| Work Detail |
Chinese manufacturer Jolywood is currently applying a laser-assisted baking process in the manufacturing of TOPCon solar cells that can reportedly increase contact quality and corrosion resistance, while reducing production costs. Scientists at the University of South Wales have investigated the impact of this production process on the quality of TOPCon cells and have found that it “significantly” improves their reliability.
A group of researchers from the Chinese module manufacturer Jolywood and the University of New South Wales (UNSW), in Australia, have analyzed the impact of a new laser-assisted cooking technology developed by the Chinese manufacturer itself for the production of cells. tunnel oxide passivated contact solar panels (TOPCon).
Called Jolywood Special Injected Metallization (JSIM), the new technique consists of a laser-assisted baking process that uses a customized silver (Ag) paste to form the frontal contact in TOPCon solar cells. This is a low temperature firing technique intended to facilitate the penetration of the paste through the front anti-reflective coating of the cell.
“JSIM technology is already being produced on a large scale by Jolywood, and other companies are also developing and implementing their own versions of laser-assisted cooking,” lead author of the research, Bram Hoex, told pv magazine . “Jolywood was one of the first manufacturers to push TOPCon technology into high-volume production.”
In the article “ Enhancing the reliability of TOPCon technology by laser-enhanced contact firing ,” published in Solar Energy Materials and Solar Cells , Hoex and his colleagues explain that used accelerated contaminant-induced DH85 testing to evaluate the effectiveness of the JSIM process in increasing contact quality and corrosion resistance while reducing production costs.
They built TOPCon cells with dimensions of 182 mm × 182 mm and based on Czochralski (Cz) n-type G10 silicon wafers and reference TOPCon devices developed using a standard front metallization process. The cells built using JSM were based on contacts made with plasma oxidation and plasma-assisted in situ doping deposition (POPAID), which is a physical vapor deposition technique developed by Jolywood itself.
Both cell types were subjected to DH85 tests at a temperature of 85 ºC and a relative humidity of 85%. The laser operated at a wavelength of 1030 nm with a frequency of 1000 Hz.
“To evaluate contact resistance, we specifically focused on the busbar-less regions of TOPCon cells. Using a FOBA M1000 tracing laser, we created 6 mm wide stripes to evaluate contact resistance,” explains the research team. “Instead, the reference samples were subjected to frontal metallization using standard commercial Ag/Al paste and a conventional firing process. Notably, both batches of TOPCon cells featured identical silkscreen pattern designs.”
To analyze the cross-sectional images of the metal contacts, the researchers used a Zeiss 550 Crossbeam cryogenic ion beam scanning electron microscope. They found that the JSIM solar cell achieved an average power conversion efficiency of 25.1% and a fill factor of 83.2%, while the reference cell achieved values ??of 25.0% and 82.9%, respectively.
The test also demonstrated that the metal contacts of JSIM cells are less sensitive to sodium chloride (NaCl)-induced deterioration and corrosion compared to control devices. “This improvement is attributed to the broader processing window offered by the firing technique and the ability to use non-aluminum-containing pastes to contact the lightly doped boron surface on the front of the TOPCon solar cell,” they further explained. the scientists.
Using these cells, the team built JSIM 144 half-cell modules using polyolefin elastomer (POE) and expanded polyethylene (EPE) for the front and rear encapsulation, respectively, and compared their performance with control panels manufactured without the JSIM process.
Both types of panels were subjected to DH85 testing and the JSIM sample was also found to have better performance compared to the reference module. “The JSIM modules showed a fill factor decrease of 0.6%, while the reference modules suffered a significantly larger fill factor loss of 4.9%,” the researchers stated.
The team stated that the series of tests demonstrated that the JSIM process not only results in more reliable solar cells and modules, but also reduces production costs due to fewer materials used during its execution. “This work demonstrates that a laser-assisted baking process such as JSIM can significantly improve the intrinsic corrosion resistance of TOPCon solar cells,” they concluded. |
