The delayed fluorescence of poly( p-phenylene vinylene) (PPV) and poly( p-phenylene ethynylene) (PPE) derivative solids and frozen solutions at 20 K is described. It provides strong evidence for triplet-triplet annihilation to singlets excitons, accounting for up to ~3% of the total emission in PPV films and ~1.5% in PPE powder. It also yields triplet lifetimes of 70 and 110μs in PPV films and frozen solutions, and ~200 and ~500μs in PPE powder and frozen solutions, respectively.
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Partee et al. (1999) studied this question.
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