Low-voltage operation of n-type organic field-effect transistors with ionic liquid

Abstract

High performance n-type organic field-effect transistors are developed to achieve high transconductance and low-threshold voltage using ionic-liquid electrolyte for intense electrostatic gating. Tetracyanoquinodimethane single crystals and C60 thin films are interfaced with ionic liquid of 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide known for its low viscosity and high ionic conductivity, so that high-density electrons are rapidly accumulated in the semiconductor surfaces with the application of minimum gate voltages, forming 1-nm thick electric double layers to concentrate electric field as high as 1 MV/cm. The C60 transistor shows the highest normalized transconductance among reported n-type organic transistors, together with minimum threshold voltage.