Vertical organic field effect phototransistor with two dissimilar source and drain contacts

A solution processable vertical organic field effect phototransistor was fabricated using poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 as the photo-active materials while poly(methyl methacrylate) is used as a dielectric layer. Interdigitated conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) is used as a source and lithium flouride/aluminum as a drain. The device exhibits current modulation when the gate is positively biased. A significant photoeffect is observed in the reverse bias mode. Unlike conventional organic phototransistors, this device can operate at a zero source–drain bias with a photosensitivity and responsivity proportional to the gate voltage. A photosensitivity of up to 105 and a responsivity of up to 2AW−1 are achieved in this mode. This effect is due to the presence of the weak photovoltaic behavior of this device. •A solution processable vertical field effect phototransistor is demonstrated.•Photosensitivity as high as ~105 with responsivity of 2AW−1 is achieved.•The gate can be used to modulate photocurrent with low leakage current.•The device shows weak photovoltaic behavior.