Method for testing performance of heterojunction solar cell

Abstract

The application provides a performance testing method of a heterojunction solar cell, comprising the following steps: providing a heterojunction solar cell piece; sequentially performing annealing treatment and photo-injection treatment on the heterojunction solar cell piece; and performing photoelectric conversion efficiency decay testing on the heterojunction solar cell piece after the photo-injection treatment. The performance testing method can well reflect the influence of the compactness of the film layer in the cell piece and the interface contact between the film layers on the efficiency decay of the cell piece, and truly reflects the compactness of the film layer in the cell piece and the interface contact between the film layers, thereby providing support for the production process adjustment and optimization of the heterojunction solar cell piece.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a performance testing method for heterojunction solar cells. Background Technology

[0002] The fabrication process of a heterojunction solar cell (HJT) involves several steps, including texturing and cleaning (forming a textured surface), CVD coating (forming an amorphous silicon film), PVD coating (forming a TCO conductive film), printing (silver gridding), and testing (data standardization). A key characteristic of heterojunction solar cells is their multi-interface nature, including interfaces between the N-type monocrystalline silicon substrate (n-Si) and the intrinsic amorphous silicon thin film (ia-Si-H), between the intrinsic amorphous silicon thin film and N-type / P-type amorphous silicon thin films (na-Si-H / Pa-Si-H), and between the N-type / P-type amorphous silicon thin film and the transparent conductive film (TCO).

[0003] Heterojunction solar cells improve cell efficiency through multilayer stacking technology, but they also face problems such as poor film density and poor interfacial contact between layers, affecting the conversion efficiency of heterojunction cells. In cell efficiency degradation tests, the decrease in photoelectric conversion efficiency caused by poor film density and poor interfacial contact reflects problems in the heterojunction cell manufacturing process (such as the coating process).

[0004] Therefore, it is necessary to test the photoelectric conversion efficiency degradation of heterojunction solar cells caused by poor film density and poor interfacial contact between film layers, in order to determine whether there are problems with the film density and interfacial contact. If the photoelectric conversion efficiency degradation test confirms that there are problems with the film density and interfacial contact, the production process can be adjusted to solve the problem and improve product quality.

[0005] However, when testing the photoelectric conversion efficiency (PCE) degradation of heterojunction solar cells, in addition to the density of the film layers themselves and the interfacial contact between the layers, other factors can also cause the PCE of heterojunction cells to degrade. Therefore, these other factors can interfere with the PCE degradation test, making the test results unable to accurately reflect the PCE degradation caused by the density of the film layers themselves and the interfacial contact between the layers. Summary of the Invention

[0006] Therefore, it is necessary to provide a performance testing method for heterojunction solar cells to more accurately reflect the degradation of the photoelectric conversion efficiency of the cells caused by the compactness of the film itself and the interfacial contact between the film layers.

[0007] According to one aspect of the present invention, a performance testing method for a heterojunction solar cell is provided, comprising the following steps:

[0008] Provide heterojunction solar cells;

[0009] The heterojunction solar cell is subjected to annealing and light injection treatments in sequence; and

[0010] Photovoltaic conversion efficiency degradation test was performed on heterojunction solar cells after light injection treatment.

[0011] Before conducting photoelectric conversion efficiency degradation tests on heterojunction solar cells, this invention sequentially performs annealing and light injection treatments on the heterojunction solar cells. Annealing exposes unstable defects at the interfaces between the amorphous silicon thin film and adjacent film layers. Then, light injection excites a large number of free hydrogen atoms within the film layers to fill the defects exposed after annealing, greatly improving the stability of the interfaces between film layers. This reduces the impact of environmental moisture, dirt, and other contaminants on the efficiency degradation of the solar cells, and minimizes interference from other factors on the photoelectric conversion efficiency degradation test results.

[0012] The performance testing method of the present invention can well reflect the impact of the density of the film layer itself and the interfacial contact between the film layers on the efficiency degradation of the solar cell, and truly reflect the density of the film layer and the interfacial contact between the film layers in the solar cell.

[0013] In any implementation, the photoelectric conversion efficiency degradation test includes the following steps:

[0014] The photoelectric conversion efficiency η1 of the heterojunction solar cell after light injection treatment was obtained;

[0015] The heterojunction solar cells after light injection treatment were placed in an environment below 0°C for cold degradation treatment; and

[0016] Obtain the photoelectric conversion efficiency η2 of the heterojunction solar cell after cold degradation treatment, and obtain the difference in photoelectric conversion efficiency X1 of the heterojunction solar cell before and after cold degradation treatment, where X1 = η1 - η2.

