(657e) Effect of Surface Structure on Interfacial Charge Transfer In Photoelectrochemical Cells

Photoelectrochemical cells (PECs) are the most promising of the solar cell types for inexpensive fabrication and high energy conversions. The PEC set up consists of an organo-metallic photosensitive dye physisorbed onto a nanowire mat which is sintered onto a sputter-coated indium tin oxide-glass substrate. This structure acts as a metal oxide framework which in turn is connected to the working electrode of an electrochemical cell. Light absorption occurs in the dye which leads to the generation of sub-bandgap excitations that are used as electronic charge carriers which must then be transferred across the dye-nanowire interface. Improving the mobility of these charges across the dye/metal oxide and metal oxide/electrode interface will directly impact the overall efficiency of the photochemical cells. The photocurrents produced by this process are measured by an atomic force microscopy using an electrochemical cell where the tip acts as the counter electrode to complete the electrical circuit for current generation. The charge collection along the length of the nanowire will be mapped and its relation on the adsorption of the dye molecules along its surface will be studied. The variations in the photovoltages both in light and dark conditions will also be observed. Emphasis will lie on investigating methods for decreasing the recombination efficiency and increasing the conversion efficiency of the photoelectrochemical cells.