New P-Type of Poly(4-methoxy-triphenylamine)s Derived by Coupling Reactions: Synthesis, Electrochromic Behaviors, and Hole Mobility

Methoxy-substituted poly(triphenylamine)s, poly-4-methoxytriphenylamine (PMOTPA), and poly-N,N-bis(4-methoxyphenyl)-N',N'-diphenyl-p-phenylenediamine (PMOPD), were synthesized from the nickel-catalyzed Yamamoto and oxidative coupling reaction with FeCl3. All synthesized polymers could be well characterized by H-1 and C-13 NMR spectroscopy. These polymers possess good solubility in common organic solvent, thermal stability with relatively high glass-transition temperatures (T(g)s) in the range of 152-273 degrees C, 10% weigbt-loss temperature in excess of 480 degrees C, and char yield at 800 degrees C higher than 79% under a nitrogen atmosphere. They were amorphous and showed bluish green light (430-487 nm) fluorescence with quantum efficiency up to 45-62% in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. All polymers exhibited reversible oxidation redox peaks and E-onset around 0.44-0.69 V versus Ag/AgCl and electrochromic characteristics with a color change under various applied potentials. The series of PMOTPA and PMOPD also showed p-type characteristics, and the estimated hole mobility of O-PMOTPA and Y-PMOPD were up to 1.5 x 10(-4) and 5.6 x 10(-5) cm(2) V(-1)s(-1), respectively. The FET results indicate that the molecular weight, annealing temperature, and polymer structure could crucially affect the charge transporting ability. This study suggests that triphenylamine-containing conjugated polymer is a multifunctional material for various optoelectronic device applications. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 40374050,2009