[0017] Thus, by comparing the difference in photoelectric conversion efficiency X1 between heterojunction solar cells before and after the cold degradation treatment, the interfacial contact between the film layers in the cell can be reflected.

[0018] In any embodiment, the temperature for cold degradation treatment is -10℃ to 0℃, and the treatment time is 10h to 24h. This allows for a better reflection of the interfacial contact between the film layers in the solar cell.

[0019] In any implementation, the photoelectric conversion efficiency degradation test includes the following steps:

[0020] When X1 ≤ 0.03%, the heterojunction solar cell after cold degradation treatment is subjected to thermal degradation treatment under heating conditions; and

[0021] The photoelectric conversion efficiency η3 of the heterojunction solar cell after thermal degradation treatment is obtained, and the difference in photoelectric conversion efficiency X2 before and after thermal degradation treatment is obtained, where X2 = η2 - η3.

[0022] Thus, by subjecting the heterojunction solar cells that have passed the cold degradation treatment to thermal degradation treatment under heating conditions, the density of the film layer itself in the cell can be better revealed, and the density of the film layer in the cell can be better reflected.

[0023] In any implementation, the photoelectric conversion efficiency degradation test includes the following steps:

[0024] The photoelectric conversion efficiency η1 of the heterojunction solar cell after light injection treatment was obtained;

[0025] The heterojunction solar cell after light injection treatment is subjected to thermal degradation treatment under heating conditions; and

[0026] The photoelectric conversion efficiency η3 of the heterojunction solar cell after thermal degradation treatment is obtained, and the difference in photoelectric conversion efficiency X2 of the heterojunction solar cell before and after thermal degradation treatment is obtained, where X2 = η1 - η3.

[0027] Thus, by directly subjecting the heterojunction solar cell after light injection treatment to thermal decay under heating conditions, the density of the film layer in the cell can also be reflected.

[0028] In any embodiment, the temperature for the thermal degradation treatment is 120°C to 135°C, and the treatment time is 15 min to 20 min. This allows for a more thorough exposure of the density issues of the film layers within the solar cell, providing a better reflection of the film layer density.

[0029] In any implementation, the photoelectric conversion efficiency degradation test includes the following steps:

[0030] When X2 ≤ 0.15%, the heterojunction solar cells after thermal degradation treatment are subjected to static degradation treatment in a protective atmosphere; and

[0031] Obtain the photoelectric conversion efficiency η4 of the heterojunction solar cell after static attenuation treatment, and obtain the difference in photoelectric conversion efficiency X3 of the heterojunction solar cell before and after static attenuation treatment, X3 = η3 - η4.

[0032] In this way, we can examine the stability of the solar cells after alternating cooling and heating or thermal degradation treatment, and further verify the compactness of the film layers in the solar cells.

[0033] In any embodiment, the temperature for static degradation treatment is 10°C to 30°C, and the time for static degradation treatment is 36h to 72h. In this way, the film density problem of heterojunction solar cells after alternating hot and cold degradation or hot degradation treatment can be more fully exposed.

[0034] In any embodiment, the annealing process includes the following steps: heating the heterojunction solar cell at 70°C to 110°C for 10 to 15 minutes, and annealing it at 40°C to 50°C for 15 to 20 minutes. This allows the film layer of the heterojunction solar cell to reach a stable state, preventing further changes in the film structure and allowing for the full exposure of defects in the film layer within the cell.

[0035] In any embodiment, the light injection process includes the following steps: irradiating the front and back sides of the annealed heterojunction solar cell with light at 80 to 90 standard light intensities for 60 to 120 seconds. This excites a large number of free hydrogen atoms within the film layers on the front and back sides of the heterojunction solar cell, filling the defects exposed after annealing and improving the stability of the interface layer in the cell.

[0036] In any implementation, the number of heterojunction solar cells is multiple, and the performance testing method before annealing further includes the following steps:

[0037] Obtain the photoelectric conversion efficiency of all heterojunction solar cells, and remove heterojunction solar cells whose photoelectric conversion efficiency does not meet the following condition: (Nmin+Nmax) / 2+a%, where a is 0.2~0.3;

[0038] Wherein, Nmin is the minimum photoelectric conversion efficiency among all heterojunction solar cells, and Nmax is the maximum photoelectric conversion efficiency among all heterojunction solar cells.

[0039] In this way, not only can the workload of efficiency degradation testing be effectively reduced, but the selected heterojunction solar cells can also well represent the overall conversion efficiency level of heterojunction solar cells, making the final photoelectric conversion efficiency degradation test results representative.

