Unique Temperature Dependence of NMR and UV-visible Spectra of Poly(3-hexylthiophene-2,5-diyl) and Its Related Compounds

Abstract Lowering temperature of solutions of poly(3-hexylthiophene-2,5-diyl) P3HxTh below −10 – −20 °C leads to decrease in signal intensity of aromatic-H and α-CH2 in 1H-NMR spectrum. A shift of the π-π* absorption band to a longer wavelength by 26–60 nm is also observed. These results are accounted for by aggregation of P3HxTh through intermolecular interaction of the π-conjugated system.