A method for analyzing the minority carrier lifetime of a silicon rod
By analyzing the minority carrier lifetime distribution of monocrystalline silicon rods and calculating the crystal length value and the actual minority carrier lifetime distribution value, the problem of uneven minority carrier lifetime during the mass production of silicon rods was solved, and the stability of solar cell efficiency was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JINKO SOLAR CO LTD
- Filing Date
- 2023-09-05
- Publication Date
- 2026-07-21
AI Technical Summary
During the large-scale mass production of monocrystalline silicon rods, the low segregation coefficient of metal impurities leads to a lower minority carrier lifetime for the later rods compared to the earlier rods, resulting in uneven minority carrier lifetime on the silicon wafers and affecting the stability of cell efficiency.
A method for minority carrier lifetime analysis of silicon rods is provided. By setting a standard minority carrier lifetime value, a list of test data is obtained, the crystal length of each silicon rod is determined according to a linear rule, the actual minority carrier lifetime distribution value is calculated, and the cell efficiency of the solar cell is verified to stabilize the actual minority carrier lifetime distribution value of the silicon rod.
This method achieves data quantification of minority carrier lifetime distribution in silicon rods, ensuring the stability of solar cell efficiency. By stabilizing the actual minority carrier lifetime distribution value of silicon rods, the goal of stabilizing the cell efficiency at the client end is achieved.
Smart Images
Figure CN117318615B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solar cells, and more specifically, to a method for minority carrier lifetime analysis of silicon rods. Background Technology
[0002] Currently, the monocrystalline silicon rods used in the mass production of monocrystalline silicon wafers employ a multiple crystal pulling method, where multiple rods are produced by continuously feeding the same crucible. However, due to the very low segregation coefficient of metal impurities, most metal impurities remain at the bottom of the crucible, resulting in a lower minority carrier lifetime for the later rods compared to the earlier ones. Currently, only the minimum minority carrier lifetime of the silicon rods is controlled, leading to uneven minority carrier lifetime across the entire silicon wafer, thus causing unstable cell efficiency.
[0003] Therefore, there is an urgent need to provide a method for minority carrier lifetime analysis of silicon rods, which can calculate the minority carrier lifetime distribution of monocrystalline silicon wafers and stabilize the efficiency of silicon wafer cells in different batches. Summary of the Invention
[0004] In view of this, the present invention provides a method for minority carrier lifetime analysis of silicon rods, comprising the following steps:
[0005] Preset standard minority carrier lifetime value for single-crystal silicon rods;
[0006] Obtain a list of test data for any batch of the single-crystal silicon rods;
[0007] Based on the test data list, the crystal length of each single-crystal silicon rod that satisfies the standard minority carrier lifetime value is determined according to linear rules to obtain the standard crystal length value;
[0008] The standard crystal length value is stored in the detection data list;
[0009] Obtain the standard crystal total length value and crystal total length value of any batch of the single crystal silicon rods in the test data list;
[0010] Based on the total length value of the standard crystal and the total length value of the crystal, the ratio of the total length value of the standard crystal to the total length value of the crystal is obtained, and the ratio is the actual minority carrier lifetime distribution value of the single crystal silicon rods in this batch;
[0011] Based on the actual minority carrier lifetime distribution values of this batch of monocrystalline silicon rods, the cell efficiency of the solar cells prepared from this batch of monocrystalline silicon rods is verified.
[0012] Obtain any batch of the single-crystal silicon rods and stabilize the actual minority carrier lifetime distribution value of that batch of single-crystal silicon rods.
[0013] Optionally, the single-crystal silicon rod is a P-type gallium-doped single-crystal silicon rod, and the standard minority carrier lifetime value is 250 μs; or, the single-crystal silicon rod is an N-type phosphorus-doped single-crystal silicon rod, and the standard minority carrier lifetime value is 2500 μs.
[0014] Optionally, the detection data list includes: crystal length value, minority carrier lifetime value at the crystal head, and minority carrier lifetime value at the crystal tail.
