The photovoltaic properties of alpha -bromine-terthiophene thin film were investigated by means of surface photovoltage spectroscopy and field-induced surface photovoltage spectroscopy. The surface photovoltaic (SPV) response intensity of the pi --> pi* transition band (300-430 nm) was enhanced when a positive electric field was applied and it was weakened when a negative electric field was applied. Interestingly, three new photovoltaic response bands were observed in the visible and near-IR region (430-1200 nm) under an external electric field. After the film was doped with iodine vapor, the three photovoltaic response bands can be observed without an external electric field being applied. According to the principle of FISPS and phase technique, the three bands can be explained by the charge-resonance of the dimer radical cations in the doped film.