Phototransistors of a Rigid Rod Conjugated Polymer

Phototransistors of a rigid-rod conjugated polymer, a derivative of poly(para-phenylene ethynylene)s with thioacetyl end groups (TA-PPE), were investigated. The phototransistors exhibited high photo-response properties with responsivity at 36 mA/W and switch ratio up to 3.3 x 10(3), indicating the potential applications of the phototransistors in optoelectronic devices. Moreover, the photoresponse mechanism of the transistors was examined. Two effects-photoconductive and photovoltaic effects-were both observed in the same transistors depending on the gate bias. With gate bias the polymer phototransistors were dominated by photovoltaic effect, while without gate bias the devices were decided by photoconductive effect.