A method for testing the space-charge-region metal-complex current of a solar cell

Abstract

The application provides a method for testing space charge region metal composite current of a solar cell, comprising the following steps: preparing a substrate with a PN junction, and installing a graphic screen with different metalization ratios; printing corresponding target paste on the target test surface of the substrate according to different graphic screens to obtain different metalization patterns, and then performing sintering treatment to obtain a test sample and obtain J02 corresponding to each metalization pattern; and performing linear fitting according to different metalization ratios and corresponding J02 to obtain the space charge region composite current. The application has the beneficial effect that, through the change of J02 parameters of different metalization ratios, the J02 values of the metalization area and the non-metalization area can be fitted, thereby simplifying the step of testing the composite performance of different pastes, and solving the problems that, at present, complex pre-cell processing is required to test the J02 value, only one J02 value can be measured for one cell, and the speed of testing the paste performance is slow and inaccurate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical detection and analysis equipment, and particularly relates to a method for testing metal recombination current of a space charge region of a solar cell. BACKGROUND

[0002] With the development of solar cell technology and metallization technology, the influence of the metallization process on the space charge region of a solar cell has attracted more and more attention. The metal recombination of the space charge region of a solar cell is a parameter that reflects the influence of metal impurities on the PN junction region of the solar cell. The recombination size has a great influence on the FF of the solar cell, and in particular, in the structure with a tunneling layer, the metal impurities in the junction region can be directly characterized.

[0003] The recombination mechanism of the space charge region has always been an important object of research in the solar industry. The recombination current of the space charge region has a detailed parameter significance in the double-diode model of a solar cell, and can be used as an important parameter for evaluating the quality of paste. Moreover, the recombination ability of the paste can be accurately tested, and at the same time, it is also helpful for the adjustment and optimization of the on-site process. At present, the metal grid lines on the surface of the solar cell need to be removed by cleaning with inorganic acid solution or the like during testing. The cleaning process is complex, the chemical solution consumption is large, and the test results of the specified area of the solar cell are the sum of the front and back recombination currents, which makes it difficult to directly evaluate the recombination performance of the paste. SUMMARY

[0004] The present application provides a method for testing the metal recombination current of the space charge region of a solar cell, which effectively solves the problem that the metal grid lines on the surface of the solar cell need to be removed by cleaning with inorganic acid solution or the like during testing. The cleaning process is complex, the chemical solution consumption is large, and the test results of the specified area of the solar cell are the sum of the front and back recombination currents, which makes it difficult to directly evaluate the recombination performance of the paste.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a method for testing the metal recombination current of the space charge region of a solar cell, comprising:

[0006] manufacturing a substrate with a PN junction, and installing a graphic screen with different metallization ratios;

[0007] printing corresponding target paste on the target test surface of the substrate according to different graphic screens to obtain different metallization patterns, and then performing sintering treatment to obtain test samples;

[0008] testing each metallization pattern on the test sample to obtain J02 corresponding to each metallization pattern;

[0009] linear fitting the different metallization ratios and the corresponding J02 to obtain the space charge region recombination current.

[0010] Preferably, in the step of linear fitting according to different metallization ratios and corresponding J02, the metallization ratio is taken as the abscissa and the corresponding J02 is taken as the ordinate, and linear fitting is performed according to the formula

[0011] J02_metal=a+1\2*b

[0012] J02_pass=1\2*b

[0013] wherein a is the slope of the fitted straight line; b is the intercept of the straight line; J02_metal is the complex current of the metallized part; and J02_pass is the complex current of the non-metallized part.

[0014] Preferably, the metallization pattern is a pattern of a plurality of base grid lines or a pattern composed of the base grid lines and additional grid lines.

[0015] Preferably, the width of the base grid line is 20-50 μm.

[0016] Preferably, the two ends of the base grid line are in contact with the edges of the substrate.

[0017] Preferably, the number of the additional grid lines is 1-5 times the number of the base grid lines.

[0018] Preferably, the additional grid line is shorter than the base grid line and the two ends of the additional grid line are not in contact with the edges of the substrate.

[0019] Preferably, the mesh number of the pattern screen is 380-520.

[0020] Preferably, the sintering temperature for sintering treatment is determined according to the target test surface of the substrate and the target paste.

