Surface Modification of ZnO Nanorods with Small Organic Molecular Dyes for Polymer-Inorganic Hybrid Solar Cells

ZnO nanorod arrays modified with dye molecules demonstrate specific light-harvesting and charge-collecting properties which are promising for the enhancement of the characteristic performance of hybrid solar cells based on ZnO/poly(3-hexylthiophene). The properties of dyes commonly used for dye sensitized solar cells were investigated in relation to the performance of polymer inorganic hybrid photovoltaic devices. The use of indoline dye D205, which has dipole moments directing away from the ZnO surface, was found to suppress the reverse saturation dark current density and charge recombination and to consequently lead to higher open-circuit voltage and improved power conversion efficiency (PCE) from 0.22% to 0.71%. Derivatized squaraine molecules were synthesized and were found to improve device performance by extending the light-harvesting range to the near-infrared region, leading to increased short-circuit current density and the highest PCE of 1.02%.