Platinum decorated zinc oxide nanowires as an efficient counter electrode for dye sensitized solar cells

Well aligned ZnO NWs arrays served as a scaffold for the deposition of Pt by evaporation and their electrocatalytic properties were examined against the iodide/triiodide redox shuttle. By varying the amount of deposited Pt and the aspect ratio of the NWs arrays, an increment in the peak current density (up to 87%) and in the reaction rate for I3− reduction were observed, as compared to planar Pt based electrodes prepared by evaporation and electrodeposition. The observed improvements are due to the enhanced surface area, provided by the NWs arrays for Pt deposition, that facilitates also the diffusion of I3− ions to the catalytic active sites. The efficiency of the resulting dye sensitized solar cells (DSSCs) was found to be 12% and 14% higher than that of equivalent DSSCs with evaporated and electrodeposited electrodes, respectively. These results demonstrate that Pt decorated ZnO NWs electrodes can ensure better utilization of the expensive Pt, helping in the cost reduction of DSSCs.