[0021] With the above technical solution, a pattern with different metallization ratios is printed on a substrate with a PN junction. The pattern is a square region with a side length of 3-5 cm, and 10-20 base grid lines are arranged in the square region. An additional grid line is printed in the middle of the base grid line, and the top end of the additional grid line is not connected to the square region. The Rs is unchanged when the Sunsvoc instrument is used for testing, and only the J02 changes due to the metallization ratio. Through the changes of the J02 parameters of different metallization ratios, the J02 values of the metallized region and the non-metallized region can be fitted, thereby simplifying the step of testing the complex performance of different pastes, solving the problem that a complex pre-battery treatment is required to test the J02 value, and only one J02 value can be measured for one battery, and the speed of testing the paste performance is slow and inaccurate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1is a metallization pattern schematic diagram of testing the metal recombination current of the space charge region of a solar cell

[0023] Figure 2 is a test sample structure schematic diagram of testing the metal recombination current of the space charge region of a solar cell

[0024] In the figure:

[0025] 1, base 2, base grid line 3, new grid line DETAILED DESCRIPTION

[0026] The application will be further described below in conjunction with embodiments and drawings:

[0027] In the description of the embodiments of the application, it should be understood that the orientation or positional relationship indicated by the terms "end" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0028] A method for testing the metal recombination current of the space charge region of a solar cell, comprising:

[0029] S1: making a base 1 with a PN junction, which can be a base of a battery structure such as NPP, PNN, etc., and installing a pattern screen with different metallization ratios, one pattern screen can have only one pattern of metallization ratio, or can have several patterns of different metallization ratios, which is designed according to the needs and the size of the pattern screen, and the pattern screen is generally designed as 9, 4 or 16 grid, etc., wherein the basic pattern is a square area, and there are 10-20 base grid lines 2 inside the square, and the thread count of the pattern screen is generally 380-520 threads; the width of the base grid line 2 is generally 20-50 μm, and the two ends of the base grid line 2 are in contact with the edge of the base 1, and the specific metallization ratio is designed to increase more new grid lines 3 between the base grid lines 2 of the square pattern, and the general metallization ratio is 3%, 6%, 9%, 12%, etc., which is determined according to the test requirements or different targets.

[0030] S2: as Figure 1 A metallization pattern schematic diagram of testing the metal recombination current of the space charge region of a solar cell and Figure 2 A test sample structure schematic diagram of testing the metal recombination current of the space charge region of a solar cell is shown, and the corresponding target paste is printed on the target test surface of the base 1 according to different pattern screens, different metallization patterns are obtained, and then sintering treatment is carried out to obtain a test sample; wherein the metallization pattern is a plurality of base grid line 2 patterns printed on the base 1 by the pattern screen according to the corresponding target paste;

[0031] The metalized pattern or the pattern composed of the base grid lines 2 and the new grid lines 3 is printed on the substrate 1 by printing the corresponding pattern with a corresponding pattern printing plate. The number of the new grid lines 3 is 1-5 times of the base grid lines 2, and the new grid lines 3 are shorter than the base grid lines 2 and do not contact the edges of the substrate 1 to keep the test Rs unchanged. The sintering temperature and the sintering time are determined according to the target test surface of the substrate 1 and the target paste, and the test sample is obtained after sintering.

[0032] S3: test each metalized pattern on the test sample by using Sunsvoc to obtain the J02 corresponding to each metalized pattern;

[0033] S4: linear fitting is performed according to different metalization ratios and corresponding J02 to obtain the space charge region recombination current, wherein,

[0034] In the step of linear fitting according to different metalization ratios and corresponding J02, the metalization ratio is taken as the abscissa, and the corresponding J02 is taken as the ordinate, linear fitting is performed, and according to the formula:

[0035] J02_metal=a+1\2*b

[0036] J02_pass=1\2*b

[0037] Wherein, a is the slope of the fitted straight line; b is the intercept of the straight line; J02_metal is the recombination current of the metalized part; J02_pass is the recombination current of the non-metal part; and the size of the recombination current of the metalized part is finally obtained.

[0038] The above technical solution uses the change of the battery J02 parameter with different metalization ratios to extract the size of the recombination current of the metal in the PN junction space charge region, provides relevant basis for the PN junction process production and characterization of the junction region passivation, provides improvement direction for the function and performance test of different metalization paste in different battery structures, and is of great significance for the development of paste. The test results also clearly show the damage of the metal to the tunneling layer for the battery structure with the tunneling layer.

