Novel Triarylamine-Based Alternating Conjugated Polymer with High Hole Mobility: Synthesis, Electro-Optical, and Electronic Properties

Novel bi-triphenylamine-containing aromatic dibromide M3, N,N-bis(4-bromophenyl)-N',N'-dipheny-1,4-phenylenediamine, was successfully synthesized. The novel conjugated polymer P1 having number-average molecular weight of 1.31 x 10(4) was prepared via Suzuki coupling from the dibromide M3 and 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester. Polymer P1 had excellent thermal stability associated with a high glass-transition temperature (T-g = 141 degrees C). The hole-transporting and UV-vis-near-infrared electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the conjugated polymer films cast onto indium-tin oxide-coated glass substrates exhibited two reversible oxidation redox couples at E-1/2 values of 0.73 and 1.13 V versus Ag/Ag+ in acetonitrile solution. The hole mobility of the conjugated polymer P1 revealed similar to 10(-3) cm(2) V-1 s(-1), which is much higher than that of other conjugated polymer systems. The observed UV-vis-near-infrared absorption change in the conjugated polymer film P1 at applied potentials ranging from 0.00 to 1.23 V are fully reversible and associated with strong color changes from pale yellowish in its neutral form to green and blue in its oxidized form. Using a combination of experimental study and theoretical investigation, we proposed an oxidation mechanism based on molecular orbital theory, which explains the cyclic voltammetry experimental results well. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4654-4667, 2010