Solar cell short-circuit current testing method

Abstract

The invention discloses a method for testing short-circuit current of a solar cell. The method comprises the following steps: acquiring a first corresponding relation between the photoluminescence intensity of a standard cell under standard illumination intensity and the electroluminescence intensity of the standard cell under open-circuit voltage; providing a battery piece to be tested; irradiating partial areas of the first surface of the to-be-measured battery piece through a plurality of light sources with different wavelengths, and measuring to obtain bright area luminous intensity of a light receiving area and dark area luminous intensity of a non-light receiving area under the irradiation of the light sources with different wavelengths; according to the first corresponding relation and the luminous intensity of each bright area, obtaining basic electroluminescence intensity corresponding to the luminous intensity of each bright area; obtaining the equivalent external quantum efficiency under the irradiation of each wavelength light source according to the basic electroluminescence intensity and the dark space luminescence intensity corresponding to each wavelength light source; constructing a wavelength-equivalent external quantum efficiency curve; carrying out integral calculation on the wavelength-equivalent external quantum efficiency curve to obtain short-circuit current density, and calculating the short-circuit current of the battery piece to be measured according to the area of the first surface.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell testing, and in particular to a method for testing short-circuit current of a solar cell. Background Art

[0002] The pursuit of higher conversion efficiency has long been a pursuit in the solar industry, and the short-circuit current of solar cells is a key indicator of conversion efficiency. In recent years, continuous innovation in product technology has placed higher demands on the accuracy of short-circuit current testing. The current testing method connects a probe to the cell and collects the current after exposure to light. This testing method poses the risk of probe damage to the cell, and test accuracy depends on the proper contact between the probe and the cell. This makes testing more difficult for some solar cells, such as those without a main grid, affecting test accuracy. Summary of the Invention

[0003] The object of the present invention is to provide a method for testing the short-circuit current of a solar cell, which avoids damage to the solar cell and improves the test accuracy when testing the short-circuit current of the solar cell.

[0004] In a first aspect, the present invention provides a method for testing a short-circuit current of a solar cell, comprising:

[0005] Obtaining a first corresponding relationship between the photoluminescence intensity of a standard cell under standard light intensity and the electroluminescence intensity under open circuit voltage;

[0006] Providing a battery cell to be tested, having a first surface and a second surface opposite to each other;

[0007] Irradiating partial areas of the first surface with a plurality of light sources of different wavelengths, respectively, so that the cell to be tested forms a light-receiving area and a non-light-receiving area, and measuring the luminous intensity of the bright area of ​​the light-receiving area and the luminous intensity of the dark area of ​​the non-light-receiving area under the irradiation of the light sources of each wavelength;

[0008] Obtaining a basic electroluminescent intensity corresponding to the luminous intensity of each bright area according to the first corresponding relationship and the luminous intensity of each bright area;

[0009] Obtaining the equivalent external quantum efficiency of the cell to be tested under the illumination of the light source of each wavelength according to the basic electroluminescence intensity and the dark area luminescence intensity corresponding to the light source of each wavelength;

[0010] Constructing a wavelength-equivalent external quantum efficiency curve according to the wavelengths of a plurality of light sources with different wavelengths and the corresponding equivalent external quantum efficiencies;

[0011] Integrating the wavelength-equivalent external quantum efficiency curve to calculate the short-circuit current density;

[0012] The short-circuit current of the battery cell to be tested is calculated according to the short-circuit current density and the area of ​​the first surface.

[0013] When adopting the above technical solution, the solar cell short-circuit current testing method uses multiple light sources of different wavelengths to illuminate partial areas of the first surface of the test cell, and measures the luminous intensity of the bright area of ​​the illuminated area and the luminous intensity of the dark area of ​​the unilluminated area under the illumination of each wavelength light source; then, based on the first correspondence between the photoluminescence intensity of the standard cell under standard light intensity and the electroluminescence intensity under open-circuit voltage and the luminous intensity of each bright area, the basic electroluminescence intensity corresponding to the luminous intensity of each bright area is obtained; then, based on the basic electroluminescence intensity and the dark area luminous intensity corresponding to each wavelength light source, the equivalent external quantum efficiency of the test cell under the illumination of each wavelength light source is obtained and a wavelength-equivalent external quantum efficiency curve is constructed; the wavelength-equivalent external quantum efficiency curve is integrated to calculate the short-circuit current density; and the short-circuit current of the test cell is calculated based on the short-circuit current density and the area of ​​the first surface of the test cell. The entire short-circuit current test process does not require contact measurement of the cell. This means that no probes need to touch the cell electrodes, thus avoiding damage to the cell. Test accuracy is independent of probe-cell contact. This is especially true for some solar cells, such as those without a busbar, because no probe contact is required. Therefore, the test is unaffected by the absence of a busbar, ensuring test accuracy. Furthermore, this test method is fast and can be applied to full inspections on mass production lines.

