Significant increase in efficiency and limited toxicity of a solar cell based on Sb2Se3 with SnO2 as a buffer layer

Abstract

Antimony selenide (Sb₂Se₃) thin films are attractive light-absorbing materials used in low-cost and highly efficient thin-film solar cells. In order to increase the efficiency of Sb₂Se₃ solar cells based on a tin oxide (SnO₂) buffer layer, an ultrathin cadmium sulfide (CdS) film was introduced at the interface between the fluorine doped SnO₂ glass (FTO) and the SnO₂ film. Different thicknesses of the CdS/SnO₂ compound buffer layers were used to form p–n junctions with the Sb₂Se₃ film. The ultrathin CdS layer not only increased the carrier connection and transport, but also decreased the conduction band offset and grain boundary density of the Sb₂Se₃ film. Lastly, an efficiency of 5.27% for the FTO/CdS (10 nm)/SnO₂ (40 nm)/Sb₂Se₃/Au solar cells was obtained, which is higher than the reported highest efficiency of Sb₂Se₃ solar cells based on a SnO₂ buffer layer.