AC modulation of the recombination electroluminescence in anthracene single crystal

The recombination electroluminescence (REL) in an anthracene single crystal has been modulated by ac voltage at different dc biasing voltages. The frequency and ac voltage dependences observed are interpreted in terms of the presented model of sinusoidal current wave. The dc-voltage-induced changes in the modulation are explained by the voltage variation of the triplet exciton lifetime and wavelength of the current wave based on concomitant evolution of the triplet-to-singlet exciton concentration ratio responsible for the contribution of delayed and prompt components of the REL.