Photovoltaic properties of polythiophene nano-tubule films

The electronic properties of the polythiophene nano-tubule films were studied with surface photovoltage spectrum (SPS) and field-induced surface photovoltage spectrum (FISPS). The surface photovoltaic responses were resulted from the π–π∗ transition of polythiophene chains. Two extra photovoltaic responses in the near-IR region were observed under the external electric field. Based on the band theory and the principle of FISPS, these responses were ascribed to the charged surface electronic states, which were led by the interaction between polythiophene nano-tubules and the oxygen absorbed on the surface.