[0015] Optionally, the linear rule includes:
[0016] Determine whether the minority carrier lifetime value at the tail of the crystal is greater than the standard minority carrier lifetime value;
[0017] The minority carrier lifetime value at the tail of the crystal is greater than the standard minority carrier lifetime value, and the standard crystal length value is the crystal length value.
[0018] or,
[0019] If the minority carrier lifetime value at the tail of the crystal is less than or equal to the standard minority carrier lifetime value, then it is determined whether the minority carrier lifetime value at the head of the crystal is greater than the standard minority carrier lifetime value.
[0020] If the minority carrier lifetime value at the crystal head is greater than the standard minority carrier lifetime value, the standard crystal length value is calculated.
[0021] or,
[0022] The minority carrier lifetime value at the crystal head is less than or equal to the standard minority carrier lifetime value, and the standard crystal length value is zero.
[0023] Optionally, calculating the standard crystal length value includes:
[0024] Obtain the temporary crystal length, and round the temporary crystal length to an integer value, where the integer value is the standard crystal length value;
[0025] The temporary crystal length value = crystal length value × (head minority carrier lifetime value - standard minority carrier lifetime value) ÷ (head minority carrier lifetime value - tail minority carrier lifetime value).
[0026] Optionally, before each of the single-crystal silicon rods reaches a crystal length that satisfies the standard minority carrier lifetime value according to a linear rule, the following steps are included:
[0027] The type of the monocrystalline silicon rod is determined based on the list of test data.
[0028] Optionally, the detection data list includes a crystal code; the type of the single-crystal silicon rod is determined based on the crystal code.
[0029] Optionally, verifying the cell efficiency of the solar cells fabricated from this batch of monocrystalline silicon rods includes:
[0030] Based on the actual minority carrier lifetime distribution value of any batch of the single crystal silicon rods, the single crystal silicon rods of each batch are classified into grades;
[0031] Obtain any batch of the monocrystalline silicon rods within any grade range to prepare solar cells;
[0032] The cell efficiency of the solar cells at each preset level is used to obtain the preset cell efficiency value;
[0033] Verify the cell efficiency of the solar cells at each level to obtain the actual cell efficiency value;
[0034] The actual battery efficiency value is equal to the preset battery efficiency value, and the actual battery efficiency value of this batch of solar cells is directly stored.
[0035] or,
[0036] The actual battery efficiency value is not equal to the preset battery efficiency value. The preset battery efficiency value is adjusted according to the actual battery efficiency value, and the actual battery efficiency value of this batch of solar cells is stored.
[0037] Optionally, stabilizing the actual minority carrier lifetime distribution value of the batch of single-crystal silicon rods includes:
[0038] The minority carrier lifetime distribution of any batch of the single crystal silicon rods is preset to obtain the preset minority carrier lifetime distribution value;
[0039] Determine whether the actual minority carrier lifetime distribution value conforms to the preset minority carrier lifetime distribution value;
[0040] If the actual minority carrier lifetime distribution value is greater than or equal to the preset minority carrier lifetime distribution value, the single crystal silicon rod will proceed to the next process.
[0041] or,
[0042] The actual minority carrier lifetime distribution value is less than the preset minority carrier lifetime distribution value, thereby increasing the minority carrier lifetime distribution value of the single crystal silicon rods in this batch.
[0043] Optionally, improving the minority carrier lifetime distribution value of the single-crystal silicon rods in this batch includes:
[0044] Screen out defective silicon rods from the batch of monocrystalline silicon rods, the defective silicon rods having low minority carrier lifetime values;
[0045] Determine whether the silicon rods in the inventory have a high minority carrier lifetime value;
[0046] The stock silicon rods have high minority carrier lifetime values, and the stock silicon rods are used to replace the defective silicon rods.
[0047] or,
[0048] The stockpiled silicon rods do not have a high minority carrier lifetime value, so the minority carrier lifetime value of the stockpiled silicon rods should be increased.
