Phosphorescence kinetics of complex organic molecules in solid solutions under conditions of bimolecular quenching of excitation

An investigation was made of the low-temperature (T= 77 K) kinetics of the phosphorescence and fluorescence emitted by solid solutions of coronene in polymer matrices under conditions of strong pulsed excitation. Nonexponential decay of both phosphorescence and fluorescence was observed under these conditions and it was attributed to bimolecular annihilation quenching. A theoretical analysis of the dynamics of deactivation of excitations was made allowing for the processes of triplet-triplet annihilation (TTA), and of dipole-dipole singlet-singlet and singlet-triplet annihilation. A comparison of the experimental results with those obtained by theoretical analysis yielded an estimate of the characteristic TTA distance: R 0 = 55 ± 5 A