Test method and abnormality analysis method for back contact cell

Abstract

The application discloses a kind of back contact cell test method and abnormal analysis method, the test method includes: the back contact cell to be measured is cut to obtain test sample piece;Two first electrodes on the test sample piece are obtained at different intervals Transmission resistance;The interval between two first electrodes and transmission resistance are fitted as a straight line;According to the straight line fitted to obtain the evaluation parameter of back contact cell, the evaluation parameter includes at least one of the square resistance of silicon substrate and the contact resistivity of first doped region.The application changes the test principle and method of back contact cell, without using special sample preparation, can directly test and abnormal analysis on finished back contact cell parameter.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a testing method and anomaly analysis method for back-contact solar cells. Background Technology

[0002] In existing BC (Back Contact) solar cells, the sheet resistance R of the silicon substrate is... sheet N / P region contact resistivity ρ c These parameters can only be tested through special sample preparation, that is, by preparing N-region and N-gate electrodes or P-region and P-gate electrodes only on a silicon substrate. However, in the finished BC battery, the electron transport path is different from that in the special sample preparation. The parameters obtained through special sample preparation cannot fully represent the parameters of the finished BC battery. Therefore, it is not possible to effectively test the parameters and analyze anomalies of the finished BC battery.

[0003] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a testing method and anomaly analysis method for back contact batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a testing method and anomaly analysis method for back contact batteries, so as to realize parameter testing and anomaly analysis of finished BC batteries.

[0005] To achieve the above objectives, an embodiment of the present invention provides the following technical solution:

[0006] A test method for a back-contact battery, the test method comprising:

[0007] The back contact cell to be tested is cut to obtain a test sample. The test sample includes a silicon substrate, a first doped region and a second doped region located on the back light surface of the silicon substrate and distributed at intervals, a first electrode electrically in contact with the first doped region and a second electrode electrically in contact with the second doped region.

[0008] Obtain the transmission resistance of the two first electrodes on the test sample at different spacings;

[0009] The distance between the two first electrodes and the transmission resistance are fitted to a straight line;

[0010] Evaluation parameters for the back contact cell are obtained based on the fitted straight line. These evaluation parameters include at least one of the sheet resistance of the silicon substrate and the contact resistivity of the first doped region.

[0011] In one embodiment, the sheet resistance R of the silicon substrate sheet For: R sheet =k*W;

[0012] Wherein, the horizontal coordinate x of the straight line is the distance between the two first electrodes, the vertical coordinate y is the transmission resistance between the two first electrodes, k is the slope of the straight line, and W is the width of the test sample.

[0013] In one embodiment, the contact resistivity ρ of the first doped region c For: ρ c =k*W*L T 2 ;

[0014] Wherein, the x-coordinate of the straight line is the distance between the two first electrodes, the y-coordinate is the transmission resistance between the two first electrodes, k is the slope of the straight line, W is the width of the test sample, and L... T The transmission distance is 1 / 2 of the x-intercept of the line.

[0015] In one embodiment, the transmission resistance is tested using a resistance testing device, which includes a first probe and a second probe. The first probe is fixed in electrical contact with a first electrode, and the second probe is in electrical contact with different first electrodes.

[0016] In one embodiment, the silicon substrate is an N-type silicon substrate, the first doped region is N-type doped, and the second doped region is P-type doped; or,

[0017] The silicon substrate is a P-type silicon substrate, the first doped region is P-type doped, and the second doped region is N-type doped.

[0018] Another embodiment of the present invention provides the following technical solution:

[0019] A test method for a back-contact battery, the test method comprising:

[0020] The back contact cell to be tested is cut to obtain a test sample. The test sample includes a silicon substrate, a first doped region and a second doped region located on the back light surface of the silicon substrate and distributed at intervals, a first electrode electrically in contact with the first doped region and a second electrode electrically in contact with the second doped region.

[0021] Obtain the transmission resistance of the first and second electrodes on the test sample at different spacings;

[0022] The distance between the first electrode and the second electrode and the transmission resistance are fitted to a straight line;

[0023] The evaluation parameters of the back contact battery are obtained based on the fitted straight line, where the evaluation parameters are the intercepts of the straight line.

[0024] In one embodiment, the transmission resistance is tested using a resistance testing device, which includes a first probe and a second probe, wherein...

[0025] The first probe is fixed in electrical contact with a first electrode, and the second probe is in electrical contact with different second electrodes; or, the first probe is fixed in electrical contact with a second electrode, and the second probe is in electrical contact with different first electrodes.

[0026] In one embodiment, the x-coordinate of the straight line is the distance between the first electrode and the second electrode, the y-coordinate is the transmission resistance between the first electrode and the second electrode, and the evaluation parameter is the x-intercept of the straight line.

