Testing method, testing device and storage medium for metal contact composite value

Abstract

The present disclosure relates to a method, a testing device, and a storage medium for testing metal contact composite values. The method comprises: providing a solar cell to be tested having a double-sided symmetrical structure, wherein a non-metallic contact area and multiple metal contact areas are formed on a test surface of the solar cell to be tested, and the coverage area ratio of the grid lines in each metal contact area is different; testing to obtain parameter information of the solar cell to be tested, the parameter information including the metal ratio of the grid lines in each metal contact area and the grid line brightness value, and the calibrated brightness value and calibrated invisible open-circuit voltage of the non-metallic contact area; obtaining the total dark-state saturation current density value of the grid lines in each metal contact area based on the grid line brightness value, the calibrated brightness value, and the calibrated invisible open-circuit voltage; performing linear fitting on the metal ratio and the total dark-state saturation current density value corresponding to each metal contact area to obtain the metal contact composite value of the solar cell to be tested, thereby accurately testing the metal contact composite value of the test surface.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a method for testing a metal contact composite value, a testing device, and a storage medium. Background Art

[0002] In solar cells, metal-induced recombination is an important component of the total recombination loss. There is a serious recombination loss in the metal-semiconductor contact area at the grid line position of the solar cell, which has become an important factor restricting the development of solar cell efficiency. The dark saturation current density (J 0，pass ) less than 20fA / cm 2 , the dark saturation current density (J 0，metal ) is 1000fA / cm 2 ~2000fA / cm 2 , one to two orders of magnitude higher than the emitter passivation region, significantly affecting the open-circuit voltage and photoelectric conversion efficiency of solar cells. By testing the contact recombination in the metal contact region, it is possible to monitor the manufacturing process of solar cells, facilitating improvements in the slurry and sintering processes used in solar cell fabrication. This is of great significance in reducing contact recombination in the metal-semiconductor contact region of solar cells and improving their conversion efficiency. Summary of the Invention

[0003] Based on this, it is necessary to provide a test method, a test device and a storage medium that can quickly and accurately test the metal contact composite value of a solar cell in order to address the above technical problems.

[0004] A method for testing a metal contact composite value, comprising:

[0005] A solar cell to be tested having a double-sided symmetrical structure is provided, wherein a non-metallic contact area and a plurality of metal contact areas are formed on a surface to be tested of the solar cell to be tested, and the proportion of the coverage area of ​​the grid lines in each of the metal contact areas is different;

[0006] The parameter information of the solar cell to be tested is obtained by testing, wherein the parameter information includes a metal ratio of the gate line in each of the metal contact areas and a gate line brightness value, and the parameter information also includes a calibrated brightness value and a calibrated invisible open-circuit voltage of the non-metallic contact area;

[0007] Obtaining a total dark-state saturation current density value of the gate line of each metal contact area according to the gate line brightness value, the calibration brightness value and the calibration invisible open-circuit voltage;

[0008] A linear fit is performed on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain a metal contact composite value of the solar cell to be tested.

[0009] In the above-mentioned method for testing the metal contact composite value, the solar cell to be tested adopts a double-sided symmetrical structure, which eliminates the influence of the solar cell structure on the metal contact composite value obtained by linear fitting of the solar cell to be tested, thereby reducing the error of the linear fitting. The grid line brightness value reflects the luminescence magnitude of the metal-induced composite generated by the grid line in the metal contact area formed by the test surface, and is unrelated to the electrical conductivity. The presence of the grid line on the non-test surface does not affect the grid line brightness value obtained by the test, and can accurately test the metal contact composite value of the test surface. By preparing a single-sided grid line on the test surface of the solar cell to be tested, the metal contact composite value of the test surface can be tested. The preparation of the solar cell to be tested is simple and the preparation cost is low.

[0010] In one embodiment, obtaining the gate line total dark state saturation current density value of each metal contact area according to the gate line brightness value, the calibration brightness value and the calibration invisible open circuit voltage includes:

[0011] Obtaining a standard constant of the solar cell to be tested according to the calibrated brightness value and the calibrated invisible open-circuit voltage;

[0012] Based on the standard constant and the gateline brightness value of each metal contact area, the total dark-state saturation current density value of the gateline in each metal contact area is obtained. The standard brightness value of the non-metallic contact area represents the initial state of the brightness test machine, and the standard constant reflects the optical and emission characteristics of the solar cell under test and the brightness test machine.

[0013] In one embodiment, obtaining the total dark-state saturation current density value of the gate line of each metal contact area according to the standard constant and the brightness value of each gate line includes:

[0014] Obtaining a gate line invisible open circuit voltage of each metal contact area according to the standard constant and the brightness value of each gate line;

[0015] The total dark-state saturation current density of the gate lines in each metal contact area is obtained based on the photogenerated current and the gate line invisible open-circuit voltage of each metal contact area. The total dark-state saturation current density of the gate lines in the metal contact area is obtained using the photogenerated current and the gate line invisible open-circuit voltage to eliminate the influence of the photogenerated current generated by illumination on the total dark-state saturation current density of the gate lines in the metal contact area, thereby improving the accuracy of the metal contact composite value test.

[0016] In one embodiment, according to and the photogenerated current, the gate line invisible open circuit voltage of each metal contact area, to obtain the total dark state saturation current density value of the gate line of each metal contact area;

[0017] Among them, iV oc2is the gate line invisible open circuit voltage, k is the Boltzmann constant, T is the temperature, q is the charge number, J SC is the photocurrent, and J0 is the total dark-state saturation current density of the gate line.

[0018] In one embodiment, performing linear fitting on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain the metal contact composite value of the solar cell to be tested includes:

[0019] Performing linear fitting on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain a linear function;

[0020] The metal contact composite value is obtained according to the slope and intercept of the linear function.

[0021] In one embodiment, providing a solar cell to be tested having a double-sided symmetrical structure includes:

[0022] providing a substrate of a first conductivity type;

[0023] forming a doped layer of a second conductivity type on the light-receiving surface and the backlight surface of the substrate, wherein the second conductivity type is opposite to the first conductivity type;

[0024] forming an anti-reflection layer on each of the doped layers;

[0025] forming the gate structure penetrating the anti-reflection layer and contacting the doped layer on the surface of the anti-reflection layer in each metal contact area on the surface to be tested, and sintering the gate structure to obtain the solar cell to be tested;

[0026] Wherein, the surface to be measured includes the light-receiving surface or the backlight surface.

