A unified decay formula for luminescence decays

We suggest a unified decay formula for luminescence decays in light-emitting diodes by modifying the classical stretched exponential decay. From fundamental considerations we find that the stretched exponent, which is a constant in the classical stretched exponential decay, intrinsically changes with time for luminescence decays. On this basis we develop a unified decay formula by introducing a time-dependent stretched exponent. The time dependence of the stretched exponent is attributed to the lifetime dispersion of localized excitons.