[0039] The following are several specific embodiments:

[0040] Example 1

[0041] S1: make a substrate 1 with PN junction, in this embodiment, NPP battery structure is adopted, and a pattern screen with different metalization ratios is installed, one pattern screen can have only one metalization ratio pattern, or can have several different metalization ratio patterns, which is designed according to the demand and the size of the pattern screen, the pattern screen is designed as a 4-mesh design, and the basic pattern is a square area, the square area has 15 basic grid lines 2, and the mesh of the pattern screen is generally 450 meshes; the width of the basic grid line 2 is generally 35 μm, and the two ends of the basic grid line 2 are in contact with the edge of the substrate 1, and the specific metalization ratio is designed to increase more new grid lines 3 between the basic grid lines 2 of the square pattern, and the metalization ratio in this embodiment is 9%.

[0042] S2: as shown in Figure 1 A metalization pattern diagram for testing the metal recombination current of the space charge region of a solar cell and Figure 2 A test sample structure diagram for testing the metal recombination current of the space charge region of a solar cell is shown, and different metalization patterns are obtained by printing corresponding target paste on the target test surface of the substrate 1 according to different pattern screens, and then sintering treatment is performed to obtain a test sample; wherein the metalization pattern is a plurality of basic grid line 2 patterns printed on the substrate 1 by the pattern screen according to the corresponding target paste;

[0043] The metalization pattern can also be a pattern composed of basic grid lines 2 and new grid lines 3, and the corresponding target paste is printed on the substrate 1 by the corresponding pattern screen to form the pattern. The number of new grid lines 3 is 3 times that of basic grid lines 2, and the new grid lines 3 are shorter than the basic grid lines 2, and the two ends do not contact the edge of the substrate 1, so as to keep the test Rs unchanged; during sintering treatment, the sintering temperature is determined according to the target test surface of the substrate 1 and the target paste, and in this embodiment, the sintering temperature is 800 ℃, and the test sample is obtained after sintering.

[0044] S3: use Sunsvoc to test each metalization pattern on the test sample, and obtain the J02 corresponding to each metalization pattern, which is 10.2 nA\cm 2 , 23.3 nA\cm 2 , 32.1 nA\cm 2 , 45.9 nA\cm 2 ;

[0045] S4: linear fitting is performed according to different metalization ratios and corresponding J02 to obtain the space charge region recombination current, wherein,

[0046] In the step of linear fitting according to different metalization ratios and corresponding J02, the metalization ratio is taken as the abscissa, and the corresponding J02 is taken as the ordinate, and linear fitting is performed, according to the formula:

[0047] J02_metal = a + 1 / 2 * b

[0048] J02_pass = 1 / 2 * b

[0049] Wherein, a is the slope of the fitted straight line; b is the intercept of the straight line; J02_metal is the composite current of the metallized part; J02_pass is the composite current of the non-metallized part; a is 3.86 nA\cm 2 ; b is 0.99 nA\cm 2 , substituted into the formula, the final size of the composite current of the metallized part is 4.36 nA\cm 2 .

[0050] Example 2

[0051] S1: Make a substrate 1 with a PN junction, this embodiment uses NPP battery structure, and install a graphic screen with different metallization ratios, one graphic screen can have only one pattern of metallization ratio, or several patterns of different metallization ratios, according to the demand and the size of the graphic screen, the graphic screen is designed as a 4-mesh design, the basic pattern is a square area, and there are 20 basic grid lines 2 inside the square, the mesh of the graphic screen is generally 450 meshes; The width of the basic grid line 2 is generally 25 μm, and the two ends of the basic grid line 2 are in contact with the edge of the substrate 1, and the specific metallization ratio is designed to increase more new grid lines 3 between the basic grid lines 2 of the square pattern, and the metallization ratio in this embodiment is 12%.

