Photoelectrochemical application of tin doped ZnO nanostructures

The simple hydrothermal method was used for synthesizing zinc oxide (ZnO) and tin (Sn) doped ZnO. The photovoltaic performances of Sn doped ZnO photoanodes were studied for the application of dye sensitized solar cells (DSSCs). The doping of Sn significantly altered the morphology of ZnO into spindle shape by the arrangement of small ZnO nanoparticles. The crystalline and structural properties deduced the clear decrement in the crystallite sizes from ∼143.9 nm to ∼82.2 nm. The decrement in the crystallite sizes revealed the incorporation of Sn-ion into ZnO nanomaterials, suggested the doping of Sn-ions into ZnO nanostructures. X-ray photoelectron spectroscopy (XPS) study showed Sn-O and Zn- O bonding in the synthesized spindle shaped Sn-ion doped ZnO nanostructures, which confirmed the Zn substitution by the Sn-ions. Dye sensitized solar cell (DSSC) fabricated with Sn-ZnO photoanode achieved a solar-to-electricity conversion efficiency of ∼1.82% with short circuit current (J_SC) of 5.1 mA/cm², open circuit voltage (V _OC) of 0.786 V and fill factor (FF) of 0.45, which was higher than that of DSSC with ZnO photoanode. The increased conversion efficiency and the photocurrent density were attributed to the significant Sn-ion doping into ZnO nanostructures and considerable arrangement of ZnO nanoparticles into spindle shaped morphology which might improve the high charge collection and the transfer of electrons at the interfaces of doped ZnO layer and the electrolyte layer.