Bimolecular recombination in solution-processed 6, 13- bis(pentylphenylethynyl) pentacene thin-film transistor

We have studied the light intensity dependence of drain current under illumination for the organic thin-film transistor using 6, 13-bis (pentylphenylethynyl)pentacene, having photosensitivity of up to 107. The carrier concentration in the channel could be achieved by comparing the currents at dark induced by gate potential and those generated under illumination at zero gate voltage. It increases with illumination intensity with a power law of 0.61, suggesting that the bimolecular recombination is the dominant one during the light illumination, resulting in no photocurrent at high gate potential.