[0049] Compared with existing technologies, the minority carrier lifetime analysis method for silicon rods provided by this invention achieves at least the following beneficial effects:
[0050] This invention provides a method for minority carrier lifetime analysis of silicon rods, comprising: presetting a standard minority carrier lifetime value for monocrystalline silicon rods; obtaining a test data list for any batch of monocrystalline silicon rods; determining the crystal length of each monocrystalline silicon rod that meets the standard minority carrier lifetime value according to a linear rule based on the test data list, and obtaining a standard crystal length value; storing the standard crystal length value in the test data list; obtaining the standard total crystal length value and the total crystal length value for any batch of monocrystalline silicon rods in the test data list; obtaining the ratio of the standard total crystal length value to the total crystal length value based on the standard total crystal length value and the total crystal length value, the ratio being the actual minority carrier lifetime distribution value of the batch of monocrystalline silicon rods; verifying the cell efficiency of the solar cell prepared from the batch of monocrystalline silicon rods based on the actual minority carrier lifetime distribution value of the batch of monocrystalline silicon rods; obtaining any batch of monocrystalline silicon rods and stabilizing the actual minority carrier lifetime distribution value of the batch of monocrystalline silicon rods. By calculating the actual minority carrier lifetime distribution value of monocrystalline silicon rods, the relationship between the minority carrier lifetime distribution value of silicon rods and the cell efficiency of solar cells is obtained, and in the mass production process, by stabilizing the actual minority carrier lifetime distribution value of silicon rods, the goal of stabilizing the cell efficiency of the end user is achieved.
[0051] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time.
[0052] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description
[0053] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.
[0054] Figure 1 This is a flowchart of a method for minority carrier lifetime analysis of silicon rods provided by the present invention;
[0055] Figure 2 This is a flowchart illustrating the method for analyzing the minority carrier lifetime of silicon rods provided by this invention, used to verify the cell efficiency of solar cells fabricated from monocrystalline silicon rods.
[0056] Figure 3 This is a flowchart illustrating the actual minority carrier lifetime distribution value of a stable single-crystal silicon rod in the minority carrier lifetime analysis method provided by this invention.
[0057] Figure 4This is a flowchart illustrating how to improve the minority carrier lifetime distribution value of a single-crystal silicon rod in the minority carrier lifetime analysis method provided by this invention. Detailed Implementation
[0058] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the invention.
[0059] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.
[0060] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.
[0061] In all the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.
[0062] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.
[0063] Reference Figure 1 This invention provides a method for minority carrier lifetime analysis of silicon rods, comprising the following steps:
[0064] Preset standard minority carrier lifetime value for single-crystal silicon rods;
[0065] Obtain a list of test data for any batch of monocrystalline silicon rods;
[0066] Based on the test data list, the crystal length of each single-crystal silicon rod that meets the standard minority carrier lifetime value is determined according to the linear rule, and the standard crystal length value is obtained.
[0067] Store the standard crystal length value in the detection data list;
[0068] Obtain the standard crystal total length value and crystal total length value of any batch of monocrystalline silicon rods in the test data list;
[0069] Based on the standard crystal total length value and the crystal total length value, the ratio of the standard crystal total length value to the crystal total length value is obtained. The ratio is the actual minority carrier lifetime distribution value of this batch of single crystal silicon rods.
[0070] The cell efficiency of the solar cells prepared from this batch of monocrystalline silicon rods was verified based on the actual minority carrier lifetime distribution values of this batch of monocrystalline silicon rods.
[0071] Obtain any batch of single-crystal silicon rods and stabilize the actual minority carrier lifetime distribution value of that batch of single-crystal silicon rods.
[0072] It should be noted that minority carrier lifetime refers to the average survival time of minority carriers, and lifetime indicates the time it takes for the minority carrier concentration to decrease to 1 / e of its original value. For solar cells, the shorter the minority carrier lifetime, the lower the cell efficiency.
