Phosphorus diffusion method for improving photoelectric conversion efficiency of BC type battery

Abstract

The invention discloses a phosphorus diffusion method for improving photoelectric conversion efficiency of a BC type battery, which realizes high sheet resistance (20-150 omega) with excellent uniformity while obtaining high impurity concentration PSG by improving a phosphorus diffusion process after an N-type BC type battery LP route N-poly, thereby improving FF of the BC type battery, reducing contact resistance Rs and finally improving the photoelectric conversion efficiency of the battery to a greater extent. And secondly, a multi-step source-passing method is adopted, the source-passing time is shortened, the source-passing flow is increased, rapid temperature rise propulsion and the like are adopted, a conventional phosphorus diffusion method is changed, high sheet resistance with excellent uniformity is realized while high-impurity-concentration PSG is obtained, reduction of N-region carrier recombination is ensured, FF and Uoc are improved, and finally the conversion efficiency of the battery is improved to the maximum extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cell production, and particularly relates to a phosphorus diffusion method for improving photoelectric conversion efficiency of BC type cells. BACKGROUND

[0002] Under the premise of matching the conventional N-type BC cell LP route N-poly post-phosphorus diffusion process and other related technologies, the diffusion sheet resistance is kept at 30±10 Omega, and the efficiency is optimal, but there is still a gap from the highest efficiency of the BC cell. The carrier recombination of the N region needs to be reduced, the passivation effect of the N region needs to be improved, and the series resistance of the N region needs to be reduced to obtain the maximum efficiency, and the maximum efficiency improvement is realized.

[0003] Therefore, a phosphorus diffusion method for improving photoelectric conversion efficiency of BC type cells needs to be developed to solve the above problems. SUMMARY

[0004] The present application is designed to solve the above problems and provides a phosphorus diffusion method for improving photoelectric conversion efficiency of BC type cells.

[0005] The present application achieves the above-mentioned purposes through the following technical solutions: A phosphorus diffusion method for improving photoelectric conversion efficiency of BC type cells, comprising the following steps: Step S1: first pre-deposition on the front of the cell: when the temperature in the quartz tube diffusion furnace is stabilized at a predetermined temperature, nitrogen gas carrying phosphorus oxychloride and oxygen gas are introduced; Step S2: first temperature rise: stop introducing nitrogen gas carrying phosphorus oxychloride, stop oxygen gas introduction, and ensure that the furnace tube is heated to a predetermined temperature: Step S3: second pre-deposition: continue to introduce nitrogen gas carrying phosphorus oxychloride and oxygen gas: Step S4: second temperature rise: stop introducing nitrogen gas carrying phosphorus oxychloride, stop oxygen gas introduction, and ensure that the furnace tube is heated to a predetermined temperature: Step S5: advance: stop introducing nitrogen gas carrying phosphorus oxychloride, and continue to introduce oxygen gas: Step S6: third pre-deposition: continue to introduce nitrogen gas carrying phosphorus oxychloride and oxygen gas: Step S7: oxidation: stop introducing nitrogen gas carrying phosphorus oxychloride, and increase oxygen gas introduction: Step S8: temperature reduction: continuously increase oxygen gas introduction, and ensure that the temperature reduction amplitudes of each temperature zone inside the furnace tube are consistent.

[0006] Preferably, in step S1, the duration of introducing nitrogen gas carrying phosphorus oxychloride and oxygen gas is 3-4 min, the flow rate of nitrogen gas is 1000-10000 sccm, the flow rate of oxygen gas is 1500-1700 sccm, and the temperature is 785±2℃.

[0007] Preferably, in step S2, the duration of temperature rise is 6-8 min until the furnace tube is heated to 805±2℃.

[0008] Preferably, in step S3, the duration of nitrogen and oxygen carrying phosphorus oxychloride is 5-7 min, the flow rate of nitrogen is 1700-1900sccm, the flow rate of oxygen is 500-850sccm, and the temperature is 805±2℃.

[0009] Preferably, in step S4, the duration of temperature rise is 15-20 min until the furnace tube is heated to 890±2℃.

[0010] Preferably, in step S5, the duration of oxygen is 15-25 min, the flow rate of oxygen is 900-1100sccm, and the temperature is 890±2℃.

