Method for improving photoelectric conversion efficiency of BC type and TOPCon batteries

Abstract

The invention discloses a method for improving photoelectric conversion efficiency of BC type and TOPCon batteries, and belongs to the field of photovoltaic technology, the technical effect of improving Voc and FF of a battery piece is achieved through a technical means of irradiating a passivation layer of an N-type BC type battery piece or a TOPCon battery piece by using ultraviolet light, so that the photoelectric conversion efficiency of the battery piece is improved, and particularly, the method is suitable for improving the photoelectric conversion efficiency of the battery piece. Contact damage caused by LECO laser in a battery piece preorder process can be repaired through ultraviolet irradiation, the FF of the battery piece can be improved after repairing, in the light injection process of the battery piece, the wavelength of light injection lacks an ultraviolet wave band, the aluminum oxide passivation effect does not reach the optimal state, the deficiency can be made up through ultraviolet irradiation, and the service life of the battery piece is prolonged. According to the technical scheme of the invention, the method is extremely low in implementation cost, can be quickly deployed on a production line, and achieves the remarkable improvement of the photoelectric conversion efficiency by about 0.1%.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaics, and particularly relates to a method for improving the photoelectric conversion efficiency of BC-type and TOPCon cells. Background Art

[0002] TOPCon cells are a type of photovoltaic crystalline silicon cells. In recent years, due to their obvious advantages such as high conversion efficiency, low attenuation performance, and high mass production cost performance, they have been gradually adopted by industry enterprises. BC-type cells are a type of solar cell combined with multiple technical routes, and their advantages in aesthetics and distributed photovoltaics are more prominent.

[0003] However, the improvement speed of the photoelectric conversion efficiency of existing N-type BC-type or TOPCon cells is slow. Without superimposing new technologies and new structures, there are only methods such as improving efficiency by conventional printing pastes, stencils, and diffusion matching, reducing cost and improving efficiency by new printing methods, improving efficiency by Poly process matching annealing process, and improving efficiency by new wet additives. Although these efficiency improvement means can obtain a certain efficiency improvement, the improvement amplitude is limited, generally within the range of 0.02 - 0.05%, and it is difficult to optimize the production line process to improve efficiency, which requires high requirements for process technicians and equipment stability and is not easy to achieve the expected efficiency improvement purpose. For improving efficiency by introducing raw materials and auxiliary materials, although a certain efficiency improvement can be achieved, the improvement amplitude is also within the range of 0.03 - 0.05%, and the increase in efficiency is small. Summary of the Invention

[0004] To solve the problems raised in the above background art, the present invention provides a back poly multi-stack structure and a preparation method for improving the TOPCON bifacial ratio, so as to solve the problems that the existing efficiency improvement methods have a limited improvement amplitude and it is difficult to optimize the production line process to improve efficiency.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for improving the photoelectric conversion efficiency of BC-type and TOPCon cells, which performs ultraviolet light irradiation operation on the passivation layer of N-type BC-type cell wafers or TOPCon cell wafers for a preset duration.

[0006] Preferably, the wavelength of the ultraviolet light is 280 - 390 nm.

[0007] Preferably, in the ultraviolet light irradiation operation, the ultraviolet light generated by an ultraviolet lamp is used to irradiate the passivation layer of N-type BC-type cell wafers or TOPCon cell wafers.

[0008] Preferably, the power of the power supply of the ultraviolet lamp is 10 - 1000 W, and the ultraviolet light power of the ultraviolet lamp is 5 - 1000 W.

[0009] Preferably, the ultraviolet light irradiation operation is set between the laser-induced sintering process and the testing and sorting process of N-type BC solar cells or TOPCon solar cells. The ultraviolet lamp is fixedly installed above the transmission track between the laser-induced sintering process and the testing and sorting process of N-type BC solar cells or TOPCon solar cells, and the light-emitting end of the ultraviolet lamp is directed towards the transmission track.

[0010] Preferably, the distance between the light-emitting end of the ultraviolet lamp and the N-type BC solar cell or TOPCon solar cell on the transmission track is 1 - 2000 mm.

