Highly efficient photon-to-electron conversion with mercurochrome-sensitized nanoporous oxide semiconductor solar cells

Abstract

Dye-sensitized solar cells based on nanoporous oxide semiconductor thin films such as TiO 2, Nb 2O 5, ZnO, SnO 2, and In 2O 3 with mercurochrome as the sensitizer were investigated. Photovoltaic performance of the solar cell depended remarkably on the semiconductor materials. Mercurochrome can convert visible light in the range of 400–600 nm to electrons. A high incident photon-to-current efficiency (IPCE), 69%, was obtained at 510 nm for a mercurochrome-sensitized ZnO solar cell with an I −/I 3 − redox electrolyte. The solar energy conversion efficiency under AM1.5 (99 mW cm −2) reached 2.5% with a short-circuit photocurrent density ( J sc) of 7.44 mA cm −2, a open-circuit photovoltage ( V oc) of 0.52 V, and a fill factor (ff) of 0.64. The J sc for the cell increased with increasing thickness of semiconductor thin films due to increasing amount of dye, while the V oc decreased due to increasing of loss of injected electrons due to recombination and the rate constant for reverse reaction. Dependence of photovoltaic performance of mercurochrome-sensitized solar cells on semiconductor particles, light intensity, and irradiation time were also investigated. High performance of mercurochrome-sensitized ZnO solar cells indicate that the combination of dye and semiconductor is very important for highly efficient dye-sensitized solar cells and mercurochrome is one of the best sensitizers for nanoporous ZnO photoelectrode. In addition, a possibility of organic dye-sensitized oxide semiconductor solar cells has been proposed as well as one using metal complexes.