Synthesis and Characterization of a New Ethynyl-Linked Alternating Anthracene/Fluorene Copolymer for Organic Thin Film Transistor

Abstract

A new p-type conjugated copolymer, poly(9,10-diethynylanthracene-alt-9,9-didodecylfluorene) (PDADF), which is composed of ethynyl-linked alternating anthracene/fluorene, is synthesized via a palladium(II)-catalyzed Sonogashira coupling reaction with 9,10-diethynylanthracene and 2,7-diiodo-9,9-didodecyl-fluorene. The obtained polymer is confirmed by FTIR, H-1-NMR, C-13-NMR and elemental analysis. The PDADF had very good solubility in organic solvents such as chloroform and had a weight average molecular weight of 29,300 with a polydispersity index of 1.29. The PL maximum of the polymer was found at 533 and 568 nm for a solution and 608 nm for film, respectively. The highest occupied molecular orbital (HOMO) energy of the polymer is -5.62 eV as measured via cyclic voltammetry (CV). A solution-processed thin film transistor device showed a carrier mobility value of 6.0 X 10(-4) cm(2)/Vs with a threshold voltage of -17 V and a capacitance (C-i) of 10 nF/cm(2). The out-of-plane and in-plane GIXD pattern of spin-coated polymer on SiO2 dielectric Surfaces showed an amorphous halo near 2 theta = 20 degrees. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1609-1616, 2009