[0040] In any implementation, after selecting heterojunction solar cells with a photoelectric conversion efficiency of (Nmin+Nmax) / 2+a%, the selected cells are further subjected to EL testing and visual inspection. Cells with no abnormalities in appearance and EL (i.e., Grade A cells) are selected for efficiency degradation testing. In this way, more representative cells can be further selected for efficiency degradation testing.

[0041] In any implementation, the number of heterojunction solar cells is multiple. After the light injection treatment and before the photoelectric conversion efficiency degradation test, the performance testing method further includes the following steps:

[0042] Perform EL testing and visual inspection on heterojunction solar cells, and remove heterojunction solar cells that fail the EL testing and visual inspection.

[0043] In this way, some defective solar cells from EL testing and appearance inspection can be eliminated, and the efficiency degradation test results can more accurately reflect the film density and interfacial contact between the film layers in the solar cell.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] This invention performs annealing and light injection treatments on heterojunction solar cells before testing their photoelectric conversion efficiency degradation. Annealing exposes unstable defects at the interfaces between the amorphous silicon thin film and adjacent layers. Light injection then excites free hydrogen atoms within the film layers to fill the defects exposed after annealing, significantly improving the stability of the film layer interfaces and reducing the impact of environmental moisture and contamination on efficiency degradation. This performance testing method effectively reflects the influence of the film layer density and interfacial contact on efficiency degradation, providing a true picture of the film layer density and interfacial contact, and supporting the optimization of heterojunction solar cell manufacturing processes. Attached Figure Description

[0046] To better describe and illustrate embodiments and / or examples of the invention, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed invention, the currently described embodiments and / or examples, or the best mode of these inventions as currently understood.

[0047] Figure 1 This is a flowchart of a performance testing method according to an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of a heterojunction solar cell.

[0049] Figure 3 This is a schematic diagram of the interface between film layers in a heterojunction solar cell.

[0050] Figure 4 This is a comparison chart of the CTM values ​​of a battery module before and after using the battery cell performance testing method of an embodiment of the present invention;

[0051] Figure 5 This is a comparison chart of the output per shift of a single production line before and after adopting the battery cell performance testing method of an embodiment of the present invention. Detailed Implementation

[0052] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this invention are commercially available or can be prepared by existing methods.

[0054] Currently, when testing the photoelectric conversion efficiency degradation of heterojunction solar cells, besides the density of the film layers themselves and the interfacial contact between the layers, other factors can also cause the conversion efficiency of heterojunction cells to decay. This interferes with the efficiency degradation test, making the test results unable to accurately reflect the efficiency degradation caused by the density of the film layers themselves and the interfacial contact between the layers. To address this, this invention provides a performance testing method for heterojunction solar cells, whose test results can more accurately reflect the efficiency degradation caused by the density of the film layers themselves and the interfacial contact between the layers.

[0055] Please see Figure 1 An embodiment of the present invention provides a performance testing method for heterojunction solar cells, the performance testing method comprising the following steps S100 to S500:

[0056] Step S100: Provide heterojunction solar cells.

[0057] Please see Figure 2In some embodiments, the heterojunction solar cell includes an N-type monocrystalline silicon substrate (n-Si), an intrinsic amorphous silicon thin film (ia-Si-H), an N-type amorphous silicon thin film (na-Si-H), a P-type amorphous silicon thin film (pa-Si-H), a transparent conductive film (TCO), and a metal electrode.

[0058] The N-type monocrystalline silicon substrate has intrinsic amorphous silicon thin films on both its front and back sides. An N-type amorphous silicon thin film is placed on the intrinsic amorphous silicon thin film on the front side of the N-type monocrystalline silicon substrate, and a P-type amorphous silicon thin film is placed on the intrinsic amorphous silicon thin film on the back side. Transparent conductive films are placed on both the N-type and P-type amorphous silicon films, and metal electrodes are placed on the transparent conductive films. The N-type monocrystalline silicon substrate is texturized and cleaned to form a textured surface. The intrinsic amorphous silicon thin film, N-type amorphous silicon thin film, and P-type amorphous silicon thin film are prepared using a CVD deposition process. The transparent conductive film is prepared using a PVD deposition process. The metal electrodes are prepared using a screen printing process.

[0059] In the aforementioned heterojunction solar cells, there are various interfaces, including the interface between the N-type monocrystalline silicon substrate and the intrinsic amorphous silicon thin film, the interface between the intrinsic amorphous silicon thin film and the N-type amorphous silicon thin film, the interface between the intrinsic amorphous silicon thin film and the P-type amorphous silicon thin film, the interface between the N-type amorphous silicon thin film and the transparent conductive film, and the interface between the P-type amorphous silicon thin film and the transparent conductive film. Among these, the interface between the N-type monocrystalline silicon substrate and the intrinsic amorphous silicon thin film is as follows: Figure 3 As shown.

