Effect of Confinement on Photophysical Properties of P3HT Chains in PMMA Matrix

The influence of arrangement of poly(3-hexylthiophene) (P3HT) chains embedded into poly(methyl methacrylate) (PMMA) matrix on photophysical properties, such as electronic absorption spectrum, band gap, and photoluminescence quantum yield, of the formed P3HT aggregates have been studied. It has been found that variation of P3HT fraction in PMMA matrix from 25 to 2 wt% is accompanied with the increasing quantum yield of photoluminescence, red shift of the band gap, and structural change of P3HT crystallites. The above changes are accompanied with disruption of the continuous network of P3HT fraction into smaller P3HT particles with size ranged from several microns to several tens of nanometers. The results are interpreted in terms of the changing intermolecular packing and reduced intramolecular torsional disorder. It is discussed that the most contribution to the above changes comes from P3HT molecules at the interface of P3HT cluster and PMMA environment.