[0014] In some possible implementations, obtaining a first correspondence between the photoluminescence intensity of a standard cell under standard light intensity and the electroluminescence intensity under open-circuit voltage includes:

[0015] Providing multiple standard battery cells with different open circuit voltages;

[0016] Illuminating a plurality of the standard cells under the standard light intensity, and measuring the photoluminescence intensity of each of the standard cells;

[0017] At the open circuit voltage corresponding to each of the standard cells, measuring the electroluminescence intensity of each of the standard cells;

[0018] A first corresponding relationship between the photoluminescence intensity and the electroluminescence intensity of the standard cell is established.

[0019] In some possible implementations, obtaining the equivalent external quantum efficiency of the cell under test under illumination of each wavelength light source according to the basic electroluminescence intensity and the dark area luminescence intensity corresponding to each wavelength light source includes:

[0020] According to the basic electroluminescence intensity and the dark area luminescence intensity corresponding to the light source of each wavelength, the equivalent external quantum efficiency of the cell to be tested under the irradiation of the light source of each wavelength is obtained by formula 1 and formula 2;

[0021] The formula 1 is: EQE eq =EL x / EL base ;

[0022] The formula 2 is: PL 暗 =EL x ;

[0023] Wherein, the EQE eq Represents the equivalent external quantum efficiency, the EL x represents the electroluminescence intensity at wavelength x, the EL base Indicates the basic electroluminescence intensity, the PL 暗 Indicates the luminous intensity of dark areas.

[0024] In some possible implementations, integrating the wavelength-equivalent external quantum efficiency curve to calculate the short-circuit current density includes:

[0025] The short-circuit current density is calculated by integrating the wavelength-equivalent external quantum efficiency curve using formula 3;

[0026] The formula three is:

[0027] Where Jsc is the short-circuit current density, q is the electron charge, EQE(λ) is the wavelength-equivalent external quantum efficiency curve, λ is the wavelength, λ1 is the minimum wavelength of the light source, λ2 is the maximum wavelength of the light source, and J ideal It indicates the ideal short-circuit current density under the condition of AM1.5G solar spectrum.

[0028] In some possible implementations, irradiating partial areas of the first surface with a plurality of light sources of different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area includes:

[0029] shielding the first surface by a mask, so that the area of ​​the first surface shielded by the mask becomes the non-light-exposed area, and the area of ​​the first surface not shielded by the mask forms the light-exposed area;

[0030] The first surface is illuminated respectively by a plurality of light sources with different wavelengths, so that the light-receiving area is illuminated and the non-light-receiving area is not illuminated.

[0031] In some possible implementations, the mask includes strip-shaped hollow areas and strip-shaped blocking areas that are alternately arranged.

[0032] In some possible implementations, irradiating partial areas of the first surface with a plurality of light sources of different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area includes:

[0033] The first surface is irradiated by a plurality of light sources with different wavelengths in a linear laser scanning manner, so that the area on the first surface scanned by the linear laser forms the light-receiving area, and the area not scanned by the linear laser forms the non-light-receiving area.

[0034] In some possible implementations, irradiating partial areas of the first surface with a plurality of light sources of different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area includes:

[0035] Irradiating partial areas of the first surface using multiple light sources of different wavelengths, and each light source of different wavelengths irradiates different areas of the first surface at least twice, so that the cell to be tested forms the light-receiving area and the non-light-receiving area, wherein the different areas on the first surface irradiated at least twice are pieced together to form a complete first surface;

[0036] After the short-circuit current of the cell to be tested is calculated based on the short-circuit current density and the area of ​​the first surface, the solar cell short-circuit current testing method further includes:

[0037] An average value is calculated for each of the short-circuit currents corresponding to the at least two irradiations on different areas of the first surface.

[0038] In some possible implementations, the number of irradiations is two, and different regions of the two irradiations are complementary, and the area ratio of the different regions of the two irradiations is 0.8-1.2.

[0039] In some possible implementations, the wavelength range of the light source is 300 nm to 1200 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 A schematic flow chart of a method for testing short-circuit current of a solar cell provided by an embodiment of the present invention;

[0042] Figure 2 A schematic diagram of a wavelength-equivalent external quantum efficiency curve provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined. "Several" means one or more, unless otherwise specifically defined.

