Post-processing method for thin-film solar cell

Abstract

The invention relates to a high-temperature post-processing method for a solar cell, and discloses a post-processing method for a thin-film solar cell, which is characterized in that a chlorine-containing raw material is deposited on the surface of a cell absorption layer by adopting a dry processing method and a near-space sublimation deposition mode, and a uniformly dispersed cadmium chloride thin film can be formed after high-temperature processing. And the conversion efficiency and the operation stability of the thin-film solar cell are improved.

Description

Technical Field

[0001] The invention relates to the field of high-temperature post-processing of solar cells, and in particular to a post-processing method for thin-film solar cells. Background Art

[0002] In the process of preparing thin-film solar cells, the light absorption layer needs to be activated to improve the performance, stability and economy of the cell. For example, in the process of preparing cadmium telluride or other II-IV thin-film solar cells, it is necessary to use Cl-containing substances for activation after the deposition of the polycrystalline thin film of the absorption layer. The post-treatment process helps to improve the crystal quality of the absorption layer, promote the regrowth of the absorption layer crystal, eliminate the deep energy level defects of the grain boundary, reduce the recombination of carriers at the interface defects, etc., and improve the photoelectric conversion efficiency of the device.

[0003] The existing cadmium chloride treatment technology is generally called a wet process. The treatment process generally uses CdCl2, MgCl2, etc. as a Cl source, and the treatment process involves the attachment, drying, high temperature treatment and temperature / atmosphere control of the source medium, such as the cadmium telluride thin film solar cell and its preparation method disclosed in patent number CN114583009B.

[0004] Generally, cadmium chloride is prepared into an aqueous solution or ethanol solution of a certain concentration, and the solution is applied to the surface of the film layer by spin coating, roller coating, spraying or immersion (usually spraying), and dried by natural drying, air drying or baking. Then the device is placed in a high temperature environment for high temperature treatment. During the treatment process, the cadmium chloride particles attached to the surface of the film diffuse into the solid phase of the film on the one hand, and vaporize and diffuse into the atmosphere on the other hand. Because the solvent drying process is difficult to control, this leads to uneven dispersion of cadmium chloride crystals and forms marks on the surface of the absorption layer, which further leads to uneven treatment of the cadmium telluride absorption film layer due to uneven distribution of chloride ion concentration during high temperature treatment, which ultimately affects the conversion efficiency of solar cells and the stability of component operation. Summary of the invention

[0005] In order to solve the technical problem mentioned in the above background technology that the wet process will lead to uneven distribution of chloride ion concentration and uneven treatment of cadmium telluride absorption film layer, thus affecting the conversion efficiency of solar cells and the stability of component operation, the present invention provides a post-processing method for thin-film solar cells, which adopts a close-space sublimation gas phase treatment method to ensure the uniformity of chloride medium distribution and treatment, and has a stable process. The process is shortened to a high-temperature treatment process, which reduces the time of the post-processing process, is environmentally friendly, and greatly improves the photoelectric conversion efficiency.

[0006] The specific technical solution of the present invention is: a post-processing method for thin-film solar cells, comprising the following steps: 1) grinding and sieving the cadmium chloride raw material, and flattening and then pressing it on a heating plate to obtain a cadmium chloride source; 2) placing a cadmium chloride heating disk source, a solar substrate and a uniform heat plate in order from bottom to top to obtain a sample to be processed, wherein the distance between the cadmium chloride source and the film surface of the heating disk solar substrate is 0.5 to 3 cm; 3) The sample to be processed is first vacuumed and then filled with gas; 4) heating the heating plate and the uniform heating plate at the same time, wherein the temperature of the heating plate is 350-440° C., the temperature of the uniform heating plate is 300-400° C., and the holding time is 1-5 min; 5) Cool the heating plate to 200-350°C, raise the temperature of the uniform heating plate to 350-400°C, and keep warm for 1-5 minutes; 6) After cooling the sample after high temperature treatment, the back contact layer and the back electrode are completed to obtain a thin film solar cell.

