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

作者：Shou, Meihua; Zhang, Qinglei; Li, Hao; Xiong, Shicheng; Hu, Bangyao; Zhou, Jiadong; Zheng, Nan; Xie, Zengqi; Ying, Lei; Liu, Linlin^*

来源：Advanced Optical Materials, 2021, 9(7): 2002031.

DOI：10.1002/adom.202002031

• near-infrared photodetectors
• organic phototransistors
• silver nanoparticles
• specific detectivity
• turn-on voltage

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 x 10(6)) 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 x 10(3) A W-1) under the same gate voltage (V-g = 0 V), exhibiting an ultrahigh detectivity (D-1/f* = 1.88 x 10(15) Jones; D-shot*= 8.21 x 10(16) Jones).