Nature of the primary photo-excitations in poly(arylene-vinylenes)

Summary form only given. We present an overview of the optical properties and related experimental results obtained from poly(paraphenylene vinylene), PPV, and its soluble derivatives, and we critically examine the interpretation of these data in the context of both the band model and the exciton model of the electronic structure of these semiconducting and luminescent polymers. Results obtained from highly oriented and structurally ordered PPVs demonstrate that the observed disparities between the physical properties of PPV and the polydiacetylenes (PDAs) are not due to disorder; these differences are intrinsic and arise from the fundamental difference in the nature of the low energy photo-excited states: excitons in the PDAs and free carriers in the PPVs.