Efficiency improvement of a-Si:H/μc-Si:H tandem solar cells by adding a-SiOx:H layer between Ag nano particles and the active layer

Abstract

In this article, we investigated the positive effect of a-SiOx:H layer between Ag surface plasmon polaritons and the active layer of a thin film a- Si:H/μc-Si:H tandem solar cell by isolating the metal nano particles that are responsible of creating surface recombination centres on the top cell. We fabricated four identical a-Si:H/μc-Si:H tandem cells having different thickness of a-SiOx:H layer like 0, 10, 20 and 30 nm just before the Ag nano particle development, and measured J-V characteristics of each to find out an optimum a-SiOx:H insulating layer thickness. We showed that the overall efficiency of a tandem cell with Ag nano particles could be improved up to 8.65% compared with the one having no a-SiOx:H layer. The most promising layer thickness for a small area tandem cell was obtained around 20 nm with an overall efficiency of 16.19%. An improvement of 14.6% in short circuit current density (JSC) and 2.64% in open circuit voltage (Voc) was achieved. © 2013 Springer-Verlag.