[0027] A device for testing metal contact composite values ​​is provided for testing a solar cell to be tested having a double-sided symmetrical structure. The solar cell to be tested has a non-metallic contact area and multiple metal contact areas formed on the test surface. The proportion of the coverage area of ​​the grid lines in each of the metal contact areas is different. The device comprises:

[0028] A testing module for testing parameter information of the solar cell to be tested, wherein the parameter information includes a metal ratio and a brightness value of the gate line in each of the metal contact areas, and the parameter information also includes a calibrated brightness value and a calibrated invisible open-circuit voltage of the non-metallic contact area;

[0029] The calculation module is used to obtain the total dark-state saturation current density value of the gate line of each metal contact area according to the gate line brightness value, the calibration brightness value and the calibrated invisible open-circuit voltage, and perform linear fitting on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain the metal contact composite value of the solar cell to be tested.

[0030] In the above-mentioned metal contact composite value test device, the solar cell to be tested adopts a double-sided symmetrical structure, which eliminates the influence of the solar cell structure on the metal contact composite value of the solar cell to be tested obtained by the linear fitting of the operation module, and reduces the error of the linear fitting. The grid line brightness value tested by the test module reflects the luminescence size of the metal-induced composite generated by the grid line in the metal contact area formed by the test surface, and is unrelated to the conductivity. The presence of grid lines on the non-test surface does not affect the grid line brightness value obtained by the test, and can accurately test the metal contact composite value of the test surface. By preparing a single-sided grid line on the test surface of the solar cell to be tested, the metal contact composite value of the test surface can be tested. The preparation of the solar cell to be tested is simple and the preparation cost is low.

[0031] In one embodiment, the computing module is further configured to obtain a standard constant for the solar cell under test based on the calibrated brightness value and the calibrated invisible open-circuit voltage; and further configured to obtain a total dark-state saturation current density value of the gate lines in each metal contact area based on the standard constant and the gate line brightness value of each metal contact area. The standard brightness value of the non-metallic contact area represents the initial state of the brightness test machine, and the standard constant reflects the optical and emission characteristics of the solar cell under test and the brightness test machine.

[0032] In one embodiment, the calculation module is further configured to obtain a gate line invisible open-circuit voltage of each metal contact region based on the standard constant and the gate line brightness value of each metal contact region; and to calculate a total dark-state saturation current density value of the gate line of each metal contact region based on the photogenerated current and the gate line invisible open-circuit voltage of each metal contact region. The total dark-state saturation current density value of the gate line of the metal contact region is obtained using the photogenerated current and the gate line invisible open-circuit voltage to eliminate the influence of the photogenerated current generated by illumination on the total dark-state saturation current density value of the gate line of the metal contact region, thereby improving the accuracy of the metal contact composite value test.

[0033] In one embodiment, the operation module is used to and the light-generated current, the gate line invisible open-circuit voltage of each metal contact area, to obtain the total dark-state saturation current density value of the gate line of each metal contact area;

[0034] Among them, iV oc2 is the gate line invisible open circuit voltage, k is the Boltzmann constant, T is the temperature, q is the charge number, J SCis the photocurrent, and J0 is the total dark-state saturation current density of the gate line.

[0035] In one embodiment, the calculation module is also used to perform linear fitting on the metal proportion corresponding to each metal contact area and the total dark state saturation current density value of the gate line to obtain a linear function; and obtain the metal contact composite value based on the slope and intercept of the linear function.

[0036] In one embodiment, the test module includes:

[0037] A width testing unit, used to test the metal ratio of the gate line in the metal contact area;

[0038] A brightness testing unit, configured to test a brightness value of the gate line in the metal contact area and a calibrated brightness value of the non-metal contact area;

[0039] A voltage testing unit is used to test the calibrated invisible open circuit voltage of the non-metallic contact area.

[0040] In one embodiment, the width test unit includes a rangefinder and a multiplier, the brightness test unit includes a brightness tester, the voltage test unit includes a light guide attenuation tester, and the operation module includes an adder, a subtractor, a multiplier, and a divider.

[0041] A device for testing metal contact composite values ​​is provided for testing a solar cell to be tested having a double-sided symmetrical structure. The solar cell to be tested has a non-metallic contact area and multiple metal contact areas formed on the test surface. The proportion of the coverage area of ​​the grid lines in each of the metal contact areas is different. The device comprises:

[0042] a light guide attenuation tester for testing the calibrated invisible open circuit voltage of the non-metallic contact area;

[0043] A brightness tester, used to test the brightness value of the gate line of the metal contact area and the calibrated brightness value of the non-metal contact area;

[0044] The controller includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of any one of the above-mentioned test methods when executing the computer program.

[0045] In the above-mentioned metal contact composite value test device, the solar cell to be tested adopts a double-sided symmetrical structure, which eliminates the influence of the solar cell structure on the metal contact composite value of the solar cell to be tested obtained by linear fitting, and reduces the error of linear fitting. The grid line brightness value tested by the brightness tester reflects the luminescence size of the metal-induced composite generated by the grid line in the metal contact area formed by the surface to be tested, and is unrelated to the electrical conductivity. The presence of grid lines on the non-surface to be tested does not affect the grid line brightness value obtained by the test, and can accurately test the metal contact composite value of the surface to be tested. By preparing a single-sided grid line on the surface to be tested of the solar cell to be tested, the metal contact composite value of the surface to be tested can be tested. The preparation of the solar cell to be tested is simple and the preparation cost is low.

[0046] A computer-readable storage medium stores a computer program, wherein the computer program implements the steps of any one of the above-mentioned testing methods when executed by a processor. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 Schematic diagram of a process for testing a metal contact composite in one embodiment;

[0049] Figure 2 is a schematic cross-sectional view of a solar cell to be tested in one embodiment;

[0050] Figure 3 is a schematic top view of a surface to be measured in one embodiment;

[0051] Figure 4 A schematic diagram of a metal contact composite value testing device according to an embodiment of the present invention;

[0052] Figure 5 This is a testing device for metal contact composite value in another embodiment.

