EPR study of the PPV conducting polymers

Summary form only given. I/sub 2/ doped Poly(2-butoxy-5-Methoxy-1,4-Phenylenevinylene) (PBMPV) has been studied by the techniques of electron paramagnetic resonance (EPR). The spin density and linewidth of the undoped and lightly doped samples showed only weak temperature dependence. On the other hand, a heavily doped sample showed Curie behavior at low temperatures up to 180 K and increased with increasing temperature up to 220 K, and then leveling off up to room temperature. This is understood as showing the recombination process of the polarons into the bipolarons at low temperatures. For this sample, the linewidth increases rapidly with increasing temperature in the temperature range 180 to 220 K, and then decreasing up to room temperature. This temperature dependence is believed to arise from the same mechanism that gives rise to the temperature dependence of the spin density.