Synthesis and characterization of triphenylamine derivatives by oxidative polymerization

Hole transport polymers consisting of 4-methoxytriphenylamine (P-MOTPA) and 4-n-butyltriphenylamine (P-BTPA) were synthesized by oxidative coupling reaction using FeCl3 as an oxidant. These polymers had good solubility and their thin films showed sufficient morphological stability. 1H NMR and 13C NMR revealed that the monomers were exclusively connected at the p-positions of unsubstituted phenyl groups. Polymers had UV absorption maximum around 370 nm. Cyclic voltammograms of polymers showed well-defined pairs of reduction and oxidation peaks at 1.1 V versus Ag/AgCl, indicating that the polymers are electrochemically active. P-MOTPA and P-BTPA had hole drift mobility of being 4.04 × 10−5 and 2.98 × 10−5 cm2/V s at the electric field of 50 V/μm, respectively.