[0053] Description of reference numerals:

[0054] 10. Solar cell to be tested; 100. Substrate; 102. Doping layer; 104. Anti-reflection layer; 202. Non-metallic contact area; 204. Metallic contact area; 302. Test module; 304. Operation module; 402. Width test unit; 404. Brightness test unit; 406. Voltage test unit; 502. Light guide attenuation tester; 504. Brightness tester; 506. Controller. DETAILED DESCRIPTION

[0055] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0057] Spatially relative terms such as "under," "beneath," "beneath," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under" or "beneath" or "beneath" the other elements will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" can include both upper and lower orientations. In addition, the device can also include alternative orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0058] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intervening element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc., if there is transmission of electrical signals or data between the connected objects.

[0059] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0060] Figure 1 FIG. 1 is a flow chart of a method for testing metal contact composites in one embodiment. Figure 2 is a schematic cross-sectional view of a solar cell to be tested in one embodiment, Figure 3FIG. 1 is a schematic top view of a surface to be measured in one embodiment. Figure 1-Figure 3 As shown, in this embodiment, a method for testing a metal contact composite value is provided, comprising:

[0061] S102, providing a solar cell to be tested having a double-sided symmetrical structure.

[0062] Specifically, a solar cell 10 to be tested having a double-sided symmetrical structure is provided, wherein the substrate 100 of the solar cell 10 to be tested has a light-receiving surface and a backlight surface that are relatively arranged, the light-receiving surface being the surface of the solar cell 10 to be tested that faces the sunlight (the light-facing surface), and the double-sided symmetrical structure means that the structures formed on the light-receiving surface and the backlight surface of the substrate 100 before the grid lines are formed are symmetrical about the axis of the substrate 100, and a non-metallic contact area 202 and a plurality of metal contact areas 204 are formed on the surface to be tested of the solar cell 10 to be tested, and the proportion of the coverage area of ​​the grid lines in each of the metal contact areas 204 is different, the surface to be tested is any one of the light-receiving surface and the backlight surface, and the non-metallic contact area 202 is an area on the surface to be tested where no grid lines electrically connected to the doped layer are present. It can be understood that the electrodes (grid lines) are not printed on the surface to be tested. The area is a non-metallic contact area 202; the metal contact area 204 is an area on the surface to be tested where a gate line electrically connected to the doped layer exists. The two adjacent contact areas are arranged at intervals, for example, between the non-metallic contact area 202 and the metal contact area 204, and between the metal contact area 204 and the metal contact area 204. The metal contact area 204 includes a gate line covering area where the gate line is located and a passivation area (non-gate line covering area) located on one side of the gate line covering area. The ratio of the total area of ​​the gate line covering area where the gate line is located corresponding to different gate metal contact areas 204 to the area of ​​the metal contact area 204 is different. The structure of the passivation area here is the same as that of the non-metallic contact area 202. The difference is that the passivation area is adjacent to the gate covering area and is part of the metal contact area 204, while the non-metallic contact area 202 is adjacent to the metal contact area 204.

[0063] S104, testing to obtain parameter information of the solar cell to be tested.

[0064] Test the brightness and invisible open circuit voltage of the non-metallic contact area 202 on the test surface to obtain the calibrated brightness value PL of the non-metallic contact area 202 initial and calibrate the invisible open circuit voltage iV oc1 Test the brightness of each metal contact area 204 on the test surface and the ratio of the coverage area of ​​the gate line to obtain the gate line brightness value PL of each metal contact area 204 counts And the metal ratio fmet of the grid line, calibrate the brightness value PL initial , calibrate the invisible open circuit voltage iV oc1 , the gate line brightness value PL of each metal contact area 204 countsThe metal proportion fmet of the gate line in each metal contact area 204 is parameter information of the solar cell 10 to be tested.

[0065] S106 , obtaining a total dark-state saturation current density value of the gate line in each metal contact area according to the gate line brightness value, the calibration brightness value, and the calibration invisible open-circuit voltage.

[0066] According to the gate line brightness value PL of the metal contact area 204 counts , calibrated brightness value PL initial and calibrate the invisible open circuit voltage iV oc1 , the total dark-state saturation current density value J0 of the metal contact region 204 can be obtained, and the total dark-state saturation current density value J0 of the gate line corresponding to each metal contact region 204 can be obtained in turn.

[0067] S108 , performing linear fitting on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain a metal contact composite value of the solar cell to be tested.

[0068] Specifically, the total dark saturation current density J0 of the gate line in the metal contact area 204 is related to the metal proportion fmet of the gate line in the metal contact area 204, the dark saturation current density J 0，metal and the dark state saturation current density J in the passivation region 0，film The total dark saturation current density J0 of the gate line and the metal proportion fmet of the gate line in different metal contact areas 204 have been obtained in step S104 and step S106. The dark saturation current density J 0，metal The dark state saturation current density J of the metal contact region 204 is the same and different 0，film The metal proportion fmet and the total dark saturation current density value J0 of each metal contact area 204 corresponding to the gate line are linearly fitted to obtain a linear function, and the dark saturation current density J of the gate line coverage area can be obtained according to the constant in the linear function. 0，metal and the dark state saturation current density J in the passivation region 0，film , that is, the metal contact composite value of the solar cell 10 to be tested is obtained.

[0069] It is understandable that the greater the number of metal contact regions 204 on the surface to be tested, the more closely the linear function obtained by linear fitting matches the actual linear function, and the higher the accuracy of the obtained metal contact composite value of the solar cell 10 to be tested.

[0070] In the above-mentioned metal contact composite value test method, the solar cell 10 to be tested adopts a double-sided symmetrical structure, which eliminates the influence of the solar cell structure on the metal contact composite value of the solar cell 10 to be tested obtained by linear fitting, thereby reducing the error of linear fitting. countsIt reflects the luminescence magnitude of the metal-induced recombination generated by the gate line in the metal contact area 204 formed on the test surface, which has nothing to do with the conductivity. The presence of the gate line on the non-test surface does not affect the gate line brightness value PL obtained by the test. counts , can accurately test the metal contact composite value of the surface to be tested. The metal contact composite value of the surface to be tested can be tested by preparing a single-sided grid line on the surface to be tested of the solar cell 10 to be tested. The preparation of the solar cell 10 to be tested is simple and the preparation cost is low.

