Method and device for testing contact resistivity of solar cell and electronic equipment

Abstract

The invention provides a contact resistivity testing method and device for a solar cell and electronic equipment, and the method comprises the steps: cutting a solar cell to be tested from the middle of a main grid, and obtaining a rectangular cell which does not contain the main grid; obtaining the first square resistance of the heavily doped region, and obtaining the contact resistance of the rectangular battery piece by using automatic test equipment; according to the contact resistance and the first square resistance, the transmission distance between the adjacent gate electrodes in the rectangular battery piece and the contact resistivity between the gate electrodes and the silicon wafer are iteratively calculated through a transmission line method until the contact resistivity meeting the preset requirement is obtained, operation is simple, and the method is suitable for large-scale popularization and application. The method can accurately obtain the contact resistivity of the solar cell, is suitable for other types of solar cells, and is convenient to popularize.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more specifically to a method, apparatus, and electronic device for testing the contact resistivity of solar cells. Background Technology

[0002] In the field of solar cells, contact resistivity is a crucial parameter for determining the quality of contact between the metal grid lines and the silicon wafer. Lower contact resistivity indicates better contact and higher solar cell performance; conversely, higher contact resistivity indicates poorer contact and lower solar cell performance. The industry typically uses PV-tools or other automated testing equipment, all employing the Transmission Line Matrix (TLM) method. Contact electrodes are fabricated on strip-shaped semiconductor material insulated from the surrounding environment. In solar cells, this is typically achieved by cutting the finished solar cell along the main grid direction, resulting in a strip-shaped silicon wafer between the two main grids. Equally spaced grid line electrodes are mounted on this wafer, and current flows laterally from one grid line to another. The total resistance R... T From the metal resistor R M Contact resistance R C and semiconductor resistor R semi Composition. A sheet resistor R on a silicon surface can be used. sheet When treated as a semiconductor resistor R semi .

[0003] However, selective emitter (SE) solar cells refer to selectively emitted polarimetric silicon solar cells. These cells are heavily doped at the contact points between the metal grid electrodes and the silicon wafer, and lightly doped between the electrodes. The presence of these heavily and lightly doped regions results in two sheet resistances on the silicon wafer: the lightly doped sheet resistance R0. sheet轻 With heavily doped sheet resistance R sheet重 This allows the silicon wafer sheet resistance R to be measured when the contact resistivity of such solar cells is tested using automated equipment. sheet Problems will arise in the processing, leading to significant errors in the calculated contact resistivity. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method, apparatus and electronic device for testing the contact resistivity of solar cells, which is simple to operate, can accurately obtain the contact resistivity of solar cells, and is easy to promote.

[0005] According to one aspect of the present invention, an embodiment of the present invention provides a method for testing the contact resistivity of a solar cell, the solar cell comprising a silicon wafer and a plurality of grid electrodes equally spaced on the silicon wafer, wherein the region in contact with the silicon wafer by the grid electrodes is a heavily doped region, and the region between adjacent grid electrodes is a lightly doped region, the method comprising: cutting the solar cell to be tested from the middle of the main grid to obtain a rectangular cell without the main grid; obtaining a first sheet resistance of the heavily doped region and obtaining the contact resistance of the rectangular cell using an automated testing device; iteratively calculating the transmission distance between adjacent grid electrodes in the rectangular cell and the contact resistivity between the grid electrodes and the silicon wafer using the transmission line method based on the contact resistance and the first sheet resistance, until the contact resistivity that meets the preset requirements is obtained.

[0006] In one embodiment, the step of iteratively calculating the transmission distance between adjacent gate electrodes in the rectangular solar cell and the contact resistivity between the gate electrode and the rectangular solar cell using the transmission line method based on the contact resistance and the first sheet resistance, until a contact resistivity that meets a preset requirement, includes: giving any initial contact resistivity; using the initial contact resistivity as a first contact resistivity, calculating the transmission distance between the gate electrode and the silicon wafer in the rectangular solar cell based on a first relationship using the first sheet resistance and the first contact resistivity, wherein the first relationship characterizes the relationship between the transmission distance and the first contact resistivity and the first sheet resistance; calculating a second contact resistivity based on the contact resistance and the transmission distance using a second relationship, wherein the second relationship characterizes the relationship between the second contact resistivity obtained by applying the transmission line method and the contact resistance and the transmission distance; using the calculated second contact resistivity as the first contact resistivity, repeatedly iteratively calculating the transmission distance and the second contact resistivity; if the second contact resistivity meets the preset requirement, stopping the iterative calculation, and determining the second contact resistivity as the contact resistivity between the gate electrode and the silicon wafer.

[0007] In one embodiment, the second contact resistivity meeting the preset requirement means that the error between the second contact resistivity and the first contact resistivity is less than or equal to a preset difference.

