Roll-to-roll chemical shower deposition apparatus for buffer layer of copper indium gallium selenide solar cell

Abstract

The application relates to a kind of copper indium gallium selenide solar cell buffer layer's roll-to-roll chemical shower deposition equipment, solve the unevenness of flexible thin film photovoltaic substrate when CSD shower coating film, leading to the problem of uneven heating and coating film.The device is sequentially transported by conveying roller between unwinding area and winding area, heat-conducting base plate is arranged below each conveying roller, the upper surface of the heat-conducting base plate is provided with two upwardly curved U-shaped grooves, and the middle is flat, heating pipe is arranged below the U-shaped groove in the heat-conducting base plate, heat insulation board and magnetic body are sequentially arranged below the heat-conducting base plate, sealing insulation cover plate is arranged above the heat-conducting base plate, and the substrate is transported by being magnetically attached to the U-shaped groove of the heat-conducting base plate.The application adopts the method of CSD shower coating film, cooperates with the heat-conducting base plate of U-shaped magnetic type, can keep the bottom surface of the substrate flat, ensure that the coating solution is uniform, the substrate is heated uniformly everywhere, so as to ensure the uniformity of CdS buffer layer film on the substrate.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of solar cell production and relates to a roll-to-roll chemical spray deposition device for a buffer layer of a copper-indium-gallium-selenium solar cell. BACKGROUND

[0002] The roll-to-roll technology is one of the standard methods for the continuous production of CIGS (copper-indium-gallium-selenium), amorphous silicon, CdTe, perovskite, etc. thin film cells. The technology generally uses a flexible stainless steel thin strip as the substrate of the CIGS thin film cell, and realizes the continuous production of the thin film cell through the winding mechanism and the unwinding mechanism. The production process is easy to control, the product quality is stable, and the yield is high. It is the most mature process technology route for large-scale production of flexible CIGS thin film cells at present.

[0003] At present, the CdS thin film prepared by the roll-to-roll chemical water bath deposition (CBD) process is a commonly used method for low-cost large-scale production of CIGS buffer layer thin film. In the CBD process, a CBD solution is formed by mixing deionized water, ammonia, thiourea and cadmium sulfate, and a dense CdS thin film with a thickness of 10-80 nm is formed on the surface of CIGS at a temperature of 50-90°C through flow casting or immersion. However, the utilization rate of cadmium sulfate in this method is less than 5%, and the excess Cd 2 +ion is dissolved in the wastewater to form Cd 2 -containing wastewater, which will cause great pollution to the ecological environment if directly discharged. Therefore, in the CIGS factory using the CBD process to produce CdS buffer layer, a series of complex physical and chemical purification treatment equipment must be built for the treatment of Cd-containing wastewater, which will undoubtedly increase the production cost of CIGS thin film cells.

[0004] The applicant's previous application for a Chinese patent, application number 2021107271108, entitled "Flexible thin film photovoltaic roll-to-roll CSD spray plating device", uses the chemical spray deposition (CSD) process to produce CIGS buffer layer CdS thin film, replacing the current chemical water bath deposition (CBD) process, which can greatly improve the uniformity of the CdS thin film, reduce the deposition of powder particles and the pinhole rate during the growth of CdS, and improve the photoelectric conversion efficiency of the copper-indium-gallium-selenium solar cell. At the same time, less reaction solution is used in the CSD process, which has higher raw material utilization rate and less wastewater generation rate, thereby reducing the production cost of the CdS buffer layer thin film and the treatment cost of the Cd-containing wastewater. In the patent, the press roller is used to press down on both sides of the substrate to form a groove on both sides, which is used for the reaction solution to continuously react and ensure the plating quality. However, due to the elasticity and stress of the substrate itself, the substrate pressed down on both sides is still prone to unevenness in the middle, resulting in uneven solution and substrate heating during the plating process. SUMMARY

[0005] The present application aims at solving the problem of unevenness of the flexible thin film photovoltaic substrate in CSD shower plating, which leads to uneven heating and plating, and provides a roll-to-roll chemical shower deposition equipment for the buffer layer of a copper indium gallium selenide solar cell, which forms a lower groove by adsorbing the middle part of the substrate in a magnetic manner, keeps the substrate flat, can keep it flat and uniformly heated during plating, and improves the uniformity of the CdS buffer layer film.

