High-performance n-type organic thin-film phototransistors based on a core-expanded naphthalene diimide

Abstract

High-performance n-type organic phototransistors (OPTs) based on a core-expanded naphthalene diimide are reported in this letter. The photo responsivity is as high as 27000 AW−1 and photocurrent/dark-current ratio reaches 1.1 × 107 under a white light illumination with a power density of 107 μWcm−2. In such OPTs, persistent photoconductivity (PPC) is observed, which can be instantly eliminated by a positive gate voltage pulse. This is explained in terms of trapped photo holes in the channel. In the light on-off switching test, such PPC also leads to well-reproducible memory effect in the OPTs.