[0008] In one embodiment, the step of using the initial contact resistivity as the first contact resistivity and calculating the transmission distance between the gate electrode and the silicon wafer based on a first relationship according to the first sheet resistance and the first contact resistivity includes: using the initial contact resistivity as the first contact resistivity, calculating a first ratio of the first contact resistivity to the first sheet resistance; and calculating the square root of the first ratio to obtain the transmission distance between the gate electrode and the silicon wafer.

[0009] In one embodiment, the step of calculating the second contact resistivity based on the second relationship between the contact resistance and the transmission distance includes: determining the electrode width and electrode length of the grid electrode in the rectangular battery cell; calculating the hyperbolic cotangent function value of the ratio of the electrode width to the transmission distance; and calculating a second ratio of the product of the contact resistance, the transmission distance, and the electrode length to the hyperbolic cotangent function value to obtain the second contact resistivity between the grid electrode and the rectangular battery cell.

[0010] In one embodiment, the method of obtaining the contact resistance of the rectangular solar cell using an automated testing device includes: obtaining the contact resistance of the rectangular solar cell by using the automated testing device to test the weighted average sheet resistance of the second sheet resistance of the heavily doped region and the first sheet resistance of the lightly doped region.

[0011] In one embodiment, obtaining the first sheet resistance of the heavily doped region includes: taking a silicon wafer whose entire surface is heavily doped, wherein the heavy doping concentration of the silicon wafer is the same as the heavy doping concentration of the heavily doped region; and testing the sheet resistance of the silicon wafer using a four-probe method to obtain the first sheet resistance.

[0012] According to another aspect of the present invention, an embodiment of the present invention provides a contact resistivity testing device for a solar cell, the solar cell comprising a silicon wafer and a plurality of grid electrodes equally spaced on the silicon wafer, wherein the region in contact with the silicon wafer by the grid electrodes is a heavily doped region, and the region between adjacent grid electrodes is a lightly doped region; the contact resistivity testing device for the solar cell comprises: a silicon wafer acquisition unit for cutting the solar cell to be tested from the middle of the main grid to obtain a rectangular cell without the main grid; a resistance acquisition unit for acquiring a first sheet resistance of the heavily doped region and acquiring the contact resistance of the rectangular cell using automated testing equipment; and a resistivity testing unit for iteratively calculating the transmission distance between adjacent grid electrodes in the rectangular cell and the contact resistivity between the grid electrodes and the silicon wafer using the transmission line method based on the contact resistance and the first sheet resistance, until the contact resistivity meets a preset requirement.

[0013] According to another aspect of the present invention, an electronic device is provided in one embodiment of the present invention, comprising: a memory for storing executable program code; and a processor for calling and running the executable program code from the memory, such that the processor executes the above-described method for testing the contact resistivity of a solar cell.

[0014] This invention provides a method, apparatus, and device for testing the contact resistivity of solar cells. The method involves cutting the solar cell under test from the middle of the main grid to obtain a rectangular cell excluding the main grid; obtaining the first sheet resistance of the heavily doped region; and using automated testing equipment to obtain the contact resistance of the rectangular cell. Based on the contact resistance and the first sheet resistance, the transmission line method is used to iteratively calculate the transmission distance between adjacent grid electrodes in the rectangular cell and the contact resistivity between the grid electrodes and the silicon wafer until a contact resistivity meeting preset requirements is obtained. The method is simple to operate, can accurately obtain the contact resistivity of solar cells, is applicable to other types of solar cells, and is easy to promote. Attached Figure Description

[0015] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0016] Figure 1 The diagram shown is a flowchart illustrating a method for testing the contact resistivity of a solar cell according to an embodiment of this application.

[0017] Figure 2 The diagram shown is a structural schematic of a contact resistivity testing device for solar cells provided in an embodiment of this application.

[0018] Figure 3 The diagram shown is a structural schematic of an electronic device provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Furthermore, in exemplary embodiments, since the same reference numerals denote the same components having the same structure or the same steps of the same method, if one embodiment has been described by way of example, then in other exemplary embodiments only structures or methods different from those described in the embodiment will be described.

[0021] Throughout the specification and claims, when a component is described as being “connected” to another component, that component may be “directly connected” to the other component or “electrically connected” to the other component via a third component. Furthermore, unless explicitly stated otherwise, the term “comprising” and its corresponding terms should be understood only to include the stated component and not to exclude any other component.