[0060] Step S200: Select heterojunction solar cells.

[0061] In some embodiments, the photoelectric conversion efficiency of all heterojunction solar cells provided in step S100 above is obtained, and heterojunction solar cells whose photoelectric conversion efficiency does not meet the following condition are removed: (Nmin+Nmax) / 2+a%, where a is 0.2 to 0.3; where Nmin is the minimum photoelectric conversion efficiency among all heterojunction solar cells, and Nmax is the maximum photoelectric conversion efficiency among all heterojunction solar cells.

[0062] Due to differences in silicon wafer sources, resistivity, batches, and manufacturing processes from different manufacturers, the photoelectric conversion efficiency of different heterojunction solar cells will vary. Testing the efficiency degradation performance of all heterojunction solar cells would be extremely labor-intensive. Therefore, this invention, through research on the efficiency range of heterojunction solar cells, found that although the efficiency of different heterojunction solar cells varies within a certain range (i.e., the range between the minimum and maximum efficiency), the overall efficiency of the cells is relatively high, with most heterojunction solar cells concentrated in the mid-to-high efficiency range.

[0063] This invention selects heterojunction solar cells by adding the minimum (Nmin) and maximum (Mmax) photoelectric conversion efficiency of the measured heterojunction solar cells, taking the average value, and adding a certain value. Heterojunction solar cells with photoelectric conversion efficiency within the above range are selected for subsequent efficiency degradation testing, while heterojunction solar cells with photoelectric conversion efficiency outside the above range are discarded and not subjected to subsequent efficiency degradation testing.

[0064] In this way, not only can the workload of efficiency degradation testing be effectively reduced, but the selection method also conforms to the actual law that the photoelectric conversion efficiency of most heterojunction solar cells is mainly concentrated in the medium to high range. The selected heterojunction solar cells can well represent the overall level of conversion efficiency of heterojunction solar cells, making the final photoelectric conversion efficiency degradation test results representative.

[0065] In a specific example, a batch of heterojunction solar cells has a minimum photoelectric conversion efficiency (Nmin) of 23.9% and a maximum photoelectric conversion efficiency (Mmax) of 25%. The efficiency range of this batch of heterojunction solar cells is 1.1%. Based on a 0.1% difference in photoelectric conversion efficiency as a range, this batch of heterojunction solar cells can be divided into 11 different efficiency levels. Selecting heterojunction solar cells at excessively low or high efficiency levels for efficiency degradation testing will not represent the overall efficiency level of this batch of heterojunction solar cells. In this specific example, selecting a heterojunction solar cell with a photoelectric conversion efficiency of (Nmin+Nmax) / 2+0.25% (its efficiency is 24.7%) for efficiency degradation testing can well represent the overall efficiency level of this batch of heterojunction solar cells.

[0066] In some embodiments, after screening heterojunction solar cells with a photoelectric conversion efficiency of (Nmin+Nmax) / 2+a%, the screened cells are further subjected to EL (Electroluminescent) testing and visual inspection. Cells with no abnormalities in appearance and EL (i.e., Grade A cells) are selected for efficiency degradation testing. In this way, more representative cells can be further screened for efficiency degradation testing.

[0067] Step S300: Annealing and light injection treatment of heterojunction solar cells.

[0068] Heterojunction solar cells have a multilayer stacked structure. Besides the density of the film layers themselves and the interfacial contact between them affecting the photoelectric conversion efficiency (PCE), numerous unsaturated dangling bonds also create a large number of defect states between the layers and adjacent layers. This makes recombination of effective charge carriers highly likely, leading to a decrease in PCE efficiency. Due to the presence of these defect states, external environmental factors such as moisture, dirt, and air currents (ozone, hydrogen sulfide, etc.) can also cause some degree of efficiency degradation. Therefore, dangling bonds and defects in heterojunction solar cells, as well as environmental factors like moisture and dirt, can interfere with efficiency degradation testing, making the test results inaccurate in reflecting the efficiency degradation caused by the density of the film layers and the interfacial contact between them.

[0069] This invention involves annealing the heterojunction solar cell before testing its photoelectric conversion efficiency degradation. This process exposes unstable defects at the interface between the amorphous silicon thin film and adjacent layers. Then, light injection is performed under illumination, which excites a large number of free hydrogen atoms within the cell layers to fill the defects exposed after annealing. This significantly improves the stability of the interfaces between the layers and reduces the impact of environmental air currents such as water vapor, dirt, ozone, and hydrogen sulfide on the cell's efficiency degradation.