[0046] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0047] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and may encompass internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0048] The current short-circuit current test method involves connecting a probe to the cell and collecting the current after exposure to light. This method poses a risk of damage to the cell due to the probe, and test accuracy depends on the proper contact between the probe and the cell. This makes testing difficult for some solar cells, such as those without a main grid, and affects test accuracy. Furthermore, contact-based testing is slow, making it unsuitable for mass production lines.

[0049] In view of this, if Figure 1As shown, an embodiment of the present invention provides a method for testing short-circuit current of a solar cell, comprising the following steps:

[0050] Step S100: Obtain a first correspondence between the photoluminescence intensity of a standard cell under standard illumination intensity and the electroluminescence intensity at an open circuit voltage. The first correspondence represents the correspondence between the photoluminescence intensity of a plurality of standard cells under standard illumination intensity and the electroluminescence intensity at an open circuit voltage. The first correspondence is a proportional relationship of a linear function.

[0051] It should be noted that the standard light intensity is the light intensity under the STC standard test conditions. The standard light intensity is 1sun, that is, the irradiance is less than 1000W / m 2 A standard cell refers to a cell used to obtain the first correspondence between the photoluminescence intensity under standard light intensity and the electroluminescence intensity under open-circuit voltage. It is not a cell used to test short-circuit current. The external quantum efficiency (EQE) of a standard cell under illumination with a light source of a specific wavelength (550-650nm for positive-junction cells and 800-900nm for back-junction cells) is EQE≈1. The external quantum efficiency indicates the ability of a solar cell to convert photons incident on its surface into photogenerated carriers.

[0052] When a standard cell is exposed to light, electrons in the cell's ground state enter an excited state after absorbing photons. Excited electrons are metastable and return to the ground state within a short period of time, emitting light of a specific wavelength. This phenomenon is known as photoluminescence. The intensity of the light emitted by the cell after exposure to light is measured using a photoluminescence intensity meter to obtain the photoluminescence intensity. When an external voltage equal to the open-circuit voltage of the standard cell is applied to the cell, the electrons excited by the electric field in the cell collide with the luminescence center, causing electron dissociation transitions, changes, and recombination, resulting in luminescence. This phenomenon is known as electroluminescence, and the intensity of the emitted light is the electroluminescence intensity.

[0053] In step S200, a battery cell to be tested is provided, which has a first surface and a second surface opposite to each other. The battery cell to be tested is any battery cell.

[0054] In step S300, a plurality of light sources of different wavelengths are used to illuminate partial areas of the first surface of the cell to be tested, so that both the light-receiving area and the non-light-receiving area are formed, and the luminous intensity of the bright area of ​​the light-receiving area and the luminous intensity of the dark area of ​​the non-light-receiving area are measured under the illumination of the light source of each wavelength. That is, each light source of each wavelength illuminates the same partial area of ​​the first surface of the cell to be tested, so that the same partial area of ​​the first surface illuminated by the light forms the light-receiving area, and the area on the first surface not illuminated by the light forms the non-light-receiving area. Both the light-receiving area and the non-light-receiving area can emit light. The non-light-receiving area emits light because the light-receiving area generates a photocurrent that flows to the non-light-receiving area after being illuminated. There is a potential difference between the light-receiving area and the non-light-receiving area. The potential difference acts on the non-light-receiving area, causing the non-light-receiving area to electroluminesce. The luminous intensity of the non-light-receiving area is the electroluminescence intensity. The luminous intensity of the bright area of ​​the light-receiving area and the luminous intensity of the dark area of ​​the non-light-receiving area under the illumination of the light source of the wavelength are measured. The luminous intensity of the bright area PL 亮 Greater than the dark area luminous intensity PL 暗 ; By irradiating with multiple light sources of different wavelengths, the luminous intensity of the bright area and the luminous intensity of the dark area corresponding to the light sources of different wavelengths can be measured.

[0055] In step S400, based on the first correspondence obtained in step S100 and the luminous intensity of each bright area measured in step S300, the electroluminescent intensities corresponding to the luminous intensity of each bright area are obtained as basic electroluminescent intensities. Specifically, if the first correspondence between the photoluminescent intensities and the electroluminescent intensities is known, a corresponding electroluminescent intensity can be obtained based on a known luminous intensity of a bright area using the first correspondence.

[0056] Step S500: Calculate the equivalent external quantum efficiency of the cell under test at each wavelength based on the base electroluminescence intensity and dark-area luminescence intensity corresponding to each wavelength. The dark-area luminescence intensity is the electroluminescence intensity in the dark area. This means that the base electroluminescence intensity and dark-area luminescence intensity under each wavelength can each yield an equivalent external quantum efficiency.

