Synthesis and characterization of novel polythiophenes with graphene-like structures via intramolecular oxidative coupling

Novel polythiophenes with graphene structures (GPTs) could be synthesized based on intramolecular oxidative coupling of the polythiophene precursors having phenyl groups at the 3-position, poly(3-(4′-(3′′,7′′-dimethyloctoxy)phenyl)thiophene) (P3PhT) and poly(3-hexylthiophene)-b-P3PhT (P3HT-b-P3PhT), using FeCl₃ as an oxidative agent. The GPTs were characterized by ¹H NMR spectroscopy, UV-vis spectroscopy, FT-IR spectroscopy, cyclic voltammetry and X-ray diffraction. The thin film transistor (TFT) characteristics were also performed for P3HT-b-GPT. The progression of oxidative coupling of P3PhTs was confirmed by ¹H NMR and FT-IR spectroscopies. Moreover, GPTs showed significant red-shifts in the UV-vis spectra due to their high coplanarity, extended π-conjugation length, and strong π-stacking formation. P3HT-b-GPT also showed a red-shift in the UV-vis spectra and a reduced band gap as compared to the pristine P3HT. P3HT-b-GPT exhibited hole mobility (∼10⁻⁵ cm² V⁻¹ s⁻¹) which is comparable to that of pristine P3HT having a similar molecular weight.