[0006] The technical scheme adopted by the present application to solve the technical problem is: a roll-to-roll chemical shower deposition equipment for the buffer layer of a copper indium gallium selenide solar cell, the front and rear ends are respectively provided with an unwinding area and a winding area, a plurality of conveying rollers are arranged between the unwinding area and the winding area to convey a stainless steel substrate, characterized in that: a plating solution pretreatment area and a thin film growth area are sequentially arranged between the unwinding area and the winding area, an ammonia and cadmium sulfate mixed solution sprayer is arranged above the substrate at the front part of the plating solution pretreatment area, a thiourea solution sprayer is arranged above the substrate at the front part of the thin film growth area, a heat-conducting base plate is arranged below the substrate between the conveying rollers in the plating solution pretreatment area and the thin film growth area, the upper surface of the heat-conducting base plate is provided with a U-shaped groove with two sides up and a flat middle, a heating pipe is arranged through the U-shaped groove in the heat-conducting base plate, a heat-insulating board and a magnetic body are sequentially arranged below the heat-conducting base plate, a sealing heat-insulating cover plate is arranged above the heat-conducting base plate, and the substrate is conveyed by being magnetically attached to the U-shaped groove of the heat-conducting base plate.

[0007] In the device, the heat-conducting base plate uses a magnetic adsorption method to adsorb the stainless steel substrate, the substrate is conveyed by being attached to the U-shaped groove of the heat-conducting base plate in the entire plating process, the bottom surface of the substrate is kept flat, the depth of the deposition solution is stabilized, the heating pipe uniformly heats the substrate, and the uniformity of the CdS buffer layer film on the surface of the substrate is fully ensured.

[0008] Preferably, the heating pipe is a circulating hot water pipe, the circulating hot water pipe is transversely arranged through the heat-conducting base plate, the circulating hot water pipes are uniformly arranged, and a thermocouple is arranged through the heat-conducting base plate between adjacent circulating hot water pipes.

[0009] Preferably, the magnetic body is an electromagnet or a permanent magnet.

[0010] Preferably, the heat-conducting base plate is an aluminum base plate.

[0011] As preferred, in the plating solution pretreatment zone, the heat-conducting substrate in front of the ammonia and cadmium sulfate mixed solution sprayer is a first preheating substrate, and the heat-conducting substrate in back of the first preheating substrate is a first heating substrate, and the temperature of the first heating substrate is 70-90°C; in the thin film growth zone, the heat-conducting substrate in front of the thiourea solution sprayer is a first cooling substrate, and the heat-conducting substrate in back of the first cooling substrate is a second heating substrate, and the temperature of the first cooling substrate is 20-30°C, and the temperature of the second heating substrate is 70-90°C. The temperature of each preheating substrate is higher than the temperature of the substrate in front and lower than the temperature of the substrate in back, so as to ensure stable temperature heating. The first cooling substrate is arranged to make the first time temperature of the thiourea solution sprayed by the thiourea solution sprayer lower, so as to avoid homogeneous reaction of the solution and make the plating solution produce heterogeneous reaction in uniform temperature change.

[0012] As preferred, a direct wastewater treatment zone is arranged behind the thin film growth zone, a cadmium-containing wastewater suction nozzle is arranged above the substrate of the direct wastewater treatment zone, and a conveying roller is arranged below the substrate and aligned with the cadmium-containing wastewater suction nozzle. The cadmium-containing wastewater suction nozzle is connected with a water suction pump, so as to suck away the solution participating in the reaction.

[0013] As preferred, a cleaning zone is arranged behind the direct wastewater treatment zone, a drying zone is arranged behind the cleaning zone, a deionized water sprayer is arranged above the substrate at the front end of the cleaning zone, a cleaning liquid suction nozzle is arranged above the substrate at the rear end of the cleaning zone, and a heat-conducting substrate is arranged between the conveying rollers below the substrate of the cleaning zone. The heat-conducting substrate at the front end of the cleaning zone is a second cooling substrate, the temperature of the second cooling substrate is 20-30°C, and the heat-conducting substrate at the rear end of the cleaning zone is a second preheating substrate. The cleaning zone is cleaned by deionized water, and the cleaning liquid suction nozzle is used for suction after cleaning. The front end of the cleaning zone is cooled first to avoid reaction of residual solution, and the rear end is preheated to prepare for subsequent heating and drying.

[0014] As preferred, a first sealing cover is integrally arranged above the plating solution pretreatment zone, the thin film growth zone, the direct wastewater treatment zone and the cleaning zone.