[0057] Step S600: construct a wavelength-equivalent external quantum efficiency curve based on the wavelengths of multiple light sources with different wavelengths and their corresponding equivalent external quantum efficiencies, such as Figure 2 As shown, the horizontal axis is the wavelength of the light source, and the vertical axis is the equivalent external quantum efficiency. The equivalent external quantum efficiencies corresponding to the wavelengths obtained by multiple light sources with different wavelengths are used to draw a wavelength-equivalent external quantum efficiency curve.

[0058] Step S700, integrating the wavelength-equivalent external quantum efficiency curve to obtain the short-circuit current density;

[0059] Step S800, the short-circuit current of the cell to be tested is calculated based on the short-circuit current density in step S700 and the area of ​​the first surface of the cell to be tested. sc =J sc *A, where, I sc Indicates short-circuit current, J sc It represents the short-circuit current density, and A represents the area of ​​the battery cell to be tested.

[0060] When adopting the above technical solution, the solar cell short-circuit current testing method uses multiple light sources of different wavelengths to illuminate partial areas of the first surface of the test cell, and measures the luminous intensity of the bright area of ​​the illuminated area and the luminous intensity of the dark area of ​​the unilluminated area under the illumination of each wavelength light source; then, based on the first correspondence between the photoluminescence intensity of the standard cell under standard light intensity and the electroluminescence intensity under open-circuit voltage and the luminous intensity of each bright area, the basic electroluminescence intensity corresponding to the luminous intensity of each bright area is obtained; then, based on the basic electroluminescence intensity and the dark area luminous intensity corresponding to each wavelength light source, the equivalent external quantum efficiency of the test cell under the illumination of each wavelength light source is obtained and a wavelength-equivalent external quantum efficiency curve is constructed; the wavelength-equivalent external quantum efficiency curve is integrated to calculate the short-circuit current density; and the short-circuit current of the test cell is calculated based on the short-circuit current density and the area of ​​the first surface of the test cell. The entire short-circuit current test process does not require contact measurement of the cell. This means that no probes need to touch the cell electrodes, thus avoiding damage to the cell. Test accuracy is independent of probe-cell contact. This is especially true for some solar cells, such as those without a busbar, because no probe contact is required. Therefore, the test is unaffected by the absence of a busbar, ensuring test accuracy. Furthermore, this test method is fast and can be applied to full inspections on mass production lines.

[0061] In some embodiments, obtaining a first correspondence between the photoluminescence intensity of a standard cell under standard light intensity and the electroluminescence intensity under open circuit voltage in step S100 specifically includes the following steps:

[0062] Step S101 : providing a plurality of standard cells with different open circuit voltages, and ensuring that the EQE of each standard cell is ≈ 1 at a specific wavelength.

[0063] Step S102: Illuminate multiple standard cells under standard light intensity and measure the photoluminescence intensity of each standard cell. That is, each standard cell emits light under standard light intensity, and the photoluminescence intensity of the standard cell is measured. In this way, multiple photoluminescence intensities corresponding to multiple different standard cells are obtained.

[0064] Step S103 measures the electroluminescence intensity of each standard cell at the open circuit voltage corresponding to each standard cell. The electroluminescence intensity can be measured using a contact method. That is, a voltage equal to the open circuit voltage of each standard cell is applied to the cell, and the electroluminescence intensity at the open circuit voltage is measured. In this way, multiple electroluminescence intensities corresponding to multiple standard cells are obtained. Since different standard cells have different open circuit voltages, electroluminescence intensities corresponding to different open circuit voltages can be obtained.

[0065] Step S104: Establishing a first correspondence between the photoluminescence intensity and the electroluminescence intensity of the standard cell. Since each standard cell is measured to obtain a photoluminescence intensity and an electroluminescence intensity, the first correspondence between the photoluminescence intensity and the electroluminescence intensity of the standard cell is established based on the multiple photoluminescence intensities corresponding to the multiple standard cells measured in step S102 and the multiple electroluminescence intensities corresponding to the multiple standard cells measured in step S103.

[0066] The first correspondence relationship obtained by the above method is applicable to the relationship between the photoluminescence intensity and electroluminescence intensity of the subsequent battery cells to be tested. As a benchmark relationship for the battery cells, it is only necessary to measure a certain number of standard battery cells in advance. After obtaining the first correspondence relationship, it can always be used as the benchmark relationship for subsequent tests of the battery cells to be tested. There is no need to re-test the standard battery cells and establish the first correspondence relationship before each test of the battery cells to be tested.