[0070] Through the above-mentioned annealing and light injection processes, the results of the efficiency degradation test can well reflect the impact of the compactness of the film layers in the solar cell and the interfacial contact between the film layers on the efficiency degradation of the solar cell. This reflects the compactness of the film layers in the solar cell and the interfacial contact between the film layers, providing data support for the adjustment and optimization of the production process of heterojunction solar cells.

[0071] In some embodiments, the annealing process specifically involves heating the heterojunction solar cell at 70°C to 110°C for 10 to 15 minutes, and then annealing it at 40°C to 50°C for 15 to 20 minutes.

[0072] Heterojunction solar cells are low-temperature processed cells and are highly sensitive to temperature. Studies have found that placing heterojunction solar cells below 70°C for 12 hours shows no significant reaction; however, when placed between 70°C and 110°C, the interfacial microstructure between different film layers begins to change after 10 minutes. Loosening starts from the weakest bonding points, forming tiny, dense pores and gaps, which can be fully exposed within 15 minutes. These pores and gaps trap photogenerated carriers, reducing the cell's photoelectric conversion efficiency. Lowering the temperature to 40°C–50°C and holding it there for 15–20 minutes allows the film layers to reach a stable state, where the structure no longer changes. By employing the above-described annealing process, the defects in the heterojunction solar cell film layers can be fully exposed.

[0073] It is understood that the heating temperature in the annealing process can be, but is not limited to, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, and 110℃; the heating time can be, but is not limited to, 10min, 11min, 12min, 13min, 14min, and 15min; the annealing temperature can be, but is not limited to, 40℃, 42℃, 44℃, 46℃, 48℃, and 50℃; and the annealing time can be, but is not limited to, 15min, 16min, 17min, 18min, 19min, and 20min.

[0074] In some embodiments, the light injection process specifically involves irradiating the front and back sides of the annealed heterojunction solar cell with light at 80 to 90 standard light intensities for 60 to 120 seconds. By performing this light injection process on the front and back sides of the annealed heterojunction solar cell, a large number of free hydrogen atoms within the film layers on both sides can be excited, filling the defects exposed after annealing. This significantly improves the stability of the interface layer in the cell and reduces the impact of dangling bonds, defects, and environmental factors such as moisture and dirt on the cell's efficiency degradation.

[0075] It is understood that the illumination intensity of the light injection process can be, but is not limited to, 80, 82, 84, 86, 88, or 90 standard light intensities; and the light injection time can be, but is not limited to, 60s, 70s, 80s, 90s, 100s, 110s, or 120s.

[0076] Step S400: Perform EL testing and visual inspection on the heterojunction solar cells.

[0077] During the annealing and light injection processes of heterojunction solar cells, some defective cells may appear due to mechanical or manual contact with the cells. This invention performs EL testing and visual inspection on the heterojunction solar cells after annealing and light injection. Using the principle of electroluminescence, an EL camera is used to image and visually inspect the internal defects of the cells, thereby eliminating defective cells with fingerprints, scratches, airflow marks, microcracks, etc. This allows the efficiency degradation test results to more accurately reflect the film density and interfacial contact between the film layers in the cell.

[0078] Step S500: Perform a photoelectric conversion efficiency degradation test on the heterojunction solar cell.

[0079] In some embodiments, the specific steps of the photoelectric conversion efficiency degradation test include: obtaining the photoelectric conversion efficiency η1 of the heterojunction solar cell after light injection treatment; placing the heterojunction solar cell after light injection treatment in an environment below 0°C for cold degradation treatment; obtaining the photoelectric conversion efficiency η2 of the heterojunction solar cell after cold degradation treatment, and obtaining the difference in photoelectric conversion efficiency X1 between the heterojunction solar cell before and after cold degradation treatment, where X1 = η1 - η2.

[0080] Heterojunction solar cells are low-temperature cells, which are photosensitive but averse to high temperatures. Under normal circumstances, the photoelectric conversion efficiency of heterojunction solar cells does not decrease significantly in low-temperature environments below 0°C. If the cell exhibits significant efficiency degradation under low-temperature conditions, it indicates an abnormality in the interface matching between the cell's film layers. This invention performs a cold degradation treatment on heterojunction solar cells after light injection and conducts efficiency degradation tests. By comparing the efficiency difference before and after the cold degradation treatment, the interfacial contact condition between the cell's film layers can be reflected.