[0027] In one embodiment, the silicon substrate is an N-type silicon substrate, the first doped region is N-type doped, and the second doped region is P-type doped; or,

[0028] The silicon substrate is a P-type silicon substrate, the first doped region is P-type doped, and the second doped region is N-type doped.

[0029] Another embodiment of the present invention provides the following technical solution:

[0030] An anomaly analysis method for a back contact battery, the anomaly analysis method comprising:

[0031] Obtain IV performance parameters for batteries with different back contacts;

[0032] Determine whether the back contact battery is abnormal based on the IV performance parameters. If the result is abnormal, then use the above test method to test the back contact battery.

[0033] In one embodiment, the IV performance parameters include at least one of short-circuit current Isc, open-circuit voltage Voc, fill factor FF, conversion efficiency Eff, parallel resistance Rsh, series resistance Rs, and short-circuit current density Jsc.

[0034] In one embodiment, determining whether the back contact battery is abnormal based on IV performance parameters includes:

[0035] Using the back contact battery with the highest IV performance parameter as a benchmark, the deviation amplitude of the IV performance parameter of each back contact battery is obtained. If the deviation amplitude is greater than or equal to the preset amplitude, the back contact battery is determined to be abnormal.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention, by changing the testing principle and method of back contact batteries, can directly perform parameter testing and anomaly analysis on finished back contact batteries, which can reduce the process experiment tracking of special sample preparation processes and save manpower, material resources and costs for experimental tracking. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the testing principle for special sample preparation in region N in the existing technology;

[0040] Figure 2 This is a schematic diagram of the testing principle for special sample preparation in region P in the existing technology;

[0041] Figure 3 This is a flowchart illustrating a back-contact battery testing method according to the present invention.

[0042] Figure 4 This is a flowchart illustrating another back-contact battery testing method in this invention.

[0043] Figure 5 This is a partial structural diagram of the test sample in Embodiment 1 of the present invention;

[0044] Figure 6 This is a schematic diagram of the test of the transmission resistance of the N-region on the test sample in Embodiment 1 of the present invention;

[0045] Figure 7 This is a straight line graph obtained by fitting the N region of the high-resistivity test sample in Embodiment 1 of the present invention;

[0046] Figure 8 This is a straight line graph obtained by fitting the N region of the low-resistivity test sample in Embodiment 2 of the present invention;

[0047] Figure 9 This is a partial structural diagram of the test sample in Embodiment 3 of the present invention;

[0048] Figure 10 This is a schematic diagram of the test of the transmission resistance of the NP region on the test sample in Embodiment 3 of the present invention;

[0049] Figure 11 This is a line graph obtained by fitting the NP region of the high-resistivity test sample in Embodiment 3 of the present invention;

[0050] Figure 12 This is a straight line graph obtained by fitting the NP region of the low-resistivity test sample in Embodiment 4 of the present invention. Detailed Implementation

[0051] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0052] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0053] Figure 1 The diagram shown illustrates the testing principle of a special sample preparation method for the N-region in the prior art. This special sample preparation method for the N-region is a special sample preparation method for TBC batteries, and includes:

[0054] The silicon substrate 10' is the same as the silicon substrate in the finished TBC cell, for example, an N-type silicon substrate;

[0055] The tunneling layer 111' can be one or a combination of silicon oxide layer and silicon oxynitride layer, and its thickness is consistent with that in the finished TBC battery, which is 0.5nm to 3nm, preferably 1.5nm to 2.5nm.

[0056] The N-type doped layer 121' is an N-type doped polycrystalline silicon layer, such as a phosphorus-doped layer, with a thickness consistent with that in the finished TBC battery, ranging from 1 nm to 150 nm, preferably from 50 nm to 100 nm.

[0057] The passivation layer 131' is the same as the passivation layer in the finished TBC battery, and can be an aluminum oxide passivation layer, etc., with a thickness of 2nm to 7nm, preferably 3nm to 6nm.

[0058] Antireflection layer 141' is the same as the antireflection layer in the finished TBC battery. It can be a stacked film formed by any one or more of silicon nitride layer, silicon oxynitride layer, and silicon oxide layer, with a thickness of 60nm to 130nm.

[0059] The first electrode 151' is a grid line electrode with line width and spacing consistent with the fine grid in the finished TBC battery, and it penetrates the antireflection layer 141' and the passivation layer 131' and is in contact with the N-type doped layer 121'.

[0060] In this special N-region sample preparation, the silicon substrate is N-type. Electrons will be transported through two paths: the N-type doped layer 121' and the silicon substrate 10'. The transport resistance of the N-type doped layer 121' is smaller than that of the silicon substrate 10', and most electrons will be transported through the N-type doped layer 121'. Figure 1 In path ①, a small number of electrons will be transported from the silicon substrate 10', such as... Figure 1 Path ② in the diagram; during TLM testing, parameters such as the contact resistivity of path ① + path ② can be measured through linear fitting.