[0073] Understandably, by calculating the ratio of the actual minority carrier lifetime distribution value (i.e., the standard crystal total length value) to the total crystal length value of a single-crystal silicon rod, the minority carrier lifetime distribution of any batch of silicon rods can be quantified. Furthermore, the relationship between the minority carrier lifetime distribution value of the silicon rod and the cell efficiency of the solar cell can be obtained. During mass production, by stabilizing the actual minority carrier lifetime distribution value of the silicon rod, the goal of stabilizing the cell efficiency for end-users can be achieved.
[0074] In some optional embodiments, the single-crystal silicon rod is a P-type gallium-doped single-crystal silicon rod with a standard minority carrier lifetime of 250 μs; or, the single-crystal silicon rod is an N-type phosphorus-doped single-crystal silicon rod with a standard minority carrier lifetime of 2500 μs.
[0075] It should be noted that semiconductor materials contain two types of charge carriers: electrons and holes. If a certain type of charge carrier is in the minority and plays a minor role in conductivity, it is called a minority carrier. For example, in an N-type semiconductor, holes are minority carriers and electrons are majority carriers; in a P-type semiconductor, holes are majority carriers and electrons are minority carriers. Therefore, a P-type gallium-doped single-crystal silicon rod has electrons as the minority carrier, with a standard minority carrier lifetime of 250 μs; an N-type phosphorus-doped single-crystal silicon rod has holes as the minority carrier, with a standard minority carrier lifetime of 2500 μs.
[0076] In some optional embodiments, the list of detection data includes: crystal length value, minority carrier lifetime value at the crystal head, and minority carrier lifetime value at the crystal tail.
[0077] Understandably, by obtaining the minority carrier lifetime values at the crystal head and tail, and comparing these values with standard minority carrier lifetime values, the total crystal length of a single-crystal silicon rod can be obtained. Furthermore, the standard total crystal length value for any batch of silicon rods can be obtained. The total crystal length value for any batch of silicon rods can be obtained from the crystal length values of each rod. Finally, by calculating the ratio of the standard total crystal length value to the total crystal length value, the actual minority carrier lifetime distribution value for any batch of single-crystal silicon rods can be obtained.
[0078] In some alternative embodiments, the linearity rule includes:
[0079] Determine whether the minority carrier lifetime value at the tail of the crystal is greater than the standard minority carrier lifetime value;
[0080] The minority carrier lifetime value at the tail of the crystal is greater than the standard minority carrier lifetime value, and the standard crystal length value is the crystal length value.
[0081] or,
[0082] If the minority carrier lifetime value at the tail of the crystal is less than or equal to the standard minority carrier lifetime value, then determine whether the minority carrier lifetime value at the head of the crystal is greater than the standard minority carrier lifetime value; if the minority carrier lifetime value at the head of the crystal is greater than the standard minority carrier lifetime value, calculate the standard crystal length value.
[0083] or,
[0084] The minority carrier lifetime value at the crystal head is less than or equal to the standard minority carrier lifetime value, and the standard crystal length value is zero.
[0085] It should be noted that silicon rods typically have a higher minority carrier lifetime at the head and a lower lifetime at the tail.
[0086] For example, if the minority carrier lifetime value at the crystal head is less than or equal to the standard minority carrier lifetime value, then by default the minority carrier lifetime value at the crystal tail is less than or equal to the standard minority carrier lifetime value, and there is no need to measure the minority carrier lifetime value at the crystal tail. In this case, the standard crystal length value of the silicon rod is zero.
[0087] For example, if the minority carrier lifetime value at the tail of the crystal is greater than the standard minority carrier lifetime value, then it is assumed that the minority carrier lifetime value at the tail of the crystal is greater than the standard minority carrier lifetime value, and there is no need to measure the minority carrier lifetime value at the head of the crystal. In this case, the crystal length value is the standard crystal length value.