[0081] If there is a significant difference in photoelectric conversion efficiency between heterojunction solar cells before and after cold degradation treatment, it indicates poor interfacial contact between cell film layers. The production line needs to be investigated, and the process adjusted and optimized to improve interfacial contact and enhance product quality.

[0082] In some embodiments, the cold degradation treatment temperature is -10℃ to 0℃, and the cold degradation treatment time is 10h to 24h. That is, the heterojunction solar cell after light injection treatment is placed in an environment of -10℃ to 0℃ for 10h to 24h. Performing cold degradation treatment on the heterojunction solar cell under the above process conditions can better reflect the interfacial contact between the film layers of the cell.

[0083] It is understood that the temperature for cold decay treatment can be, but is not limited to, -10℃, -9℃, -8℃, -7℃, -6℃, -5℃, -4℃, -3℃, -2℃, -1℃, and 0℃; and the time for cold decay treatment can be, but is not limited to, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, and 24h.

[0084] In some embodiments, if the difference in photoelectric conversion efficiency X1 between the heterojunction solar cell before and after the cold degradation treatment is ≤0.03%, the heterojunction solar cell is considered to have passed the cold degradation test and the interfacial contact between the film layers of the heterojunction solar cell is good; otherwise, the heterojunction solar cell is considered to have failed the cold degradation test and the interfacial contact between the film layers of the cell is poor, and the production line needs to be checked and adjusted.

[0085] In some embodiments, when the difference in photoelectric conversion efficiency X1 before and after the cold attenuation treatment is ≤0.03% (i.e., the cold attenuation is qualified), the heterojunction solar cell after the cold attenuation treatment is subjected to thermal attenuation treatment under heating conditions; the photoelectric conversion efficiency η3 of the heterojunction solar cell after the thermal attenuation treatment is obtained, and the difference in photoelectric conversion efficiency X2 of the heterojunction solar cell before and after the thermal attenuation treatment is obtained, X2=η2-η3.

[0086] By subjecting heterojunction solar cells that have passed cold degradation treatment to further thermal degradation under heating conditions, the density of the film layers within the cell can be better revealed. If the film layers have density issues, free hydrogen within the film layers will separate during the thermal degradation process. This ionized hydrogen has high energy and can bombard the interfacial thin film and crystalline silicon structure, leading to a decrease in cell efficiency. Thermal degradation treatment can better reflect the density of the film layers within the solar cell.

[0087] In some embodiments, the temperature for thermal degradation treatment is 120°C to 135°C, and the treatment time is 15 min to 20 min. Under the above-mentioned temperature and time conditions for thermal degradation treatment, the density problem of the film layer itself in the solar cell can be more fully exposed, and the density of the film layer in the solar cell can be better reflected.

[0088] It is understood that the temperature for thermal decay treatment can be, but is not limited to, 120℃, 121℃, 122℃, 123℃, 124℃, 125℃, 126℃, 127℃, 128℃, 129℃, 130℃, 131℃, 132℃, 133℃, 134℃, and 135℃; and the time for thermal decay treatment can be, but is not limited to, 15min, 16min, 17min, 18min, 19min, and 20min.

[0089] In some embodiments, if the difference in photoelectric conversion efficiency X2 before and after the thermal degradation treatment of the heterojunction solar cell is ≤0.15%, the thermal degradation of the heterojunction solar cell is considered to be qualified, and the film layer in the heterojunction solar cell has good density; otherwise, the film layer in the heterojunction solar cell is considered to have poor density, and the production line needs to be investigated and adjusted.

[0090] In some embodiments, when the difference in photoelectric conversion efficiency X2 between the heterojunction solar cell before and after the thermal degradation treatment is ≤0.15% (i.e., the thermal degradation is qualified), the heterojunction solar cell after thermal degradation treatment is subjected to static degradation treatment in a protective atmosphere; the photoelectric conversion efficiency η4 of the heterojunction solar cell after static degradation treatment is obtained, and the difference in photoelectric conversion efficiency X3 between the heterojunction solar cell before and after static degradation treatment is obtained, where X3 = η3 - η4.

[0091] By subjecting heterojunction solar cells to static degradation treatment after they have passed the thermal degradation treatment, we can examine the stability of the cells under alternating hot and cold degradation or after thermal degradation, and further verify the compactness of the film layers in the cells.

[0092] In some embodiments, the temperature for static degradation treatment is 10°C to 30°C, and the treatment time is 36h to 72h. This allows the film density problem of heterojunction solar cells after alternating hot and cold degradation or thermal degradation to be fully exposed, and the stability of the cells after thermal degradation can be better examined.

