Ultrahigh Detectivity in Spatially Separated Hole/Electron Dual Traps Based Near‐Infrared Organic Phototransistor

In phototransistors, the photovoltaic‐induced current is proportional to the turn‐on voltage shift and the total number of trapped charges. However, it is challenging to obtain a high turn‐on voltage shift simply by using minority carrier trap sites because high‐concentration carrier trap sites introduce strong current traps and carrier recombination. In this study, spatially separated, hole/electron, dual traps are introduced into a phototransistor, demonstrating the possibility of combining hole and electron traps without and with illumination, respectively, to obtain a large turn‐on voltage shift. The near‐infrared phototransistor demonstrates a high light‐to‐dark current ratio (1 × 106) alongside a turn‐on voltage shift of 28 V. The current quenching of the charge trap is effectively compensated by the threshold voltage shift, resulting in an increase of the drain–source current. The dual traps induce a low‐noise current and a high photoresponsivity (5.26 × 103 A W–1) under the same gate voltage (Vg = 0 V), exhibiting an ultrahigh detectivity (D1/f∗ = 1.88 × 1015 Jones; Dshot∗= 8.21 × 1016 Jones). Spatially separated, hole/electron, dual traps are introduced into a near‐infrared organic phototransistor to produce a large shift in the turn‐on voltage and a high photocurrent. The current quenching of the charge trap is effectively compensated by the turn‐on voltage shift, which achieves an ultrahigh detectivity of up to 1017 Jones.