[0007] The present invention provides a post-processing method for thin-film solar cells. The sublimation process is adopted to shorten the spraying, drying, high-temperature treatment, water washing, drying and other processes in the traditional wet process to one high-temperature treatment process, thereby greatly reducing the post-processing process time, ensuring the uniformity of chlorine medium distribution and treatment, and ensuring good repeatability and stability of the process. Solid raw materials are directly used without the participation of solutions, so that there is less residue on the surface of the battery after the treatment is completed, and no cleaning is required, thereby reducing costs and improving the photoelectric conversion efficiency, and the photoelectric conversion efficiency is improved by an average of 1.46%.

[0008] Preferably, the purity of the cadmium chloride raw material is ≥4N.

[0009] Furthermore, in step 1), the mesh size during sieving is 50 to 100.

[0010] Furthermore, in step 1), the thickness of the paved cadmium chloride raw material is 2 to 3 cm.

[0011] Furthermore, in step 1), the thickness of the cadmium chloride source is 1 to 2 cm.

[0012] Preferably, the obtained cadmium chloride source is subjected to high temperature sintering to increase the service life of the cadmium chloride source. The sintering atmosphere is nitrogen, air, nitrogen-oxygen mixed gas or inert gas, and the sintering temperature is 350-500°C.

[0013] Furthermore, in step 2), the solar substrate comprises glass, a TCO layer, a window layer and an absorption layer.

[0014] Furthermore, in step 2), the absorption layer of the solar substrate faces the cadmium chloride source.

[0015] Furthermore, in step 3), the gas is one or more of air, nitrogen and oxygen.

[0016] Furthermore, in step 3), when the gas is filled, the gas pressure of the control system is 10 2 ~10 5 Pa.

[0017] Furthermore, in step 4), the heating rates of the heating plate and the uniform heating plate are both 1-10° C. / s.

[0018] Furthermore, the cooling rate of the heating plate is 1 to 10°C / s, and the heating rate of the uniform heating plate is 1 to 10°C / s.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1) High efficiency: Compared with the traditional wet process, the photoelectric conversion efficiency of the small solar cells treated by this process is increased by an average of 1.46% (absolute value).

[0020] 2) Uniformity: The vacuum sublimation process is used to ensure the uniformity of the Cl medium distribution and the uniformity of the treatment, and there is basically no residue on the surface after treatment. The process also has good repeatability and is stable.

[0021] 3) Fast: The multiple processes of spraying, drying, high temperature treatment, water washing, drying, etc. in the traditional solution method are shortened to a high temperature treatment process, which greatly reduces the time of the post-processing process.

[0022] 4) Environmentally friendly: Directly use solid raw materials, no need to prepare solutions; after treatment, there is little residue on the surface and no need to clean. No Cd or Cl-containing waste liquid is generated, which is environmentally friendly and reduces costs.

[0023] 5) Has industrial potential: Compared with the traditional wet method, this process is simple, with only one process of high-temperature treatment, except for spraying, drying, high-temperature treatment, water washing, and drying. After the source is prepared, it can be used many times without frequent replacement. The substrate can directly enter this treatment section from the previous high-temperature and vacuum section without cooling to room temperature or breaking the vacuum. The process is shortened, and the labor, equipment, and site costs are greatly reduced, which has the potential to achieve high-throughput preparation and large-scale industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the device of the present invention.

[0025] Figure 2 This is a schematic diagram of the surface of the solar substrate after cadmium chloride treatment obtained in Example 1.

[0026] Figure 3 This is a schematic diagram of the surface of the solar substrate after cadmium chloride treatment obtained in Comparative Example 1.

[0027] The accompanying drawings are marked as follows: 1. sampling rod; 2. uniform heating plate; 3. heating plate; 4. cadmium chloride source; 5. heating tube; 6. furnace insulation layer; 7. quartz tube; 8. solar substrate; 9. gas; 10. sample delivery track. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the embodiments.

[0029] Overall embodiment 1) Source preparation The cadmium chloride raw material is ground, sieved and placed in a graphite heating plate 3, and the raw material is flattened with a pressing plate to obtain a cadmium chloride source 4. The cadmium chloride source 4 is sintered at a high temperature of 350-500° C. The sintering atmosphere is nitrogen and oxygen, the nitrogen-oxygen volume ratio is 1-10, and the duration is 0.5-5 minutes.