[0067] It should be noted that the order of step S102 and step S103 is not limited. The photoluminescence intensity of the standard cell can be measured first, and then the electroluminescence intensity of the standard cell can be measured. The electroluminescence intensity of the standard cell can also be measured first, and then the photoluminescence intensity of the standard cell can be measured. The photoluminescence intensity and electroluminescence intensity of different standard cells can also be measured at the same time.

[0068] In some embodiments, step S300 of irradiating partial areas of the first surface with a plurality of light sources of different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area specifically includes the following steps:

[0069] Step S301 , shielding the first surface of the cell to be tested by a mask, so that the area of ​​the first surface shielded by the mask becomes a non-light-receiving area, and the area of ​​the first surface not shielded by the mask becomes a light-receiving area.

[0070] The mask has a hollow pattern. To facilitate conversion and calculation, the hollow pattern is a strip-shaped hollow area arranged at intervals. There is a strip-shaped shielding area between adjacent strip-shaped hollow areas. When the cell to be tested is shielded, a light-receiving area is formed at the strip-shaped hollow area, and a non-light-receiving area is formed at the strip-shaped shielding area. The length direction of the strip-shaped hollow area can be perpendicular to the length direction of the fine grid on the cell to be tested, and there is no need to consider the angle of the strip-shaped hollow area relative to the fine grid, which facilitates calculation. If the angle of the strip-shaped hollow area relative to the fine grid needs to be considered, the photoluminescence intensity component perpendicular to the length direction of the fine grid needs to be calculated, and the calculation process is more complicated. In addition, the strip-shaped hollow area and the strip-shaped shielding area are alternately arranged along the length direction of the fine grid, which improves the uniformity of light received by the cell under the strip-shaped hollow area and the strip-shaped shielding area, and the obtained measurement results are more accurate.

[0071] In addition, the mask can directly block the first side of the cell to be tested. Since the mask is close to the cell to be tested, the accuracy of the blocking pattern is easy to control, and it can be used with various light sources, such as parallel light and scattered light, and it is not easy for the light outside the hollow pattern of the mask to illuminate the cell to be tested. Alternatively, the light source can be directly blocked by the mask to adjust the range of the light emitted by the light source, so that the light from the light source passes through the hollow pattern of the mask and illuminates a portion of the cell to be tested. The light source is preferably a planar array laser light source, and the light emitted is parallel light. This method can be referred to as the grating method.

[0072] Step S302 , irradiating the first surface with a plurality of light sources of different wavelengths respectively, so that the light-receiving areas receive light and the non-light-receiving areas do not receive light.

[0073] The mask can be reused for different cells under test, with the masked position remaining fixed each time, ensuring consistency in short-circuit current testing. Of course, if different areas of the same cell under test need to be masked, the position of the mask can be moved, or a mask with a different cutout pattern can be used.

[0074] In some other embodiments, another method of irradiating partial areas of the first surface by using multiple light sources of different wavelengths in step S300 so that the cell to be tested forms a light-receiving area and a non-light-receiving area specifically includes the following steps:

[0075] In step S310, multiple light sources of different wavelengths are used to illuminate the first surface using line laser scanning. The areas on the first surface scanned by the line lasers become the light-receiving areas, while the areas not scanned by the line lasers become the non-light-receiving areas. This is achieved by directly adjusting the light emission range of the light source to adjust the illumination area on the cell under test.

[0076] This method can eliminate the need for mask shielding, reduce the risk of mask contact with the battery cell to be tested, further protect the battery cell from damage, and is more convenient to operate.

[0077] In some embodiments, step S300 of irradiating partial areas of the first surface with a plurality of light sources of different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area may further specifically include the following steps:

[0078] In step S320, a plurality of light sources of different wavelengths are used to illuminate partial areas of the first surface, and each light source of different wavelengths illuminates a different area of ​​the first surface at least twice, so that the cell to be tested forms a light-receiving area and a non-light-receiving area, wherein the different areas on the first surface illuminated at least twice are pieced together to form a complete first surface.

[0079] That is, each wavelength light source illuminates the cell under test at least twice. For example, each wavelength light source illuminates two different areas on the first surface twice, and the two different areas are combined to form a complete first surface. The first illumination forms a first light-receiving area and a first non-light-receiving area on the first surface, and the second illumination forms a second light-receiving area and a second non-light-receiving area on the first surface. The first light-receiving area and the second light-receiving area are different and complementary. Furthermore, each wavelength light source illuminates the same area during the first illumination, forming a first light-receiving area. The first bright area luminous intensity of the first light-receiving area and the first dark area luminous intensity of the first non-light-receiving area corresponding to each wavelength light source are measured. Subsequently, steps S400, S500, S600, S700, and S800 are performed to obtain the first short-circuit current of the cell under test after the first illumination by multiple different wavelength light sources. Similarly, each wavelength light source irradiates the same area during the second irradiation to form a second light-receiving area, and the second bright area luminous intensity of the second light-receiving area corresponding to each wavelength light source and the second dark area luminous intensity of the second non-light-receiving area are measured. Thereafter, steps S400, S500, S600, S700 and S800 are continued to obtain the second short-circuit current of the battery cell to be tested after the second irradiation by multiple light sources of different wavelengths.

