A rework scheme for solar silicon cell post-electric injection CID abnormality

Abstract

The application discloses a solar silicon cell electric injection post-CID abnormality rework scheme, which comprises the following steps: S1, electric injection stage, performing electric injection on the solar silicon cell, and the total process time of the electric injection is 1000-1600s; S2, temperature rising stage, starting simultaneously with the electric injection stage S1, heating the solar silicon cell from normal temperature to a first temperature under the condition of passing through 4-6A current, and the temperature rising stage takes less time than the electric injection stage; S3, temperature maintaining stage, after completing the temperature rising process of S2, maintaining the solar silicon cell at the first temperature under the condition of passing through 1-1.5A current until the end of S1; S4, temperature falling stage, after completing S3, falling the temperature of the solar silicon cell to normal temperature. The application can reduce the phenomenon that the electrically induced degradation of the cell piece after passivation is inconsistent due to the current process abnormality and the silicon wafer itself abnormality, effectively solves the problem of the CID abnormality of the solar silicon cell after electric injection, and improves the product yield.

Description

Technical Field

[0001] This invention relates to the field of passivation technology after metallization of solar cells, and more particularly to a rework solution for CID abnormalities after electrical injection of solar crystalline silicon cells. Background Technology

[0002] The tunneling oxide layer and doped layer of a solar cell together form a passivation contact structure, which provides good surface passivation for the back of the silicon wafer. In existing technologies, manufacturers typically use electro-injection to achieve H-passivation of solar cells. However, during the passivation process, some processes, such as poor annealing in the sintering furnace or defects in the silicon wafer itself, may fail to ensure that electro-induced degradation is kept at a low level. This results in differences in brightness after infrared stringing of such cells. Cells with CID anomalies need to be reworked. Currently, the common rework solution is to use multiple electro-injection cycles, which is time-consuming and the effectiveness cannot be guaranteed. Summary of the Invention

[0003] Purpose of the invention

[0004] To address the issues of CID abnormalities caused by process anomalies and silicon wafer defects, this invention provides a rework solution that can effectively resolve CID abnormalities after electrical injection of solar crystalline silicon cells.

[0005] Technical solution

[0006] A rework solution for CID anomalies after electrical injection of a solar crystalline silicon cell includes the following steps:

[0007] In the S1 electrical injection stage, the solar crystalline silicon cells are electrically injected, and the total process time for electrical injection is 1000-1600 seconds.

[0008] The S2 heating stage begins simultaneously with the S1 electric injection stage, heating the solar crystalline silicon cell from room temperature to the first temperature while applying a current of 4-6A. The heating stage takes less time than the electric injection stage.

[0009] In the S3 heat preservation stage, after the heating process is completed in step S2, the solar crystalline silicon cell is maintained at the first temperature while passing a current of 1 to 1.5A until the end of step S1.

[0010] In the S4 cooling stage, after completing step S3, the solar crystalline silicon cells are cooled to room temperature.

[0011] Furthermore, the first temperature ranges from 105 to 135°C.

[0012] Furthermore, the heating stage takes 20% to 30% of the time of the electrical injection stage, and the heat preservation stage takes 70% to 80% of the time of the electrical injection stage.

[0013] Furthermore, during the electrical injection stage, a trough-type transmission method is used to transmit multiple solar crystalline silicon cells.

[0014] Furthermore, during the electrical injection stage, a DC power supply is used to transmit power to the solar crystalline silicon cells.

[0015] Furthermore, during the heating stage, a heating block is used to heat both the upper and lower electrodes simultaneously to carry out the heating process.

[0016] The principle of this invention is that after a normal high-temperature passivation process via electrical injection, the finished crystalline silicon solar cell can fully activate the H ions in the backsheet of the solar cell. The high energy of the electrical injection causes the activated H ions to migrate from the backsheet to the crystalline silicon layer, saturating the dangling bonds and completing interface passivation, thus improving efficiency. However, some silicon wafers have inherent problems and cannot achieve good passivation even at this high temperature, resulting in a relatively high CID (Cellular Ingress Displacement) level, requiring further rework. In the rework solution proposed in this invention, temperature plays a major role. At a low temperature of 105-135℃, the electro-degradation remaining after passivation can be attenuated at the cell end, achieving a uniformly low level of electro-degradation across all cells after electrical injection. If the temperature is too high, the uniform electro-degradation across all cells cannot be achieved; if the temperature is too low, the internal resistance of the cell is high, and DC power cannot perform electrical injection.