[0015] As preferred, a second sealing cover is arranged above the substrate of the drying zone, a wind knife is arranged at the front end inside the sealing cover, a heating lamp is arranged at the rear end inside the sealing cover, an air suction pipe is arranged at the upper part of the front end of the sealing cover, and a heat-conducting substrate is arranged between the conveying rollers below the substrate of the drying zone. The heat-conducting substrate corresponding to the wind knife is a third preheating substrate, the heat-conducting substrate corresponding to the heating lamp is a third heating substrate, and the temperature of the third heating substrate is 50-70°C. The wind knife blows the residual liquid on the upper surface of the substrate with great force, and the air flow of the wind knife is sucked away through the air suction pipe. The heating lamp can be an infrared lamp, and the heating process cooperates with the heating bottom plate below to form simultaneous heating from top to bottom.

[0016] As preferred, the front side of the winding area is also provided with a thickness measuring area, a thickness measuring sensor is arranged above the base of the thickness measuring area, a third sealing cover is arranged outside the thickness measuring sensor, a heat conducting base plate is arranged between the conveying rollers below the base of the thickness measuring area, the heat conducting base plate of the thickness measuring area is a third cooling base plate, and the third cooling base plate is 20-30℃. The thickness measuring area is the last process before winding, and the thickness measuring is performed after film plating, cleaning and drying.

[0017] The present application adopts the method of CSD spray film plating, cooperates with the heat conducting base plate of U-shaped magnetic attraction type, can make the stainless steel base of copper indium gallium selenide solar cell adsorbed in the U-shaped groove of the heat conducting base plate, keeps the bottom surface flat, ensures that the film plating solution is uniform and the heating of the base is uniform everywhere, thereby ensuring the uniformity of the CdS buffer layer film on the base. The technology is also applicable to the deposition of ZnS, ZnO 1-x S x , In2S3, Cd 1-x Zn x S and other thin films. BRIEF DESCRIPTION OF DRAWINGS

[0018] The present application will be further described below in combination with the drawings.

[0019] Figure 1 is a structural schematic diagram of the present application.

[0020] Figure 2 is a side view structural schematic diagram of the heat conducting base plate of the present application.

[0021] Figure 3 is a sectional structural schematic diagram of the heat conducting base plate of the present application.

[0022] Figure 4 is a schematic diagram of the heating pipe penetrating the heat conducting base plate from the top view angle of the present application.

[0023] Figure 5 is a schematic diagram of the comparison between the magnetic attraction base plate of the present application and the conventional non-magnetic attraction base plate.

[0024] In the figure: 101, unwinding area, 102, coating solution pretreatment area, 103, thin film growth area, 104, direct wastewater treatment area, 105, cleaning area, 106, drying area, 107, thickness measurement area, 108, winding area; 1, unwinding shaft, 2, first tension control roller, 3, first turning roller, 4-8, horizontal conveying roller, 9, second turning roller, 10, second tension control roller, 11, winding shaft, 12, first preheating substrate, 13, first heating substrate, 14, first cooling substrate, 15, second heating substrate, 16, second cooling substrate, 17, second preheating substrate, 18, third preheating substrate, 19, third heating substrate, 20, third cooling substrate, 21, ammonia and cadmium sulfate mixed solution sprayer, 22, thiourea solution sprayer, 23, cadmium-containing wastewater suction nozzle, 24, deionized water sprayer, 25, cleaning liquid suction nozzle, 26, air knife, 27, heating lamp tube, 28, thickness measurement sensor, 29, first sealing cover, 30, second sealing cover, 31, third sealing cover, 32, exhaust pipe, 33, sealing and heat preservation cover plate, 34, heat conducting substrate, 35, heat insulation board, 36, magnetic body, 37, U-shaped groove, 38, heating pipe, 39, thermocouple, 40, substrate. DETAILED DESCRIPTION

[0025] The application will be further described below by specific examples and in conjunction with the drawings.

[0026] Embodiment: A roll-to-roll chemical spray deposition equipment for a copper indium gallium selenide solar cell buffer layer is shown in the figure. The equipment is provided with unwinding area 101, coating solution pretreatment area 102, thin film growth area 103, direct wastewater treatment area 104, cleaning area 105, drying area 106, thickness measurement area 107, and winding area 108 from front to back. Figure 1 The unwinding area is provided with unwinding shaft 1, first tension control roller 2, and first turning roller 3. The winding area is provided with second turning roller 9, second tension control roller 10, and winding shaft 11 in sequence. Horizontal conveying roller 4-8 is arranged between first turning roller 3 and second turning roller 9. First turning roller 3, second turning roller 9, and horizontal conveying roller 4-8 are all kinds of conveying rollers.

