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

• ZnO@TiO2 core shell nanorod has been grown on FTO substrate using low temperature solution method.
• TEM, XRD, EDX results confirmed the existing of titana shell, uniformly covered rod's surface.
• TiO2 shell suppressed recombination, demonstrated significant enhancement in cell's efficiency.
• Core shell DSSC's efficiency achieved as high as 3.03%, 3 times higher than that of ZnO nanorods.

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 5.2 mA/cm2), open circuit voltage (from 0.6 V to 0.8 V) 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 18–22 nm shell thickness, a nearly threefold increase.

The synthesis process of coating TiO2 shell onto ZnO nanorod core is shown schematically. A thin, uniform, and conformal shell had been grown on the surface of the ZnO core after immersing in the (NH4)2·TiF6 solution for 5–15 min.Figure optionsDownload as PowerPoint slide