[0011] Preferably, in step S6, the duration of nitrogen and oxygen carrying phosphorus oxychloride is 3-5 min, the flow rate of nitrogen is 1500-1700sccm, the flow rate of oxygen is 600-900sccm, and the temperature is 890±2℃.

[0012] Preferably, in step S7, the duration of oxygen is 15-20 min, the flow rate of oxygen is 15000-20000sccm, and the temperature is 890±2℃.

[0013] Preferably, in step S8, the duration of oxygen is 10-15 min.

[0014] The beneficial effects of the present application are: By improving the N-type BC battery LP route N-poly post-phosphorus diffusion process, high impurity concentration PSG is obtained while realizing high sheet resistance (20~150Ω) with good uniformity, thereby improving the FF of BC battery, reducing the contact resistance Rs, and ultimately maximizing the battery conversion efficiency.

[0015] Secondly, by adopting multi-step source method, reducing source time, increasing source flow, and rapid temperature rise, the conventional phosphorus diffusion method is changed, high impurity concentration PSG is obtained while realizing high sheet resistance with good uniformity, which ensures to reduce N region carrier recombination, improve FF and Uoc, and ultimately maximize the battery conversion efficiency.

[0016] The new diffusion process adopted by the present application has basically the same process time as the conventional production line, and can realize stable mass production under the premise of maintaining the conventional production capacity, and has high compatibility with the conventional production line, without the need to improve equipment or add new equipment, etc., and has good practicability. DETAILED DESCRIPTION

[0017] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described in the following. Obviously, the described embodiments are part of the embodiments of the present application and not all the embodiments. The components of the embodiments of the present application described and shown herein can be arranged and designed in various different configurations.

[0018] Therefore, the detailed description of the embodiments of the present application provided below is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0019] In addition, the terms "first", "second" and the like are only used to distinguish description and cannot be understood as indicating or implying relative importance.

[0020] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrange", "connect" and the like should be understood broadly, for example, "connect" can be fixedly connected, or detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0021] The specific embodiments of the present application will be described in detail below.

[0022] A phosphorus diffusion method for improving the photoelectric conversion efficiency of BC type battery, comprising the following steps: Step S1: first pre-deposition on the front of the battery: when the temperature in the quartz tube diffusion furnace is stabilized at a predetermined temperature, nitrogen and oxygen carrying phosphorus oxychloride are introduced; the duration of introducing nitrogen and oxygen carrying phosphorus oxychloride is 3-4 min, the flow rate of nitrogen is 1000-10000 sccm, the flow rate of oxygen is 1500-1700 sccm, and the temperature is 785±2℃; Step S2: first temperature rise: stop introducing nitrogen carrying phosphorus oxychloride, and stop oxygen introduction, to ensure that the furnace tube is heated to a predetermined temperature: the duration of heating is 6-8 min, until the furnace tube is heated to 805±2℃; Step S3: second pre-deposition: continue to introduce nitrogen and oxygen carrying phosphorus oxychloride: the duration of introducing nitrogen and oxygen carrying phosphorus oxychloride is 5-7 min, the flow rate of nitrogen is 1700-1900 sccm, the flow rate of oxygen is 500-850 sccm, and the temperature is 805±2℃; Step S4; second temperature rise: stop the nitrogen carrying phosphorus oxychloride, stop the oxygen, ensure the furnace tube temperature to the predetermined temperature: the duration of the temperature rise is 15-20 min, until the furnace tube temperature to 890±2℃; Step S5; push: stop the nitrogen carrying phosphorus oxychloride, continue to oxygen: the duration of oxygen is 15-25 min, the flow rate of oxygen is 900-1100sccm, the temperature is 890±2℃; Step S6; third pre-deposition: continue to carry phosphorus oxychloride and oxygen: the duration of nitrogen carrying phosphorus oxychloride and oxygen is 3-5 min, the flow rate of nitrogen is 1500-1700sccm, the flow rate of oxygen is 600-900sccm, the temperature is 890±2℃; Step S7; oxidation: stop the nitrogen carrying phosphorus oxychloride, increase the oxygen: the duration of oxygen is 15-20 min, the flow rate of oxygen is 15000-20000sccm, the dimension is 890±2℃; Step S8; cooling: continue to increase the oxygen, ensure the temperature of each temperature zone inside the furnace tube to drop consistently; the duration of oxygen is 10-15 min.

