Near-infrared-II balanced ambipolar phototransistors realized by the optimized planar-heterojunction channel layer and charge-transfer-complex photosensitive layer

Abstract

Ambipolar organic phototransistors (OPTs) operating in the near-infrared II (NIR-II) were successfully fabricated by using an organic planar-heterojunction channel layer and an organic–inorganic charge-transfer-complex (CTC) photosensitive layer. After optimizations of the ratio of vanadium pentoxide in CTC hybrid system and the substrate temperature of the deposited channel layer, the devices shows the most balanced output characteristics in the dark and under 1310 nm light illumination. These OPTs yielded significantly enhanced currents upon infrared light illumination with the photoresponsivities as high as 0.115 A/W for the n-channel, and 2.600 A/W for the p-channel, respectively. By analyzing the energy band of the heterojunction structure, the operating mechanisms of the balanced ambipolar NIR-II OPTs were derived. This work will be helpful to design the ambipolar infrared phototransistor and brings forward design thought of realization of optical complementary MOS logic circuits in the future.