Transparent-conducting-oxide nanowire arrays for efficient photoelectrochemical energy conversion

Abstract

We report one dimensional (1-D) transparent-conducting-oxide arrays coated with light-absorbing semiconductors to simultaneously maximize light harvesting and charge collection in a photoelectrochemical (PEC) system. Tin-doped indium oxide (ITO) nanowire (NW) arrays are prepared on ITO thin-film substrates as the transparent-conducting-oxide, and TiO₂ or CdSe/CdS/TiO₂ thin layers were coated on the ITO NW arrays as the solar light-absorbing layers. The optimal PEC performance, 0.85% under 100 mW cm⁻² of light illumination, is obtained from ∼30 μm-long ITO NW, which is covered with ∼20 nm-thick TiO₂ nanoshell. We finally demonstrate that the ITO NW-based photoelectrode is also compatible with one of the most efficient visible-light sensitizers, the CdS/CdSe quantum dot. Our approach using the transparent conducting 1-D array has wide potential to improve the PEC performances of conventional semiconducting materials through liberation from the poor charge transport.