Method of processing heterojunction cells

Abstract

The application relates to the technical field of solar cells, and particularly provides a heterojunction cell processing method, which comprises the following steps: providing a heterojunction cell and a cell box, wherein the heterojunction cell at least comprises a semiconductor substrate layer, a semiconductor functional layer and a transparent conductive layer which are arranged in a stack; the cell box is suitable for placing the heterojunction cell; further comprising the following steps: providing a sealing bag; placing the heterojunction cell in the cell box; after the heterojunction cell is placed in the cell box, placing the cell box in the sealing bag; performing vacuumizing treatment on the sealing bag so that the sealing bag closely adheres to the cell box; after the vacuumizing treatment on the sealing bag, placing the sealing bag in a low-temperature environment for storage; further comprising the following steps: after the storage in the low-temperature environment, taking out the heterojunction cell before use and performing recovery treatment on the heterojunction cell; the recovery treatment comprises electro-injection treatment and / or light injection treatment; and the heterojunction cell processing method provided by the application can inhibit the dark decay of the heterojunction cell.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a heterojunction cell processing method. BACKGROUND

[0002] Heterojunction cells have the advantages of high conversion efficiency, simple manufacturing process, thin silicon wafer application, low temperature coefficient, no light-induced decay and potential decay, and double-sided power generation. The heterojunction cell module has an advantage in conversion efficiency, which greatly exceeds other types of cells (such as PERC, TOPCon), and the average conversion efficiency is expected to break through 25%. However, in actual production, the heterojunction cells produced often cannot be made into heterojunction cell modules at the first time, and need a long storage time; or when the heterojunction cell is sent for detection, it also needs a long storage time due to logistics. After a certain period of storage, the heterojunction cell efficiency will have a certain degree of dark decay, that is, the photoelectric conversion efficiency of the heterojunction cell will decrease under the condition of packaging and sealing without strong light irradiation after the heterojunction cell is produced. Correspondingly, other types of solar cells, such as PERC and TOPCon cells, generally do not have obvious photoelectric conversion efficiency decay during light storage.

[0003] In order to inhibit the dark decay of the heterojunction cell, the current method is to place the heterojunction cell in a nitrogen environment. However, placing the heterojunction cell in a nitrogen environment requires nitrogen to be introduced into a nitrogen cabinet specially storing the heterojunction cell, and a professional needs to check the pipeline airtightness regularly, which has high maintenance cost. Moreover, the above-mentioned scheme is not ideal for inhibiting the dark decay of the heterojunction cell, and tests show that the conversion efficiency will decrease by 0.12% due to dark decay after 21 days of storage.

[0004] Therefore, there is an urgent need for a better way to properly store or process the heterojunction cell to inhibit the dark decay of the heterojunction cell. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is how to better inhibit the dark decay of the heterojunction cell, thereby providing a heterojunction cell processing method.

[0006] The application provides a processing method of a heterojunction battery, which comprises the following steps: the heterojunction battery comprises at least a semiconductor substrate layer, a semiconductor functional layer and a transparent conductive layer which are arranged in a stack; the method comprises the following steps: providing a sealing bag; placing the heterojunction battery in a battery box; placing the battery box in the sealing bag after the heterojunction battery is placed in the battery box; performing vacuumizing treatment on the sealing bag so that the sealing bag is tightly attached to the battery box; placing the sealing bag in a low-temperature environment for storage after the vacuumizing treatment; the temperature of the low-temperature environment is-20℃ to-10℃; the method further comprises the following steps: after the storage in the low-temperature environment, taking out the heterojunction battery before use and performing recovery treatment on the heterojunction battery; the recovery treatment comprises the following steps: electric injection treatment and / or light injection treatment.

[0007] Optionally, the suction force of the vacuumizing treatment is 50kPa to 80kPa, and the time of the vacuumizing treatment is 5s to 8s.

[0008] Optionally, before the vacuumizing treatment is performed on the sealing bag, the method further comprises the following step: placing a drying agent in the sealing bag; the drying agent comprises anhydrous calcium chloride.

