Low temperature grown ZnO@TiO2 core shell nanorod arrays for dye sensitized solar cell application

Abstract

High aspect ratio ZnO nanorod arrays were synthesized on fluorine-doped tin oxide glasses via a low temperature solution method. By adjusting the growth condition and adding polyethylenimine, ZnO nanorod arrays with tunable length were successfully achieved. The ZnO@TiO2 core shells structures were realized by a fast growth method of immersion into a (NH4)2·TiF6 solution. Transmission electron microscopy, X-ray Diffraction and energy dispersive X-ray measurements all confirmed the existence of a titania shell uniformly covering the ZnO nanorod's surface. Results of solar cell testing showed that addition of a TiO2 shell to the ZnO nanorod significantly increased short circuit current (from 4.2 to 5.2mA/cm2), open circuit voltage (from 0.6V to 0.8V) and fill factor (from 42.8% to 73.02%). The overall cell efficiency jumped from 1.1% for bare ZnO nanorod to 3.03% for a ZnO@TiO2 core shell structured solar cell with a 18–22nm shell thickness, a nearly threefold increase.