INTERFACIAL ENGINEERING FOR MESOSCOPIC SEMICONDUCTOR-SENSITIZED PHOTOELECTROCHEMICAL CELLS

Abstract

Narrow bandgap semiconductor nanocrystals are promising materials for solar cell applications. The critical issue, however, is the poor stability in liquid junction devices, resulting from dissolution of the materials in electrolyte, which leads to a moderate performance. The reason presumably lies in the sluggish charge transfer at the non-optimized semiconductor/electrolyte interface. In this study, several methods were explored in order to modify the semiconductor sensitizer surface, among which relay molecules revealed superior performance to inert materials. Thereafter, various semiconductor-relay systems were systematically investigated in photoelectrochemical cells. More significantly, the mechanism for the performance enhancement was scrutinized by various time-resolved techniques. Transient absorption measurement indicates that the photo-generated holes reside in semiconductor sensitizer only for a short time (~ps) before transferring into the surface grafted relay molecules. The results imply the importance of interfacial engineering for mesoscopic semiconductor-sensitized photoelectrochemical cells.