Photocontrol of charge injection/extraction at electrode/semiconductor interfaces for high-photoresponsivity organic transistors

Abstract

Charge injection typically occurring at the electrode/semiconductor interface in organic field-effect transistors (OFETs) is of great importance to the device performance and stability. Therefore, the chemical modulation of electrode/semiconductor heterojunctions provides a promising approach to enhance the performance and even incorporate new functionalities. In this study, we develop an efficient route for constructing optically switchable OFETs featuring a photochromic spirothiopyran (SP) self-assembled monolayer (SAM)-functionalized electrode/semiconductor interface. The photoisomerization of SPs induces a reversible change in the dipole moment of SP-SAMs, which affects the work function of gold electrodes. This change in the electrode work function enables the tuning of the contact resistance between organic semiconductors and metal electrodes. Consequently, the channel conductance of these devices is modulated in a nondestructive manner, thus leading to a new type of cost-effective OFET-based photodetector with high photosensitivity. These results help us to better understand interfacial phenomena and offer novel insights into developing a new generation of multifunctional interfaces and ultrasensitive OFET-based sensors by interface engineering.