Nitrogen doped TiO2–CuxO core–shell mesoporous spherical hybrids for high-performance dye-sensitized solar cells

Abstract

We report on high-performance dye-sensitized solar cells (DSSCs) based on nitrogen doped anatase TiO₂–Cu_xO core–shell mesoporous hybrids synthesized through a facile and controlled combined sol–gel and hydrothermal process in the presence of hexadecylamine as the structure-directing agent. The matching of band edges between Cu_xO and TiO₂ to form a semiconductor heterojunction plays an important role in effective separation of light induced electrons and holes, providing a promising photoanode for DSSCs because of its wide absorption spectrum, high electron injection efficiency, and fast electron transference. DSSCs based on the mesoporous TiO₂–Cu_xO core–shell hybrids show a high short-circuit current density of 9.60 mA cm⁻² and a conversion efficiency of 3.86% under one sun illumination. While DSSCs based on the N-doped mesoporous TiO₂–Cu_xO hybrids exhibit the higher short-circuit current density of 13.24 mA cm⁻² and a conversion efficiency of 4.57% under one sun illumination. In comparison with un-doped TiO₂–Cu_xO hybrids, the doping of nitrogen into the lattice of TiO₂ can extend the light absorption in the ultraviolet range to the visible light region and effectively decrease the recombination rate of photo-generated electrons and holes. The presented N-doped mesoporous TiO₂–Cu_xO hybrids as photoanodes could find potential applications for high performance DSSCs.