[0061] However, in finished batteries, electrons cannot be transported via path ①, but only via path ②. Therefore, the values ​​obtained from the special sample test in region N cannot fully represent parameters such as the contact resistivity of the finished battery.

[0062] Figure 2 The diagram shown illustrates the testing principle of a special sample preparation method for the P-region in the prior art. This special sample preparation method for the P-region is a special sample preparation method for TBC batteries, and it includes:

[0063] The silicon substrate 10' is the same as the silicon substrate in the finished TBC cell, for example, an N-type silicon substrate;

[0064] The tunneling layer 112' can be one or a combination of silicon oxide layer and silicon oxynitride layer, and its thickness is consistent with that in the finished TBC battery, which is 0.5nm to 3nm, preferably 1.5nm to 2.5nm.

[0065] The P-type doped layer 122' is a P-type doped polycrystalline silicon layer, such as a boron-doped layer, with a thickness consistent with that in the finished TBC cell, ranging from 1 nm to 150 nm, preferably from 50 nm to 100 nm.

[0066] The passivation layer 132' is the same as the passivation layer in the finished TBC battery, and can be an aluminum oxide passivation layer, etc., with a thickness of 2nm to 7nm, preferably 3nm to 6nm.

[0067] Antireflection layer 142' is the same as the antireflection layer in the finished TBC battery. It can be a stacked film formed by any one or more of silicon nitride layer, silicon oxynitride layer, and silicon oxide layer, with a thickness of 60nm to 130nm.

[0068] The second electrode 152' is a grid line electrode, the line width, spacing and the like of which are consistent with the fine grid in a finished TBC cell, and the second electrode 152' penetrates through the anti-reflection layer 142' and the passivation layer 132' and contacts the P-type doped layer 122'.

[0069] In the special sample preparation for the P region, the silicon substrate is N-type, and electrons can only be transmitted from the P-type doped layer 122', as shown in Figure 2 path ③; during TLM testing, parameters such as the contact resistivity of path ③ can be measured through linear fitting.

[0070] The above two special sample preparation testing methods can only perform anomaly monitoring on silicon wafers of special sample preparation batches. In the actual anomaly analysis process of mass production, the electrical performance of the cell can only be measured after the cell is printed and sintered. For the analysis of abnormal cells, due to the special structural characteristics of the back contact cell, it cannot be directly obtained through the special sample preparation method.

[0071] Refer Figure 3 , the present invention discloses a testing method for a back contact cell, comprising:

[0072] cutting a back contact cell to be tested to obtain a test sample;

[0073] obtaining the transmission resistance of two first electrodes on the test sample under different spacings;

[0074] fitting the spacing between the two first electrodes and the transmission resistance into a straight line;

[0075] obtaining evaluation parameters of the back contact cell according to the fitted straight line, wherein the evaluation parameters include at least one of the sheet resistance of the silicon substrate and the contact resistivity of the first doped region.

[0076] Refer Figure 4 , the present invention also discloses a testing method for a back contact cell, comprising:

[0077] cutting a back contact cell to be tested to obtain a test sample;

[0078] obtaining the transmission resistance of the first electrode and the second electrode on the test sample under different spacings;

[0079] fitting the spacing between the first electrode and the second electrode and the transmission resistance into a straight line;

[0080] obtaining evaluation parameters of the back contact cell according to the fitted straight line, wherein the evaluation parameter is the intercept of the straight line.

[0081] In addition, the present invention also discloses an anomaly analysis method for a back contact cell, comprising:

[0082] obtaining IV performance parameters of different back contact cells;

[0083] Determine whether the back contact battery is abnormal based on the IV performance parameters. If so, test the back contact battery using the above-mentioned test method.

[0084] Existing technologies for back-contact batteries can only perform parameter testing through special sample preparation and can only monitor a specific batch of battery cells. However, this invention, by changing the testing principle and method, can directly perform parameter testing and anomaly analysis on finished back-contact batteries, which can reduce the process experiment tracking of special sample preparation and save manpower, material resources and costs for experimental tracking.

[0085] The present invention will be further described below with reference to specific embodiments.

[0086] Example 1:

[0087] Combination Figure 3 As shown, the testing method for the back contact battery in this embodiment includes the following steps:

[0088] S11. Cut the back contact battery to be tested to obtain the test sample;

[0089] S12. Obtain the transmission resistance of the two first electrodes on the test sample at different spacings;

[0090] S13. Fit the distance between the two first electrodes and the transmission resistance to a straight line;

[0091] S14. Obtain the evaluation parameters of the back contact cell based on the fitted straight line. The evaluation parameters include at least one of the sheet resistance of the silicon substrate and the contact resistivity of the first doped region.

