Ambipolar organic phototransistor based on F16CuPc/α6T pn heterojunction

We studied the electrical performance of ambipolar organic transistors based on an F16CuPc/α6T pn heterojunction illuminated by a light from a white LED. As the illumination intensity is increased up to ca. 3000 Lux, the hole mobility decreases to about 1/3 while the electron mobility is only slightly increased. Photogeneration carriers (electrons) enhances n-channel operating characteristics, which results a decrease in gate voltage applied to the second active layer (or the increase in gate voltage applied in the depletion layer or the first layer), which suppresses p-channel operating characteristics although the photogeneration carriers (holes) also enhances p-channel operating characteristics. This result implies that the photoinduced charge transfer in the F16CuPc/α6T pn heterojunction devices is mainly dominated by the acceptor semiconductor (F16CuPc). The drain current is significantly increased (n-channel) or decreased (p-channel) by a light, which is used as an additional control parameter making the device interesting for sensor applications.