The delicate tuning of TiO2 electronic structure is essential to achieve the maximized photoresponse of light harvesting energy devices such as photocatalysis and photovoltaic cells. In this study, the photocurrent response of TiO2-based diodes with and without Fluorine doping method was investigated. The differences in electronic structure between undoped and F-doped TiO2 thin films are associated to the Fermi energy level which determines the available empty state energy against the valence band maximum. The incident photoconversion efficiency results indicate that the visible photoabsorption process and charge transport can be enhanced by energy matching between subgap states in TiO2 and the interference light and provides an effective strategy for light harvesting using TiO2.