[0088] For example, if the minority carrier lifetime value at the tail of the crystal is less than or equal to the standard minority carrier lifetime value, and the minority carrier lifetime value at the head of the crystal is greater than the standard minority carrier lifetime value, the standard crystal length value of the silicon rod can be further calculated using the minority carrier lifetime value at the tail of the crystal, the minority carrier lifetime value at the head of the crystal, and the standard minority carrier lifetime value.
[0089] In some optional embodiments, calculating the standard crystal length value includes:
[0090] Obtain the temporary crystal length, round the temporary crystal length to an integer value, and the integer value is the standard crystal length value;
[0091] Temporary crystal length value = crystal length value × (head minority carrier lifetime value - standard minority carrier lifetime value) ÷ (head minority carrier lifetime value - tail minority carrier lifetime value).
[0092] Understandably, the standard crystal length of a silicon rod can be calculated by substituting the minority carrier lifetime values at the tail of the crystal, the minority carrier lifetime values at the head of the crystal, and the standard minority carrier lifetime value into the formula.
[0093] In some optional embodiments, before each monocrystalline silicon rod is calibrated to obtain a crystal length that satisfies the standard minority carrier lifetime value according to a linear rule, the type of monocrystalline silicon rod is determined based on a list of test data.
[0094] It should be noted that, since the standard minority carrier lifetime values of P-type silicon rods and N-type silicon rods are different, the standard minority carrier lifetime value of P-type gallium-doped single crystal silicon rod is 250 μs, and the standard minority carrier lifetime value of N-type phosphorus-doped single crystal silicon rod is 2500 μs; before calculating the crystal length of the silicon rod that meets the standard minority carrier lifetime value according to the linear rule, it is necessary to first determine the type of silicon rod in order to accurately obtain the standard minority carrier lifetime value of the silicon rod.
[0095] In some optional embodiments, the detection data list includes a crystal code; the type of the single-crystal silicon rod is determined based on the crystal code.
[0096] It should be noted that the test data list also includes crystal codes; specifically, the crystal coding rules can be as follows: the first digit indicates the production base, the second digit indicates oriented or non-oriented, the third digit indicates N-type, and the rest are furnace batch information; for example, the crystal code can be SBNX234A251231N, from which the third digit of the crystal code can be used to determine that the single crystal silicon rod is an N-type silicon rod; the crystal code can be SCPX233A640211N, from which the third digit of the crystal code can be used to determine that the single crystal silicon rod is a P-type silicon rod.
[0097] Understandably, since the standard minority carrier lifetime values of P-type silicon rods and N-type silicon rods are different, before calculating the crystal length of a silicon rod that meets the standard minority carrier lifetime value according to the linear rule, it is necessary to first determine the type of single-crystal silicon rod based on the crystal code in order to accurately obtain the standard minority carrier lifetime value of the silicon rod.
[0098] In some alternative embodiments, refer to Figure 2 To verify the cell efficiency of the solar cells fabricated from this batch of monocrystalline silicon rods, including:
[0099] Based on the actual minority carrier lifetime distribution value of any batch of monocrystalline silicon rods, the batches of monocrystalline silicon rods are classified into grades.
[0100] Obtain any batch of monocrystalline silicon rods within any grade and fabricate solar cells;
[0101] The preset cell efficiency of each solar cell is obtained;
[0102] Verify the cell efficiency of solar cells at each grade level to obtain the actual cell efficiency value;
[0103] The actual battery efficiency value is equal to the preset battery efficiency value, and the actual battery efficiency value of this batch of solar cells is stored directly.
[0104] or,
[0105] The actual battery efficiency value is not equal to the preset battery efficiency value. The preset battery efficiency value is adjusted according to the actual battery efficiency value, and the actual battery efficiency value of this batch of solar cells is stored.
[0106] It should be noted that cell efficiency refers to the conversion efficiency of a solar cell, or simply cell efficiency. Cell efficiency is the ratio of the output power of a solar cell to the energy incident on the surface of the solar cell. The photoelectric conversion efficiency of a solar cell is an important parameter for measuring cell quality and technological level.