[0092] Specifically, in this embodiment, the back contact battery is described using a TBC battery as an example. Figure 5 The diagram shown is a partial structural schematic of the test sample in this embodiment. The test sample includes:

[0093] The silicon substrate 10 includes a first surface and a second surface disposed opposite to each other. The second surface includes a first region and a second region distributed at intervals. The first surface is the front side (i.e., the main light-receiving surface) of the silicon substrate 10, and the second surface is the back side (i.e., the secondary light-receiving surface) of the silicon substrate. In this embodiment, the silicon substrate 10 is an N-type silicon substrate.

[0094] The tunneling layer 11 can be one or a combination of silicon oxide layer and silicon oxynitride layer, with a thickness of 0.5nm to 3nm, preferably 1.5nm to 2.5nm.

[0095] The first doped region 121 and the second doped region 122 are respectively located in a first region and a second region of a second surface of a silicon substrate 10. The first doped region 121 is N-type doped, which may be a phosphorus-doped polycrystalline silicon (poly) layer with a thickness of 1 nm to 150 nm, preferably 50 nm to 100 nm. The second doped region 122 is P-type doped, which may be a boron-doped polycrystalline silicon (poly) layer with a thickness of 1 nm to 150 nm, preferably 50 nm to 100 nm;

[0096] A passivation layer 13, which may be an aluminum oxide passivation layer, having a thickness of 2 nm to 7 nm, preferably 3 nm to 6 nm;

[0097] An anti-reflection layer 14, which may be a laminated film formed by any one or more of a silicon nitride layer, a silicon oxynitride layer and a silicon oxide layer, having a thickness of 60 nm to 130 nm;

[0098] A first electrode 151 and a second electrode 152, both of which are grid line electrodes. The first electrode 151 penetrates through the anti-reflection layer 14 and the passivation layer 13 and is in contact with the first doped region 121, and the second electrode 152 penetrates through the anti-reflection layer 14 and the passivation layer 13 and is in contact with the second doped region 122.

[0099] In step S11, a plurality of Figure 5 test samples shown are obtained by cutting from a finished interdigitated back contact cell firstly. The cutting width is designed according to actual requirements, but it is necessary to ensure that each test sample has a plurality of first electrodes 151 and a plurality of second electrodes 152. The width of the cut test sample can be 6 mm, 8 mm, etc. Illustratively, in this embodiment, the width W of the test sample is 6 mm, and each test sample includes more than 8 first electrodes 151 and more than 8 second electrodes 152.

[0100] In step S12, the transfer resistance of two first electrodes 151 on the test sample at different spacings is obtained.

[0101] Reference Figure 5 and in combination with Figure 6 shown, the test sample in this embodiment is a high-resistance test sample cut from a high-resistance (for example, the resistivity is 5Ω·cm to 9Ω·cm) interdigitated back contact cell. The two first electrodes on the test sample are one first electrode and another first electrode located on the same side of the first electrode.

[0102] Reference Figure 6As shown, in this embodiment, the test sample uses eight first electrodes 151-1 to 151-8 and eight second electrodes 152-1 to 152-8 as examples. The distance L1 and transmission resistance R1 between the first first electrode 151-1 and the second first electrode 151-2, the distance L2 and transmission resistance R2 between the first first electrode 151-1 and the third first electrode 151-3, and the distance between the first first electrode 151-1 and the fourth first electrode 151-4 are obtained respectively. The spacing and transmission resistance between different first electrodes are as follows: L3 and R3; L4 and R4 (distance between the first electrode 151-1 and the fifth electrode 151-5); L5 and R5 (distance between the first electrode 151-1 and the sixth electrode 151-6); L6 and R6 (distance between the first electrode 151-1 and the seventh electrode 151-7); and L7 and R7 (distance between the first electrode 151-1 and the eighth electrode 151-8). The specific spacing and transmission resistance between the different first electrodes are shown in the table below.

[0103] Table 1: Spacing and Transmission Resistance of High-Resistance Test Samples

[0104]

[0105]

[0106] The distance between the two first electrodes 151 refers to the distance between the two first electrodes 151 at the middle position. In this embodiment, the first electrodes 151 and the second electrodes 152 are distributed alternately with equal spacing. The present invention is also applicable to cases where the first electrodes 151 are not distributed with equal spacing or the second electrodes 152 are not distributed with equal spacing.

[0107] In addition, this embodiment measures the distance and transmission resistance between the first electrode 151-1 and the first electrodes 151-2 to 151-8. In other embodiments, the transmission resistance between any two first electrodes with different distances can also be measured. For example, number 2 can measure the distance and transmission resistance between the second first electrode 151-2 and the fourth first electrode 151-4, and number 3 can measure the distance and transmission resistance between the second first electrode 151-2 and the fifth first electrode 151-5. Examples will not be given here.

[0108] The transmission resistance is tested using a resistance testing device, which includes a first probe and a second probe. Preferably, the first probe is fixed in electrical contact with a first electrode, and the second probe is in electrical contact with different first electrodes, thereby optimizing the testing process and improving testing efficiency.

