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 0 ,N 0 -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 1 H and 13 C NMR spectroscopy. These polymers possess good solubility in common organic solvent, thermal stability with relatively high glass-transition temperatures (Tgs) in the range of 152-273 � C, 10% weight-loss temperature in excess of 480 � C, and char yield at 800 � 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 Eonset 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 charac- teristics, and the estimated hole mobility of O-PMOTPA and Y-PMOPD were up to 1.5 � 10 � 4 and 5.6 � 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-con- taining conjugated polymer is a multifunctional material for various optoelectronic device applications. V C 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4037- 4050, 2009