Air-exposure Effects on Complementary Organic Thin-Film Transistors and Inverter

Abstract

We demonstrated the balancing of p-type and n-type organic thin-film transistors (OTFTs) and complementary inverters using air-exposure effects. Pentacene and N,N′-ditridecylperylene- 3,4,9,10-tetracarboxylic diimide (PTCDI-C13) are used as the p-type and n-type semiconductors, respectively. Based on ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) analysis, we found that HOMO energy levels of both p-type and n-type semiconductor films were upward shifted when they were exposed to ambient air. These mechanisms account for the measured electrical characteristics of OTFTs, which exhibited shifts of on current level ION and turn-on voltages VTO as a function of exposure time to air. By using such air-exposure effects, we demonstrate the balanced p- and n-type OTFTs with comparable ION and VTO. Finally, we also demonstrate complementary inverter based on the balanced p- and n-type OTFTs.