[0080] Of course, each wavelength light source can be used to illuminate the cell under test three, four, or more times. Each illumination step targets a different area on the first side of the cell, forming a different light-receiving area. These light-receiving areas are then combined to form a complete first side. Finally, after each step, multiple short-circuit currents, such as a first short-circuit current, a second short-circuit current, a third short-circuit current, and a fourth short-circuit current, are obtained.

[0081] In this embodiment, based on the above step S320, after calculating the short-circuit current of the cell to be tested according to the short-circuit current density and the area of ​​the first surface in step S800, the solar cell short-circuit current testing method further includes:

[0082] In step S900, the short-circuit currents corresponding to the different areas of the first surface irradiated at least twice are averaged. That is, the first short-circuit current, the second short-circuit current, the third short-circuit current, the fourth short-circuit current and other multiple short-circuit currents obtained above are averaged to obtain the short-circuit current of the solar cell. Since the short-circuit current obtained each time is not the short-circuit current obtained by irradiating the entire cell, the short-circuit current of the complete cell can be obtained by averaging the multiple short-circuit currents obtained after multiple irradiations, thereby improving the test accuracy. The averaging method can adopt weighted averaging, and the multiple short-circuit currents are weighted averaged according to the ratio of the area irradiated on the first surface each time to the area of ​​the entire first surface, so as to further improve the accuracy of the short-circuit current results.

[0083] In some embodiments, each wavelength light source is illuminated twice, and the two illuminations complement each other, with the area ratio of the two illuminations ranging from 0.8 to 1.2. Specifically, the area ratio can be 0.8, 0.9, 1.0, 1.1, 1.2, etc. That is, the size of the two illumination areas is not much different, ensuring the balance of the two different light-receiving areas of the cell under test. Furthermore, if the proportion of one of the light-receiving areas is too small, the impact of the minority carrier lifetime on the PL test value will increase, thereby reducing the accuracy of the short-circuit current test. Therefore, by reducing the size difference between the two illumination areas, the accuracy of the short-circuit current test results can be improved.

[0084] In some embodiments, step S500 of obtaining the equivalent external quantum efficiency of the cell under test under illumination of each wavelength light source according to the basic electroluminescence intensity and dark area luminescence intensity corresponding to each wavelength light source specifically includes the following steps:

[0085] Step S501, according to the basic electroluminescence intensity and dark area luminescence intensity corresponding to the light source of each wavelength, the equivalent external quantum efficiency of the cell to be tested under the illumination of the light source of each wavelength is obtained by formula 1 and formula 2;

[0086] Formula 1 is: EQE eq =EL x / EL base ;

[0087] Formula 2 is: PL 暗 =EL x ;

[0088] Among them, EQE eq Represents the equivalent external quantum efficiency, EL xIndicates the electroluminescence intensity at wavelength x, EL base Indicates the basic electroluminescence intensity, PL 暗 Indicates the luminous intensity of dark areas.

[0089] Since the light emitted from the unilluminated area is electroluminescent due to the potential difference formed by the photocurrent generated by the light in the illuminated area, the dark area luminescence intensity measured in step S300 is the electroluminescence intensity at wavelength x. After substituting the basic electroluminescence intensity obtained in step S400 and the dark area luminescence intensity measured in step S300 into formulas 1 and 2, the equivalent external quantum efficiency is calculated by calculating the ratio of the electroluminescence intensity at wavelength x to the basic electroluminescence intensity. Each wavelength of light irradiating the cell under test can produce a corresponding equivalent external quantum efficiency.

[0090] It can be seen that the acquisition of the equivalent external quantum efficiency does not require a special external quantum efficiency meter for testing. It only needs to measure the photoluminescence intensity and calculate the equivalent external quantum efficiency through formula conversion. The test is convenient and fast, and is suitable for full-line testing of battery cells. There is no need for contact measurement of the battery cells to be tested, which protects the battery cells from damage and will not affect the test accuracy due to test tools such as probes.