[0022] In related technologies, particularly in the field of solar cells, contact resistivity is a crucial parameter for determining the quality of contact between the metal grid lines and the silicon wafer. Lower contact resistivity indicates better contact and higher solar cell performance; conversely, higher contact resistivity indicates poorer contact and lower solar cell performance. The industry typically uses PV-tools or other automated testing equipment, all employing the Transmission Line Matrix (TLM) method. Contact electrodes are fabricated on strip-shaped semiconductor material insulated from the surrounding environment. In solar cells, this is typically achieved by cutting the finished solar cell along the main grid direction to obtain a strip-shaped silicon wafer between the two main grids. The wafer contains equally spaced grid line electrodes, and current flows laterally from one fine grid to another. The total resistance R... T From the metal resistor R M Contact resistance R C and semiconductor resistor R semi Composition. Since the electrical conductivity of metals is high, the metal resistance is negligible here, and we can obtain... R T =2R M +R semi +2R C ≈R semi +2R C (1) Because the current is not uniformly distributed at the cross-section where the electrode contacts the semiconductor, R cannot be directly used. C Divide by the contact area to get ρ C By introducing the transmission length L T To calculate the specific contact resistance, the sheet resistance R of the silicon surface is used. sheet When treated as a semiconductor resistor R semi We can obtain: R T =R sheet *L / W+2R C (2) R C = (R sheet *L T / W) *coth(L f / L T (3) (4) Among them, L f Let W be the electrode width, W be the electrode length, and L be the spacing between two adjacent gate electrodes. The coth function is the hyperbolic cotangent function, which is the reciprocal of the hyperbolic tangent function. By changing the transmission distance L... T The total resistance R is obtained. T A linear curve that varies with transmission distance. The slope of the curve is R. sheet / W, with an intercept of 2R on the y-axis. C The contact resistivity ρ can be calculated from equations (2), (3), and (4) above. C .

[0023] However, the TLM method in automated equipment presents certain challenges when testing SE (Selective Emitter) solar cells. SE cells are characterized by heavy doping at the contact points between the metal grid electrodes and the silicon wafer, and light doping between the electrodes. This structure reduces diffusion layer recombination and lowers the contact resistance between the metal electrodes and silicon, thereby improving conversion efficiency and cell performance. When testing the contact resistivity of such cells in automated equipment, the sheet resistance R of the silicon wafer... sheet The processing will encounter problems. This is because the presence of heavily doped and lightly doped regions will result in two sheet resistances on the silicon wafer: one for the lightly doped region and one for the lightly doped region. sheet轻 With heavily doped sheet resistance R sheet重 At this point, by changing the transmission distance L T The total resistance R is obtained. T A linear curve showing how the transmission distance changes, from which the slope R is derived. sheet / W, where R sheet This leads to a situation where the definition of R is unclear. sheet It should be R sheet轻 With R sheet重 The weighted average of the two sheet resistors, with respect to their lengths, is expressed as R. sheet轻 The main focus is on calculating the contact resistivity ρ using equations (3) and (4). C At that time, the area where the battery grid electrode contacts the silicon wafer is heavily doped, and R in equations (3) and (4) is... sheet Then it should be R. sheet重 However, during the testing process using automated testing equipment, it is impossible to distinguish R... sheet轻 With R sheet重 It only takes the slope R sheet R in / W sheet As the sheet resistance of silicon wafers is considered, the results will have a large error when calculating contact resistivity.

[0024] To address the technical problem of significant errors in contact resistivity calculation, this application provides a method for testing the contact resistivity of solar cells. Figure 1The diagram shows a flowchart illustrating a method for testing the contact resistivity of a solar cell according to an embodiment of this application. The solar cell includes a silicon wafer and a plurality of gate electrodes equally spaced on the silicon wafer. The region where the gate electrodes contact the silicon wafer is a heavily doped region, and the region between adjacent gate electrodes is a lightly doped region. Figure 1 As shown, the contact resistivity test method for this solar cell includes: Step S11: Cut the solar cell to be tested from the middle of the main grid to obtain a rectangular cell that does not include the main grid; The finished solar cell is cut from the center of the main grid using a laser cutting machine into rectangular cells of a preset width, which do not include the main grid. The preset width can be set as needed, preferably 8 cm. It should be noted that the solar cell under test can be without a main grid; it can be directly cut to obtain a rectangular cell. Alternatively, the solar cell under test can have a main grid; the main grid can be removed after or before dicing to obtain a gridless rectangular cell, allowing direct testing of the electrode width L of the rectangular cell. f The electrode length W and the distance L between adjacent electrodes are considered. A rectangular cell excluding the main grid is cut from the solar cell under test, allowing for convenient calculation of the contact resistivity using the transmission line method.

[0025] Step S12: Obtain the first sheet resistance of the heavily doped region, and use automated testing equipment to obtain the contact resistance of the rectangular solar cell.

[0026] When the solar cell under test is an SE cell, the region between adjacent grid electrodes is a lightly doped region, and the second sheet resistance of the lightly doped region is R. sheet轻 The region where the gate electrode contacts the silicon wafer is a heavily doped region, and the first sheet resistance of the heavily doped region is R. sheet重 Due to the presence of different sheet resistors, equations (2), (3), and (4) will become... R T =R sheet轻 *L / W+2R C (5) R C = (R sheet重 *L T / W) *coth(L f / L T (6) (7).

[0027] Among them, R sheet轻 With R sheet重The numerical value cannot be recognized by automated testing equipment; the automated testing equipment can only recognize the two sheet resistances, R, during the test. sheet轻 With R sheet重 The weighted average. This weighted average is related to R. sheet轻 The difference is not significant, so the weighted average equation (5) holds true, but equations (6) and (7) do not hold true, so there are errors in the measured contact resistivity and sheet resistance.

