Dependence of the vibronic emission on self-absorption and reemission processes in conjugated polymers

Abstract

Photoluminescence spectra from the edge of thin films of a conjugated polymer were obtained by varying the self-absorption level at different temperatures. This technique together with the use of a Franck-Condon analysis enabled a clear identification of the vibrational relaxation processes, providing a way to recognize the participating vibrational modes. The higher order vibronic bands were observed to shift to lower energies than those predicted theoretically. This was interpreted as an effect of self-absorption processes, which lead to the loss of energy by intramolecular interactions due to the increase of thermal disorder.