[0009] Optionally, the humidity of the low-temperature environment is 60% to 75%; during the process of placing the sealing bag in the low-temperature environment for storage, the method further comprises the following step: introducing a protective atmosphere into the low-temperature environment; the protective atmosphere comprises at least one of nitrogen, helium or argon.

[0010] Optionally, the step of placing the heterojunction battery in the battery box comprises the following steps: providing a plurality of heterojunction batteries, stacking the plurality of heterojunction batteries; during the stacking process, arranging a spacing layer between adjacent heterojunction batteries, arranging a buffer layer on the surface of the outermost heterojunction battery, arranging a support layer on the side of the buffer layer which is far away from the heterojunction battery after the buffer layer is arranged; after the stacking and the arrangement of the spacing layer, the buffer layer and the support layer, placing the stacked heterojunction batteries in the battery box; wherein: the spacing layer comprises sulfuric acid paper; the buffer layer comprises a foam board; the support layer comprises a hard plastic plate, and the hardness of the hard plastic plate is 80HD to 90HD.

[0011] Optionally, the method further comprises the following step: before the recovery treatment is performed, taking out the heterojunction battery in the sealing bag in the low-temperature environment and performing static treatment; the time of the static treatment is 8min to 15min.

[0012] Optionally, the step of performing the electro-injection treatment on the heterojunction cell comprises: performing a pre-heating treatment on the heterojunction cell; contacting the surface electrode of the heterojunction cell for the electro-injection treatment; during the electro-injection treatment, performing a ventilation treatment on the heterojunction cell by using a blower; the current of the electro-injection treatment is 6A-10A, the time is 10min-15min, and the temperature is 60℃-80℃.

[0013] Optionally, the step of performing the light-injection treatment on the heterojunction cell comprises: performing a pre-heating treatment on the heterojunction cell; performing a light treatment on the heterojunction cell; during the light treatment, performing a blowing treatment on the heterojunction cell by using a blower; the light intensity of the light treatment is 70kW / m2-90kW / m2, the temperature is 180℃-190℃, and the time is 2min-4min; the light treatment uses one of halogen light, red light, and infrared light.

[0014] Optionally, the method further comprises: before placing the heterojunction cell in the battery box, forming a grid electrode on the side of the transparent conductive layer away from the semiconductor substrate layer, or after taking out the heterojunction cell in the sealed bag in a low-temperature environment for standing treatment, forming a grid electrode on the side of the transparent conductive layer away from the semiconductor substrate layer before the recovery treatment of the heterojunction cell.

[0015] Optionally, the method further comprises: during the process of forming a grid electrode on the side of the transparent conductive layer away from the semiconductor substrate layer, first forming an uncured grid electrode, and then performing a curing treatment on the grid electrode to form a cured grid electrode; the curing treatment has a temperature of 120℃-140℃ and a time of 5min-10min.

[0016] The present application has the following advantages:

[0017] The method for processing the heterojunction cell provided by the present application first performs a vacuumizing treatment on the sealed bag to remove the water vapor existing in the battery box due to exposure to the atmospheric environment, and during the vacuumizing treatment, the vacuumizing is performed by controlling the suction force, so that the sealed bag can be tightly attached to the battery box, and the damage to the heterojunction cell can be avoided; after the vacuumizing treatment of the sealed bag, the sealed bag is stored in a low-temperature environment, and specifically, a device with refrigeration function can be selected, such as a refrigerator or a freezer. In this way, the complex factory requirements can be saved, and the maintenance cost can be reduced; secondly, the storage in the low-temperature environment can inhibit the reduction of the lifetime of the minority carriers in the heterojunction cell, thereby inhibiting the dark decay of the heterojunction cell. According to tests, the conversion efficiency does not decrease obviously at the 21st day, and the power loss of the battery piece caused by the dark decay during the storage process is effectively avoided. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the specific embodiments or the related art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the related art description. Obviously, the drawings described below are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.