[0011] Preferably, the preset irradiation duration is 0.1 - 60 s.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: By using the technical means of irradiating the passivation layer of N-type BC solar cells or TOPCon solar cells with ultraviolet light, the present invention achieves the technical effect of improving the Voc (open-circuit voltage) and FF (fill factor) of the solar cells, so as to improve the photoelectric conversion efficiency of the solar cells. Specifically, the contact damage caused by LECO laser in the previous process of the solar cells can be repaired by ultraviolet light irradiation. After repair, the FF of the solar cells can be improved. In the light injection process of the solar cells, the wavelength of the light injection is 400 - 1100 nm, which can improve the passivation effect of alumina. However, due to the lack of the ultraviolet light band, the passivation effect of alumina does not reach the optimal state. Through ultraviolet light irradiation in this application, the deficiency can be made up, and the passivation effect of alumina can be improved, thereby improving the Voc of the solar cells. The technical solution of this application has extremely low implementation cost, can be quickly deployed on the production line, and can achieve a significant improvement in the photoelectric conversion efficiency of about 0.1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a comparative schematic diagram of the Eta, Voc, Isc, and FF of the solar cell before and after ultraviolet light irradiation. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] To facilitate the understanding of the technical content of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and specific examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] Example 1 A method for improving the photoelectric conversion efficiency of BC and TOPCon solar cells, specifically, an ultraviolet light irradiation operation with a preset duration is performed on the passivation layer of N-type BC solar cells or TOPCon solar cells.

[0016] In this embodiment, the BC-type solar cell includes a silicon substrate. The back structure of the silicon substrate, from bottom to top, is a back n+, p+ doping layer, an ultra-thin tunneling oxide layer (SiO2), and a back silver electrode, and the front structure is a passivation layer; The TOPCon solar cell includes a silicon substrate. A boron diffusion doping layer is provided on the front of the silicon substrate. The boron diffusion doping layer, from inside to outside, includes an aluminum oxide and a silicon nitride passivation layer and a front metal electrode in sequence. The back of the silicon substrate, from inside to outside, is a tunneling oxide layer, a phosphorus-doped polysilicon layer, a silicon nitride layer, and a back metal electrode. The part irradiated by ultraviolet light is the passivation layer of both the BC-type solar cell / TOPCon solar cell; By using the technical means of irradiating the passivation layer of the N-type BC-type solar cell or TOPCon solar cell with ultraviolet light, the present invention achieves the technical effect of improving the Voc (open-circuit voltage) and FF (fill factor) of the solar cell, so as to improve the photoelectric conversion efficiency of the solar cell. Specifically, the contact damage caused by LECO laser in the previous process of the solar cell can be repaired by ultraviolet light irradiation. After repair, the FF of the solar cell can be improved. In the light injection process of the solar cell, the wavelength of the light injection is 400-1100nm. Although the passivation effect of aluminum oxide can be improved, due to the lack of the ultraviolet light band, the passivation effect of aluminum oxide does not reach the optimal state. Through ultraviolet light irradiation in this application, the deficiency can be made up, and the passivation effect of aluminum oxide can be improved, thereby improving the Voc of the solar cell. The technical solution of this application has extremely low implementation cost, can be quickly deployed on the production line, and realizes a significant improvement in the photoelectric conversion efficiency of about 0.1%.

[0017] Example 2 The difference between this embodiment and Embodiment 1 is that the wavelength of the ultraviolet light is 280-390nm.

[0018] In this embodiment, ultraviolet light irradiation can repair the problem of insufficient light injection. Because the wavelength of the light in the light injection process is 400-1100nm (the fixed wavelength of the light injection lamp tube), there is no light irradiating the solar cell below 400nm. Therefore, an ultraviolet lamp with <400nm is used to irradiate to make up for the missing part of the light injection. When funds are sufficient, an ultraviolet lamp with 100-400nm can be used. Generally speaking, the ultraviolet lamp with a wavelength of 280-390nm is a conventional choice. The ultraviolet lamp in this wavelength range is easily obtained, while the ultraviolet lamp with a wavelength below 280nm needs to be customized separately, with high costs, and there are unstable situations in continuous irradiation, which is not significantly helpful for improving the solar cell efficiency, and the too short wavelength cannot reach the inside of the film layer.

[0019] Example 3 The difference between this embodiment and Embodiment 2 lies in that during the ultraviolet light irradiation operation, the passivation layer of the N-type BC class solar cell or TOPCon solar cell is irradiated with the ultraviolet light generated by an ultraviolet lamp. The ultraviolet lamp has the ability to irradiate with a long-term stable light intensity and a relatively low cost, which can reduce the cost of optimizing the production line and enable rapid deployment, saving the production line optimization time and improving efficiency.

[0020] Embodiment 4 The difference between this embodiment and Embodiment 3 lies in that the power supply power of the ultraviolet lamp is 45W and the ultraviolet light power of the ultraviolet lamp is 450W.