[0109] In this embodiment, the transmission resistance between two first electrodes is tested by a TLM (Transmission Line Modeling) tester, two TLM probes are in electrical contact with two first electrodes respectively, one TLM probe (a first TLM probe) is fixed to be in electrical contact with the first electrode 151-1, and the other TLM probe (a second TLM probe) is in electrical contact with first electrodes 151-2 to 151-8 in sequence.

[0110] The transmission resistance in this embodiment consists of three parts: the metal contact resistance R between the probes and the electrodes on both sides m , the contact resistance R between the electrode and the polysilicon c , and the sheet resistance of the intermediate silicon substrate is R sheet , both the first electrode and the second electrode of the finished back-contact solar cell are located on the back side of the silicon substrate and isolated by a Gap region. At this time, electrons can only be transmitted through the silicon substrate, satisfying R m <<R c , therefore R m can be neglected.

[0111] Refer to Figure 6 , the transmission resistance in this embodiment is: R1=2R c +R sheet1 , R2=2R c +R sheet2 , R3=2R c +R sheet3 ... and so on. R sheet1 , R sheet2 , R sheet3 etc. are proportional to the spacing between the first electrodes, therefore the spacing between the first electrodes and the transmission resistance can be approximately considered to have a proportional relationship.

[0112] In step S13, the spacing between two first electrodes and the transmission resistance are fitted into a straight line, the abscissa x of the straight line is the spacing between the two first electrodes, and the ordinate y is the transmission resistance between the two first electrodes, the fitted linear expression is y=kx+b, wherein k is the slope of the straight line.

[0113] Specifically, in this embodiment, the spacing L and the transmission resistance R in Table 1 can be fitted to obtain a straight line as shown in Figure 7 , the linear expression is y=29.25x+1.07, with a slope k=29.25.

[0114] In step S14, evaluation parameters of the back-contact solar cell are obtained according to the fitted straight line, the evaluation parameters include at least one of the sheet resistance R of the silicon substrate sheet and the contact resistivity ρ of the first doped region (N region) c .

[0115] Among them, the sheet resistance R of the silicon substrate sheet for:

[0116] R sheet =k*W;

[0117] Where k is the slope of the line and W is the width of the test sample.

[0118] In this embodiment, the sheet resistance R of the silicon substrate sheet For: R sheet =k*W=29.25*6Ω=175.44Ω.

[0119] In addition, the contact resistivity ρ of the first doped region (N region) c for:

[0120] ρ c =R sheet *L T 2 =k*W*L T 2 ;

[0121] Among them, L T The transfer length is half the x-intercept of the line.

[0122] According to the line y = 29.25x + 1.07, the transmission distance L in this embodiment is... T It is 0.018mm;

[0123] Furthermore, in this embodiment, the contact resistivity ρ of the first doped region c For: ρ c =R sheet *L T 2 =175.44 * 1000 * 0.018 2 *0.01=0.568mΩ·cm 2 .

[0124] The sheet resistance R of the silicon substrate in the high-resistivity test sample can be obtained by following the above steps. sheet and the contact resistivity ρ of the first doped region c This means that the sheet resistance R of the silicon substrate in the finished high-resistivity back contact battery was obtained. sheet and the contact resistivity ρ of the first doped region c .

[0125] Example 2:

[0126] The testing method for the back contact battery in this embodiment is basically the same as that in Embodiment 1. The difference is that the test sample in this embodiment is a low-resistance test sample cut from a low-resistance (e.g., resistivity of 0.6Ω·cm to 3Ω·cm) back contact battery.

[0127] Using the same method, the spacing and transmission resistance between different first electrodes can be obtained, as shown in the table below:

[0128] Table 2: Spacing and Transmission Resistance of Low-Resistance Test Samples

[0129] Serial Number Spacing L (mm) Transmission resistance R (Ω) 1 0.86 13.1 2 1.72 25.6 3 2.58 38.3 4 3.44 51.0 5 4.3 63.7 6 5.16 76.7 7 6.02 89.1

[0130] In this embodiment, the spacing L and transmission resistance R in Table 2 can be fitted to obtain the following... Figure 8 The line shown has the expression y = 14.77x + 0.28 and a slope k = 14.77.

[0131] The sheet resistance R of the silicon substrate in this embodiment of the low-resistivity test sample can also be obtained using the above method. sheet and the contact resistivity ρ of the first doped region c .

[0132] Specifically, the sheet resistance R of the silicon substrate sheet For: R sheet =k*W=14.77*6Ω=88.62Ω.

[0133] According to the line y = 14.77x + 0.28, the transmission distance L in this embodiment is... T It is 0.019mm;

[0134] Furthermore, in this embodiment, the contact resistivity ρ of the first doped region c For: ρ c =R sheet *L T 2 =88.62 * 1000 * 0.019 2 *0.01=0.319mΩ·cm 2 .