[0030] Specifically, the thickness of the flattened cadmium chloride raw material is 2 to 3 cm.

[0031] Specifically, the sieve plate has a mesh size of 50 to 100.

[0032] Specifically, the graphite heating plate 3 has a size of 10 cm×10 cm and a depth of 3 cm.

[0033] Specifically, the thickness of the cadmium chloride source 4 is 1 to 2 cm.

[0034] 2) Sample injection Place the solar substrate 8 with the absorption layer facing downward on the heating plate of the cadmium chloride source 4 after high-temperature sintering, cover the solar substrate with a graphite uniform heating plate 2, insert a temperature measuring thermocouple on the graphite uniform heating plate 2 and the graphite heating plate 3, and connect the sampling rod. After loading, use the sample rod 5 to push the whole along the sample delivery track 10 into the special tube furnace, close the hatches on both sides of the quartz tube 7, evacuate the internal chamber, and then introduce gas 9 to control the air pressure at 1×10 2 ~1×10 5 Pa, such as Figure 1 shown.

[0035] Specifically, the gas is one or more of air, nitrogen and oxygen.

[0036] Specifically, the distance between the cadmium chloride source 4 and the absorption layer of the solar substrate 8 is 0.5-3 cm.

[0037] 3) High temperature treatment The graphite heating plate 3 and the graphite uniform heating plate 2 are heated at the same time. After the graphite heating plate 3 and the graphite uniform heating plate 2 are heated to the required temperature at the same time, high temperature treatment is performed. The high temperature treatment time is 1 to 5 minutes.

[0038] Specifically, the heating temperature of the graphite heating disk 3 is 350-440° C., and the heating rate of the graphite heating disk 3 is 1-10° C. / s.

[0039] Specifically, the heating temperature of the graphite uniform heat plate 2 is 300-400° C., and the heating rate of the graphite uniform heat plate 2 is 1-10° C. / s.

[0040] 4) Anti-sublimation treatment The graphite heating plate is heated while the graphite uniform heating plate is heated. After the graphite heating plate 3 and the graphite uniform heating plate 2 reach the specified temperature at the same time, an anti-sublimation treatment is performed. The anti-sublimation treatment time is 1 to 2 minutes.

[0041] Specifically, the temperature of the graphite heating disk 3 is 200-350° C., and the cooling rate of the graphite heating disk 3 is 1-10° C. / s.

[0042] Specifically, the temperature of the graphite uniform heat plate 2 is 300-400° C., and the cooling rate of the graphite uniform heat plate 2 is 1-10° C. / s.

[0043] 5) Subsequent processing After the treatment is completed, the samples are taken out after natural cooling for characterization and performance testing.

[0044] Specific examples and comparative examples.

[0045] Example 1 1) Source preparation The cadmium chloride raw material is ground, sieved and placed on a graphite heating plate, and the raw material is flattened with a pressing plate to obtain a cadmium chloride source. The cadmium chloride source is sintered at a high temperature of 350°C in a sintering atmosphere of nitrogen and oxygen with a nitrogen-oxygen volume ratio of 4:1 for 30 seconds.

[0046] Specifically, the thickness of the paved cadmium chloride raw material is 2.0 cm.

[0047] Specifically, the sieve plate is 100 mesh.

[0048] Specifically, the graphite heating plate has a size of 10 cm×10 cm and a depth of 3 cm.

[0049] Specifically, the thickness of the cadmium chloride source is 1.0 cm.

[0050] 2) Sample injection Place the solar substrate with the absorption layer facing downward on the cadmium chloride source heating plate after high-temperature sintering, cover the solar substrate with a graphite uniform heating plate, insert temperature measuring thermocouples on the graphite uniform heating plate and the graphite heating plate, connect the push rod, and after loading, use the lofting rod to push the whole along the track into the special tube furnace, close the hatches on both sides of the quartz tube, evacuate the internal chamber, and then introduce gas to control the air pressure at 1×10 2Pa.

[0051] The gas is nitrogen.

[0052] Specifically, the spacing between the cadmium chloride source and the absorber layer of the solar substrate is 2 cm.

