Grafting Fluorinated Polymer Nano layer for Advancing the Electrical Stability of Organic Field-Effect Transistors

Abstract

With the goal of achieving high-performance electrically stable organic field-effect transistors (OFETs), we chemically graft a fluorinated polymer nanolayer onto the polar oxide dielectric surfaces via a simple and easy fabrication process in ambient air. The para-fluorine-thiol click reaction between poly(pentafluorostyrene) (PFS) and mercaptopropyltrimethoxysilane is used to synthesize a graftable fluorinated polymer (gPFS). The surface characteristics of the gPFS-treated SiO2 dielectrics and the crystal structure and grain growth of the overlying organic semiconductors are investigated. Various semiconductor materials are employed for the OFETs prepared with gPFS-treated SiO2 dielectrics, including vacuum-processed pentacene, N,N-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide, solution-processed 5,11-bis(triethylsilylethynyl)anthradithiophene, and poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-(E)-1,2-di(2,2'-bithiophen-5-yl)ethane. Three OFETs are prepared with different dielectrics: (i) bare SiO2, (ii) gPFS-treated SiO2, and (iii) perfluorooctyltriethoxysilane-treated SiO2. The OFETs prepared with the gPFS-treated SiO2 dielectrics display the highest mobilities and smallest hysteresis. Furthermore, the gPFS-treated SiO2 provides the best device stability under a sustained gate bias, suggesting that the gPFS surface minimize the number of traps present in the OFET.