In this paper we present latest results in the development of a process for the fabrication of a selective emitter structure on mono- and multicrystalline silicon solar cells. The process is based on an approach that was first introduced by Zerga et al. [1]. We have chosen a wet chemical route for an emitter etch back where the areas of the wafer that are intended for emitter metallization are shielded from etching by a screen printable etch barrier. The etch barrier is later removed by wet chemical etching. The process has yielded a gain in open circuit voltage of more than 1% and a gain in short circuit current of more than 2%. The overall efficiency gain was more than 0.3%abs due to slightly lower fill factor of the cells
We have developed a simple and industrially applicable selective emitter cell process using only one diffusion step and an emitter etchback to create the high sheet resistance emitter [1, 2]. The process generates a deeper doping profile with a lower surface phosphorous concentration than a directly diffused emitter with the same sheet resistance. This results in an extremely low emitter saturation current j0E even at a moderate sheet resistance of 60-80 Ω/. The highest independently confirmed cell efficiency on Cz-Si (146 cm²) was 18.7%. In this work the etching behavior of the acidic solution at the grain boundaries is studied by SEM imaging and high resolution LBIC measurements at 405 nm wavelength. The etchback also leads to a change in reflectivity, which is quantified by reflectance measurements. We furthermore investigate the influence of the base material quality on the gain that can be achieved by this process. Large area solar cells have been processed from solar grade and UMG mc silicon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.