100°C. Using the same target material and deposition process parameters as in Example 1, a 100 nm thick molybdenum metal layer 15, a 600 nm thick aluminum metal layer 16, and a 20 nm thick chromium metal layer 17 were sequentially sputtered to form a metal back electrode layer 14 with a total thickness of 720 nm. After deposition, the chamber of the magnetron sputtering equipment was cooled to atmospheric pressure using the same vacuum gradient cooling method as in step S3 of Example 1, and the battery cells were removed and temporarily stored in a clean environment for 30 min.

[0043] Step 2: The solar cell with the metal back electrode layer deposited in Step 1 is fed into the cavity of the second magnetron sputtering equipment, and a vacuum is drawn until the gas pressure in the cavity does not exceed 5 × 10⁻⁶. -3 Argon gas was introduced until the pressure stabilized at 0.5 Pa, and the chamber temperature was heated to 100°C. Using a copper-nickel alloy target, a homogeneous copper-nickel alloy layer 19 with a thickness of 100 nm was directly formed on the surface of the chromium metal layer 17 by sputtering at a constant rate of 400 nm / min for 0.25 min, resulting in an unencapsulated solar cell. In the copper-nickel alloy target, the mass ratio of copper to nickel was 3:7.

[0044] Step 3: While maintaining the air pressure, temperature and argon atmosphere in the cavity of the second magnetron sputtering device, turn off the sputtering power supply and the target baffle, and keep it warm for 3 minutes.

[0045] Step 4: Use the same parameters and methods as in step S3 of Example 1 to discharge the material and encapsulate it to form a finished thin-film solar cell.

[0046] Comparative Example 2: The technical solution of Comparative Example 2 uses the same magnetron sputtering equipment as Example 1, and includes the following steps: Step 1: Place the semi-finished battery with the same specifications as in Example 1 into the cavity of the magnetron sputtering equipment, and evacuate the chamber until the gas pressure inside the chamber does not exceed 5 × 10⁻⁶. -3Argon gas was introduced until the pressure stabilized at 0.5 Pa, and the temperature inside the chamber was heated to 100°C. Using the same target material and deposition process parameters as in Example 1, a 100 nm thick molybdenum metal layer 15, a 600 nm thick aluminum metal layer 16, and a 20 nm thick chromium metal layer 17 were sequentially sputtered and deposited, ultimately forming a metal back electrode layer 14 structure with a total thickness of 720 nm.

[0047] Step 2: Under conditions where the chamber pressure, temperature, and argon atmosphere remain completely constant, a homogeneous copper-nickel alloy layer 19 with a thickness of 100 nm is formed on the surface of the chromium metal layer 17 by sputtering at a constant rate of 400 nm / min for 0.25 min using a copper-nickel alloy target, resulting in an unencapsulated solar cell. In the copper-nickel alloy target, the mass ratio of copper metal to nickel metal is 3:7.

[0048] Step 3: While maintaining the gas pressure, temperature and argon atmosphere inside the magnetron sputtering equipment, turn off the sputtering power supply and target baffle, and keep it warm for 3 minutes.

[0049] Step 4: Use the same parameters and methods as in step S3 of Example 1 to discharge the material and encapsulate it to form a finished thin-film solar cell.

[0050] One hundred tablets each from the same batch of samples from Example 1, Comparative Example 1, and Comparative Example 2 were compared, and the results are shown in the table below: Example 1 Comparative Example 1 Comparative Example 2 The proportion of copper-nickel alloy layer peeling off to the total area 0.2% 1.3% 0.2% Yield 98% 79% 97% Average contact resistance between the copper-nickel alloy layer and the metal back electrode layer 0.12mΩ・cm² 0.38mΩ・cm² 0.21mΩ・cm² It can be seen that, since the metal back electrode layer 14 inevitably needs to undergo a process of cooling and pressurizing followed by heating and pressurizing during equipment transfer, the copper-nickel alloy layer 19 in Comparative Example 1 experienced delamination. However, Examples 1 and 2, which used in-situ deposition of the copper-nickel alloy layer 19, completely avoided delamination and achieved a higher yield. Furthermore, Examples 1 and 2 show that the copper-nickel-chromium composite transition layer 18 reduced the contact resistance between the copper-nickel alloy layer 19 and the metal back electrode layer 14, thus improving electrical performance.

