Light-induced performance increase of silicon heterojunction solar cells

by Eiji Kobayashi, Stefaan De Wolf, Jacques Levrat, Gabriel Christmann, Antoine Descoeudres, Sylvain Nicolay, Matthieu Despeisse, Yoshimi Watabe, Christophe Ballif
Year: 2016

Bibliography

Kobayashi, Eiji, Stefaan De Wolf, Jacques Levrat, Gabriel Christmann, Antoine Descoeudres, Sylvain Nicolay, Matthieu Despeisse, Yoshimi Watabe, and Christophe Ballif. "Light-induced performance increase of silicon heterojunction solar cells." Applied Physics Letters 109, no. 15 (2016): 153503.

Abstract

​Silicon heterojunction solar cells consist of crystalline silicon (c-Si) wafers coated with doped/intrinsic hydrogenated amorphous silicon (a-Si:H) bilayers for passivating-contact formation. Here, we unambiguously demonstrate that carrier injection either due to light soaking or (dark) forward-voltage bias increases the open circuit voltage and fill factor of finished cells, leading to a conversion efficiency gain of up to 0.3% absolute. This phenomenon contrasts markedly with the light-induced degradation known for thin-film a-Si:H solar cells. We associate our performance gain with an increase in surface passivation, which we find is specific to doped a-Si:H/c-Si structures. Our experiments suggest that this improvement originates from a reduced density of recombination-active interface states. To understand the time dependence of the observed phenomena, a kinetic model is presented.

Keywords

silicon heterojunction (SHJ) surface passivation recombination