Singlet and triplet exciton percolation in benzene isotopic mixed crystals

Abstract

New, closed form, approximate expressions are obtained for the calculation of ideal percolation thresholds which are determined by the migration topology. Excitation tunneling theory is briefly reviewed and extended for application to nonresonant, long range energy migration in mixed molecular crytals. These theories are applied to new singlet and triplet exciton percolation data for benzene isotopic mixed crytals. The differences between these results and the theoretical expectations are used to emphasize the importance of exciton lifetime and exciton trapping in determining the extent of long range energy transport in molecular crytals.