[0071] In one embodiment, according to the brightness value PL of each grid line counts , the calibrated brightness value PL initial and the calibrated invisible open circuit voltage iV oc1 , obtaining the total dark-state saturation current density value J0 of the gate line of each metal contact region 204 , including steps S202 to S204 .

[0072] S202, according to the calibration brightness value PL initial and calibrate the invisible open circuit voltage iV oc1 , and obtain the standard constant C of the solar cell 10 to be tested.

[0073] S204, based on the standard constant C and the gate line brightness value PL of each metal contact area 204 counts , and obtain the total dark state saturation current density value J0 of the gate line of each metal contact area 204.

[0074] Specifically, in step S202 to step S204, the non-metallic contact area 202 characterizes the optical characteristics (composite luminescence not affected by the gate line) and emission characteristics (invisible open-circuit voltage not affected by the gate line) of the solar cell 10 to be tested before the gate line is formed (passivation area), and the standard brightness value PL obtained by testing the non-metallic contact area 202 is initial and calibrate the invisible open circuit voltage iV oc1 In the standard brightness value PL initial It reflects the composite luminescence (compound luminescence in the passivation region) caused by the structure before the grid lines are formed on the test surface of the solar cell 10 to be tested and the influence of the brightness test machine itself on the brightness value (the influence of the brightness test machine itself on the measured brightness value); calibrates the invisible open circuit voltage iV oc1 It reflects the invisible open circuit voltage generated by the structure before the grid line is formed on the test surface of the solar cell 10 to be tested; according to the calibration brightness value PL initial and calibrate the invisible open circuit voltage iV oc1 The obtained standard constant C reflects the influence of the gate line coverage area in the metal contact area 204 on the structure before the gate line is formed; according to the standard constant C and the gate line brightness value PL of each metal contact area 204 countsIn the process of obtaining the total dark-state saturation current density value J0 of the gate line of each metal contact area 204, the influence of the composite luminescence of the structure before the gate line is formed in the gate line coverage area, the invisible open-circuit voltage, and the brightness measurement deviation of the brightness test machine on the measured brightness value on the total dark-state saturation current density is eliminated, and a more accurate total dark-state saturation current density value J0 is obtained. The deviation between the subsequent fitting metal contact composite value and the actual metal contact composite value is smaller, thereby improving the accuracy of the tested metal contact composite value.

[0075] In one embodiment, according to The calibrated brightness value PL of the non-metal contact area 202 initial and the calibrated invisible open circuit voltage iV of the non-metallic contact area 202 oc1 , we get the standard constant C, where n i is the intrinsic carrier concentration of the substrate 100, q is the charge number, i.e., q is a unit positive charge, which is 1 coulomb, K is the Boltzmann constant, and T is the temperature. For example, T is room temperature, i.e., 298.15 K, and the standard constant C is 1.0-1.5*10 27 .

[0076] In one embodiment, according to the standard constant C and the gate line brightness value PL of each metal contact area 204 counts , obtaining the total dark state saturation current density value J0 of the gate line of each metal contact region 204, including steps S302 to S304.

[0077] S302, based on the standard constant C and the gate line brightness value PL of each metal contact area 204, counts , and obtain the gate line invisible open circuit voltage iV of each metal contact area 204 oc2 .

[0078] S304, according to the photocurrent J SC and the gate line invisible open circuit voltage iV of each metal contact area 204 oc2 , and obtain the total dark state saturation current density value J0 of the gate line of each metal contact area 204.

[0079] Specifically, in step S302 to step S304, according to the standard constant C and the gate line brightness value PL of the metal contact area 204 counts In the process of obtaining the invisible open-circuit voltage of the metal contact area 204, the influence of the structure of the surface to be tested before the gate line is formed corresponding to the gate line coverage area has been eliminated. At this time, the gate line invisible open-circuit voltage iV oc2 Closer to the true value; photocurrent J SC Reflects the test calibration invisible open circuit voltage iV oc1 The influence of the illumination and measurement deviation in the test machine on the total dark state saturation current density is shown by the photocurrent J SCand the gate line invisible open circuit voltage iV of each metal contact area 204 oc2 , the total dark state saturation current density value J0 of the gate line of each metal contact area 204 is obtained, eliminating the test calibration invisible open circuit voltage iV oc1 The influence of the lighting in the test machine and the measurement deviation of the machine on the total dark-state saturation current density further improves the accuracy of the total dark-state saturation current density value J0, so that the deviation between the subsequent fitting metal contact composite value and the actual metal contact composite value is smaller, further improving the accuracy of the tested metal contact composite value.

[0080] In one embodiment, according to and the gate line brightness value PL of the metal contact area 204 counts , standard constant C, and obtain the gate line invisible open circuit voltage iV of the metal contact area 204 oc2 ; where n i is the intrinsic carrier concentration of the substrate 100, q is the charge number, i.e., unit positive charge, which is 1 coulomb, K is the Boltzmann constant, and T is the temperature. For example, T is room temperature, i.e., 298.15K; the standard constant C is 1.0-1.5*10 27 .

[0081] In one embodiment, according to and the photocurrent J SC , the gate line invisible open circuit voltage iV of each of the metal contact areas 204 oc2 , obtain the total dark state saturation current density value J0 of the gate line of each metal contact area 204; wherein, iV oc2 is the gate line invisible open circuit voltage of the metal contact area 204, K is the Boltzmann constant, T is the temperature, q is the charge number, that is, q is a unit positive charge, which is 1 coulomb, J SC is the photocurrent, J0 is the total dark state saturation current density of the gate line, and the gate line invisible open circuit voltage iV oc2 The total dark state saturation current density of the gate line J0 corresponds to one by one. For example, T is room temperature, i.e. 298.15k. For example, the invisible open circuit voltage iV oc1 The test equipment includes Sinton WCT-120 Photoconductor Degradation (PCD) tester, which can obtain the photocurrent J by testing the standard of the tester. SC , J SC 38.5mA / cm 2 .

[0082] In one embodiment, performing linear fitting on the metal fraction fmet corresponding to each metal contact region 204 and the total dark-state saturation current density value J0 of the gate line to obtain the metal contact composite value of the solar cell 10 to be tested includes steps S402 to S404.

