Layout-Dependent Vertical and In-Plane Leakage Current Reduction of Organic Thin-Film Transistors by Layer Contact Restriction

Organic thin-film transistors (OTFTs) are promising devices for designing flexible large-area sensor circuits. However, owing to the low carrier mobility of n-type organic semiconductors and relatively high leakage currents, the on/off current ratio cannot be sufficiently high, making the stable logic operation of OTFT circuits difficult. In this paper, the evaluation and reduction of layout-dependent leakage currents in OTFTs are presented. Experiments revealed that the layout design, in which the source and drain electrodes were contained within the gate metal and the semiconductor area, reduced the leakage current and improved the pull-down voltage level of the bottom-gate top-contact (BG-TC) OTFT logic gates. Additionally, the rail-to-rail operation of the OTFT logic gates was successfully demonstrated.