OPTICAL AND MORPHOLOGY OF SELF-ASSEMBLED POLYHEXYLTHIOPHENE (P3HT) NANOWIRES

Abstract

Poly (3-hexylthiophene-2, 5-diyl) (P3HT) is a well-known p-type semiconductor for electronic and optoelectronic applications with a bandgap of ~ 1.9 eV. It is believed that the nanowire form of the polymer offers better structure, stability, and carrier pathways as an electronic device. In this study, P3HT nanowires were synthesized by aggregation under the dark for 72 h in a partial solvent, toluene. To investigate the change in polymer chain entanglement, spectra of UV-Vis absorption, FTIR and Raman of both P3HT nanowires and amorphous P3HT films were compared and further analysed. The result shows that the optical absorption of P3HT nanowires had blue shifted to higher energy indicating bandgap widening compared to amorphous P3HT. This electronic behaviour change is supported by FTIR and Raman results that implied increasing P3HT conjugation length with nanowire formation. The randomly oriented nanowires had an estimated diameter size of 10 – 20 nm. This improved nanostructure is majorly driven by intermolecular π-π stacking interactions that can produce P3HT film with better performance as charge carrier layer and photon absorber.