Non-exponential phosphorescence decay of some aromatic hydrocarbons in poly(methylmethacrylate) matrices

Abstract

The phosphorescence decays of several aromatic molecules in poly(methylmethacrylate) matrices at concentrations of < 10^–2 mol dm^–3 have been investigated. Significant deviations from exponential behaviour have been observed at or near room temperature with molecules having first order lifetimes of the order of several seconds. The anomalous decay profiles have been successfully interpreted in terms of a triplet–triplet annihilation mechanism. P-type delayed fluorescence has been observed at 298 K in matrices containing [²H₈]naphthalene, triphenylene, decafluorobiphenyl and fluorene. The possibility that the T–T annihilation process occurs by a diffusive mechanism is discussed on the basis of available information about diffusion constant in poly(methylmethacrylate) matrices.