[0017] Beneficial effects

[0018] This invention can reduce the inconsistency in electro-induced degradation after passivation of solar cells caused by some process defects and silicon wafer defects, effectively solve the problem of CID abnormality after electro-injection of solar crystalline silicon cells, and improve product yield. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process logic of the present invention;

[0020] Figure 2 This is a statistical chart of CID attenuation rate in an embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0022] Example

[0023] A rework solution for CID anomalies after electrical injection of a solar crystalline silicon cell includes the following steps:

[0024] In the S1 electrical injection stage, a DC power supply is used to electrically inject solar crystalline silicon cells in a slotted transmission manner. The total process time for electrical injection is 1200 seconds.

[0025] S2 heating stage, which starts simultaneously with step S1 electric injection stage, uses a heating block to heat the upper and lower electrodes at the same time, heating the solar crystalline silicon cell from room temperature to 120°C with a current of 6A. The heating stage takes 400 seconds.

[0026] In the S3 heat preservation stage, after the heating process is completed in step S2, the solar crystalline silicon cell is maintained at the first temperature with a current of 1.5A for 800 seconds.

[0027] In the S4 cooling stage, after completing step S3, a cooling fan is used to cool the solar crystalline silicon cells to room temperature.

[0028] The conventional process group in Table 1 represents the electrical injection data performance of commonly used process solutions in the industry, while the experimental process group identifies the electrical injection data performance using the solution of this invention.

[0029]

[0030] Table 1

[0031] Where Eta represents energy conversion efficiency, Uoc represents open-circuit voltage, Isc represents short-circuit current, FF represents fill factor, Rs represents series resistance of solar cell, IRev2 represents reverse leakage current, and the electrical performance data in the table are average values.

[0032] As can be seen from the test results of the above embodiments, the rework scheme for CID abnormalities after electro-injection of solar crystalline silicon cells proposed in this invention can effectively improve the CID abnormality of the cells. In this embodiment, the CID decay rate of the experimental rework process group is significantly lower than that of the conventional multiple electro-injection rework process. The average CID decay rate of this invention is 0.1%, with a maximum of 0.25%, and the decay rate of each cell is highly consistent. In contrast, the decay rate of the conventional process is 0.16%, with a maximum of 0.88%, and the decay rate of each cell is less consistent. It is evident that this invention effectively reduces the problem of excessively large CID decay in crystalline silicon solar cells after conventional electro-injection processes and solves the problem of brightness issues after module stringing caused by inconsistent decay.

[0033] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rework solution for CID anomalies after electrical injection in solar crystalline silicon cells, characterized in that, Includes the following steps: In the S1 electrical injection stage, the solar crystalline silicon cells are electrically injected, and the total process time for electrical injection is 1000~1600S. S2 Heating stage, which starts simultaneously with step S1 Electric injection stage, heats the solar crystalline silicon cell from room temperature to the first temperature with a current of 4~6A. The heating stage takes less time than the electric injection stage. S3 In the heat preservation stage, after the heating process is completed in step S2, the solar crystalline silicon cell is maintained at the first temperature while passing a current of 1~1.5A until the end of step S1. S4 Cooling stage: After completing step S3, the solar crystalline silicon cell is cooled to room temperature. The first temperature ranges from 105 to 135°C; The heating stage takes 20% to 30% of the time of the electrical injection stage, and the heat preservation stage takes 70% to 80% of the time of the electrical injection stage.

2. The rework solution for CID anomalies after electrical injection of a solar crystalline silicon cell according to claim 1, characterized in that: During the electrical injection stage, multiple solar crystalline silicon cells are transferred using a trough-type transfer method.

3. The rework solution for CID anomalies after electrical injection of a solar crystalline silicon cell according to claim 1, characterized in that: During the electrical injection stage, a DC power supply is used to transmit power to the solar crystalline silicon cells.

4. A rework solution for CID anomalies after electrical injection of a solar crystalline silicon cell according to claim 1, characterized in that: During the heating stage, a heating block is used to heat the upper and lower electrodes simultaneously to carry out the heating process.

Images