[0135] The sheet resistance R of the silicon substrate in the low-resistivity test sample can be obtained by following the above steps. sheet and the contact resistivity ρ of the first doped region c This means that the sheet resistance R of the silicon substrate in the finished low-resistance back contact cell was obtained. sheet and the contact resistivity ρ of the first doped region c .

[0136] It should be understood that both Example 1 and Example 2 are N-type back-contact batteries. In an N-type back-contact battery, only the contact resistivity of the N-region can be obtained, while the contact resistivity of the P-region cannot be obtained. In a P-type back-contact battery, the silicon substrate is a P-type substrate, the first doped region is a P-type doped region, and the second doped region is an N-type doped region. The contact resistivity of the P-region can also be obtained through the above method, but the contact resistivity of the N-region cannot be obtained.

[0137] Example 3:

[0138] The testing method for a back-contact battery in this embodiment comprises the following steps:

[0139] S31, cutting the back-contact battery to be tested to obtain a test sample;

[0140] S32, acquiring the transmission resistance of the first electrode and the second electrode on the test sample at different spacings;

[0141] S33, fitting the spacing between the first electrode and the second electrode and the transmission resistance into a straight line;

[0142] S34, acquiring an evaluation parameter of the back-contact battery according to the fitted straight line, wherein the evaluation parameter is the intercept of the straight line.

[0143] Step S31 in this embodiment is completely the same as step S11 in Example 1, and the test sample is a high-resistance test sample cut from a high-resistance back-contact battery, which will not be repeated herein.

[0144] In step S32, this embodiment acquires the transmission resistance of the first electrode 151 and the second electrode 152 on the test sample at different spacings.

[0145] Refer Figure 9 and combine Figure 10As shown, in this embodiment, the test sample uses eight first electrodes 151-1 to 151-8 and eight second electrodes 152-1 to 152-8 as examples. The distance L1 and transmission resistance R1 between the first first electrode 151-1 and the first second electrode 152-1, the distance L2 and transmission resistance R2 between the first first electrode 151-1 and the second second electrode 152-2, and the distance between the first first electrode 151-1 and the third second electrode 152-3 are obtained respectively. The spacing between the first and second electrodes, L3 and its transmission resistance R3; the spacing between the first electrode 151-1 and the fourth electrode 152-4, L4 and its transmission resistance R4; the spacing between the first electrode 151-1 and the fifth electrode 152-5, L5 and its transmission resistance R5; the spacing between the first electrode 151-1 and the sixth electrode 152-6, L6 and its transmission resistance R6; and the spacing between the first electrode 151-1 and the seventh electrode 152-7, L7 and its transmission resistance R7. The specific spacing and transmission resistance between the first and second electrodes are shown in the table below.

[0146] Table 3: Spacing and Transmission Resistance of High-Resistance Test Samples

[0147]

[0148]

[0149] The distance between the first electrode 151 and the second electrode 152 refers to the distance between the middle positions of the first electrode 151 and the second electrode 152. In this embodiment, the first electrode 151 and the second electrode 152 are alternately distributed with equal spacing. The present invention is also applicable to cases where the first electrode 151 is not distributed with equal spacing or the second electrode 152 is not distributed with equal spacing.

[0150] In addition, this embodiment measures the distance and transmission resistance between the first electrode 151-1 and the second electrodes 152-1 to 152-7. In other embodiments, the transmission resistance between any two first electrodes and second electrodes with different distances can also be measured. For example, number 2 can measure the distance and transmission resistance between the second first electrode 151-2 and the third second electrode 152-3, and number 3 can measure the distance and transmission resistance between the second first electrode 151-2 and the fourth first electrode 152-4. Examples will not be given here.

[0151] The transmission resistance is tested using a resistance testing device, which includes a first probe and a second probe. Preferably, the first probe is fixed in electrical contact with a single first electrode, and the second probe is in electrical contact with different second electrodes, thereby optimizing the testing process and improving testing efficiency. Alternatively, the first probe can be fixed in electrical contact with a single second electrode, and the second probe can be in electrical contact with different first electrodes.

[0152] In step S33, the distance between the first electrode and the second electrode and the transmission resistance are fitted into a straight line. The horizontal coordinate x of the straight line is the distance between the first electrode and the second electrode, and the vertical coordinate y is the transmission resistance between the first electrode and the second electrode. The expression of the fitted straight line is y = kx + b, where k is the slope of the straight line.

[0153] Specifically, in this embodiment, the spacing L and transmission resistance R in Table 3 can be fitted to obtain the following: Figure 11 The line shown has the expression y = 44.04x + 49.02.

[0154] In step S14, the evaluation parameters of the back contact battery are obtained based on the fitted straight line. The evaluation parameter is the horizontal intercept B of the straight line.

