The role of back contact patterning on stability and performance of Si IBC heterojunction solar cells

Abstract

Interdigitated back contact (IBC) Si heterojunction solar cell initial performance and stability over time exhibits a critical dependence on the patterning processes, especially in defining the gap structure between emitter and base contacts. Patterning processes using photoresist can result in degradation even with dark storage in a dry environment over days, while other processes using a-SiN X :H for patterning yield stable devices over months. Use of photoresist (PR) as a mask in PECVD to form interdigitated contacts results in a gap that is insufficiently passivated and leads to cell degradation. Use of a-SiN X :H as a mask creates a multi-layer gap structure which improves the cell performance and stability. The laser fired base contact (LFC) reduces V OC slightly due to increased recombination loss, but does not cause additional instability. A stable efficiency of 17.9% was achieved in an IBC-Si heterojunction solar cell using all low temperature processes that incorporated a multi-layer gap passivation structure.Index Terms -cell stability, gap composition, interdigitated back contact, patterning approach, silicon heterojunction solar cell.

Dual Liquid Junction Photoelectrochemistry: Part I. Dual-Cuvette and Dual-Thin-Film Cells for Screening and Quantification of Back-Contact Properties

“…Studies on photovoltaic systems indicate that the back contact plays an important role on the efficiency of solar cell systems, 55 and introducing a proper back contact can improve energy conversion efficiencies. 56 Remaining cognizant of the interfacial chemistry at the back contact is necessary, and utilizing interfacial species so improve the properties of the back face of the semiconductor can be as beneficial as the surface chemistry of the illuminated face.…”