Phototransistors based on a donor–acceptor conjugated polymer with a high response speed

Abstract

A photoresponsive polymer thin-film transistor based on a donor–acceptor conjugated polymer ambipolar semiconductor (PBIBDF-BT) is proposed in this report. The device exhibited both hole- and electron-carrier transport response to incident light with photoswitching speeds below 14 ms. In addition, the photocurrent/dark-current ratio and the photoresponsivity were 4552 and 108.43 mA W⁻¹ for the p-type channel, and 1044 and 38.72 mA W⁻¹ for the n-type channel, respectively. The PBIBDF-BT films exhibit more pronounced sensitivity to red light than previous polymer semiconductors, and the drain current gradually increased with an increase in the illumination intensity, resulting in typical output field-effect transistor characteristics. The influence of mobility of PBIBDF-BT thin films, which were formed via spin coating at different spinning speeds on the OTS/SiO₂/Si substrate, on the phototransistor response to light illumination was further investigated.