[0083] S402 , performing linear fitting on the metal proportion fmet corresponding to each metal contact region 204 and the total dark-state saturation current density value J0 of the gate line to obtain a linear function.

[0084] S404: Obtain the metal contact composite value according to the slope and intercept of the linear function.

[0085] Specifically, in step S402-step S404, the metal proportion fmet corresponding to each metal contact area 204 and the total dark state saturation current density value J0 of the gate line constitute a coordinate point in a two-dimensional coordinate system, and a linear fitting is performed on each coordinate point to obtain a linear function of the coordinate point corresponding to each metal contact area 204. The slope and intercept of the linear function reflect the dark state saturation current density J0 of the gate line coverage area in the metal contact area 204. 0，metal and the dark state saturation current density J in the passivation region 0，film According to the slope and intercept of the linear function, the dark state saturation current density J in the gate line coverage area can be obtained. 0，metal , that is, the metal contact composite value of the solar cell 10 to be tested is obtained.

[0086] In one embodiment, according to J0=J 0,metal *fmet+J 0,film *(1-fmet) and the total dark saturation current density J0 of the gate line in the metal contact area 204, the metal proportion fmet of the gate line in the metal contact area 204, and the dark saturation current density J of the gate line coverage area where the gate line in the metal contact area 204 is located. 0，metal , the dark state saturation current density J in the passivation region of the metal contact region 204 0，film , and obtain the dark state saturation current density J in the gate line coverage area of ​​the metal contact area 204 0，metal , that is, the metal contact composite value of the solar cell 10 to be tested is obtained.

[0087] like Figure 2 As shown, in one embodiment, a solar cell 10 to be tested having a double-sided symmetrical structure is provided, including steps S502 to S508.

[0088] S502 , providing a substrate 100 of a first conductivity type.

[0089] Specifically, a substrate 100 of a first conductivity type is provided. The first conductivity type can be either N-type or P-type. The substrate 100 includes a light-receiving surface and a light-receiving surface oppositely disposed. The light-receiving surface is the surface of the solar cell 10 to be tested that faces sunlight (the light-facing surface), and the light-receiving surface is the surface of the substrate 100 opposite the light-receiving surface. The substrate 100 can include a semiconductor substrate made of silicon or germanium, or a compound semiconductor substrate made of silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide, or gallium oxide. As an example, in this embodiment, the substrate 100 is formed of single-crystal silicon.

[0090] S504 , forming a second conductive type doping layer 102 on the light-receiving surface and the backlight surface of the substrate 100 .

[0091] Specifically, a second conductive type doping layer 102 is formed on the light-receiving surface and the backlight surface of the substrate 100, respectively. A PN junction in the solar cell 10 to be tested is formed between the doping layer 102 and the substrate 100. The second conductive type is opposite to the first conductive type. When the first conductive type is P-type, the second conductive type is N-type. When the first conductive type is N-type, the second conductive type is P-type.

[0092] In one embodiment, the forming of the second conductive type doping layer 102 on the light-receiving surface and the backlight surface of the substrate 100 includes: forming a doping film layer having doping ions of the second conductive type on the light-receiving surface and the backlight surface; using a full-area laser doping process to diffuse the doping ions into the upper surface layer of the substrate 100 on the light-receiving surface and the upper surface layer of the substrate 100 on the backlight surface to obtain the doping layer 102; and removing the doping film layer on the light-receiving surface and the backlight surface.

[0093] In one embodiment, the second conductive type doping layer 102 is formed on the light-receiving surface and the backlight surface of the substrate 100, including: forming a velvet structure, such as a pyramid velvet structure, on the light-receiving surface and the backlight surface; and forming the doping layer 102 on the surface of the velvet structure on the light-receiving surface and the backlight surface.

[0094] S506 , forming an anti-reflection layer 104 on each doped layer 102 .

[0095] Specifically, an anti-reflection layer 104 is formed on the doped layer 102 on the light-receiving side and the backlight side, respectively. Exemplarily, the material of the anti-reflection layer 104 includes one or more of Al2O3 and SiNx. Exemplarily, the anti-reflection layer 104 is formed on the surface of the doped layer 102 on the light-receiving side and the backlight side, respectively, or a tunneling layer, a polysilicon doped layer, and the anti-reflection layer 104 are sequentially formed on the surface of the doped layer 102 on the light-receiving side and the backlight side, respectively.

[0096] S508 , forming a gate electrode penetrating the anti-reflection layer 104 and in contact with the doping layer 102 on the surface of the anti-reflection layer 104 of each metal contact area 204 on the surface to be tested, and sintering the gate electrode to obtain the solar cell 10 to be tested; wherein the surface to be tested includes the light-receiving surface or the backlight surface.

[0097] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. In addition, Figure 1 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The order of execution of these steps or stages is not necessarily one by one, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0098] Figure 4 FIG. 1 is a schematic diagram of a metal contact composite value testing device according to an embodiment of the present invention. Figure 2-Figure 4 As shown, in this embodiment, a device for testing a metal contact composite value is provided. Parts identical or corresponding to the embodiments of the metal contact composite value testing method described above will not be described in detail below. The device for testing a metal contact composite value is used to test a solar cell 10 to be tested having a bilaterally symmetrical structure. The test surface of the solar cell 10 to be tested includes a non-metallic contact region 202 and multiple metal contact regions 204, each of which has a different ratio of gridline coverage area. The testing module of the device includes a testing module 302 and a calculation module 304.

[0099] The test module 302 is used to test the parameter information of the solar cell 10 to be tested, and the parameter information includes the metal proportion fmet and the brightness value PL of the gate line in each metal contact area 204. counts The parameter information also includes the calibration brightness value PL of the non-metal contact area 202 initial and calibrate invisible open circuit voltage iV oc1 ; The calculation module 304 is used according to the gate line brightness value PL counts , the calibrated brightness value PL initial and the calibrated invisible open circuit voltage iV oc1, obtain the total dark-state saturation current density value J0 of the gate line of each metal contact area 204, and perform linear fitting on the metal proportion fmet and the total dark-state saturation current density value J0 corresponding to each metal contact area 204 to obtain the metal contact composite value of the solar cell to be tested.

