Industrially Feasible Rear Passivation and Contacting Scheme for High-Efficiency n-Type Solar Cells Yielding a $V_{\rm oc}$ of 700 mV

TLDR: In this paper, a rear passivation scheme based on doped amorphous silicon carbide was investigated, which results in excellent surface passivation and, at the same time, acts as a doping source.

Abstract: n-Type solar cells with passivated rear surface and point contacts have been proven to have an enormous efficiency potential. However, an industrially feasible process for the realization of the passivated locally contacted rear side of this solar cell type is still missing. Therefore, a rear passivation scheme based on doped amorphous silicon carbide was investigated. The newly developed PassDop layer results in excellent surface passivation and, at the same time, acts as a doping source. After the PECVD of the PassDop layer, contact points are locally opened by a laser pulse, and simultaneously, a local back surface field is formed using the phosphorus contained in the layer. In the last step, the rear side is contacted by the evaporation of aluminum. Due to the very effective passivation of the rear side by the doped passivation layer as well as the excellent contact formation by the laser process, the best cell (aperture area of 4 cm2) exhibits an open-circuit voltage of 701 mV and a fill factor of 80.1%, resulting in a confirmed solar cell efficiency of 22.4%.