Momentum-space theory of exciton transport. II. Sensitized luminescence calculations for specific trapping models

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Abstract
On the basis of a recently developed formalism utilizing exciton transport equations in momentum space, experimentally relevant sensitized luminescence quantities are calculated for specific models of exciton capture by traps in molecular crystals. The quantities studied are host and trap luminescence (fluorescence or phosphorescence), quantum yield, and energy-transfer rate. Exact expressions are obtained and the behavior valid for long times is examined. The effect of variation in the initial condition involved in photon absorption is studied. While most of the calculations are based on the assumption that the temperatures are low enough to allow the neglect of detrapping, a brief description of detrapping effects is also given. The analysis is also applicable to situations other than those involving excitons or luminescence and generally describes the kinetics of a capture process occurring simultaneously with scattering in a band characteristic of motion in a crystal, without reference to the detailed nature of the moving quasiparticles.