Application of energy transfer model to partially DCM-doped Alq₃ light-emitting diode

Theelectroluminescent (EL) properties of partially-DCM doped Alq₃ (tris(8-quinoline) aluminum) light-emitting diodes (LEDs) are discussed on the basis of a simple energy transfer model due to exciton diffusion. The EL process is described as the product of the distribution of exciton density of Alq₃ and the radiative probability of excited molecule. Using the separated EL intensities from Alq₃ and DCM, the various ratios of EL intensities calculated from the model were compared with the experimental results. The diffusion length of the Alq₃ exciton was estimated to be 20 nm. The radiative probability of DCM-doped Alq₃ was found to be 4.4 times higher than that of Alq₃. The ratio of the former to the latter almost agreed with the ratio of the quantum photoluminescent yield. The doped DCM molecules are speculatd to suppress the generation of the Alq₃ exciton. The model is very simple, but explains the practical EL characteristics in organic dye-doped Alq₃ LEDs. © 1997 John Wiley & Sons, Ltd.