Experimental study on the elimination of over-plating problems in industrial manufacturing of large-area acidic-textured laser-doped multi-crystalline solar cells

Light-induced plating (LIP) techniques, which are self-aligned and are used in the fabrication of well-shaped metal grids, have been widely studied and used in solar cells, particularly in laser-doped selective emitter (LDSE) ones. However, the application of LIP techniques in standard acidic-textured multi-crystalline silicon wafers with SiNx-coated surfaces can be challenging because of the presence of some unwanted metals on the SiNx surface during the plating process. This phenomenon is called over-plating, a problem in industrial LDSE multi-crystalline Si solar cell manufacturing that this paper aims to eliminate without the addition of any new process steps. The feasibility of changing the texturing process as well as the pretreatment before plating and the deposition of SiNx to reduce over-plating was investigated. The effects of over-plating on solar cell performance were also investigated to determine the mechanism of performance degradation. The cells reached a maximum efficiency of 17.2% and an average efficiency of 17.1% on large-area, commercial-grade, p-type multi-crystalline Si substrates when the over-plating problem was eliminated.

► Over-plating problems are eliminated without the addition of any new processes.
► Texturing, SiNx deposition and pretreatment are optimized for the purpose of eliminating overplating.
► Each over-plating mechanism causes a high local ideality factor in a different voltage range.
► An efficiency of 17.2% is obtained on large size multi-crystalline Si substrates.