[0019] Figure 1 The flowchart of the processing method of the heterojunction battery in the embodiments of the present application. Specific embodiments

[0020] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0022] The present embodiment provides a processing method of a heterojunction battery, comprising: providing a heterojunction battery and a battery box, the heterojunction battery comprising at least a semiconductor substrate layer, a semiconductor functional layer and a transparent conductive layer stacked; the battery box is suitable for placing the heterojunction battery;

[0023] Reference Figure 1 Further comprising:

[0024] S1: providing a sealed bag;

[0025] S2: placing the heterojunction battery in the battery box;

[0026] S3: after placing the heterojunction battery in the battery box, placing the battery box in the sealed bag;

[0027] S4: vacuumizing the sealed bag to make the sealed bag tightly adhere to the battery box;

[0028] S5: after vacuumizing the sealed bag, placing the sealed bag in a low-temperature environment for storage;

[0029] Wherein, the temperature of the low-temperature environment is-20℃ to-10℃.

[0030] Further comprising, S6: after storage in the low-temperature environment, taking out for use, recovering the heterojunction battery; the recovery processing comprises:

[0031] Electro-injection treatment and / or optical injection treatment.

[0032] In this embodiment, the sealed bag is first vacuum-sealed to remove moisture from the heterojunction battery compartment exposed to the atmosphere. During vacuuming, suction is controlled to ensure the sealed bag adheres tightly to the battery compartment, preventing damage to the heterojunction battery. After vacuuming, the sealed bag is stored in a low-temperature environment, such as a refrigerator or freezer. This eliminates complex factory requirements and reduces maintenance costs. Secondly, low-temperature storage suppresses the reduction in minority carrier lifetime in the heterojunction battery, thus inhibiting dark decay. Furthermore, while low-temperature storage significantly suppresses dark decay, some degree of dark decay still occurs in heterojunction batteries. To recover from dark decay caused during storage, a recovery process is needed, which can further improve the passivation effect of the semiconductor functional layer, reduce carrier recombination, and improve the effective doping rate.

[0033] In this embodiment, the semiconductor substrate layer is made of silicon wafer, typically an N-type silicon wafer for heterojunction solar cells. The semiconductor functional layer includes intrinsic semiconductor layers on opposite sides of the semiconductor substrate layer and a doped semiconductor layer on the side of the intrinsic semiconductor layer facing away from the semiconductor substrate layer. The intrinsic semiconductor layer includes an amorphous silicon layer, typically used to passivate the N-type silicon wafer. The doped semiconductor layer includes an amorphous silicon layer, a single-sided microcrystalline silicon layer, or a double-sided microcrystalline silicon layer. The doped semiconductor layers located on both sides of the semiconductor substrate layer are of P-type or N-type conductivity, forming PN junctions or high-low junctions with the N-type silicon wafer, respectively. Under sunlight, charge carriers move in a certain direction, forming a voltage difference. In other embodiments, the semiconductor substrate layer is made of single crystal or silicon-germanium wafer.

[0034] It's important to understand that any degradation in a heterojunction solar cell that doesn't occur under particularly strong light conditions can be called dark degradation. In the case of heterojunctions, dark degradation is an anomalous SW effect. The SW effect occurs when a heterojunction solar cell is exposed to strong light or current for an extended period, causing defects to form inside and degrading the performance of the transparent conductive layer.

[0035] Specifically, the suction force for vacuuming is 50 kPa to 80 kPa, for example, 50 kPa, 60 kPa, 70 kPa, or 80 kPa. If the suction force for vacuuming is too high, the effect of preventing damage to the heterojunction battery is reduced; if the suction force for vacuuming is too low, the battery box will still be in contact with air, and the probability of expelling moisture from the battery box is small.

[0036] In one embodiment, the time for the vacuumizing process is 5s-8s, for example, 5s, 6s, 7s or 8s. In this embodiment, the suction force for the vacuumizing process is 50kPa-80kPa, and by controlling the time for the vacuumizing process to be 5s-8s, the heterojunction cell can be prevented from being damaged, and in particular, from being cracked, while meeting the vacuum condition.

[0037] In one embodiment, before the vacuumizing process is performed on the sealed bag, the method further comprises: placing a desiccant in the sealed bag. The desiccant can absorb moisture in the air, further inhibiting the dark decay of the heterojunction cell.

