Comparison of electroluminescent quantum efficiencies of PPV and a PPV-related alternating block copolymer

A comparison of the electroluminescent properties of poly(p-phenylene vinylene) (PPV) and a conjugated/non-conjugated alternating block copolymer has been made. The chromophoric sequences in the latter contain about 76 mol% of sequences containing three phenylene or dimethoxy phenylene rings interspersed with vinylene units, with the remaining chromophores being a distribution of longer sequences containing additional phenylene vinylene units. Photoluminescent and electroluminescent spectra of PPV and the block copolymer are very similar, but the quantum efficiency of the latter is up to two orders of magnitude greater. This is attributed largely to morphological differences between the two macromolecules; the block copolymer can provide greater excitonic confinement by virtue of a phase-segregated morphology.