[0052] S2: As shown in Figure 1 A schematic diagram of a metallization pattern for testing the space charge region metal recombination current of a solar cell and Figure 2 A schematic diagram of a test sample structure for testing the space charge region metal recombination current of a solar cell, as shown, the target test surface of the substrate 1 is printed with the corresponding target paste according to different graphic screens, different metallization patterns are obtained, and then sintering treatment is performed to obtain a test sample; wherein the metallization pattern is a plurality of basic grid line 2 patterns printed on the substrate 1 by the graphic screen according to the corresponding target paste;

[0053] The metallization pattern can also be a pattern composed of basic grid lines 2 and new grid lines 3, and the corresponding target paste is printed on the substrate 1 by the corresponding graphic screen to form the pattern. Wherein, the number of new grid lines 3 is 4 times that of basic grid lines 2, and the new grid lines 3 are shorter than the basic grid lines 2, and the two ends do not contact the edge of the substrate 1 to keep the test Rs unchanged; during sintering treatment, the sintering temperature is determined according to the target test surface of the substrate 1 and the target paste, in this embodiment, the sintering temperature is 810 ℃, and the test sample is obtained after sintering is completed.

[0054] S3: test each metallized pattern on the test piece using Sunsvoc test, obtain J02 corresponding to each metallized pattern, which is 22.3nA\cm 2 , 30.4nA\cm 2 , 53.2nA\cm 2 , 67.7nA\cm 2 ;

[0055] S4: linear fitting according to different metallization ratios and corresponding J02, obtain space charge region recombination current, wherein,

[0056] In the step of linear fitting according to different metallization ratios and corresponding J02, the metallization ratio is taken as the abscissa, and the corresponding J02 is taken as the ordinate, linear fitting is performed, and according to the formula:

[0057] J02_metal=a+1 / 2*b

[0058] J02_pass=1 / 2*b

[0059] Wherein, a is the slope of the fitted straight line; b is the intercept of the straight line; J02_metal is the recombination current of the metallized part; J02_pass is the recombination current of the non-metallized part; a is 3.97nA\cm 2 ; b is 3.65nA\cm 2 , substitute into the formula, finally obtain the recombination current of the metallized part is 5.7nA\cm 2 .

[0060] The above embodiments of the present application are described in detail, but the content described is only the preferred embodiments of the present application, and cannot be considered as limiting the scope of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the scope of the present application.

Claims

1. A method for testing the metal recombination current in the space charge region of a solar cell, comprising: Fabricate a substrate with a PN junction and mount graphic screens with different metallization ratios; Different metallized patterns are obtained by printing corresponding target pastes on the target test surface of the substrate according to different pattern screens, and then sintering is performed to obtain test samples; the metallized pattern is a pattern composed of several basic grid lines or a pattern composed of the basic grid lines and newly added grid lines; the two ends of the basic grid lines are in contact with the edge of the substrate; the newly added grid lines are shorter than the basic grid lines and their two ends are not in contact with the edge of the substrate. Each of the metallized patterns on the test sample is tested to obtain J02 corresponding to each of the metallized patterns; Based on different metallization ratios and the corresponding J02, a linear fit is performed to obtain the space charge region recombination current.

2. The method for testing the metal recombination current in the space charge region of a solar cell according to claim 1, characterized in that: In the step of linear fitting based on different metallization ratios and the corresponding J02, the metallization ratio is used as the abscissa and the corresponding J02 is used as the ordinate for linear fitting, according to the formula... J02_metal=a+1\2*b J02_pass=1\2*b The J02_metal and J02_pass were calculated, where, a is the slope of the fitted line; b is the intercept of the line; J02_metal is the composite current of the metallized part; J02_pass is the composite current of the non-metallized part.

3. The method for testing the metal recombination current in the space charge region of a solar cell according to claim 2, characterized in that: The width of the basic grid lines is 20-50 μm.

4. The method for testing the metal recombination current in the space charge region of a solar cell according to claim 2, characterized in that: The number of newly added grid lines is 1-5 times that of the basic grid lines.

5. A method for testing the metal recombination current in the space charge region of a solar cell according to claim 2 or 4, characterized in that: The newly added gate line is shorter than the base gate line, and its two ends do not contact the edge of the substrate.

6. The method for testing the metal recombination current in the space charge region of a solar cell according to claim 1, characterized in that: The mesh count of the graphic screen is 380-520.

7. The method for testing the metal recombination current in the space charge region of a solar cell according to claim 1, characterized in that: The sintering temperature for sintering is determined based on the target test surface of the substrate and the target slurry.

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