Influence of VB group doped TiO2 on photovoltaic performance of dye-sensitized solar cells

Dye-sensitized solar cell with VB group (vanadium (V), niobium (Nb) and tantalum (Ta)) doped TiO2 prepared by hydrothermal method shows a higher photovoltaic efficiency compared with the undoped TiO2. All the VB doping shift the flat band potential positively and increase the doping density which is investigated by Mott–Schottky plot. The positive shift of flat band potential improves the driving force of injecting electron from the LUMO of dye to the conduction band of TiO2 and the photocurrent. On the other hand, the increase of doping density accelerates transfer rate of electrons in TiO2 than the un-doped, which is confirmed by intensity-modulated photocurrent. V-, Nb-, Ta-doped TiO2 exhibited photovoltaic performance with 7.80%, 8.33%, 8.18%, respectively, compared with that of the cells based on pure TiO2 (7.42%).