A comparison of ZnS and ZnSe passivation layers on CdS/CdSe co-sensitized quantum dot solar cells

The design and synthesis of passivation materials are of significant importance to reducing surface charge recombination in quantum dot-sensitized solar cells (QDSCs). In this study, the systematic characterization and comparison of the optical and electrochemical properties of ZnS and ZnSe passivation layers and their impacts on the performance of the resulting QDSCs have been investigated. The ZnS and ZnSe passivation layers were all deposited via a reproducible and controlled successive ionic layer adsorption and reaction method. QDSCs with a ZnSe passivation layer demonstrated strongly inhibited interfacial charge recombination and greatly enhanced light harvesting, resulting in a power conversion efficiency of up to 6.4%, which is appreciably higher than 4.9% for the solar cells with a ZnS passivation layer and 3.4% for the solar cells without a passivation layer.