[0107] Understandably, based on the actual minority carrier lifetime distribution of any batch of monocrystalline silicon rods, each batch of monocrystalline silicon rods is categorized and solar cells are fabricated. Furthermore, experiments are conducted to verify whether the actual cell efficiency of each category of solar cells meets the preset cell efficiency value, thus avoiding significant errors between the actual cell efficiency value and the preset cell efficiency value, which could affect the performance.
[0108] Currently, solar cells made from N-type silicon rods with an actual minority carrier lifetime distribution of 85% have a cell conversion efficiency of around 25.500%, while solar cells made from P-type silicon rods with an actual minority carrier lifetime distribution of 85% have a cell conversion efficiency of around 23.500%.
[0109] Table 1. Actual minority carrier lifetime distribution and preset cell efficiency of N-type solar cells.
[0110] Actual minority carrier lifetime distribution of single-crystal silicon rods Preset battery efficiency 100％ 25.530％ 95％ 25.520％ 90％ 25.510％ 85％ 25.500％ 80％ 25.490％ 75％ 25.475％ 70％ 25.467％ 65％ 25.455％ 60％ 25.445％ 55％ 25.438％ 50％ 25.429％ 45％ 25.415％ 40％ 25.410％ 35％ 25.390％ 30％ 25.375％
[0111] For example, referring to Table 1, a preset cell efficiency value is set for each grade of solar cell, based on a solar cell made from an N-type silicon rod with an actual minority carrier lifetime distribution of 85%. For instance, a solar cell made from an N-type silicon rod with an actual minority carrier lifetime distribution of 90% has a preset cell efficiency value of 25.510%. Experiments are conducted to verify whether the actual cell efficiency value of any solar cell in this batch meets the preset cell efficiency value. If its actual cell efficiency value meets 25.510%, then its preset cell efficiency value is used as the actual cell efficiency value, which is 25.510%. If it does not meet the preset cell efficiency value, the actual cell efficiency value of this batch of solar cells is recalculated and replaced with the actual cell efficiency value.
[0112] In some alternative embodiments, refer to Figure 3 To stabilize the actual minority carrier lifetime distribution of this batch of single-crystal silicon rods, including:
[0113] The minority carrier lifetime distribution of any batch of single-crystal silicon rods is preset, and the preset minority carrier lifetime distribution value is obtained.
[0114] Determine whether the actual minority carrier lifetime distribution value conforms to the preset minority carrier lifetime distribution value;
[0115] If the actual minority carrier lifetime distribution value is greater than or equal to the preset minority carrier lifetime distribution value, the single crystal silicon rod will proceed to the next process.
[0116] or,
[0117] The actual minority carrier lifetime distribution value is less than the preset minority carrier lifetime distribution value, thus increasing the minority carrier lifetime distribution value of this batch of single crystal silicon rods.
[0118] Understandably, by calculating the actual minority carrier lifetime distribution value of any batch of monocrystalline silicon rods, we can verify whether the actual minority carrier lifetime distribution value meets the preset minority carrier lifetime distribution value. If it does not meet the preset value, we can increase the minority carrier lifetime distribution value of that batch of monocrystalline silicon rods to ensure that the solar cells prepared from that batch of monocrystalline silicon rods meet the preset cell efficiency requirements. In other words, we can stabilize the cell efficiency of solar cells by stabilizing the actual minority carrier lifetime distribution value of each batch of monocrystalline silicon rods.
[0119] In some alternative embodiments, refer to Figure 4 To improve the minority carrier lifetime distribution of this batch of single-crystal silicon rods, the following measures were taken:
[0120] Defective silicon rods in this batch of monocrystalline silicon rods were screened out; these defective rods had low minority carrier lifetime values.
[0121] Determine whether the silicon rods in the inventory have a high minority carrier lifetime value;
[0122] The stockpiled silicon rods have high minority carrier lifetime values; replace the defective silicon rods with the stockpiled silicon rods.
