Transient photovoltage(PV) technique was applied to investigate the separation and the transport mechanism of the photo-induced charge carriers on nano-TiO_ 2 film electrode. The positive PV transients were observed w...Transient photovoltage(PV) technique was applied to investigate the separation and the transport mechanism of the photo-induced charge carriers on nano-TiO_ 2 film electrode. The positive PV transients were observed whenever the light was incident from the gauze platinum(top illumination) or the ITO electrode(bottom illumination). This implies that the photo-induced electrons always accumulate near the ITO. Simultaneously, it is found that under the singe pulse illumination, PV transient at bottom illumination needs a shorter time to reach its maximum than that at top illumination. This indicates that the photo-induced carriers are separated faster on TiO_ 2/ITO interface than that in the bulk of the TiO_ 2 film. These demonstrate the existence of the contact potential on the TiO_ 2/ITO interface, with the downward band bending from the TiO_ 2 to ITO, which may cause the excess carriers to be separated by drift. Under the repeated pulses illumination, the PV transients at top illumination remained unchanged, while those at bottom illumination changed significantly. This results from the trapping of the excess electrons on the TiO_ 2/ITO interface.展开更多
文摘Transient photovoltage(PV) technique was applied to investigate the separation and the transport mechanism of the photo-induced charge carriers on nano-TiO_ 2 film electrode. The positive PV transients were observed whenever the light was incident from the gauze platinum(top illumination) or the ITO electrode(bottom illumination). This implies that the photo-induced electrons always accumulate near the ITO. Simultaneously, it is found that under the singe pulse illumination, PV transient at bottom illumination needs a shorter time to reach its maximum than that at top illumination. This indicates that the photo-induced carriers are separated faster on TiO_ 2/ITO interface than that in the bulk of the TiO_ 2 film. These demonstrate the existence of the contact potential on the TiO_ 2/ITO interface, with the downward band bending from the TiO_ 2 to ITO, which may cause the excess carriers to be separated by drift. Under the repeated pulses illumination, the PV transients at top illumination remained unchanged, while those at bottom illumination changed significantly. This results from the trapping of the excess electrons on the TiO_ 2/ITO interface.