[0028] Therefore, the calculation of equations (6) and (7) requires the first sheet resistance R of the heavily doped region. sheet重 The first sheet resistance R of the heavily doped region can be obtained through testing. sheet重 When calculating the contact resistivity according to equations (6) and (7), both the transmission distance and the contact resistivity are unknown. Therefore, it is necessary to obtain the contact resistance. Automated testing equipment can be used to obtain the contact resistance of the rectangular solar cell. Since only the transmission distance and the contact resistivity are unknown in equations (6) and (7), the transmission distance and the contact resistivity can be obtained based on equations (6) and (7).

[0029] Step S13: Based on the contact resistance and the first sheet resistance, use the transmission line method to iteratively calculate the transmission distance between adjacent gate electrodes in the rectangular solar cell and the contact resistivity between the gate electrode and the silicon wafer until the contact resistivity that meets the preset requirements is obtained.

[0030] Although the transmission distance and contact resistivity can be obtained by solving a binary equation based on known quantities using equations (6) and (7), directly solving the binary equation is computationally complex and the results may contain certain errors. In step S13, the transmission line method can be applied to iteratively calculate the transmission distance between adjacent gate electrodes in the rectangular solar cell and the contact resistivity between the gate electrode and the silicon wafer, based on equations (6) and (7). That is, given an arbitrary contact resistivity, the transmission distance is calculated based on the first block resistance and the given contact resistivity. Then, the contact resistivity is updated based on the transmission distance, contact resistance, and other known quantities. The next round of iterative calculation is then performed based on the updated contact resistivity until the calculated contact resistivity meets the preset requirements. The contact resistivity calculated in the last iteration is the final contact resistivity, which simplifies the calculation and provides an accurate contact resistivity.

[0031] This invention provides a method for testing the contact resistivity of a solar cell. The method involves cutting the solar cell under test from the middle of the main grid to obtain a rectangular cell without the main grid; obtaining the first sheet resistance of the heavily doped region; and using automated testing equipment to obtain the contact resistance of the rectangular cell. Based on the contact resistance and the first sheet resistance, the transmission line method is used to iteratively calculate the transmission distance between adjacent grid electrodes in the rectangular cell and the contact resistivity between the grid electrodes and the silicon wafer until a contact resistivity meeting preset requirements is obtained. This method is simple to operate, can accurately obtain the contact resistivity of solar cells, is applicable to other types of solar cells, and is easy to promote.

[0032] In one embodiment, obtaining the first sheet resistance of the heavily doped region includes: taking a silicon wafer whose entire surface is heavily doped, wherein the heavy doping concentration of the silicon wafer is the same as the heavy doping concentration of the heavily doped region; and testing the sheet resistance of the silicon wafer using a four-probe method to obtain the first sheet resistance. A silicon wafer whose entire surface is heavily doped ensures uniform doping concentration and that it matches the doping concentration of the heavily doped region, accurately characterizing the heavily doped region. The four-probe method for testing sheet resistance is simple to operate and can accurately obtain the first sheet resistance of the heavily doped region. It should be noted that during the fabrication process of solar cells, the workshop is generally monitored, tracking various performance parameters. Therefore, in one embodiment, the first sheet resistance of the heavily doped region can also be directly extracted from the monitoring data.

[0033] In one embodiment, the method of obtaining the contact resistance of the rectangular solar cell using an automated testing device includes: obtaining the contact resistance of the rectangular solar cell by measuring the weighted average sheet resistance of the second sheet resistance of the heavily doped region and the first sheet resistance of the lightly doped region using the automated testing device. The cut rectangular solar cell is placed on the automated testing device, and the measurement parameters of the rectangular solar cell are input, including: the electrode width L of the rectangular solar cell. f The electrode length W and the spacing L between two adjacent gate electrodes are defined. The automated testing equipment obtains the weighted average sheet resistance of the rectangular solar cell based on the second sheet resistance of the heavily doped region and the first sheet resistance of the lightly doped region, and then uses this weighted average resistance to test and obtain the contact resistance R of the rectangular solar cell. C Due to the difference between the weighted average sheet resistance and the lightly doped sheet resistance R... sheet轻 The difference is not significant; the total resistance R in equation (5) is... T To test the resistance value, it can be obtained through testing. Since L and W are both definite values, the contact resistance R can be considered as such. C The value is accurate. Therefore, the contact resistance R measured by the automated equipment can be directly extracted. CContact resistance R can be accurately obtained through testing with automated testing equipment. C This facilitates accurate calculation of contact resistivity and helps improve the accuracy of contact resistivity calculation.