[0038] In one embodiment, the desiccant comprises anhydrous calcium chloride.

[0039] In one embodiment, the temperature of the low-temperature environment is -20℃--10℃, for example, -20℃, -15℃ or -10℃. If the temperature of the low-temperature environment is greater than -10℃, the effect of inhibiting the dark decay of the heterojunction cell is weakened; if the temperature of the low-temperature environment is less than -20℃, the heterojunction cell is prone to cracking, causing damage to the heterojunction cell.

[0040] In one embodiment, the humidity of the low-temperature environment is 60%-75%, for example, 60%, 70% or 75%. If the humidity of the low-temperature environment is greater than 75%, there is water vapor inside the battery box, which contacts the heterojunction cell and causes poor reliability of the heterojunction cell; if the humidity of the low-temperature environment is less than 60%, it can cause the packaging to be too dry and the heterojunction cell to crack.

[0041] In one embodiment, during the process of storing the sealed bag in the low-temperature environment, the method further comprises: introducing a protective atmosphere into the low-temperature environment. This can prevent the sealed bag from leaking, avoid oxidation of the transparent conductive layer in the structure of the heterojunction cell, and thus inhibit the dark decay of the heterojunction cell.

[0042] In one embodiment, the protective atmosphere comprises at least one of nitrogen, helium or argon. In other embodiments, the protective atmosphere comprises other inert gases.

[0043] In one embodiment, the step of placing the heterojunction cells in the battery box comprises: providing a plurality of heterojunction cells, stacking the plurality of heterojunction cells; during the stacking process, arranging a spacing layer between adjacent heterojunction cells, arranging a buffer layer on the surface of the outermost heterojunction cell, and after arranging the buffer layer, arranging a support layer on the side of the buffer layer away from the heterojunction cell; after stacking and arranging the spacing layer, the buffer layer and the support layer, the stacked heterojunction cells are placed in the battery box (i.e., the entire structure containing the alternately arranged heterojunction cells, the spacing layer between the heterojunction cells, the outermost buffer layer and the support layer is placed in the battery box). First, the spacing layer is arranged between adjacent heterojunction cells to prevent friction between adjacent heterojunction cells and avoid wear of the transparent conductive layer in the heterojunction cell structure. Then, the buffer layer is formed on the surface of the outermost heterojunction cell to avoid impact of external force on the outermost heterojunction cell and avoid damage to the heterojunction cell. After forming the buffer layer, the support layer is formed on the side of the buffer layer away from the heterojunction cell. The heterojunction cells need to be transported when placed in the battery box. The support layer can ensure the horizontal force during transportation and provide a certain rigidity to the heterojunction cell.

[0044] In one embodiment, the spacing layer comprises sulfuric acid paper; the buffer layer comprises a foam board; and the support layer comprises a hard plastic plate with a Shore hardness of 80HD-90HD, such as 80HD, 85HD or 90HD.

[0045] The processing method of the heterojunction cell further comprises: before the recovery treatment, taking out the heterojunction cell in the sealed bag in the low temperature environment for static treatment. The purpose of the static treatment is to recover the heterojunction cell from low temperature to room temperature. The heterojunction cell recovered to room temperature is subjected to recovery treatment, so that the recovery treatment can normally take effect, and additional output is not required in the recovery treatment step to recover the heterojunction cell to room temperature.

[0046] In this embodiment, the static treatment is performed at room temperature, and the temperature of the static treatment is not specifically described. The time of the static treatment is 8-15 minutes, such as 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes. In other embodiments, the time of the static treatment can be set according to actual conditions.

[0047] Specifically, the step of performing the electro-injection treatment on the heterojunction cell includes: performing a pre-heating treatment on the heterojunction cell; contacting the surface electrode of the heterojunction cell for the electro-injection treatment; and performing a ventilation treatment on the heterojunction cell during the electro-injection treatment. The local overheating of the heterojunction cell caused by the heat effect of the current is avoided. Specifically, for example, an air blower is used to blow air on the processing space and the heterojunction cell, so that the temperature of the space and the temperature of the cell are both maintained within a suitable range.

