Highly sensitive near infrared organic phototransistors based on conjugated polymer nanowire networks

Abstract

Highly sensitive near-infrared (NIR) organic phototransistors (OPTs) were fabricated using nanowire network based on a narrow bandgap donor-acceptor (D-A) polymer as the photoactive channel. The D-A polymer nanowire network-based NIR-OPTs exhibit high responsivity of ∼246 A/W under an NIR illumination source (850 nm) with a light intensity of ∼0.1 mW/cm2. This value is over one order of magnitude higher than that of the structurally identical planar D-A polymer thin film OPTs. The high performance of the nanowire network-based phototransistors is attributed to the excellent hole transport ability, reduced density of the structural defects in the polymer nanowires, and improved contact at the channel layer/electrode interfaces. The high sensitivity and low cost solution-fabrication process render this OPT technology appealing and practically viable for application in large area NIR sensors.