339 FY 2008 Annual Progress Report DOE Hydrogen Program II

Investigation into integrated PEC/PVC for water splitting and light harvesting has focused on doping, QD sensitization and nanomaterials morphology. We have demonstrated, for the first time, PVC based on combined use of nitrogen doping and CdSe QD sensitization of nanocrystalline TiO2 thin films with promising results for solar energy conversion. Such TiO2:N/CdSe PVC produced an incident-photon-to-current efficiency (IPCE) of 95% at 300 nm, a 27.7% fill factor (FF) and a power conversion efficiency of 0.84%. Many aspects of that system are still not optimized including nitrogen doping level, properties of CdSe QDs, and TiO2 film morphology. PEC based on ZnO nanostructures produced via pulsed laser deposition (PLD), oblique angle deposition (OAD) and electron beam glancing angle deposition (GLAD) show differing morphological, photophysical and PEC characteristics due to each technique. A combination of HRSEM, UV-vis spectroscopy, XRD and photoelectrochemistry has been used to characterize the fundamental properties of the ZnO PEC. Hybrid nanorod structures of WO3 and TiO2 in a stacked configuration via the GLAD technique have also been studied for their light harvesting and water splitting abilities.