[0048] In one embodiment, the current of the electro-injection treatment is 6A-10A, for example, 6A, 7A, 8A, 9A or 10A, the time is 10min-15min, for example, 10min, 11min, 12min, 13min, 14min or 15min, and the temperature is 60℃-80℃, for example, 60℃, 70℃ or 80℃.

[0049] In this embodiment, during the electro-injection treatment of the heterojunction cell, the electro-injection treatment can be performed on a single heterojunction cell or on multiple heterojunction cells. When the electro-injection treatment is performed on a single heterojunction cell, one side of the heterojunction cell contacts a copper electrode and the other side contacts an aluminum electrode. When the electro-injection treatment is performed on multiple heterojunction cells, the multiple heterojunction cells are re-stacked, and the outermost side of the heterojunction cell contacts a copper electrode and the other side contacts an aluminum electrode. That is, the top of the heterojunction cell contacts a copper electrode or an aluminum electrode, and the bottom of the heterojunction cell contacts an aluminum electrode or a copper electrode. It should be noted that the adjacent heterojunction cells need to be aligned before stacking to ensure the uniformity of the electro-injection treatment of each heterojunction cell and to avoid wear during the stacking of the heterojunction cells.

[0050] The step of performing the light-injection treatment on the heterojunction cell includes: performing a pre-heating treatment on the heterojunction cell; then, performing a light treatment on the heterojunction cell; and performing a blowing treatment on the heterojunction cell during the light treatment. The temperature of the surface of the heterojunction cell is kept uniform to prevent local overheating. Specifically, for example, an air blower is used to blow air on the processing space and the surface of the heterojunction cell, so that the temperature of the space and the temperature of the cell are both maintained within a suitable range.

[0051] In one embodiment, the light intensity of the light treatment is 70 kW / m2-90 kW / m2, for example 70 kW / m2, 80 kW / m2 or 90 kW / m2, the temperature is 180℃-190℃, for example 180℃ or 190℃, and the time is 2 min-4 min, for example 2 min, 3 min or 4 min. The length of the photothermal treatment is as long as possible within the allowable range, and is adjusted according to actual needs.

[0052] In one embodiment, the light treatment uses one of halogen light, red light or infrared light. Among them, the halogen light has simple structure, easy to adjust brightness and low energy consumption; the red light has good penetration and good thermal effect.

[0053] In one embodiment, during the light injection treatment, a protective atmosphere is introduced to prevent oxidation of the surface of the heterojunction cell. The protective atmosphere includes at least one of nitrogen, helium or argon.

[0054] In other embodiments, the heterojunction cell is subjected to an electrical injection treatment and / or a light injection treatment before being placed in the battery box; the heterojunction cell is subjected to an electrical injection treatment and / or a light injection treatment again after the standing treatment. The semiconductor functional layer can be passivated further to reduce dark decay to some extent, but due to the complexity of the steps and the process time, the actual production adopts the technical solutions mentioned in the present application.

[0055] In the present embodiment, the method for processing the heterojunction cell further includes: forming a gate line electrode on the side of the transparent conductive layer away from the semiconductor substrate layer. Specifically:

[0056] In one embodiment, a gate line electrode is formed on the side of the transparent conductive layer away from the semiconductor substrate layer before the heterojunction cell is placed in the battery box.

[0057] In another embodiment, a gate line electrode is formed on the side of the transparent conductive layer away from the semiconductor substrate layer before the heterojunction cell placed in a sealed bag in a low-temperature environment is taken out for standing treatment and before the heterojunction cell is subjected to recovery treatment.

[0058] In the process of forming a gate line electrode on the side of the transparent conductive layer away from the semiconductor substrate layer, an uncured gate line electrode is first formed, and then the gate line electrode is subjected to a curing treatment to form a cured gate line electrode.

