Implementation of Selective Emitter for Industrial-Sized PERCs Using Wet Chemical Etch-Back Process

Abstract

This paper introduces a selective phosphorus emitter formed by screen-printed resist masking combined with a wet chemical etch-back process for an industrial-sized passivated emitter and rear cell (PERC). Applying the selective emitter (SE) concept is expected to decrease the recombination losses at the front surface of the PERC cell. With the SE structure, we observed an increase in the open-circuit voltage $(V_{{\rm{oc}}})$ and short-circuit current density $(J_{{\rm{sc}}})$ , but a decrease in the fill factor (FF), compared with homogeneous emitter cells. The sheet resistance $(R_{{\rm{sheet}}})$ of the lightly doped emitter (n+-emitter) by the etch-back process had a considerable impact on the $V_{{\rm{oc}}}$ and $J_{{\rm{sc}}}$ , which we attributed to the reduced emitter saturation current density $(J_{0e})$ caused by a reduction in the Auger recombination in the n+ -emitter. The diminished FF was owing to the higher $R_{{\rm{sheet}}}$ , resulting in an increased series resistance of the cell. These results suggest that an SE structure made by the wet etch-back process is a very promising technology to improve the conversion efficiency of industrial-sized PERC solar cells.