[0093] It is understood that the temperature for static attenuation treatment can be, but is not limited to, 10℃, 12℃, 14℃, 16℃, 18℃, 20℃, 22℃, 24℃, 26℃, 28℃, and 30℃; and the time for static attenuation treatment can be, but is not limited to, 36h, 38h, 40h, 42h, 44h, 46h, 48h, 50h, 52h, 54h, 56h, 58h, 60h, 62h, 64h, 66h, 68h, 70h, and 72h.

[0094] In one specific example, nitrogen is used as the protective atmosphere.

[0095] In some embodiments, if the difference in photoelectric conversion efficiency X3 between the heterojunction solar cell before and after the static decay treatment is ≤0.05%, the heterojunction solar cell is considered to have passed the static decay test and the film layer in the heterojunction solar cell has good density; otherwise, the film layer in the heterojunction solar cell is considered to have poor density and the production line needs to be checked and adjusted.

[0096] It is understood that conventional equipment and methods in the art can be used to obtain the photoelectric conversion efficiency of heterojunction solar cells in this invention.

[0097] In some embodiments, after performing cold degradation treatment on the heterojunction solar cell, no thermal degradation treatment or static degradation treatment is performed on the cell. That is, only the heterojunction solar cell is subjected to cold degradation treatment and the difference in photoelectric conversion efficiency X1 before and after the cold degradation treatment is obtained, without performing thermal degradation treatment or static degradation treatment on the cell.

[0098] In some embodiments, the heterojunction solar cell is not subjected to cold degradation treatment; instead, a thermal degradation treatment is performed directly on the cell after light injection treatment. That is, only the heterojunction solar cell undergoes thermal degradation treatment, and the difference in photoelectric conversion efficiency (X2) before and after thermal degradation treatment is obtained; neither cold degradation treatment nor static degradation treatment is performed. In this case, the difference in photoelectric conversion efficiency (X2) before and after thermal degradation treatment is X2 = η1 - η3; where η1 is the photoelectric conversion efficiency of the heterojunction solar cell after light injection treatment, and η3 is the photoelectric conversion efficiency of the heterojunction solar cell after thermal degradation treatment.

[0099] In some embodiments, instead of performing cold degradation treatment on the heterojunction solar cells, the cells are directly subjected to thermal degradation treatment and tested after light injection treatment, followed by static degradation treatment and testing. That is, only the heterojunction solar cells are subjected to thermal degradation treatment and static degradation treatment, and the difference in photoelectric conversion efficiency X2 before and after thermal degradation treatment and the difference in photoelectric conversion efficiency X3 before and after static degradation treatment are obtained, without performing cold degradation treatment on the cells.

[0100] It is understood that in the photoelectric conversion efficiency degradation test step of the present invention, only cold degradation treatment can be performed on the battery cell, only hot degradation treatment can be performed on the battery cell, hot degradation treatment and static degradation treatment can be performed on the battery cell in sequence, or cold degradation treatment, hot degradation treatment and static degradation treatment can be performed on the battery cell in sequence.

[0101] It should be noted that when combining cold degradation, hot degradation, and static degradation treatments on solar cells, the tests must be conducted in the following order: cold degradation, hot degradation, and static degradation. This is because cold degradation generally causes less efficiency loss than hot degradation; performing hot degradation first and then cold degradation renders the cold degradation treatment meaningless. Static degradation primarily aims to assess the stability of the solar cells after alternating hot and cold degradation treatments and should be performed after hot degradation treatment.