[0034] In one embodiment, the step of iteratively calculating the transmission distance between adjacent gate electrodes in the rectangular solar cell and the contact resistivity between the gate electrode and the rectangular solar cell using the transmission line method based on the contact resistance and the first sheet resistance, until a contact resistivity that meets a preset requirement, includes: giving any initial contact resistivity; using the initial contact resistivity as a first contact resistivity, calculating the transmission distance between the gate electrode and the silicon wafer in the rectangular solar cell based on a first relationship using the first sheet resistance and the first contact resistivity, wherein the first relationship characterizes the relationship between the transmission distance and the first contact resistivity and the first sheet resistance; calculating a second contact resistivity based on the contact resistance and the transmission distance using a second relationship, wherein the second relationship characterizes the relationship between the second contact resistivity obtained by applying the transmission line method and the contact resistance and the transmission distance; using the calculated second contact resistivity as the first contact resistivity, repeatedly iteratively calculating the transmission distance and the second contact resistivity; if the second contact resistivity meets the preset requirement, stopping the iterative calculation, and determining the second contact resistivity as the contact resistivity between the gate electrode and the silicon wafer.

[0035] The initial contact resistivity can be any value within the possible range of values. The possible range of contact resistivity can be determined based on needs or experience, and is preferably 0.001-0.003. To facilitate the calculation of the second contact resistivity based on the contact resistance and transmission distance, equation (7) can be substituted into equation (6) to obtain the contact resistivity ρ. C For transmission distance L T The second relation is thus obtained. This yields the transmission distance L shown in equation (7). T For contact resistivity ρ C The first relationship, and the contact resistivity ρ C For transmission distance L TThe second relation is used. Since the known quantities in the first and second relations differ, subsequent iterations can be used based on the first relation to obtain a simple solution, rather than directly solving the equations, to obtain the final contact resistivity. During iteration, the initial contact resistivity is used as the first contact resistivity. Based on the first sheet resistance and the first contact resistivity, the transmission distance between the grid electrode and the silicon wafer in the rectangular solar cell is calculated using the first relation, yielding the transmission distance for the first iteration. Then, based on the contact resistance and the first iteration transmission distance, the second contact resistivity is calculated using the second relation, yielding the contact resistivity for the first iteration, completing one iteration. The calculated second contact resistivity is used as the first contact resistivity, i.e., based on the contact resistivity for the first iteration and the first relation, to begin the next round of iterations. It is determined whether the contact resistivity obtained in the current iteration meets the preset conditions. If it does, the iteration stops, and the second contact resistivity obtained in the last iteration is used as the final contact resistivity. By iteratively calculating the transmission distance and contact resistivity based on the first and second relations, complex equation solving is not required, making the operation simple and accurately obtaining the contact resistivity of the solar cell.

[0036] In one embodiment, the second contact resistivity meeting the preset requirement means that the error between the second contact resistivity and the first contact resistivity is less than or equal to a preset difference. The preset difference can be set as needed and is not specifically limited here. Considering that the iterative calculation of transmission distance and contact resistivity cannot continue indefinitely, the iterative calculation needs to be terminated when the requirement is met to obtain the final contact resistivity. The second contact resistivity is the contact resistivity calculated in the current iteration, and the first contact resistivity is the contact resistivity calculated in the previous iteration. If the error between the second contact resistivity and the first contact resistivity is less than or equal to the preset difference, it indicates that the contact resistivity calculated in the current iteration is very close to the actual contact resistivity. Therefore, the iteration can be terminated, and the contact resistivity obtained in the last iteration can be used as the final contact resistivity, thus accurately obtaining the contact resistivity of the solar cell.

[0037] In one embodiment, the step of calculating the transmission distance between the gate electrode and the silicon wafer based on the first formula using the initial contact resistivity as the first contact resistivity and the first sheet resistance includes: using the initial contact resistivity as the first contact resistivity, calculating a first ratio of the first contact resistivity to the first sheet resistance; calculating the square root of the first ratio to obtain the transmission distance between the gate electrode and the silicon wafer. According to formula (7), using the first contact resistivity and the first sheet resistance as known quantities, the first ratio of the two is calculated, and then the square root of the first ratio is calculated to obtain the transmission distance between the gate electrode and the silicon wafer. In the calculation process, the contact resistivity is a known quantity, and the transmission distance is directly calculated through the determined first formula without the need for equation solving, which simplifies the calculation. The first formula corresponding to formula (7) also holds in other types of solar cells, so this calculation can be applied to other types of solar cells.

[0038] In one embodiment, the step of calculating the second contact resistivity based on the second relationship between the contact resistance and the transmission distance includes: determining the electrode width and electrode length of the grid electrode in the rectangular battery cell; calculating the hyperbolic cotangent function value of the ratio of the electrode width to the transmission distance; and calculating a second ratio of the product of the contact resistance, the transmission distance, and the electrode length to the hyperbolic cotangent function value to obtain the second contact resistivity between the grid electrode and the rectangular battery cell.