[0123] or,
[0124] Inventory silicon rods do not have high minority carrier lifetime values; therefore, efforts should be made to improve the minority carrier lifetime values of inventory silicon rods.
[0125] It is understandable that replacing defective silicon rods with low minority carrier lifetime distribution values in a batch of monocrystalline silicon rods with existing silicon rods that have high minority carrier lifetime distribution values improves the minority carrier lifetime value of each monocrystalline silicon rod, thereby improving the minority carrier lifetime distribution value of the entire batch of monocrystalline silicon rods. When existing silicon rods do not have high minority carrier lifetime values, reducing the number of crystal pulling operations increases the minority carrier lifetime value of the existing silicon rods, thus improving the minority carrier lifetime distribution value of the entire batch of monocrystalline silicon rods and increasing the cell efficiency of solar cells.
[0126] As can be seen from the above embodiments, the minority carrier lifetime analysis method for silicon rods provided by the present invention achieves at least the following beneficial effects:
[0127] This invention provides a method for minority carrier lifetime analysis of silicon rods, comprising: presetting a standard minority carrier lifetime value for monocrystalline silicon rods; obtaining a test data list for any batch of monocrystalline silicon rods; determining the crystal length of each monocrystalline silicon rod that meets the standard minority carrier lifetime value according to a linear rule based on the test data list, and obtaining a standard crystal length value; storing the standard crystal length value in the test data list; obtaining the standard total crystal length value and the total crystal length value for any batch of monocrystalline silicon rods in the test data list; obtaining the ratio of the standard total crystal length value to the total crystal length value based on the standard total crystal length value and the total crystal length value, the ratio being the actual minority carrier lifetime distribution value of the batch of monocrystalline silicon rods; verifying the cell efficiency of the solar cell prepared from the batch of monocrystalline silicon rods based on the actual minority carrier lifetime distribution value of the batch of monocrystalline silicon rods; obtaining any batch of monocrystalline silicon rods and stabilizing the actual minority carrier lifetime distribution value of the batch of monocrystalline silicon rods. By calculating the actual minority carrier lifetime distribution value of monocrystalline silicon rods, the relationship between the minority carrier lifetime distribution value of silicon rods and the cell efficiency of solar cells is obtained, and in the mass production process, by stabilizing the actual minority carrier lifetime distribution value of silicon rods, the goal of stabilizing the cell efficiency of the end user is achieved.
[0128] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.
Claims
1. A method for minority carrier lifetime analysis of silicon rods, characterized in that, Includes the following steps: Preset standard minority carrier lifetime value for single-crystal silicon rods; Obtain a list of test data for any batch of the single-crystal silicon rods; Based on the detection data list, which includes: crystal length value, minority carrier lifetime value at the crystal head, and minority carrier lifetime value at the crystal tail, the crystal length of each single-crystal silicon rod that meets the standard minority carrier lifetime value is determined according to a linear rule to obtain a standard crystal length value. The linear rule includes: determining whether the minority carrier lifetime value at the crystal tail is greater than the standard minority carrier lifetime value; if the minority carrier lifetime value at the crystal tail is greater than the standard minority carrier lifetime value, the standard crystal length value is the crystal length value; or, if the minority carrier lifetime value at the crystal tail is less than or equal to the standard minority carrier lifetime value, then determining whether the minority carrier lifetime value at the crystal head is greater than the standard minority carrier lifetime value; if the minority carrier lifetime value at the crystal head is greater than the standard minority carrier lifetime value, the standard crystal length value is calculated; or, if the minority carrier lifetime value at the crystal head is less than or equal to the standard minority carrier lifetime value, the standard crystal length value is zero. The standard crystal length value is stored in the detection data list; Obtain the standard crystal total length value and crystal total length value of any batch of the single crystal silicon rods in the test data list; Based on the total length value of the standard crystal and the total length value of the crystal, the ratio of the total length value of the standard crystal to the total length value of the crystal is obtained, and the ratio is the actual minority carrier lifetime distribution value of the single crystal silicon rods in this batch; Based on the actual minority carrier lifetime distribution values of this batch of monocrystalline silicon rods, the cell efficiency of the solar cells prepared from this batch of monocrystalline silicon rods is verified. Obtain any batch of the single-crystal silicon rods and stabilize the actual minority carrier lifetime distribution value of that batch of single-crystal silicon rods.
