Comparative study of photoelectric properties of regiosymmetrical poly(3,4-dialkoxythiophene)s

A series of regiosymmetrical poly(3,4-dialkoxythiophene)s: poly(3,4-diamyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-di(2-ethyl-1-hexyloxy)thiophene), and poly(3,4-didodecyloxythiophene) were synthesized by the FeCl₃-oxidative approach. All these polymers were evaluated with NMR, FT-IR, gel permeation chromatography (GPC), thermo-gravimetric analysis (TGA), UV–Vis spectroscopy, and photoluminescence (PL). The polymers have excellent solubility in common organic solvents, and TGA studies show that the polymers lost 5% of their weights on heating to 250 °C above. Investigations of the UV–Vis spectroscopy show that the absorption maxima of the polymer thin films are similar to those in solutions, and the optical band gaps of the polymer thin films are ranging from 2.27 to 2.69 eV. In PL spectra, maxima emission peaks of the polymer thin films lie at 527 to 589 nm, embodying colors from green to yellow, and the quantum yields of the polymers are in the range of 22–28%. All the data indicate that the polymers have good solubility, outstanding thermal stabilities, low band gaps, and high PL quantum yields, and they might be excellent polymeric materials for applications in organic light-emitting diodes (OLEDs), light-emitting electrochemical cells, polymer solar cells, and so on.