[0053] 3) High temperature treatment The graphite heating plate and the graphite uniform heating plate are heated at the same time. After the graphite heating plate and the graphite uniform heating plate are heated to the required temperature at the same time, high temperature treatment is performed. The high temperature treatment time is 3 minutes.

[0054] Specifically, the heating temperature of the graphite heating plate is 400°C.

[0055] Specifically, the heating temperature of the graphite uniform heating plate is 300°C.

[0056] 4) Anti-sublimation treatment The graphite heating plate is heated while the graphite uniform heating plate is heated. After the graphite heating plate and the graphite uniform heating plate reach the specified temperature at the same time, an anti-sublimation treatment is performed. The anti-sublimation treatment time is 1 minute.

[0057] Specifically, the temperature of the graphite heating plate was 200°C.

[0058] Specifically, the temperature of the graphite uniform heating plate is 400°C.

[0059] 5) Subsequent processing After the treatment is completed, the sample is taken out after natural cooling, and characterization test and performance test are performed. The solar substrate treated with cadmium chloride is as follows: Figure 2 shown.

[0060] Comparative Example 1 In this comparative example, a wet process is used for cadmium chloride treatment, and the specific steps are as follows: 1. A cadmium chloride solution with a concentration of 1 mol / L is prepared, and the prepared cadmium chloride solution is connected to a spraying device and sprayed onto the surface of the substrate (the distance between the two is 5 cm). After natural drying, the solution is placed in a tube furnace for high-temperature treatment (treatment time 20 min, treatment temperature 440°C). After the treatment is completed, the sample is taken out after natural cooling, and characterization tests and performance tests are performed. The obtained solar substrate after cadmium chloride treatment is as follows: Figure 3 shown.

[0061] Table 1 Effect of near-space sublimation vapor phase treatment of cadmium chloride on the performance of solar substrates From the data in Table 1, we can conclude that compared with the traditional wet process, the thin-film solar cell produced by the technical solution provided by the present invention is better in terms of film distribution, photoelectric conversion efficiency and film stability. The reason is speculated to be: in the wet process, due to the use of solution for production, the cadmium chloride particles attached to the surface of the film during the high-temperature treatment process will diffuse into the solid phase of the film on the one hand, and will be vaporized and diffused into the atmosphere on the other hand. Because the solvent is difficult to control during the drying process, this leads to uneven dispersion of cadmium chloride crystals and forms marks on the surface of the absorption layer, which further leads to uneven treatment of the cadmium telluride absorption film layer due to uneven distribution of chloride ion concentration during the high-temperature treatment, which ultimately affects the conversion efficiency of the solar cell and the stability of component operation.

[0062] Comparative Example 2 The difference between this comparative example and Example 1 is that the distance between the cadmium chloride source and the absorption layer of the solar substrate in step 2) is 10.0 cm, and the rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Source preparation The cadmium chloride raw material is ground, sieved and placed on a graphite heating plate, and the raw material is flattened with a pressing plate to obtain a cadmium chloride source. The cadmium chloride source is sintered at a high temperature of 350°C in a sintering atmosphere of nitrogen and oxygen with a nitrogen-oxygen volume ratio of 4:1 for 30 seconds.

[0063] Specifically, the thickness of the paved cadmium chloride raw material is 2.0 cm.

[0064] Specifically, the sieve plate is 100 mesh.

[0065] Specifically, the graphite heating plate has a size of 10 cm×10 cm and a depth of 3 cm.

[0066] Specifically, the thickness of the cadmium chloride source is 1.0 cm.

[0067] 2) Sample injection Place the solar substrate with the absorption layer facing downward on the cadmium chloride source heating plate after high-temperature sintering, cover the solar substrate with a graphite uniform heating plate, insert temperature measuring thermocouples on the graphite uniform heating plate and the graphite heating plate, connect the push rod, and after loading, use the lofting rod to push the whole along the track into the special tube furnace, close the hatches on both sides of the quartz tube, evacuate the internal chamber, and then introduce gas to control the air pressure at 1×10 2 Pa.

[0068] The gas is nitrogen.

