Light response characteristics of organic thin-film transistors with and without a P(MMA–GMA) modification layer

Abstract

This paper describes the photo-response characteristics of pentacene-based organic thin-film transistors (OTFTs) with SiO2 as the gate dielectric. The operation current increases significantly and the threshold voltage is shifted toward positive bias at the incident illumination. The distinguishable light responsive characteristics can be observed at the OTFTs with and without poly(methyl methacrylate co glycidyl methacrylate) (P(MMA–GMA)) as the modification layer, respectively. Maximum light responsivities of 24 600 and 1173 A W−1 were obtained for OTFTs with and without P(MMA–GAM), respectively, under the lower illumination power of 0.64 µW cm−2. The corresponding photo-response mechanisms were analyzed, which demonstrated that the present organic phototransistor properties have a strong dependence on the trap density at the pentacene bulk and the interface of pentacene/dielectric.