[0059] In one embodiment, the temperature of the curing treatment is 120℃-140℃, for example 120℃, 130℃ or 140℃, and the time is 5 min-10 min, for example 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0060] In this embodiment, the material of the grid line electrode is copper. Since copper has poor heat resistance, a large temperature difference can easily cause warping, so the temperature of the curing process needs to be controlled to be in the range of 120℃ to 140℃. In other embodiments, the material of the grid line electrode includes silver.

[0061] It can be understood that, before the heterojunction cell is placed in the battery box, a grid line electrode is formed on the side of the transparent conductive layer away from the semiconductor substrate layer; then, in the process of performing the vacuumizing treatment, the vacuumizing is performed by controlling the suction force, which can avoid damage to the heterojunction cell, and specifically, can avoid the risk of hidden cracking of the heterojunction cell and falling off of the grid line electrode; in the process of storing the sealed bag in a low-temperature environment, the protective atmosphere is introduced into the low-temperature environment, which is to avoid oxidation of the grid line electrode in the structure of the heterojunction cell, so as to inhibit the dark decay of the heterojunction cell.

[0062] In another embodiment, after the heterojunction cell placed in the sealed bag in the low-temperature environment is taken out for standing treatment, a grid line electrode is formed on the side of the transparent conductive layer away from the semiconductor substrate layer before the heterojunction cell is subjected to the recovery treatment; then, in the process of performing the vacuumizing treatment, the vacuumizing is performed by controlling the suction force, which can avoid hidden cracking of the heterojunction cell; in the process of storing the sealed bag in a low-temperature environment, the protective atmosphere is introduced into the low-temperature environment, which is to avoid oxidation of the transparent conductive layer. The following provides several specific embodiments and comparative examples to compare and illustrate the effect of the processing method of the heterojunction cell provided by the present application.

[0063] Embodiment 1

[0064] This embodiment 1 is implemented with reference to the above-mentioned processing method of the heterojunction cell, and specifically, the processing method includes:

[0065] The heterojunction cell is placed in the battery box.

[0066] After the heterojunction cell is placed in the battery box, the battery box is placed in the sealed bag.

[0067] The sealed bag is subjected to a vacuumizing treatment to make the sealed bag tightly adhere to the battery box.

[0068] After the sealed bag is subjected to the vacuumizing treatment, the sealed bag is stored in a low-temperature environment.

[0069] In this embodiment, the suction force of the vacuumizing treatment is 60kPa, and the time of the vacuumizing treatment is 8s.

[0070] In this embodiment, the temperature of the low-temperature environment is-10℃, and the humidity is 75%.

[0071] Example 2

[0072] This example 2 is performed with reference to the processing method of the heterojunction battery described above, and on the basis of example 1, the processing method further comprises: performing an electrical injection treatment on the heterojunction battery.

[0073] In this example, the current of the electrical injection treatment is 8A, the time is 15min, and the temperature is 60℃.

[0074] Example 3

[0075] The difference between example 3 and example 2 is that:

[0076] On the basis of example 1, it further comprises: performing a light injection treatment on the heterojunction battery.

[0077] In this example, the light intensity of the light irradiation treatment is 90kW / m2, the temperature is 190℃, and the time is 2min.

[0078] Example 4

[0079] The difference between example 4 and example 2 or example 3 is that:

[0080] On the basis of example 1, it further comprises: performing an electrical injection treatment on the heterojunction battery, and then performing a light injection treatment on the heterojunction battery.

[0081] In this example, the current of the electrical injection treatment is 8A, the time is 15min, and the temperature is 60℃.

[0082] In this example, the light intensity of the light irradiation treatment is 90kW / m2, the temperature is 190℃, and the time is 2min.

[0083] Comparative example 1

[0084] Comparative example 1 provides a processing method of a heterojunction battery, comprising: placing the heterojunction battery in an atmospheric environment.

[0085] Comparative example 2

[0086] Comparative example 2 provides a processing method of a heterojunction battery, comprising: placing the heterojunction battery in a nitrogen environment.

[0087] Comparative example 3

[0088] Comparative example 3 provides a processing method of a heterojunction battery, comprising: placing the heterojunction battery in a vacuum environment.