[0051] In the in-situ coating process for thin-film solar cells in Example 1, after the metal back electrode layer 14 is sputtered and deposited using a magnetron sputtering device, it can be directly sputtered and deposited in situ for the copper-nickel alloy layer 19 without being removed and transferred to other equipment. This achieves continuous forming of the metal back electrode and the copper-nickel alloy layer 19. This method can fundamentally avoid oxidation and interface contamination caused by environmental transfer. Simultaneously, since the metal back electrode layer 14 does not need to be removed and transferred to other equipment for the copper-nickel alloy layer 19 coating after sputtering and deposition, the production process can be simplified, mass production efficiency improved, and production costs reduced. The bonding force between the metal back electrode layer 14 and the copper-nickel alloy layer 19 is lower than that of the copper-nickel alloy layer 19 directly deposited in an environmental state. Therefore, the technical solution itself can improve the bonding force between the metal back electrode layer 14 and the copper-nickel alloy layer 19, preventing delamination. The contact surfaces of the metal back electrode layer 14 and the copper-nickel alloy layer 19 are simultaneously sputtered to form a copper-nickel-chromium composite transition layer 18, which allows the surfaces of the two layers to fuse together, improves the bonding force between the metal back electrode layer 14 and the copper-nickel alloy layer 19, and reduces the contact resistance between the copper-nickel alloy layer 19 and the metal back electrode layer 14, thereby improving the electrical performance.

[0052] Example 2: based on Figure 1 and Figure 3 As shown, this embodiment provides an in-situ deposition process for thin-film solar cells, used in the production of thin-film solar cells, for continuously attaching a metal back electrode layer 14 and a copper-nickel alloy layer 19 to the surface of the semiconductor junction functional layer 13 of a semi-finished cell. The semi-finished cell includes a transparent substrate 11, a transparent front electrode layer 12, and a semiconductor junction functional layer 13 stacked sequentially, and has been grooved. This is an intermediate product in the production process of semi-finished cells and thin-film solar cells. The technical solution of this application is used to deposit a metal back electrode layer 14 and a copper-nickel alloy layer 19 in situ on a semi-finished cell using magnetron sputtering equipment to continue manufacturing a finished thin-film solar cell. Specifically, it includes: Step S1: The semi-finished battery is fed into the cavity of the magnetron sputtering equipment. A back electrode target with a back electrode target material is set in the cavity of the magnetron sputtering equipment. Under the condition that the inner cavity of the magnetron sputtering equipment is kept at a set vacuum level, a set temperature and an argon atmosphere, a metal back electrode layer 14 is sputtered and deposited on the surface of the semiconductor junction functional layer 13 of the semi-finished battery.

[0053] Among them, the set vacuum level refers to the gas pressure in the inner chamber of the magnetron sputtering equipment before argon is filled, which is no higher than 5 × 10⁻⁶. -3 The pressure range after argon filling is 0.3 Pa to 0.8 Pa, and the set temperature is maintained between 80°C and 120°C. In this embodiment, after the semi-finished battery is placed into the chamber of the magnetron sputtering equipment, it is gradually evacuated until the pressure inside the chamber does not exceed 5 × 10⁻⁶ Pa. -3The pressure is then increased to 0.3 Pa, followed by the introduction of argon gas into the chamber until the pressure reaches 0.3 Pa, and the temperature inside the chamber is heated to 120°C. Throughout the production process, the pressure and temperature sensors inside the magnetron sputtering equipment monitor the pressure and temperature inside the chamber in real time, ensuring that the pressure is between 0.3 Pa and 0.8 Pa and the temperature is between 80°C and 120°C.

[0054] In step S1, the metal back electrode layer 14 is deposited by sputtering using common back electrode materials such as molybdenum, aluminum, chromium, or silver. The thickness of the metal back electrode layer 14 ranges from 500 nm to 1200 nm. In this embodiment, the metal back electrode layer 14 has a thickness of 1000 nm and is made of chromium metal. The chromium metal is deposited by sputtering using a back electrode target.