[0069] Specifically, the spacing between the cadmium chloride source and the absorber layer of the solar substrate was 10.0 cm.

[0070] 3) High temperature treatment The graphite heating plate and the graphite uniform heating plate are heated at the same time. After the graphite heating plate and the graphite uniform heating plate are heated to the required temperature at the same time, high temperature treatment is performed. The high temperature treatment time is 3 minutes.

[0071] Specifically, the heating temperature of the graphite heating plate is 400°C.

[0072] Specifically, the heating temperature of the graphite uniform heating plate is 300°C.

[0073] 4) Anti-sublimation treatment The graphite heating plate is heated while the graphite uniform heating plate is heated. After the graphite heating plate and the graphite uniform heating plate reach the specified temperature at the same time, an anti-sublimation treatment is performed. The anti-sublimation treatment time is 1 minute.

[0074] Specifically, the temperature of the graphite heating plate was 200°C.

[0075] Specifically, the temperature of the graphite uniform heating plate is 400°C.

[0076] 5) Subsequent processing After the treatment is completed, the samples are taken out after natural cooling for characterization and performance testing.

[0077] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, the distance between the cadmium chloride source and the absorption layer of the solar substrate in step 2) is 0.1 cm, and the rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Source preparation The cadmium chloride raw material is ground, sieved and placed on a graphite heating plate, and the raw material is flattened with a pressing plate to obtain a cadmium chloride source. The cadmium chloride source is sintered at a high temperature of 350°C in a sintering atmosphere of nitrogen and oxygen with a nitrogen-oxygen volume ratio of 4:1 for 30 seconds.

[0078] Specifically, the thickness of the paved cadmium chloride raw material is 2.0 cm.

[0079] Specifically, the sieve plate is 100 mesh.

[0080] Specifically, the graphite heating plate has a size of 10 cm×10 cm and a depth of 3 cm.

[0081] Specifically, the thickness of the cadmium chloride source is 1.0 cm.

[0082] 2) Sample injection Place the solar substrate with the absorption layer facing downward on the cadmium chloride source heating plate after high-temperature sintering, cover the solar substrate with a graphite uniform heating plate, insert temperature measuring thermocouples on the graphite uniform heating plate and the graphite heating plate, connect the push rod, and after loading, use the lofting rod to push the whole along the track into the special tube furnace, close the hatches on both sides of the quartz tube, evacuate the internal chamber, and then introduce gas to control the air pressure at 1×10 2 Pa.

[0083] The gas is nitrogen.

[0084] Specifically, the spacing between the cadmium chloride source and the absorber layer of the solar substrate is 0.1 cm.

[0085] 3) High temperature treatment The graphite heating plate and the graphite uniform heating plate are heated at the same time. After the graphite heating plate and the graphite uniform heating plate are heated to the required temperature at the same time, high temperature treatment is performed, and the high temperature treatment residence time is 3 minutes.

[0086] Specifically, the heating temperature of the graphite heating plate is 400°C.

[0087] Specifically, the heating temperature of the graphite uniform heating plate is 300°C.

[0088] 4) Anti-sublimation treatment The graphite heating plate is heated while the graphite uniform heating plate is heated. After the graphite heating plate and the graphite uniform heating plate reach the specified temperature at the same time, an anti-sublimation treatment is performed. The anti-sublimation treatment time is 1 minute.

[0089] Specifically, the temperature of the graphite heating plate was 200°C.

[0090] Specifically, the temperature of the graphite uniform heating plate is 400°C.

[0091] 5) Subsequent processing After the treatment is completed, the samples are taken out after natural cooling for characterization and performance testing.

[0092] Table 2 Effect of the distance between the cadmium chloride source and the solar substrate on the performance of the solar substrate From the data in Table 2, it can be concluded that when the distance between the cadmium chloride source and the solar substrate exceeds 3 cm or is less than 0.5 cm, the basic performance of the final solar energy will be reduced. The reasons are speculated to be: when the distance between the cadmium chloride source and the solar substrate is too short, the amount of cadmium chloride deposited on the substrate will be too large, which may easily over-treat the solar substrate and cause the substrate to turn white, ultimately leading to low efficiency and instability; when the distance between the cadmium chloride source and the solar substrate is too long, the amount of cadmium chloride deposited on the substrate will be small, which may lead to insufficient treatment, insufficient activation, and low battery efficiency.