[0039] To facilitate the calculation of the second contact resistivity based on the contact resistance and transmission distance, equation (7) can be substituted into equation (6) and the first sheet resistance R can be eliminated. sheet重 Then, we obtain equation (8) as follows: ρ C =R C *L T *W / coth(L f / L T (8) Thus, the transmission distance L shown in equation (7) is obtained. T For contact resistivity ρ C The first relationship, and the contact resistivity ρ shown in equation (8) C For transmission distance L T The second relationship holds. This second relationship also holds for the remaining types of solar cells. In the second relationship, the electrode width L... f Electrode length W and contact resistance R C It is known, based on the transmission distance L T The contact resistivity can be directly calculated based on the second relationship corresponding to equation (8). According to equation (8), first calculate the hyperbolic cotangent function value (coth(L)) of the ratio of electrode width to transmission distance.f / L T Further calculate the contact resistance R. C Transmission distance L T and the product of electrode length W and hyperbolic cotangent function value coth(L) f / L T The second ratio is the second contact resistivity calculated at the given ratio. During the calculation, the transmission distance is known, and the second contact resistivity is calculated directly using the determined second relationship, eliminating the need for equation solving. This simplifies the calculation and is applicable to other types of solar cells.

[0040] It should be noted that the number of iterations can also be set according to needs or experience. For example, after verification, if the contact resistivity after the third iteration is found to be basically the same as that of the second iteration, it can be considered that the iteration has converged after three iterations, and the contact resistivity of the third iteration can be considered as the accurate contact resistivity.

[0041] In one embodiment, if the number of iterations is determined, the transmission distance L T and contact resistivity ρ C The iterative calculation can be implemented using a table. By adding a process of importing data into the table, the transmission distance L can be achieved. T and contact resistivity ρ C The iterative calculations and testing are relatively simple and easy to operate. This method is also applicable to other types of solar cells, facilitating its widespread adoption in other types of solar cells. For example, using automated testing equipment, the first sheet resistance was 85 ohms, the contact resistance was 1.3 ohms, the electrode length W was 0.8 mm, and the electrode width L... f It is 2.60E-03mm, that is The transmission distance and contact resistivity obtained by three iterations are shown in Table 1, with a given contact resistivity of 0.002 Ω·cm.

[0042] Table 1 Iteration Examples As can be seen from Table 1, the contact resistivity of the three iterations are 2.47E-03, 2.51E-03, and 2.52E-03, respectively. The error between adjacent iterations gradually decreases. The error between the contact resistivity of the third iteration and that of the second iteration is 1E-03, which is already very low. This indicates that the contact resistivity of the third iteration is very close to the actual contact resistivity, and the contact resistivity of the third iteration can be used as the final contact resistivity.

[0043] The contact resistivity testing method for solar cells in this application obtains the final contact resistivity through iterative calculation of transmission distance and contact resistivity. The iterative calculation can be performed using tables, making the test relatively simple and easy to operate. It is also applicable to other types of solar cells, facilitating its widespread adoption in other types of solar cells. This method solves the problem of inaccurate contact resistivity testing of SE solar cells by automated equipment. For R&D personnel, it provides more accurate test data, enabling more effective product analysis and new product development.

[0044] This invention provides a method for testing the contact resistivity of a solar cell. The method involves cutting the solar cell under test from the middle of the main grid to obtain a rectangular cell without the main grid; obtaining the first sheet resistance of the heavily doped region; and using automated testing equipment to obtain the contact resistance of the rectangular cell. Based on the contact resistance and the first sheet resistance, the transmission line method is used to iteratively calculate the transmission distance between adjacent grid electrodes in the rectangular cell and the contact resistivity between the grid electrodes and the silicon wafer until a contact resistivity meeting preset requirements is obtained. This method is simple to operate, can accurately obtain the contact resistivity of the solar cell, is applicable to other types of solar cells, and is easy to promote.

[0045] Figure 2 The diagram shows a schematic representation of a contact resistivity testing device for a solar cell according to an embodiment of this application. The solar cell includes a silicon wafer and a plurality of gate electrodes evenly spaced on the silicon wafer. The region where the gate electrodes contact the silicon wafer is a heavily doped region, and the region between adjacent gate electrodes is a lightly doped region. Figure 2 As shown, the contact resistivity testing device for this solar cell includes: The silicon wafer acquisition unit 201 is used to cut the solar cell under test from the middle of the main grid to obtain a rectangular cell without the main grid. The resistance acquisition unit 202 is used to acquire the first sheet resistance of the heavily doped region and to acquire the contact resistance of the rectangular solar cell using automated testing equipment. The resistivity testing unit 203 is used to iteratively calculate the transmission distance between adjacent gate electrodes in the rectangular solar cell and the contact resistivity between the gate electrode and the silicon wafer using the transmission line method based on the contact resistance and the first sheet resistance, until the contact resistivity that meets the preset requirements is obtained.

[0046] In one embodiment, the resistivity testing unit 203 is configured to: provide any initial contact resistivity; use the initial contact resistivity as a first contact resistivity, calculate the transmission distance between the gate electrode and the silicon wafer in the rectangular solar cell based on a first relationship and the first sheet resistance and the first contact resistivity, wherein the first relationship characterizes the relationship between the transmission distance and the first contact resistivity and the first sheet resistance; calculate and obtain a second contact resistivity based on the contact resistance and the transmission distance and a second relationship, wherein the second relationship characterizes the relationship between the second contact resistivity obtained by applying the transmission line method and the contact resistance and the transmission distance; use the calculated second contact resistivity as the first contact resistivity, repeatedly iteratively calculate the transmission distance and the second contact resistivity; if the second contact resistivity meets a preset requirement, stop the iterative calculation, and determine the second contact resistivity as the contact resistivity between the gate electrode and the silicon wafer.