[0055] Step S2: A copper-nickel alloy target with a copper-nickel alloy target material is placed inside the cavity of the magnetron sputtering equipment. The copper-nickel alloy target includes a copper target and a nickel target, with the copper metal material located on the copper target and the nickel metal material located on the nickel target. Under the condition of maintaining constant gas pressure, temperature and argon atmosphere inside the magnetron sputtering equipment cavity, a copper-nickel alloy layer 19 is continuously sputtered and deposited on the surface of the metal back electrode layer 14 through the copper target and the nickel target to form an unencapsulated finished battery cell.

[0056] In step S2, as the copper-nickel alloy layer 19 is sputtered and deposited, the sputtering deposition rate of nickel metal decreases linearly, while the sputtering deposition rate of copper metal increases linearly, forming a copper-nickel alloy layer 19 in which the proportion of copper and nickel gradually increases along the direction away from the metal back electrode layer 14.

[0057] Copper atoms diffuse into the semiconductor junction functional layer 13 more easily than nickel atoms, and the diffusion of copper atoms into the semiconductor junction functional layer 13 reduces battery efficiency. Therefore, by using a content gradient, the proportion of copper atoms in the copper-nickel alloy layer 19 that are attached to the surface of the semiconductor junction functional layer 13 is reduced to decrease the impact of copper atoms on battery efficiency.

[0058] Specifically, in this embodiment, the initial sputtering deposition rate for nickel metal is 400 nm / min, and the final sputtering deposition rate is 100 nm / min. The initial sputtering deposition rate for copper metal is 400 nm / min, and the final sputtering deposition rate is 600 nm / min. The sputtering deposition time for both nickel and copper metal is the same, 8 seconds, resulting in a final copper-nickel alloy thickness of 100 nm.

[0059] In other embodiments, the initial sputtering deposition rate for nickel metal is 400 nm / min to 630 nm / min, and the final sputtering deposition rate is 70 nm / min to 100 nm / min. The initial sputtering deposition rate for copper metal is 400 nm / min to 500 nm / min, and the final sputtering deposition rate is 600 nm / min to 800 nm / min. The sputtering deposition times for both nickel and copper metal are the same and range from 3 seconds to 16 seconds. The final copper-nickel alloy layer 19 has a thickness ranging from 50 nm to 200 nm.

[0060] For example, in step S2 of some embodiments, the initial sputtering deposition rate of nickel metal is 630 nm / min, and the final sputtering deposition rate is 70 nm / min. The initial sputtering deposition rate of copper metal is 500 nm / min, and the final sputtering deposition rate is 800 nm / min. The sputtering deposition time for both nickel and copper metal is the same, 3 seconds, and the thickness of the formed copper-nickel alloy layer 19 is 50 nm.

[0061] For example, in step S2 of some embodiments, the initial sputtering deposition rate of nickel metal is 500 nm / min, and the final sputtering deposition rate is 100 nm / min. The initial sputtering deposition rate of copper metal is 400 nm / min, and the final sputtering deposition rate is 500 nm / min. The sputtering deposition time for both nickel and copper metal is the same, 16 seconds, and the thickness of the formed copper-nickel alloy layer 19 is 200 nm.

[0062] Step S2.5: While maintaining constant gas pressure, temperature, and argon atmosphere within the magnetron sputtering equipment cavity, turn off the sputtering power supply and target baffle, and hold the temperature for 2 to 5 minutes to homogenize the temperature of each layer and eliminate deposition stress. In this embodiment, the holding time is 3 minutes.

[0063] Step S3: The finished solar cells are subjected to vacuum gradient cooling inside the magnetron sputtering equipment, and after discharge, they are encapsulated to form finished thin-film solar cells.

[0064] In step S3, the vacuum gradient cooling includes the following steps: Step S3-1: While maintaining a constant gas pressure inside the magnetron sputtering equipment cavity, reduce the temperature of the cavity at a rate of 5-8°C / min until the cavity temperature is below 80°C. In this embodiment, the temperature decrease rate is 8°C / min, and after 5.5 minutes of cooling, the cavity temperature drops from 120°C to 76°C.

