Photoelectric characteristics of vertical structure organic phthalocyanine thin film transistor

In this paper, we have fabricated two types vertical structure organic thin film transistors (VOTFT) by vacuum evaporation and magnetron sputtering, the semiconductor material are copper phthalocyanine (CuPc) and lead phthalocyanine (PbPc) which have good photosensitive properties. CuPc used in this work thermally evaporated at the temperature of 400 °C, and PbPc was 330°C. The pressure were about 6.0×10^-4 pa. Excitons will be generated after the optical signal irradiating into phthalocyanine, then transform into photocurrent under the built-in electric field formed by the Schottky contact. This makes the output current multiplication. The results show that the I-V characteristics of transistor are unsaturated. When CuPc transistor V_ec=3 V, the ratio of white light and dark current is in the range of 2.9-6.4. The photocurrent I_L=0.122 μA in white light, which is the 2.227 times of base current. The optical magnification of the device is 98.65.