Tuning of threshold voltage of organic field-effect transistors by space charge polarization

Abstract

We demonstrate a tunable threshold voltage in an organic field-effect transistor (OFET) using an ion-dispersed gate dielectric. By applying an external electric field (Vex) to the gate dielectrics, the dispersed ions in the gate dielectric are separated by electrophoresis and form space charge polarization. The drain current of the OFET increases more than 1.9 times, and the threshold voltage (Vth) decreases by 22 V (from −35.1 to −13.1 V). The direction and the magnitude of Vth shift are tunable with the applied Vex. The origin of the Vth shift is attributed to the polarization of the gate dielectric.