[0023] The following shows the comparative examples and examples;

[0024] Comparative example:

[0025]

[0026] Example

[0027]

[0028] Based on the comparison of the comparative examples and examples, the higher impurity concentration PSG is obtained compared with the comparative examples, and the high sheet resistance with excellent uniformity is realized, which ensures the ideal N area passivation effect and gold half contact effect in the subsequent process, and finally maximizes the battery conversion efficiency.

[0029] The above is only the preferred embodiment of the present application, it should be pointed out that, for the ordinary skilled in the art, without departing from the technical principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A phosphorus diffusion method for improving the photoelectric conversion efficiency of BC-type batteries, characterized in that, Includes the following steps: Step S1; First pre-deposition on the front side of the battery: When the temperature inside the quartz tube diffusion furnace stabilizes at the predetermined temperature, nitrogen and oxygen carrying phosphorus oxychloride are introduced. Step S2; First heating: Stop the supply of nitrogen carrying phosphorus oxychloride and oxygen, and ensure the furnace tubes reach the predetermined temperature. Step S3; Second pre-deposition: Nitrogen and oxygen carrying phosphorus oxychloride are continuously introduced: Step S4; Second heating: Stop the supply of nitrogen carrying phosphorus oxychloride and oxygen, ensuring the furnace tubes reach the predetermined temperature. Step S5; Propulsion: Stop introducing nitrogen gas carrying phosphorus oxychloride, and continue introducing oxygen: Step S6; Third pre-deposition: Continue to introduce nitrogen and oxygen carrying phosphorus oxychloride: Step S7; Oxidation: Stop the flow of nitrogen carrying phosphorus oxychloride and increase the flow of oxygen: Step S8; Cooling: Continuously increase oxygen supply to ensure that the temperature drop in each zone inside the furnace tube is consistent.

2. The phosphorus diffusion method for improving the photoelectric conversion efficiency of BC-class batteries according to claim 1, characterized in that, In step S1, the duration of introducing nitrogen and oxygen carrying phosphorus oxychloride is 3-4 minutes, the flow rate of nitrogen is 1000-10000 sccm, the flow rate of oxygen is 1500-1700 sccm, and the temperature is 785±2℃.

3. The phosphorus diffusion method for improving the photoelectric conversion efficiency of BC-class batteries according to claim 1, characterized in that, In step S2, the heating duration is 6-8 minutes until the furnace tube temperature reaches 805±2℃.

4. The phosphorus diffusion method for improving the photoelectric conversion efficiency of BC-type batteries according to claim 1, characterized in that, In step S3, the duration of introducing nitrogen and oxygen carrying phosphorus oxychloride is 5-7 minutes, the flow rate of nitrogen is 1700-1900 sccm, the flow rate of oxygen is 500-850 sccm, and the temperature is 805±2℃.

5. The phosphorus diffusion method for improving the photoelectric conversion efficiency of a BC-type battery according to claim 1, characterized in that, In step S4, the heating duration is 15-20 minutes until the furnace tube temperature reaches 890±2℃.

6. The phosphorus diffusion method for improving the photoelectric conversion efficiency of a BC-type battery according to claim 1, characterized in that, In step S5, the oxygen introduction duration is 15-25 min, the oxygen flow rate is 900-1100 sccm, and the temperature is 890±2℃.

7. The phosphorus diffusion method for improving the photoelectric conversion efficiency of a BC-type battery according to claim 1, characterized in that, In step S6, the duration of introducing nitrogen and oxygen carrying phosphorus oxychloride is 3-5 minutes, the flow rate of nitrogen is 1500-1700 sccm, the flow rate of oxygen is 600-900 sccm, and the temperature is 890±2℃.

8. The phosphorus diffusion method for improving the photoelectric conversion efficiency of a BC-type battery according to claim 1, characterized in that, In step S7, the oxygen introduction duration is 15-20 min, the oxygen flow rate is 15000-20000 sccm, and the temperature is 890±2℃.

9. The phosphorus diffusion method for improving the photoelectric conversion efficiency of a BC-type battery according to claim 1, characterized in that, In step S8, the oxygen introduction duration is 10-15 minutes.

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