Organic-inorganic interfacial charge-transfer (ICT) transitions provide the concepts that organic-inorganic interfaces serve as a field for light absorption and charge separation directly occurs without energy loss. Here, we report efficient light-to-current conversion due to the ICT transitions in TiO2 chemically adsorbed with 2-anthroic acid. The incident photon-to-current conversion efficiency (IPCE) surpasses 85%, showing the significant improvement as compared to the reported results. Density functional analysis shows that the ICT absorption arises from strong d(pi)-pi* interactions at the inorganic-organic interface. In addition, we examined the density of states (DOS) of unoccupied surface states on TiO2 from the absorption and IPCE spectra. (C) 2014 Elsevier B.V. All rights reserved.