[0100] In the above-mentioned metal contact composite value test device, the solar cell 10 to be tested adopts a double-sided symmetrical structure, which eliminates the influence of the structure of the solar cell 10 on the metal contact composite value of the solar cell 10 to be tested obtained by the linear fitting of the calculation module 304, thereby reducing the error of the linear fitting. counts It reflects the luminescence magnitude of the metal-induced recombination generated by the gate line in the metal contact area 204 formed on the test surface, which has nothing to do with the conductivity. The presence of the gate line on the non-test surface does not affect the gate line brightness value PL obtained by the test. counts , can accurately test the metal contact composite value of the surface to be tested. The metal contact composite value of the surface to be tested can be tested by preparing a single-sided grid line on the surface to be tested of the solar cell 10 to be tested. The preparation of the solar cell 10 to be tested is simple and the preparation cost is low.

[0101] In one embodiment, the calculation module 304 is further configured to calculate the calibrated brightness value PL initial and the calibrated invisible open circuit voltage iV oc1 , obtain the standard constant C of the solar cell 10 to be tested; the operation module 304 is also used to calculate the gate line brightness value PL of each metal contact area 204 according to the standard constant C counts , and obtain the total dark state saturation current density value J0 of the gate line of each metal contact area 204.

[0102] The non-metallic contact area 202 represents the optical characteristics (composite luminescence not affected by the gate line) and emission characteristics (invisible open-circuit voltage not affected by the gate line) of the solar cell 10 to be tested before the gate line is formed (passivation area). The standard brightness value PL of the non-metallic contact area 202 is initial and calibrate the invisible open circuit voltage iV oc1 In the standard brightness value PL initial It reflects the influence of the composite luminescence (compound luminescence of the passivation area) caused by the structure before the grid line is formed on the test surface of the solar cell 10 to be tested and the test module 302 (part of the brightness test) itself on the brightness value (for example, the influence of the brightness test unit on the measured brightness value); calibrates the invisible open circuit voltage iV oc1 It reflects the invisible open circuit voltage generated by the structure before the grid line is formed on the test surface of the solar cell 10 to be tested; the calculation module 304 calculates the voltage according to the calibration brightness value PL initial and calibrate the invisible open circuit voltage iV oc1The obtained standard constant C reflects the influence of the gate line coverage area in the metal contact area 204 on the structure before the gate line is formed; the calculation module 304 calculates the gate line brightness value PL of each metal contact area 204 according to the standard constant C and the gate line brightness value PL of each metal contact area 204. counts In the process of obtaining the total dark-state saturation current density value J0 of the gate line of each metal contact area 204, the influence of the composite luminescence of the structure before the gate line is formed in the gate line coverage area, the invisible open-circuit voltage, and the measurement deviation of the brightness of the test module 302 on the total dark-state saturation current density is eliminated, and a more accurate total dark-state saturation current density value J0 is obtained. The deviation between the subsequent fitting metal contact composite value and the actual metal contact composite value is smaller, thereby improving the accuracy of the tested metal contact composite value.

[0103] In one embodiment, the operation module 304 is used to The calibrated brightness value PL of the non-metal contact area 202 initial and the calibrated invisible open circuit voltage iV of the non-metallic contact area 202 oc1 , we get the standard constant C, where n i is the intrinsic carrier concentration of the substrate 100, q is the charge number, i.e., q is a unit positive charge, which is 1 coulomb, K is the Boltzmann constant, and T is the temperature. For example, T is room temperature, i.e., 298.15 K; the standard constant C is 1.0-1.5*10 27 .

[0104] In one embodiment, the calculation module 304 is further configured to calculate the gate line brightness value PL of each metal contact region 204 based on the standard constant C and the gate line brightness value PL of each metal contact region 204. counts , and obtain the gate line invisible open circuit voltage iV of each metal contact area 204 oc2 ; and according to the photocurrent J SC and the gate line invisible open circuit voltage iV of each of the metal contact areas 204 oc2 , the total dark state saturation current density value J0 of the gate line of each metal contact area 204 is obtained by calculation.

[0105] The calculation module 304 calculates the gate line brightness value PL of the metal contact area 204 according to the standard constant C counts In the process of obtaining the invisible open-circuit voltage of the metal contact area 204, the influence of the structure of the surface to be tested before the gate line is formed corresponding to the gate line coverage area has been eliminated. At this time, the gate line invisible open-circuit voltage iV oc2 Closer to the true value; photocurrent J SC Reflects the test module 302 test calibration invisible open circuit voltage iV oc1 The influence of the illumination and measurement deviation on the total dark state saturation current density in the part, the calculation module 304 calculates the photocurrent J SC and the gate line invisible open circuit voltage iV of each metal contact area 204oc2 , obtain the total dark state saturation current density value J0 of the gate line of each metal contact area 204, eliminating the test module 302 test calibration invisible open circuit voltage iV oc1 The lighting and testing module 302 in the part tests the calibration invisible open circuit voltage iV oc1 The influence of the partial measurement deviation on the total dark state saturation current density is further improved, and the accuracy of the total dark state saturation current density value J0 is further improved, so that the deviation between the subsequent fitting metal contact composite value and the actual metal contact composite value is smaller, further improving the accuracy of the tested metal contact composite value.

[0106] In one embodiment, the computing module 304 in the testing device is further configured to: and the gate line brightness value PL of the metal contact area 204 counts , standard constant C, and obtain the gate line invisible open circuit voltage iV of the metal contact area 204 oc2 ; where n i is the intrinsic carrier concentration of the substrate 100, q is the charge number, i.e., q is a unit positive charge, which is 1 coulomb, K is the Boltzmann constant, and T is the temperature. For example, T is room temperature, i.e., 298.15 K, and the standard constant C is 1.0-1.5*10 27 .

[0107] In one embodiment, the computing module 304 in the test device is used to The photocurrent J SC , the gate line invisible open circuit voltage iV of each of the metal contact areas 204 oc2 , obtain the total dark state saturation current density value J0 of the gate line of each metal contact area 204; wherein, iV oc2 is the gate line invisible open circuit voltage of the metal contact area 204, K is the Boltzmann constant, T is the temperature, q is the charge number, that is, q is a unit positive charge, which is 1 coulomb, J SC is the photocurrent, J0 is the total dark state saturation current density of the gate line, and the gate line invisible open circuit voltage iV oc2 The total dark state saturation current density of the gate line corresponds to J0. For example, T is room temperature, i.e. 298.15K.

