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

A core-shell nanorod array of TiO 2 /CuS heterostructure is achieved by coating the TiO 2 nanorods with conformal ZnS films and subsequently converting the ZnS into CuS counterparts via ion exchange. Photovoltaic devices based on the ordered heterojunctions exhibit aging-induced photoelectric conversion enhancement effect. • A highly ordered TiO 2 /CuS core-shell nanorod array is fabricated. • The CuS shell is attached to the TiO 2 nanorods by ion exchange with ZnS films. • Photovoltaic devices exhibit an enhanced efficiency when aging in air for up to 22 days. 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 TiO 2 /CuS heterostructure is achieved by coating the TiO 2 nanorods with conformal ZnS films and subsequently converting the ZnS into its CuS counterpart via ion exchange. The TiO 2 /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. [ABSTRACT FROM AUTHOR]