[0093] Comparative Example 4 The difference between this comparative example and Example 1 is that the residence time of the high temperature treatment in step 3) is 0, and the rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Source preparation The cadmium chloride raw material is ground, sieved and placed on a graphite heating plate, and the raw material is flattened with a pressing plate to obtain a cadmium chloride source. The cadmium chloride source is sintered at a high temperature of 350°C in a sintering atmosphere of nitrogen and oxygen with a nitrogen-oxygen volume ratio of 4:1 for 30 seconds.

[0094] Specifically, the thickness of the paved cadmium chloride raw material is 2.0 cm.

[0095] Specifically, the sieve plate is 100 mesh.

[0096] Specifically, the graphite heating plate has a size of 10 cm×10 cm and a depth of 3 cm.

[0097] Specifically, the thickness of the cadmium chloride source is 1.0 cm.

[0098] 2) Sample injection Place the solar substrate with the absorption layer facing downward on the cadmium chloride source heating plate after high-temperature sintering, cover the solar substrate with a graphite uniform heating plate, insert temperature measuring thermocouples on the graphite uniform heating plate and the graphite heating plate, connect the push rod, and after loading, use the lofting rod to push the whole along the track into the special tube furnace, close the hatches on both sides of the quartz tube, evacuate the internal chamber, and then introduce gas to control the air pressure at 1×10 2 Pa.

[0099] The gas is nitrogen.

[0100] Specifically, the spacing between the cadmium chloride source and the absorber layer of the solar substrate is 2 cm.

[0101] 3) High temperature treatment The graphite heating plate and the graphite uniform heating plate are heated at the same time. After the graphite heating plate and the graphite uniform heating plate are heated to the required temperature at the same time, high temperature treatment is performed, and the high temperature treatment time is 0.

[0102] Specifically, the heating temperature of the graphite heating plate is 400°C.

[0103] Specifically, the heating temperature of the graphite uniform heating plate is 300°C.

[0104] 4) Anti-sublimation treatment The graphite heating plate is heated while the graphite uniform heating plate is heated. After the graphite heating plate and the graphite uniform heating plate reach the specified temperature at the same time, an anti-sublimation treatment is performed. The anti-sublimation treatment time is 1 minute.

[0105] Specifically, the temperature of the graphite heating plate was 200°C.

[0106] Specifically, the temperature of the graphite uniform heating plate is 400°C.

[0107] 5) Subsequent processing After the treatment is completed, the samples are taken out after natural cooling for characterization and performance testing.

[0108] Comparative Example 5 The difference between this comparative example and Example 1 is that the residence time of the high temperature treatment in step 3) is 10 minutes, and the rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Source preparation The cadmium chloride raw material is ground, sieved and placed on a graphite heating plate, and the raw material is flattened with a pressing plate to obtain a cadmium chloride source. The cadmium chloride source is sintered at a high temperature of 350°C in a sintering atmosphere of nitrogen and oxygen with a nitrogen-oxygen volume ratio of 4:1 for 30 seconds.

[0109] Specifically, the thickness of the paved cadmium chloride raw material is 2.0 cm.

[0110] Specifically, the sieve plate is 100 mesh.

[0111] Specifically, the graphite heating plate has a size of 10 cm×10 cm and a depth of 3 cm.

[0112] Specifically, the thickness of the cadmium chloride source is 1.0 cm.

[0113] 2) Sample injection Place the solar substrate with the absorption layer facing downward on the cadmium chloride source heating plate after high-temperature sintering, cover the solar substrate with a graphite uniform heating plate, insert temperature measuring thermocouples on the graphite uniform heating plate and the graphite heating plate, connect the push rod, and after loading, use the lofting rod to push the whole along the track into the special tube furnace, close the hatches on both sides of the quartz tube, evacuate the internal chamber, and then introduce gas to control the air pressure at 1×10 2 Pa.

[0114] The gas is nitrogen.