[0047] In one embodiment, the second contact resistivity meeting the preset requirement means that the error between the second contact resistivity and the first contact resistivity is less than or equal to a preset difference.

[0048] In one embodiment, the resistivity testing unit 203 is further configured to: calculate a first ratio of the first contact resistivity to the first sheet resistance using the initial contact resistivity as the first contact resistivity; and calculate the square root of the first ratio to obtain the transmission distance between the gate electrode and the silicon wafer.

[0049] In one embodiment, the resistivity testing unit 203 is further configured to: determine the electrode width and electrode length of the grid electrode in the rectangular battery cell; calculate the hyperbolic cotangent function value of the ratio of the electrode width to the transmission distance; and calculate a second ratio of the product of the contact resistance, the transmission distance, and the electrode length to the hyperbolic cotangent function value to obtain the second contact resistivity between the grid electrode and the rectangular battery cell.

[0050] In one embodiment, the resistance acquisition unit 202 is used to: use automated testing equipment to test and obtain the contact resistance of the rectangular solar cell based on the weighted average sheet resistance of the second sheet resistance of the heavily doped region and the first sheet resistance of the lightly doped region.

[0051] In one embodiment, the resistance acquisition unit 202 is used to: take a silicon wafer whose entire surface is heavily doped, wherein the heavy doping concentration of the silicon wafer is the same as the heavy doping concentration of the heavily doped region; and test the sheet resistance of the silicon wafer using a four-probe method to obtain the first sheet resistance.

[0052] This invention provides a contact resistivity testing device for solar cells. A silicon wafer acquisition unit cuts the solar cell under test from the middle of the main grid to obtain a rectangular cell without the main grid. A resistance acquisition unit obtains the first sheet resistance of the heavily doped region, and an automated testing device obtains the contact resistance of the rectangular cell. The resistivity testing unit iteratively calculates the transmission distance between adjacent grid electrodes in the rectangular cell and the contact resistivity between the grid electrodes and the silicon wafer using the transmission line method based on the contact resistance and the first sheet resistance, until a contact resistivity meeting preset requirements is obtained. The device is simple to operate, can accurately obtain the contact resistivity of solar cells, is applicable to other types of solar cells, and is easy to promote.

[0053] According to another aspect of the present invention, one embodiment of the present invention provides an electronic device, Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0054] For example, such as Figure 3 As shown, the electronic device includes a memory 301 and a processor 302. The memory 301 stores executable program code 3011, and the processor 302 is used to call and execute the executable program code 3011 from the memory, so that the processor 302 executes a method for testing the contact resistivity of solar cells.

[0055] This embodiment can divide the electronic device into functional modules according to the above method embodiment. For example, each module can correspond to a separate functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and is only a logical functional division. In actual implementation, there may be other division methods.

[0056] When each functional module is divided according to its corresponding function, the electronic device may include: a silicon wafer acquisition unit, a resistance acquisition unit, and a resistivity testing unit, etc.

[0057] It should be noted that all relevant content of each step involved in the above method embodiments can be referenced from the functional description of the corresponding functional module, and will not be repeated here.

[0058] The electronic device provided in this embodiment is used to perform the above-described method for testing the contact resistivity of solar cells, and thus can achieve the same effect as the above-described implementation method.

[0059] When using integrated units, the electronic device may include a processing module and a storage module. The processing module is used to control and manage the operation of the electronic device. The storage module is used to support the execution of program code and data by the electronic device.

[0060] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits as disclosed in this application. The processor may also be a combination of computing functions, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and microprocessors, etc., and the storage module may be a memory.

[0061] This embodiment also provides a computer-readable storage medium (including but not limited to disk storage, CD-ROM, optical storage, etc.) storing computer program code. When the computer program code is run on a computer, the computer executes the above-mentioned related method steps to implement the contact resistivity testing method for solar cells provided in the above embodiment. The computer-readable storage medium may include, but is not limited to, any type of disk, including floppy disks, optical disks, Digital Video Discs (DVDs), Compact Disc Read-Only Memory (CD-ROMs), microdrives, and magneto-optical disks, read-only memory (ROMs), random access memory (RAMs), erasable programmable read-only memory (EPROMs), electrically erasable programmable read-only memory (EEPROMs), dynamic random access memory (DRAMs), video random access memory (VRAMs), flash memory devices, magnetic cards or optical cards, nanosystems (including molecular memory ICs), or any type of media or device suitable for storing instructions and / or data.

[0062] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned related steps to implement the contact resistivity testing method for solar cells provided in the above embodiment.

[0063] The beneficial effects of the above embodiments can be referred to the beneficial effects of the corresponding methods provided above, and will not be repeated here.

