Flexible dye-sensitized solar cells using ZnO coated TiO2 nanoparticles

A photoelectrode using ZnO coated TiO2 nanoparticles was prepared for use in flexible dye-sensitized solar cells. To provide an inherent energy barrier between the electrode and electrolyte interface, the surface of the TiO2 nanoparticles was modified by thin ZnO layer. X-ray photoelectron spectroscopy and transmission electron microscopy image confirmed the formation of ZnO with a thickness of ca. ∼0.5 nm, possible thickness for tunneling process in particle-to-particle transport of electrons, on the TiO2 surface. The overall conversion efficiency was increased from 0.71 to 1.21% under a light intensity of 20 mW/cm2 (0.2 sun) due to the reduced recombination of photoinjected electrons without any post-treatment.