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%).