[0155] In this embodiment, the transmission resistance consists of three parts: the contact resistance R between the first electrode and the N-region polysilicon. cn The contact resistance R between the second electrode and the polycrystalline silicon in the P-region cp The sheet resistance of the silicon substrate in the middle is R. sheet In this finished back-contact battery, both the first and second electrodes are located on the back side of the silicon substrate and isolated by the gap region. In this case, electrons can only be transported from the N-region to the P-region, and cannot be transported in the reverse direction (due to excessively high reverse transport resistance). Therefore, in this embodiment, the transport resistance of the NP region is: R1 = R cn +R cp +R sheet1 R2 = R cn +R cp +R sheet2 ...and so on.

[0156] Because of the potential barrier between the silicon substrate and the PN junction in the P region, there is a transmission distance L. T In cases of fitting anomalies, the PN region test uses the horizontal intercept B of the straight line as the evaluation parameter for the back contact battery. Horizontal intercept B = R cn +R cp In this embodiment, the final x-intercept B of the line is 1.11.

[0157] It should be understood that the transmission resistance measured in this embodiment is between the same first electrode and different second electrodes. In other embodiments, the transmission resistance between the same second electrode and different first electrodes can also be measured. The linear fitting of the distance between the first electrode and the second electrode and the transmission resistance is similar to that in this embodiment, and will not be described again here.

[0158] Example 4:

[0159] The testing method for the back contact battery in this embodiment is basically the same as that in Embodiment 3. The difference is that the test sample in this embodiment is a low-resistance test sample cut from a low-resistance back contact battery.

[0160] The same method can be used to obtain the spacing and transmission resistance between the first and second electrodes, as shown in the table below:

[0161] Table 4: Spacing and Transmission Resistance of Low-Resistance Test Samples

[0162] Serial Number Spacing L (mm) Transmission resistance R (Ω) 1 0.43 79.2 2 1.29 87.5 3 2.15 96.3 4 3.01 105.0 5 3.87 113.9 6 4.73 122.3 7 5.59 133.2

[0163] Specifically, in this embodiment, the spacing L and transmission resistance R in Table 4 can be fitted to obtain the following: Figure 12 The line shown has the expression y = 10.35x + 74.20.

[0164] The evaluation parameters for the back contact battery are obtained based on the fitted straight line, and the evaluation parameter is the horizontal intercept B of the straight line. In this embodiment, the final horizontal intercept B of the straight line is 7.17.

[0165] Example 5:

[0166] This embodiment discloses an anomaly analysis method for a back contact battery, including the following steps:

[0167] S51. Obtain IV performance parameters for batteries with different back contacts;

[0168] S52. Determine whether the back contact battery is abnormal based on the IV performance parameters. If the result of the determination is abnormal, then the back contact battery is tested using the test method in Example 1.

[0169] In step S51, the IV performance parameters of the back contact battery include at least one of the following: short-circuit current Isc, open-circuit voltage Voc, fill factor FF, conversion efficiency Eff, parallel resistance Rsh, series resistance Rs, and short-circuit current density Jsc.

[0170] For example, the IV performance parameters of the high-resistance back contact battery in this embodiment are shown in the table below:

[0171] Table 5: IV Performance Parameters of High-Resistance Back Contact Batteries

[0172]

[0173] Specifically, this embodiment takes the fill factor FF as an example for analysis.

[0174] In step S52, taking the back contact battery with the highest IV performance parameter as a benchmark, the deviation amplitude of the IV performance parameter of each back contact battery is obtained. If the deviation amplitude is greater than or equal to the preset amplitude, the back contact battery is determined to be abnormal. If the deviation amplitude is less than the preset amplitude, the back contact battery is determined to be normal.

[0175] For example, in this embodiment, the highest fill factor FF among different high-resistivity cell sources was measured to be 82.76%, with a deviation amplitude of (82.76-82.02) / 82.76 = 0.9%, resulting in a 0.27% lower efficiency. If the preset amplitude of the fill factor is set to 0.5%, then cells with a deviation amplitude exceeding 0.5% are considered abnormal. In other embodiments, the selection of IV performance parameters and the setting of preset amplitudes can be made according to actual conditions, and will not be illustrated here.

[0176] The abnormal wafer was tested using the method described in Example 1. In this example, the low fill factor FF was affected by the high series resistance Rs. Analysis of the contact resistivity of the first doped region (N region) revealed that the high series resistance Rs was mainly due to the following reasons:

[0177] 1. Sheet resistance R of silicon substrate sheet Increasing the Ω by 240Ω, according to simulation calculations, reduces the impact on the fill factor FF by approximately 0.6%.

[0178] 2. Contact resistivity ρ in region N c Increase of 0.38 mΩ·cm 2 Simulation calculations show that the impact on FF is approximately 0.1% lower.

[0179] The above method can be used to analyze the anomalies of the back contact battery, and then make targeted improvements to the battery to enhance its performance.

