Photoluminescence in poly(3-hexylthiophene)

Abstract

We report a study of the photophysics of solutions and films of the conjugated polymer poly(3-hexylthiophene) (P3HT). We have performed measurements of absorption, photoluminescence (PL), PL quantum yield, and time-resolved PL. For P3HT in a good solvent the PL decays with a time constant of 510 +/- 20 ps, and the PL quantum yield is 0.42 +/- 0.04, we assign the PL to the intra-chain singlet exciton, and deduce a natural radiative lifetime for this species of 1.2 +/- 0.1 ns. We explore the use of solvent mixture as a way of controlling the degree of intermolecular interaction. We find that there is a red-shift of absorption and PL in poor solvent mixtures, and the spectra and PL quantum yield become similar to the film. The PL decay becomes faster and non-exponential in poor solvent mixtures and the thin film.