[0091] In some embodiments, step S600 constructs a wavelength-equivalent external quantum efficiency curve based on the wavelengths of multiple light sources with different wavelengths and their corresponding equivalent external quantum efficiencies, which can be specifically performed as follows:

[0092] When light sources of different wavelengths illuminate the cell to be tested, the greater the number of light sources of different wavelengths, the more data on the equivalent external quantum efficiency corresponding to each wavelength light source is obtained, and the more accurate the wavelength-equivalent external quantum efficiency curve drawn is.

[0093] For example, taking three wavelength light sources for irradiation, the wavelength X1 of the first wavelength light source is 350nm to 450nm, the wavelength X2 of the second wavelength light source is 800nm ​​to 900nm, and the wavelength X3 of the third wavelength light source is 950nm to 1050nm. Finally, three corresponding equivalent external quantum efficiencies are obtained. Based on these three data, the equivalent external quantum efficiencies corresponding to multiple other wavelengths on the curve are derived. On the wavelength horizontal axis, a wavelength horizontal axis is obtained at each wavelength interval before and after wavelength X1, wavelength X2, and wavelength X3 to complete the corresponding data on the curve. The wavelength interval does not exceed 20nm, and the wavelength interval can be 20nm, 15nm, 10nm, 5nm, etc.

[0094] For the equivalent external quantum efficiency at a wavelength of 450nm to 950nm, the value corresponding to the wavelength X2 can be derived; for the equivalent external quantum efficiency at a wavelength of 1200nm, the value can be derived to be 0; for the equivalent external quantum efficiency at wavelengths of 950nm to X3 and X3 to 1200nm, the corresponding equivalent external quantum efficiency can be obtained by interpolation; for the equivalent external quantum efficiency at a wavelength of 300nm to 450nm, it can be deduced by interpolating the equivalent external quantum efficiency obtained at wavelengths of X1 to 450nm. Finally, the equivalent external quantum efficiency of each wavelength in the range of 300nm to 1200nm is obtained, and a complete wavelength-equivalent external quantum efficiency curve is drawn based on these data.

[0095] The wavelength-equivalent external quantum efficiency curve obtained by this method has high accuracy, such as Figure 2 As shown, the dotted curve is the wavelength-equivalent external quantum efficiency curve obtained by the method of this application. The solid line curve is the wavelength-equivalent external quantum efficiency curve obtained by the existing contact measurement method. Figure 2 It can be seen that the wavelength-equivalent external quantum efficiency curve obtained by the method of the present application is basically consistent with the wavelength-equivalent external quantum efficiency curve obtained by the existing contact measurement method, indicating that the test accuracy of this method is met.

[0096] In some embodiments, the wavelength range of the light source is 300nm to 1200nm. Generally, the wavelength range of light that a solar cell can receive and generate photogenerated carriers is 300nm to 1200nm. Therefore, light sources outside this wavelength range may not be within the test range.

[0097] In some embodiments, integrating the wavelength-equivalent external quantum efficiency curve to calculate the short-circuit current density in step S700 specifically includes the following steps:

[0098] Step S701, integrating the wavelength-equivalent external quantum efficiency curve by formula 3 to obtain the short-circuit current density;

[0099] Formula 3 is:

[0100] Where Jsc is the short-circuit current density, q is the electron charge, EQE(λ) is the wavelength-equivalent external quantum efficiency curve, λ is the wavelength, λ1 is the minimum wavelength of the light source, λ2 is the maximum wavelength of the light source, and J ideal It represents the ideal short-circuit current density under the condition of AM1.5G solar spectrum, which is a fixed value.

[0101] The integral calculation of the wavelength-equivalent external quantum efficiency curve can be obtained by manual calculation or by computer program.

[0102] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0103] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for testing short-circuit current of a solar cell, characterized in that: include: Obtaining a first corresponding relationship between the photoluminescence intensity of a standard cell under standard light intensity and the electroluminescence intensity under open circuit voltage; Providing a battery cell to be tested, having a first surface and a second surface opposite to each other; Irradiating partial areas of the first surface with a plurality of light sources of different wavelengths, respectively, so that the cell to be tested forms a light-receiving area and a non-light-receiving area, and measuring the luminous intensity of the bright area of ​​the light-receiving area and the luminous intensity of the dark area of ​​the non-light-receiving area under the irradiation of the light sources of each wavelength; Obtaining a basic electroluminescent intensity corresponding to the luminous intensity of each bright area according to the first corresponding relationship and the luminous intensity of each bright area; Obtaining the equivalent external quantum efficiency of the cell to be tested under the illumination of the light source of each wavelength according to the basic electroluminescence intensity and the dark area luminescence intensity corresponding to the light source of each wavelength; Constructing a wavelength-equivalent external quantum efficiency curve according to the wavelengths of a plurality of light sources with different wavelengths and the corresponding equivalent external quantum efficiencies; Integrating the wavelength-equivalent external quantum efficiency curve to calculate the short-circuit current density; The short-circuit current of the battery cell to be tested is calculated according to the short-circuit current density and the area of ​​the first surface.