[0108] In one embodiment, the calculation module 304 is also used to perform linear fitting on the metal proportion fmet and the total dark state saturation current density value J0 of the gate line corresponding to each metal contact area 204 to obtain a linear function; and obtain the metal contact composite value based on the slope and intercept of the linear function.

[0109] In one embodiment, the operation module 304 in the test device is further configured to calculate the value of the test result according to J0=J0,metal *fmet+J 0,film *(1-fmet) and the total dark saturation current density J0 of the gate line in the metal contact area 204, the metal proportion fmet of the gate line in the metal contact area 204, and the dark saturation current density J of the gate line coverage area where the gate line in the metal contact area 204 is located. 0，metal , the dark state saturation current density J in the passivation region of the metal contact region 204 0，film , and obtain the dark state saturation current density J in the gate line coverage area of ​​the metal contact area 204 0，metal , that is, the metal contact composite value of the solar cell 10 to be tested is obtained.

[0110] In one embodiment, the test module 302 includes: a width test unit 402, a brightness test unit 404, and a voltage test unit 406; the width test unit 402 is used to test the metal ratio fmet of the gate line in the metal contact area 204; the brightness test unit 404 is used to test the brightness value PL of the gate line in the metal contact area 204. counts and the calibrated brightness value PL of the non-metallic contact area 202 initial ; Voltage testing unit 406 is used to test the calibration invisible open circuit voltage iV of the non-metallic contact area 202 oc1 .

[0111] In one embodiment, the width testing unit 402 includes a rangefinder and a multiplier, the rangefinder is used to test the length and width of the gate line in the metal contact area 204, the length and width of the metal contact area 204, and the multiplier is used to calculate the metal proportion fmet of the gate line in the metal contact area 204 based on the length and width of the gate line in the metal contact area 204 and the length and width of the metal contact area 204.

[0112] In one embodiment, the brightness test unit 404 includes a brightness tester, such as a SUASPL tester.

[0113] In one embodiment, the voltage test unit 406 includes a light conduction deterioration tester, for example, a Sinton WCT-120 light conduction deterioration (PCD) tester. Exemplarily, the operation module 304 is further configured to obtain the photocurrent J according to the test value of the test piece of the Sinton WCT-120 light conduction deterioration (PCD) tester. SC , J SC 38.5mA / cm 2 .

[0114] In one embodiment, the operation module 304 includes one or more of an adder, a subtractor, a multiplier, and a divider.

[0115] For the specific definition of the testing device for metal contact composite value, please refer to the definition of the testing method for metal contact composite value above, which will not be repeated here. Each module in the above-mentioned testing device for metal contact composite value can be implemented in whole or in part by software, hardware and their combination. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation.

[0116] Figure 5 In another embodiment, a device for testing the metal contact composite value is shown. Figure 5 As shown, in this embodiment, a device for testing a metal contact composite value is provided. The parts that are the same as or corresponding to the embodiments of the metal contact composite value testing method and the metal contact composite value testing device described above will not be described in detail below. The device for testing a metal contact composite value is used to test a solar cell 10 to be tested having a double-sided symmetrical structure. A non-metallic contact area 202 and a plurality of metal contact areas 204 are formed on the test surface of the solar cell 10 to be tested. The proportion of the coverage area of ​​the grid lines in each of the metal contact areas 204 is different. The device includes: a light conduction attenuation tester 502, a brightness tester 504, and a controller 506. The light conduction attenuation tester 502 is used to test the calibrated invisible open circuit voltage iV of the non-metallic contact area 202. oc1 ; Brightness tester 504 is used to test the brightness value PL of the gate line of the metal contact area 204 counts and the calibrated brightness value PL of the non-metallic contact area 202 initial ; The controller 506 includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of any one of the above-mentioned test methods when executing the computer program.

[0117] In the above-mentioned metal contact composite value test device, the solar cell 10 to be tested adopts a double-sided symmetrical structure, which eliminates the influence of the structure of the solar cell 10 on the metal contact composite value of the solar cell 10 to be tested obtained by linear fitting, thereby reducing the error of linear fitting. counts It reflects the luminescence magnitude of the metal-induced recombination generated by the gate line in the metal contact area 204 formed on the test surface, which has nothing to do with the conductivity. The presence of the gate line on the non-test surface does not affect the gate line brightness value PL obtained by the test. counts , can accurately test the metal contact composite value of the surface to be tested. The metal contact composite value of the surface to be tested can be tested by preparing a single-sided grid line on the surface to be tested of the solar cell 10 to be tested. The preparation of the solar cell 10 to be tested is simple and the preparation cost is low.

[0118] The present disclosure further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of any one of the above-mentioned testing methods when executed by a processor.

[0119] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0120] Throughout this specification, references to terms such as "some embodiments," "other embodiments," and "desired embodiments" indicate that a particular feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Although these terms are used interchangeably throughout this specification, they do not necessarily refer to the same embodiment or example.

[0121] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, 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.

