TiO2/CuS core-shell nanorod arrays with aging-induced photoelectric conversion enhancement effect

Abstract

Highly ordered three-dimensional (3D) heterojunctions are attractive for optoelectronic, photovoltaic and electronic devices due to their large interfacial contact and oriented charge transport. However, 3D heterojunctions of this type have rarely been reported because of the great difficulty in constructing an ordered structure at the nanoscale. In this study, a core-shell nanorod array of TiO2/CuS heterostructure is achieved by coating the TiO2 nanorods with conformal ZnS films and subsequently converting the ZnS into its CuS counterpart via ion exchange. The TiO2/CuS-based photovoltaic devices exhibit a gradually enhanced efficiency when aging in air up to 22 days. This is attributed to the progressive conversion from Cu deficient sulfide to CuS. This strategy could also be used to design other core-shell nanorod arrays based on metal oxide/sulfide heterojunctions.