Device characteristics of perylene-based transistors and inverters prepared with hydroxyl-free polymer-modified gate dielectrics and thermal post-treatment

Abstract

Organic field-effect transistors (OFETs) and complementary inverters were produced on the basis of n-type N,N'-dioctyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C8) using the neutral cluster beam deposition (NCBD) method. Significant improvements in surface morphology and crystallinity were observed after the surface modification of SiO2 gate dielectric layers with hydroxyl-free polymer insulators such as polymethylmethacrylate (PMMA) and cyclic olefin copolymer (COC), and thermal post-treatment. Electric characteristics and operational stability of PTCDI-C8-based OFETs were also clearly enhanced after the surface modification, and in particular, the thermally post-treated OFETs with COC-modified SiO2 gate dielectrics exhibited a high room-temperature mobility of 0.68 cm(2)/V s. Two structural types (generic vs. encapsulated) of inverters in top-contact configuration were fabricated by integration of the p-type pentacene and n-type PTCDI-C8 OFETs using COC-modified SiO2 gate dielectrics. Due to the increased electron mobilities and good coupling between p- and n-type OFETs, hysteresis-free, fast-switching inverters were realized with high gains of similar to 20 in the first and third quadrants of voltage transfer characteristics under ambient conditions. The device characteristics of the encapsulated inverters monitored as a function of the time were well maintained with slight degradation. (C) 2012 Elsevier B.V. All rights reserved.