Nanosheet arrays of TiO2 synthesized by one step conversion of ZnO nanosheets: boosting of electron transport rate and application in dye solar cells

Abstract

A TiO₂ replica of ZnO nanosheet films is synthesized using a chemical replacement process. ZnO nanosheets are grown by electrodeposition on fluorine doped tin oxide (FTO) films, and a dissolution/deposition process is used to convert the ZnO template into a TiO₂ replica. Electron microscopy shows the final TiO₂ structure follows the morphology of the initial ZnO template. X-ray diffraction and energy dispersive spectroscopy verify the total transformation of ZnO to TiO₂. The as-synthesized TiO₂ sheets are amorphous and after annealing turn into the anatase phase. The film of TiO₂ nanosheets is used as the photoanode of a dye sensitized solar cell. Despite the low roughness factor of 100, a conversion efficiency of 3.3% with D35 as sensitizer is achieved. The nanosheets show remarkably faster electron transport and longer electron lifetime compared to the conventional TiO₂ nanoparticle electrodes.