[0115] Specifically, the spacing between the cadmium chloride source and the absorber layer of the solar substrate is 2 cm.

[0116] 3) High temperature treatment The graphite heating plate and the graphite uniform heating plate are heated at the same time. After the graphite heating plate and the graphite uniform heating plate are heated to the required temperature at the same time, high temperature treatment is performed. The high temperature treatment time is 10 minutes.

[0117] Specifically, the heating temperature of the graphite heating plate is 400°C.

[0118] Specifically, the heating temperature of the graphite uniform heating plate is 300°C.

[0119] 4) Anti-sublimation treatment The graphite heating plate is heated while the graphite uniform heating plate is heated. After the graphite heating plate and the graphite uniform heating plate reach the specified temperature at the same time, an anti-sublimation treatment is performed. The anti-sublimation treatment time is 1 minute.

[0120] Specifically, the temperature of the graphite heating plate was 200°C.

[0121] Specifically, the temperature of the graphite uniform heating plate is 400°C.

[0122] 5) Subsequent processing After the treatment is completed, the samples are taken out after natural cooling for characterization and performance testing.

[0123] Table 3 Effect of high temperature treatment residence time on solar substrate performance From the data in Table 3, we can conclude that too long or too short a high-temperature treatment time will lead to a decrease in the photoelectric conversion efficiency and operating stability of the thin-film solar cell finally formed. The reasons are speculated to be: too short a high-temperature treatment time will result in insufficient treatment, insufficient activation, and low efficiency; too long a high-temperature treatment time will result in excessive treatment, causing the film surface to turn white, consuming the window layer, and Cl accumulating in the window layer and the absorption layer to produce new defects, resulting in low efficiency and poor stability.

[0124] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0125] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A post-processing method for thin-film solar cells, characterized in that: The following steps are involved: 1) Grinding and sieving the cadmium chloride raw material, flattening it on a heating plate and then pressing it to obtain a cadmium chloride source; 2) Place the heating plate, cadmium chloride source, solar cell substrate and uniform heat plate from bottom to top to obtain the sample to be processed. The distance between the cadmium chloride source and the solar cell substrate is 0.5~3cm; 3) First evacuate the sample to be processed and then fill it with gas; 4) Heat the heating plate and the uniform heating plate at the same time. The temperature of the heating plate is 350~440℃, the temperature of the uniform heating plate is 300~400℃, and the insulation time is 1~5min; 5) Cool the heating plate to 200-350°C, raise the temperature of the uniform heating plate to 350-400°C, and keep warm for 1-2 minutes; 6) Cooling down the sample after high temperature treatment, and performing back contact layer and back electrode processes to obtain a thin film solar cell.

2. A post-processing method for thin-film solar cells according to claim 1, characterized in that: In step 1), the mesh size of the sieve is 50-100.

3. A post-processing method for thin-film solar cells according to claim 1 or 2, characterized in that: In step 1), the thickness of the cadmium chloride raw material laid flat is 2 to 3 cm.

4. A post-processing method for thin-film solar cells according to claim 1, characterized in that: In step 1), the thickness of the cadmium chloride source is 1-2 cm.

5. The post-processing method for thin-film solar cells according to claim 1, characterized in that: In step 2), the solar substrate includes glass, a TCO layer, a window layer and an absorption layer.

6. A post-processing method for thin-film solar cells according to claim 5, characterized in that: The absorber layer of the solar substrate is stacked toward the cadmium chloride source.

7. A post-processing method for thin-film solar cells according to claim 1, characterized in that: In step 3), the gas is one or more of dry air, nitrogen and oxygen.

8. A post-processing method for thin-film solar cells according to claim 1 or 7, characterized in that: In step 3), when filling the gas, the air pressure of the control system is 10 2 ~10 5 Pa.

9. A post-processing method for thin-film solar cells according to claim 1, characterized in that: In step 4), the heating rates of the heating plate and the uniform heating plate are both 1-10°C / s.

10. A post-processing method for thin-film solar cells according to claim 1, characterized in that: In step 5), the cooling rate of the heating plate is 1-10°C / s, and the heating rate of the uniform heating plate is 1-10°C / s.

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