[0064] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0065] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0066] It should also be noted that in the apparatus or equipment of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0067] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0068] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for testing the contact resistivity of a solar cell, characterized in that, The solar cell includes a silicon wafer and a plurality of gate electrodes equally spaced on the silicon wafer. The region where the gate electrodes contact the silicon wafer is a heavily doped region, and the region between adjacent gate electrodes is a lightly doped region. The method includes: The solar cell under test is cut from the middle of the main grid to obtain a rectangular cell that does not include the main grid; Obtain the first sheet resistance of the heavily doped region, and use automated testing equipment to obtain the contact resistance of the rectangular solar cell; Based on the contact resistance and the first sheet resistance, the transmission line method is used to iteratively calculate the transmission distance between adjacent gate electrodes in the rectangular solar cell and the contact resistivity between the gate electrode and the silicon wafer until the contact resistivity that meets the preset requirements is obtained.

2. The method according to claim 1, characterized in that, The step of iteratively calculating the transmission distance between adjacent grid electrodes in the rectangular solar cell and the contact resistivity between the grid electrode and the rectangular solar cell using the transmission line method based on the contact resistance and the first sheet resistance, until the contact resistivity that meets the preset requirements, includes: Given any initial contact resistivity; Using the initial contact resistivity as the first contact resistivity, the transmission distance between the gate electrode and the silicon wafer in the rectangular solar cell is calculated based on the first sheet resistance and the first contact resistivity according to a first formula. The first formula characterizes the relationship between the transmission distance and the first contact resistivity and the first sheet resistance. The second contact resistivity is calculated based on the contact resistance and the transmission distance using a second formula, wherein the second formula characterizes the relationship between the second contact resistivity obtained by applying the transmission line method and the contact resistance and the transmission distance. Using the calculated second contact resistivity as the first contact resistivity, the transmission distance and the second contact resistivity are repeatedly and iteratively calculated; If the second contact resistivity meets the preset requirement, the iterative calculation stops, and the second contact resistivity is determined to be the contact resistivity between the gate electrode and the silicon wafer.

3. The method according to claim 2, characterized in that, The second contact resistivity meets the preset requirement if the error between the second contact resistivity and the first contact resistivity is less than or equal to the preset difference.

4. The method according to claim 2, characterized in that, The step of calculating the transmission distance between the gate electrode and the silicon wafer based on the first formula, using the initial contact resistivity as the first contact resistivity and the first sheet resistance, includes: Using the initial contact resistivity as the first contact resistivity, calculate the first ratio of the first contact resistivity to the first sheet resistance; Calculate the square root of the first ratio to obtain the transmission distance between the gate electrode and the silicon wafer.

5. The method according to claim 2, characterized in that, The step of calculating the second contact resistivity based on the second relationship between the contact resistance and the transmission distance includes: Determine the electrode width and electrode length of the grid electrode in the rectangular solar cell; Calculate the hyperbolic cotangent function value of the ratio of the electrode width to the transmission distance; The second contact resistivity between the grid electrode and the rectangular solar cell is obtained by calculating the second ratio of the product of the contact resistance, the transmission distance, and the electrode length to the hyperbolic cotangent function value.

6. The method according to claim 1, characterized in that, The application of automated testing equipment to obtain the contact resistance of the rectangular battery cell includes: The contact resistance of the rectangular solar cell is obtained by using automated testing equipment to measure the weighted average sheet resistance of the second sheet resistance of the heavily doped region and the first sheet resistance of the lightly doped region.

7. The method according to claim 1, characterized in that, The step of obtaining the first sheet resistance of the heavily doped region includes: Take a silicon wafer whose entire surface is heavily doped, wherein the heavy doping concentration of the silicon wafer is the same as the heavy doping concentration of the heavily doped region; The first sheet resistance is obtained by testing the sheet resistance of the silicon wafer using a four-probe method.

8. A contact resistivity testing device for solar cells, characterized in that, The solar cell includes a silicon wafer and a plurality of gate electrodes equally spaced on the silicon wafer. The area where the gate electrodes contact the silicon wafer is a heavily doped region, and the area between adjacent gate electrodes is a lightly doped region. The contact resistivity testing device for the solar cell includes: The silicon wafer acquisition unit is used to cut the solar cell under test from the middle of the main grid to obtain a rectangular cell without the main grid. A resistance acquisition unit is used to acquire the first sheet resistance of the heavily doped region and to acquire the contact resistance of the rectangular solar cell using automated testing equipment. The resistivity testing unit is used to iteratively calculate the transmission distance between adjacent gate electrodes in the rectangular solar cell and the contact resistivity between the gate electrode and the silicon wafer using the transmission line method based on the contact resistance and the first sheet resistance, until the contact resistivity that meets the preset requirements is obtained.

9. An electronic device, characterized in that, The electronic device includes: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, such that the processor performs the contact resistivity testing method for solar cells as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the contact resistivity testing method for solar cells as described in any one of claims 1 to 7.

Images