[0122] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for testing the composite value of metal contact, characterized in that: include: A solar cell to be tested having a double-sided symmetrical structure is provided, wherein a non-metallic contact area and a plurality of metal contact areas are formed on a surface to be tested of the solar cell to be tested, and the proportion of the coverage area of ​​the grid lines in each of the metal contact areas is different; The parameter information of the solar cell to be tested is obtained by testing, wherein the parameter information includes a metal ratio of the gate line in each of the metal contact areas and a gate line brightness value, and the parameter information also includes a calibrated brightness value and a calibrated invisible open-circuit voltage of the non-metallic contact area; Obtaining a total dark-state saturation current density value of the gate line of each metal contact area according to the gate line brightness value, the calibration brightness value, the intrinsic carrier concentration of the substrate in the solar cell to be tested, and the calibration invisible open-circuit voltage; Performing linear fitting on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain a metal contact composite value of the solar cell to be tested; Wherein, obtaining the total dark state saturation current density value of the gate line of each metal contact area according to the brightness value of each gate line, the calibration brightness value, the intrinsic carrier concentration of the substrate in the solar cell to be tested, and the calibration invisible open circuit voltage includes: Obtaining a standard constant of the solar cell to be tested according to the calibration brightness value, the intrinsic carrier concentration of the substrate in the solar cell to be tested, and the calibration invisible open-circuit voltage; wherein the standard constant is linearly inversely correlated with the square of the intrinsic carrier concentration; Obtaining a total dark-state saturation current density value of the gate line of each metal contact area according to the standard constant and the gate line brightness value of each metal contact area; The step of obtaining the total dark-state saturation current density value of the gate lines in each metal contact area according to the standard constant and the brightness value of each gate line includes: Obtaining a gate line invisible open circuit voltage of each metal contact region according to the standard constant, the intrinsic carrier concentration of the substrate in the solar cell to be tested, and the brightness value of each gate line; wherein the gate line invisible open circuit voltage is nonlinearly positively correlated with the square of the intrinsic carrier concentration; The total dark-state saturation current density value of the gate line in each metal contact area is obtained according to the photogenerated current and the gate line invisible open-circuit voltage of each metal contact area.

2. The testing method according to claim 1, wherein: according to and the photogenerated current, the gate line invisible open circuit voltage of each metal contact area, to obtain the total dark state saturation current density value of the gate line of each metal contact area; Among them, iV oc2 is the gate line invisible open circuit voltage, k is the Boltzmann constant, T is the temperature, q is the charge number, J SC is the photocurrent, and J0 is the total dark-state saturation current density of the gate line.

3. The testing method according to claim 1, wherein: The performing linear fitting on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain the metal contact composite value of the solar cell to be tested includes: Performing linear fitting on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain a linear function; The metal contact composite value is obtained according to the slope and intercept of the linear function.

4. The testing method according to claim 1, wherein: The method of providing a solar cell to be tested having a double-sided symmetrical structure comprises: providing a substrate of a first conductivity type; forming a doped layer of a second conductivity type on the light-receiving surface and the backlight surface of the substrate, wherein the second conductivity type is opposite to the first conductivity type; forming an anti-reflection layer on each of the doped layers; forming a gate structure penetrating the anti-reflection layer and contacting the doped layer on the surface of the anti-reflection layer in each metal contact area on the surface to be tested, and sintering the gate structure to obtain the solar cell to be tested; Wherein, the surface to be measured includes the light-receiving surface or the backlight surface.

5. A device for testing metal contact composite value, characterized in that: The testing device is used to test a solar cell to be tested having a double-sided symmetrical structure, wherein a non-metallic contact area and a plurality of metal contact areas are formed on the test surface of the solar cell to be tested, and the proportion of the coverage area of ​​the grid lines in each of the metal contact areas is different. The testing device comprises: A testing module for testing parameter information of the solar cell to be tested, wherein the parameter information includes a metal ratio and a brightness value of the gate line in each of the metal contact areas, and the parameter information also includes a calibrated brightness value and a calibrated invisible open-circuit voltage of the non-metallic contact area; a calculation module, configured to obtain a total dark-state saturation current density value of the gate line of each metal contact area according to the gate line brightness value, the calibration brightness value, the intrinsic carrier concentration of the substrate in the solar cell to be tested, and the calibration invisible open-circuit voltage, and perform a linear fit on the metal proportion corresponding to each metal contact area and the total dark-state saturation current density value of the gate line to obtain a metal contact composite value of the solar cell to be tested; In which, the calculation module is also used to obtain the standard constant of the solar cell to be tested based on the calibration brightness value, the intrinsic carrier concentration of the substrate in the solar cell to be tested and the calibration invisible open-circuit voltage, and the standard constant is linearly inversely correlated with the square of the intrinsic carrier concentration; the calculation module is also used to obtain the gate line invisible open-circuit voltage of each metal contact area based on the standard constant, the intrinsic carrier concentration of the substrate in the solar cell to be tested and the gate line brightness value of each metal contact area, and the gate line invisible open-circuit voltage is nonlinearly positively correlated with the square of the intrinsic carrier concentration; and based on the photogenerated current and the gate line invisible open-circuit voltage of each metal contact area, the total dark state saturation current density value of the gate line of each metal contact area is calculated.

6. The testing device according to claim 5, characterized in that: The operation module is used to and the photogenerated current, the gate line invisible open circuit voltage of each metal contact area, to obtain the total dark state saturation current density value of the gate line of each metal contact area; Among them, iV oc2 is the gate line invisible open circuit voltage, k is the Boltzmann constant, T is the temperature, q is the charge number, J SC is the photocurrent, and J0 is the total dark-state saturation current density of the gate line.

7. The testing device according to claim 5, characterized in that: The calculation module is also used to perform linear fitting on the metal proportion corresponding to each metal contact area and the total dark state saturation current density value of the gate line to obtain a linear function; and obtain the metal contact composite value based on the slope and intercept of the linear function.

8. The testing device according to claim 5, characterized in that: The test module includes: A width testing unit, used to test the metal ratio of the gate line in the metal contact area; A brightness testing unit, configured to test a brightness value of the gate line in the metal contact area and a calibrated brightness value of the non-metal contact area; A voltage testing unit is used to test the calibrated invisible open circuit voltage of the non-metallic contact area.

9. The testing device according to claim 8, characterized in that The width test unit includes a rangefinder and a multiplier, the brightness test unit includes a brightness tester, the voltage test unit includes a light guide attenuation tester, and the operation module includes an adder, a subtractor, a multiplier, and a divider.

10. A device for testing metal contact composite value, characterized in that: The testing device is used to test a solar cell to be tested having a double-sided symmetrical structure, wherein a non-metallic contact area and a plurality of metal contact areas are formed on the test surface of the solar cell to be tested, and the proportion of the coverage area of ​​the grid lines in each of the metal contact areas is different. The testing device comprises: a light guide attenuation tester for testing the calibrated invisible open circuit voltage of the non-metallic contact area; A brightness tester, used to test the brightness value of the gate line of the metal contact area and the calibrated brightness value of the non-metal contact area; The controller comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the testing method according to any one of claims 1 to 4 when executing the computer program.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the testing method according to any one of claims 1 to 4 are implemented.

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