Improved efficiency of p-type quasi-mono silicon blanket emitter solar cell by ion implantation and backside rounding

摘要

A novel type of silicon material, p-type quasi-mono wafer, has been produced using a seed directional solidification technique. This material is a promising alternative to traditional high-cost Czochralski (CZ) and float-zone (FZ) materials. This study evaluates the application of an advanced solar cell process that features a novel method of ion-implantation and backside rounding process on p-type quasi-mono silicon wafer. The ion implantation process substituted for thermal POCl3 diffusion leads to better Rsheet uniformity (<3 %). After screen-printing, the interface of Al and back surface field (BSF) layers was analyzed for the as prepared samples and the samples etched to three different depth. SEM showed that increased etch depth improved both BSF layer and Al-Si layer. The IQE result also showed that the samples with higher etching depth had better performance at long wavelength. The I–V cell tester showed that the sample with the etching depth of 6 μm ± 0.1 μm had the greatest efficiency, due to the highest Voc and Isc. The solar cell fabricated in this innovative process on 156 × 156mm p-type quasi-mono silicon wafer achieved 18.82 % efficiency.