Optically detected electron paramagnetic resonance and fluorescence study on geminate ion recombination in low-density polyethylene doped with pyrene

Abstract

The optically detected electron paramagnetic resonance (ODEPR) spectrum of pyrene-doped low-density polyethylene has been studied. This is the first ODEPR spectrum observed on an ordinary polymer, and its intensity was comparable to that of spectra recorded in viscous solutions. The dependence of the ODEPR and fluorescence spectra on the concentration of pyrene as well as temperature led us to deduce the geminate recombination process in this inhomogeneous material. We found that: (1) charge recombination occurs mainly through electron hopping between the solute pyrenes. (2) Hole hopping between the pyrenes following hole transfer from the polymer matrix to the solute on the ODEPR timescale is allowed only at high temperatures and high solute concentrations.