[0065] Step S3-2: Continue to decrease the temperature of the magnetron sputtering equipment cavity at a rate of 5-8℃ / min until the cavity temperature is below 50℃. Simultaneously, linearly increase the cavity pressure to 10Pa to 50Pa by introducing argon gas, then stop introducing argon gas. The pressure increase must be linear and slow to avoid stress abrupt changes caused by gas flow impacting the film layer. In this embodiment, the temperature decrease rate is maintained at 8℃ / min, and after 3.5 minutes of cooling, the cavity temperature drops from 76℃ to 48℃. During cooling, argon gas is introduced into the cavity until the cavity pressure reaches 50Pa. The introduction time is the same as the cooling time, 3.5 minutes, and the introduction rate is uniform.

[0066] Step S3-3: Continue to reduce the temperature of the inner cavity of the magnetron sputtering equipment at a rate of 5-8℃ / min until the cavity temperature is below 40℃. In this embodiment, the temperature reduction rate is maintained at 8℃ / min, and after 1.5 minutes of cooling, the cavity temperature is reduced from 48℃ to 36℃.

[0067] Step S3-4: Introduce nitrogen to increase the chamber pressure to 0.8 × 10⁻⁶. 4 Pa up to 1.2 × 10 4 Hold the pressure at 100 to 140 seconds after applying 100 Pa, then continue filling with nitrogen to increase the chamber pressure to 4 × 10⁻⁶. 4 Pa to 6×10 4 After pressing the pressure at 1000 MPa, maintain the pressure for 50 to 70 seconds, then continue filling with nitrogen until atmospheric pressure is reached before opening the cavity to remove the film. In this embodiment, nitrogen is first introduced to raise the cavity pressure to 1.2 × 10⁻⁶. 4 The pressure is maintained at 140 Pa for 3 minutes, with inflation proceeding at a constant rate and lasting at least 3 minutes. Nitrogen is then continued to be introduced to raise the chamber pressure to 5.5 × 10⁻⁶. 4 After Pa, maintain for 60 seconds, inflate at a constant rate for at least 3 minutes, and finally continue inflating with nitrogen to atmospheric pressure for at least 2 minutes before opening the cavity to remove the film.

[0068] Vacuum gradient cooling, while maintaining an oxygen-free environment during pressurization, can prevent oxidation of the semiconductor junction functional layer 13 and the metal back electrode layer 14. Cooling at a slower rate of 5-8℃ / min can slowly release the thermal stress concentrated during cooling, preventing cracking of the metal back electrode and avoiding increased contact resistance.

[0069] Comparative Example 3: In the technical solution of Comparative Example 3, the magnetron sputtering equipment has a back electrode target and a copper-nickel alloy target, and includes the following steps: Step 1: Place the semi-finished battery with the same specifications as in Example 2 into the cavity of the magnetron sputtering equipment, and evacuate the chamber until the gas pressure inside the chamber does not exceed 5 × 10⁻⁶. -3Pa, fill with argon gas until the pressure stabilizes at 0.3 Pa, and heat the chamber to 120°C. Using the same back electrode target and deposition parameters as in Example 2, a 1000 nm thick metal back electrode layer 14 is sputtered and deposited on the surface of the semiconductor junction functional layer.

[0070] Step 2: Under conditions where the chamber pressure, temperature, and argon atmosphere remain completely constant, a copper-nickel alloy target is deposited by sputtering. Since the densities of copper and nickel are considered to be the same, the mass ratio of copper to nickel in the target is 2:1. The sputtering deposition rate is maintained at 750 nm / min, and the deposition time is 8 seconds. A copper-nickel alloy layer with a thickness of 100 nm and uniform copper-nickel composition is formed on the surface of the metal back electrode layer, resulting in an unencapsulated solar cell.

[0071] Step 3: While maintaining the gas pressure, temperature and argon atmosphere inside the magnetron sputtering equipment, turn off the sputtering power supply and target baffle, and keep it warm for 3 minutes.

[0072] Step 4: Use the same parameters and methods as in step S3 of Example 2 to discharge the material and encapsulate it to form a finished thin-film solar cell.

[0073] 100 pieces of the same batch of samples from Example 2 and Comparative Example 3 were taken for comparative testing. It was found that the average photoelectric conversion efficiency of the thin-film solar cell in Example 2 was 1.2% higher than that in Comparative Example 3.

