Solid-state synthesis of ZnO and ZnFe2O4 to form p–n junction composite in the use of dye sensitized solar cells

•A ZnO–ZnFe2O4 nanostructure was fabricated by a low-temperature solid-state method.•A p–n heterojunction electric field was successfully formed at the interface between ZnFe2O4 and ZnO.•The p–n heterojunction could effectively promote the separation efficiency of photogenerated electron–hole pairs.•The power conversion efficiency of the DSSCs improved by 54.9% compared with that of pure ZnO based DSSCs (4.70%).

In this study, ZnO and ZnFe2O4 nanostructures are rapidly synthesized at relatively low temperature and without any organic surfactants using an economical, simple, and environmentally friendly solid-state synthesis. Results shows that the formation of p–n heterojunction electric field at the interface between ZnFe2O4 and ZnO is significantly effective in improving the open-circuit voltage (Voc) by efficiently promoting the separation efficiency of photogenerated electron–hole pairs on the surface of semiconductor, and an enhanced light-to-electric energy conversion efficiency of the dye-sensitized solar cell (DSSC) reaches 7.28%, which improve by 54.9% compared with that of pure ZnO based DSSCs (4.70%).