[0027] In coating solution pretreatment area 102, thin film growth area 103, direct wastewater treatment area 104, cleaning area 105, drying area 106, and thickness measurement area 107, heat conducting substrate 34 is arranged between the adjacent conveying rollers below substrate 40. The structure of the heat conducting substrate is shown in the figure. Figures 2-4As shown, the upper surface of the heat-conducting substrate 34 is provided with a U-shaped groove 37 with both sides up and the middle flat, and a heating pipe 38 is arranged below the U-shaped groove in the heat-conducting substrate. The heat-conducting substrate is sequentially provided with a heat-insulating board 35 and a magnetic body 36 below, and a sealing and heat-insulating cover plate 33 above. The substrate 40 is magnetically attached to the U-shaped groove 37 of the heat-conducting substrate 34 for conveying. The heating pipe 38 is a circulating hot water pipe, which is transversely arranged in the heat-conducting substrate 34 and uniformly arranged. The heat-conducting substrate is provided with a thermocouple 39 between adjacent circulating hot water pipes. The magnetic body 36 is an electromagnet or a permanent magnet. The heat-conducting substrate 34 is made of aluminum.

[0028] The plating solution pretreatment area 102 is provided with an ammonia and cadmium sulfate mixed solution sprayer 21 above the substrate 40. The heat-conducting substrate 40 in front of the ammonia and cadmium sulfate mixed solution sprayer 21 is a first preheating substrate 12, and the heat-conducting substrate in the rear is a first heating substrate 13. The temperature of the first heating substrate is 70-90℃. The temperature of the first preheating substrate 12 is higher than the normal temperature and lower than the temperature of the first heating substrate 13.

[0029] The thin film growth area 103 is provided with a thiourea solution sprayer 22 above the substrate 40 in the front part. The heat-conducting substrate in front of the thiourea solution sprayer 22 is a first cooling substrate 14, and the heat-conducting substrate in the rear is a second heating substrate 15. The temperature of the first cooling substrate 14 is 20-30℃, and the temperature of the second heating substrate 15 is 70-90℃.

[0030] The direct wastewater treatment area 104 is provided with a cadmium-containing wastewater suction nozzle 23 above the substrate 40. A conveying roller 6 is arranged below the cadmium-containing wastewater suction nozzle 23.

[0031] The cleaning area 105 is provided with a deionized water sprayer 24 above the substrate 40 in the front end. A cleaning liquid suction nozzle 25 is arranged above the substrate in the rear end of the cleaning area. The heat-conducting substrate in the front end of the cleaning area is a second cooling substrate 16, and the temperature of the second cooling substrate is 20-30℃. The heat-conducting substrate in the rear end of the cleaning area is a second preheating substrate 17.

[0032] The first sealing cover 29 is integrally arranged above the plating solution pretreatment area 102, the thin film growth area 103, the direct wastewater treatment area 104, and the cleaning area 105.

[0033] The drying area 106 is provided with a second sealing cover 30 above the substrate. A air knife 26 is arranged in the front end of the inside of the sealing cover 30. A heating lamp 27 is arranged in the rear end of the inside of the sealing cover. An exhaust pipe 32 is arranged in the upper part of the front end of the sealing cover. The heat-conducting substrate corresponding to the air knife in the lower part is a third preheating substrate 18. The heat-conducting substrate corresponding to the heating lamp in the lower part is a third heating substrate 19. The temperature of the third heating substrate 19 is 50-70℃. The temperature of the second preheating substrate 17 and the third preheating substrate 18 is higher than that of the second cooling substrate and lower than that of the third heating substrate 19.

[0034] The thickness measuring sensor 28 is arranged above the base 40 of the thickness measuring area 107, and a third sealing cover 31 is arranged outside the thickness measuring sensor. The heat-conducting substrate of the thickness measuring area is a third cooling substrate 20, and the third cooling substrate is at a temperature of 20-30℃.

[0035] A magnetic body is arranged below the heat-conducting substrate 34 of the device, which can adsorb the stainless steel base so that the base can be perfectly attached to the bottom surface of the U-shaped groove 37. Figure 5 The left picture is a base without magnetic adsorption, and the right picture is a base with magnetic adsorption of the device. The base of the device can obviously maintain a more flat state, so that the plating solution depth is uniform, the heating of the base is more uniform, thereby improving the uniformity of the CdS buffer layer film.