2. The solar cell short-circuit current testing method according to claim 1, characterized in that: The step of obtaining a first correspondence between the photoluminescence intensity of a standard cell under standard light intensity and the electroluminescence intensity under open circuit voltage includes: Providing multiple standard battery cells with different open circuit voltages; Illuminating a plurality of the standard cells under the standard light intensity, and measuring the photoluminescence intensity of each of the standard cells; At the open circuit voltage corresponding to each of the standard cells, measuring the electroluminescence intensity of each of the standard cells; A first corresponding relationship between the photoluminescence intensity and the electroluminescence intensity of the standard cell is established.

3. The solar cell short-circuit current testing method according to claim 1, characterized in that: The step of obtaining the equivalent external quantum efficiency of the cell to be tested under the illumination of the light source of each wavelength according to the basic electroluminescence intensity and the dark area luminescence intensity corresponding to the light source of each wavelength includes: According to the basic electroluminescence intensity and the dark area luminescence intensity corresponding to the light source of each wavelength, the equivalent external quantum efficiency of the cell to be tested under the irradiation of the light source of each wavelength is obtained by formula 1 and formula 2; The formula 1 is: EQE eq =EL x / EL base ; The formula 2 is: PL 暗 =EL x ; Wherein, the EQE eq Represents the equivalent external quantum efficiency, the EL x represents the electroluminescence intensity at wavelength x, the EL base Indicates the basic electroluminescence intensity, the PL 暗 Indicates the luminous intensity of dark areas.

4. The solar cell short-circuit current testing method according to claim 1, characterized in that: The step of integrating the wavelength-equivalent external quantum efficiency curve to obtain the short-circuit current density includes: The short-circuit current density is calculated by integrating the wavelength-equivalent external quantum efficiency curve using formula 3; The formula three is: Where Jsc is the short-circuit current density, q is the electron charge, EQE(λ) is the wavelength-equivalent external quantum efficiency curve, λ is the wavelength, λ1 is the minimum wavelength of the light source, λ2 is the maximum wavelength of the light source, and J ideal It indicates the ideal short-circuit current density under the condition of AM1.5G solar spectrum.

5. The solar cell short-circuit current testing method according to claim 1, characterized in that: The method of irradiating partial areas of the first surface by using a plurality of light sources with different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area includes: shielding the first surface by a mask, so that the area of ​​the first surface shielded by the mask becomes the non-light-exposed area, and the area of ​​the first surface not shielded by the mask forms the light-exposed area; The first surface is illuminated respectively by a plurality of light sources with different wavelengths, so that the light-receiving area is illuminated and the non-light-receiving area is not illuminated.

6. The solar cell short-circuit current testing method according to claim 5, characterized in that: The mask plate includes strip-shaped hollow areas and strip-shaped blocking areas that are alternately arranged.

7. The solar cell short-circuit current testing method according to claim 1, characterized in that: The method of irradiating partial areas of the first surface by using a plurality of light sources with different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area includes: The first surface is irradiated by a plurality of light sources with different wavelengths in a linear laser scanning manner, so that the area on the first surface scanned by the linear laser forms the light-receiving area, and the area not scanned by the linear laser forms the non-light-receiving area.

8. The solar cell short-circuit current testing method according to claim 1, characterized in that: The method of irradiating partial areas of the first surface by using a plurality of light sources with different wavelengths so that the cell to be tested forms a light-receiving area and a non-light-receiving area includes: Irradiating partial areas of the first surface using multiple light sources of different wavelengths, and each light source of different wavelengths irradiates different areas of the first surface at least twice, so that the cell to be tested forms the light-receiving area and the non-light-receiving area, wherein the different areas on the first surface irradiated at least twice are pieced together to form a complete first surface; After the short-circuit current of the cell to be tested is calculated based on the short-circuit current density and the area of ​​the first surface, the solar cell short-circuit current testing method further includes: An average value is calculated for each of the short-circuit currents corresponding to the at least two irradiations on different areas of the first surface.

9. The solar cell short-circuit current testing method according to claim 8, characterized in that: The irradiation is performed twice, and the different regions of the two irradiations are complementary, and the area ratio of the different regions of the two irradiations is 0.8-1.

2.

10. The solar cell short-circuit current testing method according to claim 1, characterized in that: The wavelength range of the light source is 300nm to 1200nm.

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