2. The method for minority carrier lifetime analysis of a silicon rod according to claim 1, characterized in that, The single-crystal silicon rod is a P-type gallium-doped single-crystal silicon rod, and the standard minority carrier lifetime value is 250 μs. or, The single-crystal silicon rod is an N-type phosphorus-doped single-crystal silicon rod, and the standard minority carrier lifetime value is 2500 μs.
3. The method for minority carrier lifetime analysis of a silicon rod according to claim 1, characterized in that, The calculation of the standard crystal length value includes: Obtain the temporary crystal length, and round the temporary crystal length to an integer value, where the integer value is the standard crystal length value; The temporary crystal length value = crystal length value (Head minority lifetime value - Standard minority lifetime value) (Head minority carrier lifetime value - Tail minority carrier lifetime value).
4. The method for minority carrier lifetime analysis of a silicon rod according to claim 1, characterized in that, Before each of the single-crystal silicon rods reaches a crystal length that satisfies the standard minority carrier lifetime value according to a linear rule, the following steps are included: The type of the monocrystalline silicon rod is determined based on the list of test data.
5. The method for minority carrier lifetime analysis of a silicon rod according to claim 4, characterized in that, The detection data list includes a crystal code; the type of the single-crystal silicon rod is determined based on the crystal code.
6. The method for minority carrier lifetime analysis of a silicon rod according to claim 1, characterized in that, The verification of the cell efficiency of the solar cells prepared from this batch of monocrystalline silicon rods includes: Based on the actual minority carrier lifetime distribution value of any batch of the single crystal silicon rods, the single crystal silicon rods of each batch are classified into grades; Obtain any batch of the monocrystalline silicon rods within any grade range to prepare solar cells; The cell efficiency of the solar cells at each preset level is used to obtain the preset cell efficiency value; Verify the cell efficiency of the solar cells at each level to obtain the actual cell efficiency value; The actual battery efficiency value is equal to the preset battery efficiency value, and the actual battery efficiency value of this batch of solar cells is directly stored. or, The actual battery efficiency value is not equal to the preset battery efficiency value. The preset battery efficiency value is adjusted according to the actual battery efficiency value, and the actual battery efficiency value of this batch of solar cells is stored.
7. The method for minority carrier lifetime analysis of a silicon rod according to claim 1, characterized in that, The stable actual minority carrier lifetime distribution value of this batch of single-crystal silicon rods includes: The minority carrier lifetime distribution of any batch of the single crystal silicon rods is preset to obtain the preset minority carrier lifetime distribution value; Determine whether the actual minority carrier lifetime distribution value conforms to the preset minority carrier lifetime distribution value; If the actual minority carrier lifetime distribution value is greater than or equal to the preset minority carrier lifetime distribution value, the single crystal silicon rod will proceed to the next process. or, The actual minority carrier lifetime distribution value is less than the preset minority carrier lifetime distribution value, thereby increasing the minority carrier lifetime distribution value of the single crystal silicon rods in this batch.
8. The method for minority carrier lifetime analysis of a silicon rod according to claim 7, characterized in that, Improving the minority carrier lifetime distribution of this batch of single-crystal silicon rods includes: Screen out defective silicon rods from the batch of single-crystal silicon rods, the defective silicon rods having low minority carrier lifetime values; Determine whether the silicon rods in the inventory have a high minority carrier lifetime value; The stock silicon rods have high minority carrier lifetime values, and the stock silicon rods are used to replace the defective silicon rods. or, The stockpiled silicon rods do not have a high minority carrier lifetime value, so the minority carrier lifetime value of the stockpiled silicon rods should be increased.