[0180] It should be understood that the above embodiments use TBC batteries as an example for illustration. The present invention is also applicable to the testing and analysis of other types of BC batteries, such as IBC batteries, HBC batteries, HPBC batteries, ABC batteries, etc., which will not be illustrated here.

[0181] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0182] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A test method for a back-contact battery, characterized in that, The testing method includes: The back contact cell to be tested is cut to obtain a test sample. The test sample includes a silicon substrate, a first doped region and a second doped region located on the back light surface of the silicon substrate and distributed at intervals, a first electrode electrically in contact with the first doped region and a second electrode electrically in contact with the second doped region. Obtain the transmission resistance of the two first electrodes on the test sample at different spacings; The distance between the two first electrodes and the transmission resistance are fitted to a straight line; Evaluation parameters for the back contact cell are obtained based on the fitted straight line. These evaluation parameters include at least one of the sheet resistance of the silicon substrate and the contact resistivity of the first doped region.

2. The test method for a back contact battery according to claim 1, characterized in that, The sheet resistance R of the silicon substrate sheet For: R sheet =k*W; Wherein, the horizontal coordinate x of the straight line is the distance between the two first electrodes, the vertical coordinate y is the transmission resistance between the two first electrodes, k is the slope of the straight line, and W is the width of the test sample.

3. The test method for a back contact battery according to claim 1, characterized in that, The contact resistivity ρ of the first doped region c For: ρ c =k*W*L T 2 ; Wherein, the x-coordinate of the straight line is the distance between the two first electrodes, the y-coordinate is the transmission resistance between the two first electrodes, k is the slope of the straight line, W is the width of the test sample, and L... T The transmission distance is 1 / 2 of the x-intercept of the line.

4. The test method for a back contact battery according to claim 1, characterized in that, The transmission resistance is tested using a resistance testing device, which includes a first probe and a second probe. The first probe is fixed in electrical contact with a first electrode, and the second probe is in electrical contact with different first electrodes.

5. The test method for a back contact battery according to claim 1, characterized in that, The silicon substrate is an N-type silicon substrate, the first doped region is N-type doped, and the second doped region is P-type doped; or, The silicon substrate is a P-type silicon substrate, the first doped region is P-type doped, and the second doped region is N-type doped.

6. A test method for a back-contact battery, characterized in that, The testing method includes: The back contact cell to be tested is cut to obtain a test sample. The test sample includes a silicon substrate, a first doped region and a second doped region located on the back light surface of the silicon substrate and distributed at intervals, a first electrode electrically in contact with the first doped region and a second electrode electrically in contact with the second doped region. Obtain the transmission resistance of the first and second electrodes on the test sample at different spacings; The distance between the first electrode and the second electrode and the transmission resistance are fitted to a straight line; The evaluation parameters of the back contact battery are obtained based on the fitted straight line, where the evaluation parameters are the intercepts of the straight line.

7. The test method for a back contact battery according to claim 6, characterized in that, The transmission resistance is tested using a resistance testing device, which includes a first probe and a second probe. The first probe is fixed in electrical contact with a first electrode, and the second probe is in electrical contact with different second electrodes; or, the first probe is fixed in electrical contact with a second electrode, and the second probe is in electrical contact with different first electrodes.

8. The test method for a back contact battery according to claim 6, characterized in that, The x-coordinate of the straight line is the distance between the first electrode and the second electrode, the y-coordinate is the transmission resistance between the first electrode and the second electrode, and the evaluation parameter is the x-intercept of the straight line.

9. The test method for a back contact battery according to claim 6, characterized in that, The silicon substrate is an N-type silicon substrate, the first doped region is N-type doped, and the second doped region is P-type doped; or, The silicon substrate is a P-type silicon substrate, the first doped region is P-type doped, and the second doped region is N-type doped.

10. A method for anomaly analysis of a back-contact battery, characterized in that, The anomaly analysis method includes: Obtain IV performance parameters for batteries with different back contacts; The back contact battery is determined to be abnormal based on the IV performance parameters. If the result of the determination is abnormal, the back contact battery is tested using the test method of any one of claims 1 to 9.

11. The anomaly analysis method for a back contact battery according to claim 10, characterized in that, The IV performance parameters include at least one of the following: short-circuit current Isc, open-circuit voltage Voc, fill factor FF, conversion efficiency Eff, parallel resistance Rsh, series resistance Rs, and short-circuit current density Jsc.

12. The anomaly analysis method for a back contact battery according to claim 10, characterized in that, Determining whether the back contact battery is abnormal based on IV performance parameters includes: Using the back contact battery with the highest IV performance parameter as a benchmark, the deviation amplitude of the IV performance parameter of each back contact battery is obtained. If the deviation amplitude is greater than or equal to the preset amplitude, the back contact battery is determined to be abnormal.

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