Excitation energy migration in highly emissive semiconducting polymers

The process of excitation energy migration (EEM) in conjugated polymers, wh ich is relevant both for light emitting diodes and laser applications, is p robed by doping the blue light emitting methyl-substituted ladder-type poly (para-phenylene) with small concentrations of a highly fluorescent pi-conju gated macromolecule. The experimentally attained temperature and concentrat ion dependence of the steady state photoluminescence is modeled and discuss ed by means of a two-step EEM process: (1) a thermally activated migration within the host and (2) transfer from the host to the guest. In particular we show that a Forster-type mechanism alone cannot account for the experime ntal facts in such a guest host system. (C) 2000 Published by Elsevier Scie nce B.V.