Bias Dependence of Organic-Oxide Phototransistors with Peak Infrared Absorption at 1550 nm

Photodetectors operating across the short-wave infrared region are essential elements of modern optoelectronic technologies. This work demonstrates the integration of an organic bulk heterojunction polymer layer on an oxide thin-film transistor to achieve a peak infrared photoresponse at 1550 nm. As the efficiency of organic semiconductors decreases at longer wavelengths, the phototransistor structure uses trap-assisted charge injection to enhance the photoresponse. This work optimizes the detector performance by investigating the balance between bias stress and signal-to-noise under different bias conditions, enabling a responsivity at 1550 nm up to 130 mA/W at a low light intensity of 2.5 × 10^–5 W/cm².