[0021] Embodiment 5 The difference between this embodiment and Embodiment 4 lies in that the TOPCon solar cell preparation process includes texturing of N-type silicon wafers, boron diffusion to form a P-type emitter, deposition of a back tunneling oxide layer (SiO2) and a polysilicon layer, double-sided screen printing of electrodes, high-temperature sintering, laser-induced sintering (LECO), and testing and sorting. The N-type BC class solar cell preparation process includes texturing of N-type silicon wafers, boron diffusion to form a P-type emitter, back passivation and polysilicon deposition, back electrode patterning and isolation, double-sided screen printing of electrodes, high-temperature sintering, laser-induced sintering (LECO), and testing and sorting. The ultraviolet light irradiation operation is set between the laser-induced sintering process and the testing and sorting process of the N-type BC class solar cell or TOPCon solar cell. The ultraviolet lamp is fixedly installed above the transmission track between the laser-induced sintering process and the testing and sorting process of the N-type BC class solar cell or TOPCon solar cell, and the light-emitting end of the ultraviolet lamp is directed towards the transmission track.

[0022] Embodiment 6 The difference between this embodiment and Embodiment 5 lies in that the distance between the light-emitting end of the ultraviolet lamp and the N-type BC class solar cell or TOPCon solar cell on the transmission track is 20mm.

[0023] Embodiment 7 The difference between this embodiment and Embodiment 6 lies in that the preset irradiation duration is 1s. If the ultraviolet light irradiation time is too short, it may result in insufficient cumulative irradiation intensity and poor effects. If the ultraviolet light irradiation time is too long, it may damage the stable silicon-hydrogen bonds and weaken the passivation effect.

[0024] In this embodiment, as shown in Table 1, Table 1 is a data table of the battery efficiency gain before and after ultraviolet lamp irradiation; Table 1

[0025] As Figure 1As shown, the horizontal axis of the Eta frequency distribution histogram represents the time efficiency interval, the vertical axis is the proportion of the sample size in different efficiency intervals, and the cumulative is 100%. The horizontal axis of the Voc open-circuit voltage histogram is the open voltage interval, the horizontal axis of the Isc short-circuit current histogram is the current interval, and the horizontal axis of the FF fill factor histogram is the fill factor interval. The vertical axis of all three is the proportion of the sample size. By comparing before and after the ultraviolet lamp irradiates the battery cell, it can be seen that by implementing the technical solution of this application, Eta has increased by 0.124%. Among them, mainly the open voltage has increased by 2 mV and FF has increased by 0.17.

Claims

1. A method for improving the photoelectric conversion efficiency of BC-type and TOPCon cells, characterized in that, Perform ultraviolet light irradiation operation on the passivation layer of N-type BC class solar cells or TOPCon solar cells for a preset duration.

2. The method for improving the optoelectronic conversion efficiency of BC-type and TOPCon cells according to claim 1, characterized in that, The wavelength of the ultraviolet light is 280 - 390 nm.

3. A method for improving the photoelectric conversion efficiency of BC type and TOPCon batteries according to claim 2, characterized in that, During the ultraviolet light irradiation operation, use the ultraviolet light generated by an ultraviolet lamp to irradiate the passivation layer of N-type BC class solar cells or TOPCon solar cells.

4. A method for improving the photoelectric conversion efficiency of BC-type and TOPCon cells according to claim 3, characterized in that, The power of the power supply of the ultraviolet lamp is 10 - 1000 W, and the ultraviolet light power of the ultraviolet lamp is 5 - 1000 W.

5. A method for improving the photoelectric conversion efficiency of BC-type and TOPCon cells according to claim 4, characterized in that, The ultraviolet light irradiation operation is set between the laser-induced sintering process and the test and sorting process of N-type BC class solar cells or TOPCon solar cells. The ultraviolet lamp is fixedly installed above the transmission track between the laser-induced sintering process and the test and sorting process of N-type BC class solar cells or TOPCon solar cells, and the light-emitting end of the ultraviolet lamp is directed towards the transmission track.

6. A method for improving the photoelectric conversion efficiency of BC-type and TOPCon cells according to claim 5, characterized in that The distance between the light-emitting end of the ultraviolet lamp and the N-type BC class solar cells or TOPCon solar cells on the transmission track is 1 - 2000 mm.

7. A method for improving the photoelectric conversion efficiency of BC-type and TOPCon cells according to claim 6, characterized in that, The preset duration of irradiation is 0.1 - 60 s.

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