Dependence of persistent photocurrent on gate bias in inkjet printed organic thin-film transistor

We have studied the photocurrent decay under gate bias in organic thin-film transistor (OTFT) using inkjet printed α,ω-dihexylquarterthiophene layer. The OTFT shows high photocurrents under light illumination and very slow decay of photocurrents under positive gate voltage. This is due to the gate voltage-controlled trapping and detrapping of the electrons near the interface. With increasing exposure time, more electrons are trapped and thus make the photocurrent decay slower. It is found that there is a power-law dependence between light exposure time and decay time constant.