[0074] In the in-situ coating process for thin-film solar cells in Example 2, the proportions of copper and nickel metals in the copper-nickel alloy layer 19 gradually increase along the direction away from the metal back electrode layer 14. While ensuring that the overall solder wettability remains unchanged, the proportion of copper atoms on the surface of the copper-nickel alloy layer 19 that is bonded to the semiconductor junction functional layer 13 is reduced, thereby reducing the impact of copper atoms on the cell efficiency.

[0075] Example 3: This embodiment provides a thin-film solar cell manufactured using the in-situ coating process for thin-film solar cells described in Embodiment 1 or 2. The thin-film solar cell can be a cadmium telluride thin-film solar cell or a perovskite thin-film solar cell.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An in-situ coating process for thin-film solar cells, characterized in that: This is used to continuously attach a metal back electrode layer and a copper-nickel alloy layer to the surface of the semiconductor junction functional layer of a semi-finished battery; wherein the semi-finished battery includes a transparent substrate, a transparent front electrode layer, and a semiconductor junction functional layer stacked sequentially, and has been etched, specifically including: Step S1: The semi-finished battery is fed into the cavity of the magnetron sputtering equipment. A back electrode target with a back electrode target material is set in the cavity of the magnetron sputtering equipment. Under the condition that the inner cavity of the magnetron sputtering equipment is kept at a set vacuum level, a set temperature and an argon atmosphere, a metal back electrode layer is formed by sputtering and depositing on the surface of the semiconductor junction functional layer of the semi-finished battery through the back electrode target. Step S2: A copper-nickel alloy target with a copper-nickel alloy target material is placed in the cavity of the magnetron sputtering equipment. Under the condition of keeping the gas pressure, temperature and argon atmosphere in the cavity of the magnetron sputtering equipment constant, a copper-nickel alloy layer is continuously sputtered and deposited on the surface of the metal back electrode layer through the copper-nickel alloy target to form an unencapsulated finished battery cell. Step S3: The finished solar cells are subjected to vacuum gradient cooling inside the magnetron sputtering equipment, and after discharge, they are encapsulated to form finished thin-film solar cells.

2. The in-situ coating process for thin-film solar cells as described in claim 1, characterized in that: The back electrode target includes a molybdenum target, an aluminum target, and a chromium target. The molybdenum target contains a molybdenum metal target, the aluminum target contains an aluminum metal target, and the chromium target contains a chromium metal target. In step S1, during the process of sputtering and depositing a metal back electrode layer on the surface of the semiconductor junction functional layer of the semi-finished battery, a molybdenum target, an aluminum target, and a chromium target are sputtered and deposited in sequence to form a three-layer metal back electrode layer structure in which molybdenum metal, aluminum metal, and chromium metal are stacked sequentially on the surface of the semiconductor junction functional layer. The steps between S1 and S2 also include: Step S1.5: Under the condition of keeping the gas pressure, temperature and argon atmosphere of the inner cavity of the magnetron sputtering equipment constant, the deposition rate of the chromium metal target decreases linearly until it reaches zero. Simultaneously, the deposition rate of the copper-nickel alloy target gradually increases linearly from zero until the set rate, so as to form a copper-nickel-chromium composite transition layer between the metal back electrode layer and the copper-nickel alloy layer. In step S2, the copper-nickel alloy layer is continuously sputtered and deposited on the surface of the metal back electrode layer using a copper-nickel alloy target.

3. The in-situ coating process for thin-film solar cells as described in claim 2, characterized in that: The total thickness of the three-layer metal back electrode structure ranges from 500 nm to 1200 nm, wherein the thickness of the molybdenum metal layer ranges from 50 nm to 150 nm, the thickness of the aluminum metal layer ranges from 400 nm to 1000 nm, and the thickness of the chromium metal layer ranges from 10 nm to 50 nm; the thickness of the copper-nickel-chromium composite transition layer ranges from 10 nm to 95 nm, and the thickness of the copper-nickel alloy layer ranges from 50 nm to 200 nm.

