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.