Eosin-Y sensitized core-shell TiO2-ZnO nano-structured photoanodes for dye-sensitized solar cell applications.

In the current investigation, TiO2 and TiO2-ZnO (core-shell) spherical nanoparticles were synthesized by simple combined hydrolysis and refluxing method. A TiO2 core nanomaterial on the shell material of ZnO was synthesized by utilizing variable ratios of ZnO. The structural characterization of TiO2-ZnO core/shell nanoparticles were done by XRD analysis. The spherical structured morphology of the TiO2-ZnO has been confirmed through field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) studies. The UV-visible spectra of TiO2-ZnO nanostructures were also compared with the pristine TiO2 to investigate the shift of wavelength. The TiO2-ZnO core/shell nanoparticles at the interface efficiently collect the photogenarated electrons from ZnO and also ZnO act a barrier for reduced charge recombination of electrolyte and dye-nanoparticles interface. This combination improved the light absorption which induced the charge transfer ability and dye loading capacity of core-shell nanoparticles. An enhancement in the short circuit current (Jsc) from 1.67 mA/cm2 to 2.1 mA/cm2 has been observed for TiO2-ZnObased photoanode (with platinum free counter electrode), promises an improvement in the energy conversion efficiency by 57% in comparison with that of the DSSCs based on the pristine TiO2. Henceforth, TiO2-ZnO photoelectrode in ZnO will effectively act as barrier at the interface of TiO2-ZnO and TiO2, ensuring the potential for DSSC application.