4. The in-situ coating process for thin-film solar cells as described in claim 2, characterized in that: In step S1, the deposition rate of the molybdenum metal layer is 200 nm / min to 800 nm / min, the deposition rate of the aluminum metal layer is 500 nm / min to 2000 nm / min, and the deposition rate of the chromium metal layer is 150 nm / min to 600 nm / min. In step S1.5, the sputtering deposition time of chromium metal and the sputtering deposition time of copper-nickel alloy layer are both between 3 seconds and 10 seconds. When the copper-nickel-chromium composite transition layer is completed, the deposition rate of copper-nickel alloy reaches a steady-state rate in the range of 300 nm / min to 500 nm / min. In step S2, the copper-nickel alloy deposition rate is maintained at the steady-state rate to achieve sputter deposition of the copper-nickel alloy layer.

5. The in-situ coating process for thin-film solar cells as described in claim 1, characterized in that: The copper-nickel alloy target includes a copper target and a nickel target, with copper metal material located on the copper target and nickel metal material located on the nickel target; In step S2, the copper target and the nickel target are sputtered and deposited simultaneously to form the copper-nickel alloy layer. As the copper-nickel alloy layer is sputtered and deposited, the sputtering deposition rate of nickel metal decreases linearly, while the sputtering deposition rate of copper metal increases linearly, forming a copper-nickel alloy layer in which the copper-nickel ratio gradually increases along the direction away from the metal back electrode layer.

6. The in-situ coating process for thin-film solar cells as described in claim 5, characterized in that: The thickness of the metal back electrode layer ranges from 500 nm to 1200 nm, and the thickness of the copper-nickel alloy layer ranges from 50 nm to 200 nm.

7. The in-situ coating process for thin-film solar cells as described in claim 5, characterized in that: In step S2, the initial sputtering deposition rate of nickel metal is 400 nm / min to 630 nm / min, and the final sputtering deposition rate is 70 nm / min to 100 nm / min; the initial sputtering deposition rate of copper metal is 400 nm / min to 500 nm / min, and the final sputtering deposition rate is 600 nm / min to 800 nm / min; the sputtering deposition time for both nickel and copper metal is the same and is between 3 seconds and 16 seconds.

8. The in-situ coating process for thin-film solar cells as described in any one of claims 1-7, characterized in that: In step S1, the gas pressure in the inner chamber of the magnetron sputtering equipment before argon gas is filled does not exceed 5 × 10⁻⁶. -3 Pa, the pressure range after filling with argon is 0.3 Pa to 0.8 Pa, and the set temperature is maintained between 80°C and 120°C.

9. The in-situ coating process for thin-film solar cells as described in any one of claims 1-7, characterized in that: The steps between S2 and S3 also include: Step S2.5: While maintaining the gas pressure, temperature and argon atmosphere inside the magnetron sputtering equipment, turn off the sputtering power supply and the target baffle, and keep it at that temperature for 2 to 5 minutes. In step S3, the vacuum gradient cooling includes the following steps: Step S3-1: While keeping the gas pressure inside the magnetron sputtering equipment constant, reduce the temperature inside the magnetron sputtering equipment at a rate of 5-8℃ / min until the temperature inside the cavity is below 80℃. Step S3-2: Continue to lower the temperature of the inner cavity of the magnetron sputtering equipment at a rate of 5-8℃ / min until the temperature inside the cavity is below 50℃, and at the same time, linearly increase the gas pressure inside the cavity to 10Pa to 50Pa by filling the cavity with argon gas, and then stop filling the cavity with argon gas. Step S3-3: Continue to reduce the temperature of the inner cavity of the magnetron sputtering equipment at a rate of 5-8℃ / min until the temperature inside the cavity is below 40℃; Step S3-4: Introduce nitrogen to increase the chamber pressure to 0.8 × 10⁻⁶. 4 Pa up to 1.2 × 10 4 Hold the pressure at 100 to 140 seconds after applying 100 Pa, then continue filling with nitrogen to increase the chamber pressure to 4 × 10⁻⁶. 4 Pa to 6×10 4 After pressing the pressure (Pa) for 50 to 70 seconds, continue filling with nitrogen until atmospheric pressure is reached before opening the cavity to remove the film.

10. A thin-film solar cell, characterized in that: It is manufactured using the in-situ coating process for thin-film solar cells as described in any one of claims 1-9.

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