Effects of annealing following back contact metal layer formation on CZTS solar cell properties

Abstract

Abstract Cu2ZnSnS4 (CZTS) is interesting as a light absorption layer for thin-film solar cells because it consists of only earth-abundant materials such as copper, zinc, tin, and sulfur. The poor adhesion between CZTS and molybdenum (Mo), which is the back metal contact material, causes CZTS to peeling off during the chemical bath deposition (CBD) for the formation of CdS as a buffer layer. This induces severe degradation of the solar cell performance. In this study, we investigated the effect of annealing following back contact metal layer formation on CZTS stability and solar cell performance. By annealing Mo/soda lime glass at 400 °C in atmosphere, Mo was oxidized, and the surface roughness of Mo increased. On the Mo surface, the CZTS peeling off was suppressed during the CBD process, resulting in an improvement in the shunt resistance.