[0089] The heterojunction cells provided by the processing method of Example 1 and Comparative Examples 1-3 were tested for performance immediately after being processed, i.e. immediately after being produced in a production line, and the following data were obtained:

[0090] Table 1

[0091]

[0092] The heterojunction cells provided by the processing method of Example 1 and Comparative Examples 1-3 were tested for performance after being processed for 7 days, and the following data were obtained:

[0093] Table 2

[0094]

[0095]

[0096] wherein ΔEff is the change in conversion efficiency.

[0097] In Example 1, ΔEff is a positive value, indicating that the conversion efficiency of the heterojunction cell has increased slightly, which shows that the processing method of the heterojunction cell provided by Example 1 can inhibit the dark decay of the heterojunction cell. In contrast, Comparative Examples 1 and 3 both have negative values, and the magnitude is relatively large, indicating that the dark decay has begun to affect and act.

[0098] The heterojunction cells provided by the processing method of Example 1 and Comparative Examples 1-3 were tested for performance after being processed for 14 days, and the following data were obtained:

[0099] Table 3

[0100]

[0101] The heterojunction cells provided by the processing method of Example 1 and Comparative Examples 1-3 were tested for performance after being processed for 21 days, and the following data were obtained:

[0102] Table 4

[0103]

[0104] According to the test results, in combination with Tables 1-4, it can be seen that the values of Example 1 decrease less as the storage time increases, and the open circuit voltage, short circuit current, fill factor, etc. remain basically unchanged, and in particular, ΔEff always remains positive. In contrast, the values of the other comparative examples decrease significantly, and in particular, ΔEff is always negative. It can be seen that the method of Example 1 can effectively inhibit dark decay.

[0105] According to the results of Table 1 to Table 4, the degree of dark decay of the heterojunction cell from small to large is in the order of: Example 1 (vacuum + low temperature environment), Comparative Example 2 (nitrogen environment), Comparative Example 3 (vacuum environment), Comparative Example 1 (atmosphere environment), that is, the processing method of the heterojunction cell provided in Example 1 can better inhibit the dark decay of the heterojunction cell.

[0106] Further, on the basis of Example 1, specifically, on the basis of processing the heterojunction cell for 7 days, another batch of cells is processed using the processing method of the heterojunction cell provided in Example 2-Example 4.

[0107] The heterojunction cell processed for 7 days in Example 1 is tested for performance before being processed in Example 2-Example 4, and the following data is obtained:

[0108] Table 5

[0109]

[0110] The heterojunction cell processed for 7 days in Example 1 is tested for performance after being processed in Example 2-Example 4, and the following data is obtained:

[0111] Table 6

[0112]

[0113] The degree of dark decay of the heterojunction cell is small, which is conducive to the accuracy of subsequent sample detection. When sending samples for detection, cold chain transportation or dry ice is used, and a bubble bag is used to cushion outside the sealed bag.

[0114] According to Table 5 and Table 6, after the heterojunction cell is stored in Example 1 (vacuum + low temperature environment) and recovered by using the methods of Example 2 (electrical injection treatment), Example 3 (light injection treatment), and Example 4 (electrical injection treatment + light injection treatment), the performance of the heterojunction cell is improved.

[0115] In summary, the heterojunction cell is placed in an environment where vacuum and low temperature coexist, which can inhibit the decrease of the lifetime of the minority carriers in the heterojunction cell, thereby inhibiting the dark decay of the heterojunction cell, and the effect is the best compared with other methods of the prior art. By controlling the suction force during vacuumizing and the temperature and humidity of the low temperature, damage to the heterojunction cell is avoided; by selecting a refrigerator or freezer with refrigeration function, complex factory requirements are saved, and maintenance costs are reduced. Then, the heterojunction cell is recovered by electrical injection treatment and / or light injection treatment, thereby improving the quality of the heterojunction cell.

