Photophysics of excitation energy transfer in highly fluorescent polymers

We report the optical properties of highly fluorescent guest host systems of two conjugated polymers. The blue emitter laddertype poly(para-phenylene) (LPPP) is blended as a host with the red emitter poly(perylene-co-diethynylbenzene) (PPDB) as a guest at sub-percent and percent level concentrations. We use transient and steady-state photoluminescence as well as near-steady-state photoinduced absorption to show that an efficient excitation energy transfer of Forster type occurs between the blue emitting host and the red emitting guest. The spectral signatures of emissive and absorptive photogenerated species in both polymers are presented. In addition, we describe analytical relations to determine the lifetime of these species from photomodulation spectroscopy.