Magnetic field effect on recombination light in anthracene crystal

Recombination light or the so called electroluminescence has been studied in anthracene crystal by measuring its spectrum; its dependence on applied voltage and its transient response. The effect of magnetic field on this electroluminescence was so investigated as a function of intensity and orientation of the field and shows the same dependence observed for delayed fluorescence. This effect is explained by the formation of triplet and singlet electron–hole pairs leading to singlet and triplet excitons, decay of singlet exciton leads to prompt electroluminescence and triplet–triplet exciton annihilation leads to delayed electroluminescence. A theoretical kinetic model based on matrix density formalism permit to reach the rate constant for the recombination and dissociation of singlet and triplet electron–hole pairs.