[0116] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A method of processing a heterojunction cell, characterized by, The heterojunction cell at least comprises a semiconductor substrate layer, a semiconductor functional layer and a transparent conductive layer arranged in a stack; the method comprises: providing a sealed bag; placing the heterojunction cell in a battery box; after placing the heterojunction cell in the battery box, placing the battery box in the sealed bag; performing vacuumizing treatment on the sealed bag to make the sealed bag closely adhere to the battery box; after performing vacuumizing treatment on the sealed bag, placing the sealed bag in a low-temperature environment for storage; the temperature of the low-temperature environment is -20℃ to -10℃; further comprising, after storage in the low-temperature environment, taking out and using, performing recovery treatment on the heterojunction cell; the recovery treatment comprises: electrical injection treatment and / or light injection treatment; the step of performing electrical injection treatment on the heterojunction cell comprises: performing pre-heating treatment on the heterojunction cell; contacting the surface electrode of the heterojunction cell for electrical injection treatment; in the process of electrical injection treatment, further comprising performing ventilation treatment on the heterojunction cell; the step of performing light injection treatment on the heterojunction cell comprises: performing pre-heating treatment on the heterojunction cell; performing light treatment on the heterojunction cell; in the process of light treatment, further comprising performing purging treatment on the heterojunction cell.

2. The method of processing a heterojunction cell according to claim 1, wherein, The suction of the vacuumizing treatment is 50kPa to 80kPa, and the time of the vacuumizing treatment is 5s to 8s.

3. The method of processing a heterojunction cell of claim 1, wherein, Before performing vacuumizing treatment on the sealed bag, the method further comprises: placing a desiccant in the sealed bag; the desiccant comprises anhydrous calcium chloride.

4. The method of processing a heterojunction cell of claim 1, wherein, The humidity of the low-temperature environment is 60% to 75%; in the process of placing the sealed bag in the low-temperature environment for storage, the method further comprises: introducing a protective atmosphere into the low-temperature environment; the protective atmosphere comprises at least one of nitrogen, helium or argon.

5. The processing method of the heterojunction cell according to claim 1, wherein the step of placing the heterojunction cell in the battery box comprises: providing a plurality of heterojunction cells, and stacking the plurality of heterojunction cells; in the stacking process, an interval layer is arranged between adjacent heterojunction cells, a buffer layer is arranged on the surface of the outermost heterojunction cell, and after arranging the buffer layer, a support layer is arranged on the side of the buffer layer away from the heterojunction cell; after stacking and arranging the interval layer, the buffer layer and the support layer, the stacked heterojunction cells are placed in the battery box; wherein: the interval layer comprises sulfuric acid paper; the buffer layer comprises a foam board; the support layer comprises a hard plastic plate, and the Shore hardness of the hard plastic plate is 80HD to 90HD.

6. The method of processing a heterojunction cell according to any one of claims 1-5, wherein, The method further comprises: before performing the recovery treatment, taking out the heterojunction cell in the sealed bag placed in the low-temperature environment for standing treatment; the standing treatment time is 8min to 15min.

7. The processing method of the heterojunction cell according to claim 1, wherein the current of the electrical injection treatment is 6A to 10A, the time is 10min to 15min, and the temperature is 60℃ to 80℃.

8. The processing method of the heterojunction cell according to claim 1, wherein The light intensity of the light treatment is 70 kW / m 2 ~ 90 kW / m 2 The temperature is 180~190℃, and the time is 2~4 min. The light treatment adopts one of halogen light, red light or infrared light.

9. The method of processing a heterojunction cell of claim 6, wherein, The method further comprises: before the heterojunction cell is placed in the battery box, forming a grid line electrode on the side of the transparent conductive layer away from the semiconductor substrate layer, or, Before the heterojunction cell placed in a sealed bag in a low-temperature environment is taken out for standing treatment and before the heterojunction cell is recovered, a grid line electrode is formed on the side of the transparent conductive layer away from the semiconductor substrate layer.

10. The method of processing a heterojunction cell according to claim 9, wherein, Further comprising: In the process of forming a grid line electrode on the side of the transparent conductive layer away from the semiconductor substrate layer, an uncured grid line electrode is first formed, and then the grid line electrode is cured to form a cured grid line electrode. The curing temperature is 120-140 DEG C, and the curing time is 5-10 minutes.

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