Work Function Engineering of Electrohydrodynamic-Jet-Printed PEDOT:PSS Electrodes for High-Performance Printed Electronics

Poly­(3,4-ethylenedioxythiophene):poly­(4-styrene sulfonate) (PEDOT:PSS) has demonstrated outstanding performance as a charge transport layer or an electrode in various electronic devices, including organic solar cells, organic light-emitting diodes, and organic field-effect transistors (OFETs). The electrical properties of these devices are affected by the contact properties at the PEDOT:PSS–semiconductor junction. In this research, we performed work function (WF) engineering of electrohydrodynamic (EHD)-jet-printed PEDOT:PSS and successfully used it as an electrode to fabricate high-performance OFETs and complementary logic circuits. Two types of PEDOT:PSS materials–one with a high WF (HWF, 5.28 eV) and the other with a low WF (LWF, 4.53 eV)–were synthesized and EHD-jet-printed. The WF of PEDOT:PSS was deterministically modulated by approximately 0.75 eV through simple mixing of the two synthesized PEDOT:PSS materials in various ratios. OFETs fabricated with HWF and LWF PEDOT:PSS electrodes showed excellent electrical properties, including the ON/OFF switching ratio higher than 10⁷ and the highest carrier mobility greater than 1 cm²·V^–1·s^–1. Furthermore, the HWF and LWF PEDOT:PSS electrodes were integrated to fabricate complementary metal–oxide–semiconductor (CMOS) NOT, NOR, and NAND circuits.