Unified approach to electroluminescence efficiency in organic light-emitting diodes

We present unified approach for analyzing experiments on electroluminescence (EL) quantum efficiency (QE) with organic light-emitting diodes (OLEDs). A crucial aspect of the approach is that it yields a general formula that describes the ELQE(j) based on the interplay between the current (j)-dependent electron-hole recombination rate and EL quenching processes such as excitonic interactions and electric field-assisted dissociation of excited states occurring simultaneously within LEDs' emitters. Experimental data on PtL(26)Cl phosphor-based highly efficient OLEDs, are satisfactorily reproduced with this unified approach including the phosphor concentration dependent ratio in the population of monomolecular exciton- and bi-molecular excimer-emitting species.