Dynamics of photoexcitations in highly fluorescent organic guest-host-systems

A guest-host-system based on a few hundred ppm of the red emitting poly(perylene-co-diethynylbenzene) (PPDB) in blue emitting ladder-type poly(para-phenylene) (LPPP) can be used to build efficient white light emitting devices. Upon photoexcitation of the films a very efficient excitation energy transfer (EET), involving the diffusion of an electron hole pair from the higher energy gap LPPP to the lower-gap PPDB, is observed. The results of optically detected magnetic resonance and photoinduced absorption of these blends, all of which are sensitive to charged spin 12 states and spin 1 triplet excitons, are described and discussed.