Photo-Induced Balanced Ambipolar Charge Transport in Organic Field-Effect Transistors

Photo-induced balanced ambipolar transports in lead phthalocyanine organic field-effect transistor are observed. The transport mode of the device is changed from typical p-channel to ambipolar under illumination at 655 nm, 100 mW/cm
²
. The physical origins of this phenomenon are resulted from the photo-induced energy barrier lowering for electrons injection at the source-channel interface, which is suggested to be the downward bending of orbital level in the channel material near the source by accumulation of photo generated holes there.