Femtosecond studies of photoexcited carriers and charge transfer nonlinearities in conducting polymers and oligomers

Despite numerous studies on the ultrafast photophysics of conjugated polymer systems such as poly(para-phenylene vinylene) (PPV) and its derivatives, great controversy persists regarding the nature and mechanisms of formation of the primary photoexcitations in these materials. Detailed knowledge of the photoexcitations is essential for developing optimized optoelectronic devices from these materials. In this paper, we report recent progress on several issues. First, the nature of the intrinsic photoexcitations and nonlinear decay mechanisms in the PPV family second, the use of photoinduced charge transfer in blends and bilayers to achieve novel nonlinear optical effects