[0102] Through the overall technical solution of this invention, heterojunction solar cells are first carefully selected, then annealed and light-injected sequentially, followed by EL testing and visual inspection. Then, cold decay, thermal decay, and static decay tests are performed sequentially, providing a more comprehensive and better reflection of the film density and interfacial contact between the film layers. This results in more accurate test results that can be directly used to guide process adjustments on the production line. If the tests are passed, the cells can be shipped directly. This overall technical solution effectively improves the CTM (Cell To Module, representing the percentage of module output power to the total cell power). Figure 4 As shown, its CTM (Customer Performance Time) can be increased from approximately 98.9% to approximately 99.7%, improving customer satisfaction. Through the above overall technical solution, reliable efficiency degradation data can also be provided to the production line, eliminating the need to repeatedly waste time waiting for verification results, significantly improving product circulation and delivery speed, and reducing product inventory and manpower turnover. Figure 5 As shown, this can increase the overall output per shift by approximately 500 pieces.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A performance testing method for a heterojunction solar cell, characterized in that, Includes the following steps: Provide heterojunction solar cells; The heterojunction solar cell is subjected to annealing and light injection treatments in sequence; and The photoelectric conversion efficiency degradation test was performed on the heterojunction solar cell after light injection treatment. The photoelectric conversion efficiency degradation test includes the following steps: obtaining the photoelectric conversion efficiency η1 of the heterojunction solar cell after light injection treatment; placing the heterojunction solar cell after light injection treatment in an environment below 0 ℃ for cold degradation treatment; obtaining the photoelectric conversion efficiency η2 of the heterojunction solar cell after cold degradation treatment, and obtaining the difference in photoelectric conversion efficiency X1 of the heterojunction solar cell before and after cold degradation treatment, where X1 = η1 - η2. Alternatively, the photoelectric conversion efficiency degradation test includes the following steps: obtaining the photoelectric conversion efficiency η1 of the heterojunction solar cell after light injection treatment; and subjecting the heterojunction solar cell after light injection treatment to thermal degradation treatment under heating conditions. The photoelectric conversion efficiency η3 of the heterojunction solar cell after thermal degradation treatment is obtained, and the difference in photoelectric conversion efficiency X2 of the heterojunction solar cell before and after thermal degradation treatment is obtained, where X2 = η1 - η3.

2. The performance testing method for heterojunction solar cells according to claim 1, characterized in that, The temperature of the cold attenuation treatment is -10 ℃ to 0 ℃, and the time of the cold attenuation treatment is 10 h to 24 h.

3. The performance testing method for heterojunction solar cells according to claim 1, characterized in that, The photoelectric conversion efficiency degradation test includes the following steps: When X1≤0.03%, the heterojunction solar cell after cold degradation treatment is subjected to thermal degradation treatment under heating conditions; as well as The photoelectric conversion efficiency η3 of the heterojunction solar cell after thermal degradation treatment is obtained, and the difference in photoelectric conversion efficiency X2 of the heterojunction solar cell before and after thermal degradation treatment is obtained, where X2 = η2 - η3.

4. The performance testing method for a heterojunction solar cell according to any one of claims 1 to 3, characterized in that, The temperature of the thermal decay treatment is 120 ℃~135 ℃, and the time of the thermal decay treatment is 15 min~20 min.

5. The performance testing method for a heterojunction solar cell according to any one of claims 1 to 3, characterized in that, The photoelectric conversion efficiency degradation test includes the following steps: When X2 ≤ 0.15%, the heterojunction solar cell after thermal degradation treatment is subjected to static degradation treatment in a protective atmosphere; and The photoelectric conversion efficiency η4 of the heterojunction solar cell after static attenuation treatment is obtained, and the difference in photoelectric conversion efficiency X3 of the heterojunction solar cell before and after static attenuation treatment is obtained, where X3 = η3 - η4.

6. The performance testing method for heterojunction solar cells according to claim 5, characterized in that, The temperature for the static attenuation treatment is 10 ℃ to 30 ℃, and the time for the static attenuation treatment is 36 h to 72 h.

7. The performance testing method for a heterojunction solar cell according to any one of claims 1 to 3 and 6, characterized in that, The annealing process includes the following steps: The heterojunction solar cell was heated at 70 ℃~110 ℃ for 10 min~15 min and annealed at 40 ℃~50 ℃ for 15 min~20 min.

8. The performance testing method for a heterojunction solar cell according to any one of claims 1 to 3 and 6, characterized in that, The optical injection process includes the following steps: The front and back sides of the annealed heterojunction solar cell were exposed to light at 80 to 90 standard light intensities for 60 to 120 seconds.

9. The performance testing method for a heterojunction solar cell according to any one of claims 1 to 3 and 6, characterized in that, The heterojunction solar cell consists of multiple cells, and the performance testing method prior to the annealing process further includes the following steps: Obtain the photoelectric conversion efficiency of all the heterojunction solar cells, and remove the heterojunction solar cells whose photoelectric conversion efficiency does not meet the following condition: (Nmin+Nmax) / 2+a%, where a is 0.2~0.3; Wherein, Nmin is the minimum photoelectric conversion efficiency among all the heterojunction solar cells, and Nmax is the maximum photoelectric conversion efficiency among all the heterojunction solar cells.

10. The performance testing method for a heterojunction solar cell according to any one of claims 1 to 3 and 6, characterized in that, The heterojunction solar cell is composed of multiple cells. After the light injection treatment and before the photoelectric conversion efficiency degradation test, the performance testing method further includes the following steps: The heterojunction solar cells are subjected to EL testing and visual inspection, and those heterojunction solar cells that fail the EL testing and visual inspection are removed.

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