Claims

1. A roll-to-roll chemical spray deposition apparatus for a buffer layer of a copper indium gallium selenide (CIGS) solar cell, comprising an unwinding zone and a rewinding zone at the front and rear ends respectively, wherein a plurality of conveying rollers are arranged between the unwinding zone and the rewinding zone to convey a stainless steel substrate, characterized in that: A coating solution pretreatment area and a thin film growth area are arranged sequentially between the unwinding area and the winding area. A mixture of ammonia and cadmium sulfate solution sprayer is installed above the substrate at the front of the coating solution pretreatment area, and a thiourea solution sprayer is installed above the substrate at the front of the thin film growth area. A thermally conductive substrate is arranged between the conveying rollers and below the substrate in the coating solution pretreatment area and the thin film growth area. A U-shaped groove with upward curves on both sides and a flat middle is provided on the upper surface of the thermally conductive substrate. A heating tube is installed inside the thermally conductive substrate below the U-shaped groove. A heat insulation board and a magnetic accumulator are arranged sequentially below the thermally conductive substrate. A sealing heat insulation cover is provided above the thermally conductive substrate. The substrate is conveyed by magnetically attaching to the U-shaped groove of the thermally conductive substrate. The heating pipe is a circulating hot water pipe, and a heat-conducting substrate is inserted horizontally through the circulating hot water pipe. The circulating heating water pipes are evenly arranged, and thermocouples are inserted between adjacent circulating heating water pipes on the heat-conducting substrate. In the pretreatment zone of the coating solution, the heat-conducting substrate in front of the ammonia and cadmium sulfate mixed solution injector is the first preheating substrate, and the heat-conducting substrate behind it is the first heating substrate, with the temperature of the first heating substrate being 70-90°C; in the thin film growth zone, the heat-conducting substrate in front of the thiourea solution injector is the first cooling substrate, and the heat-conducting substrate behind it is the second heating substrate, with the temperature of the first cooling substrate being 20-30°C and the temperature of the second heating substrate being 70-90°C. A direct wastewater treatment zone is provided behind the thin film growth zone. A cadmium-containing wastewater suction nozzle is provided above the substrate of the direct wastewater treatment zone, and a conveying roller is provided below the substrate, aligned with the cadmium-containing wastewater suction nozzle.

2. The roll-to-roll chemical spray deposition apparatus for the buffer layer of a copper indium gallium selenide solar cell according to claim 1, characterized in that: The magnetic attractor is an electromagnet or a permanent magnet.

3. The roll-to-roll chemical spray deposition apparatus for the buffer layer of a copper indium gallium selenide solar cell according to claim 1, characterized in that: The thermally conductive substrate is an aluminum substrate.

4. The roll-to-roll chemical spray deposition apparatus for the buffer layer of a copper indium gallium selenide solar cell according to claim 1, characterized in that: A cleaning zone is located behind the direct wastewater treatment zone, and a drying zone is located behind the cleaning zone. A deionized water jet is located above the base at the front end of the cleaning zone, and a cleaning liquid suction nozzle is located above the base at the rear end of the cleaning zone. A heat-conducting substrate is located between the conveying rollers below the base of the cleaning zone. The heat-conducting substrate at the front end of the cleaning zone is a second cooling substrate with a temperature of 20-30°C. The heat-conducting substrate at the rear end of the cleaning zone is a second preheating substrate.

5. The roll-to-roll chemical spray deposition apparatus for the buffer layer of a copper indium gallium selenide solar cell according to claim 4, characterized in that: A first sealing cover is integrally installed above the coating solution pretreatment zone, thin film growth zone, direct wastewater treatment zone, and cleaning zone.

6. The roll-to-roll chemical spray deposition apparatus for the buffer layer of a copper indium gallium selenide solar cell according to claim 4, characterized in that: A second sealing cover is provided above the base of the drying zone. An air knife is provided at the front end of the sealing cover, and a heating lamp is provided at the rear end of the sealing cover. An exhaust pipe is provided at the upper part of the front end of the sealing cover. A heat-conducting substrate is provided between the conveying rollers below the base in the drying zone. The heat-conducting substrate below the air knife is the third preheating substrate, and the heat-conducting substrate below the heating lamp is the third heating substrate. The temperature of the third heating substrate is 50-70°C.

7. The roll-to-roll chemical spray deposition apparatus for the buffer layer of a copper indium gallium selenide solar cell according to claim 1, 2, or 3, characterized in that: A thickness measuring area is also provided on the front side of the winding area. A thickness measuring sensor is provided above the base of the thickness measuring area. A third sealing cover is provided outside the thickness measuring sensor. A heat-conducting substrate is provided between the conveying rollers below the base of the thickness measuring area. The heat-conducting substrate of the thickness measuring area is a third cooling substrate, and the third cooling substrate is 20-30°C.

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