Integrated Optoelectronic Model to Predict the External Quantum Efficiency of Single‐Layer TADF Organic Light‐Emitting Diodes

ABSTRACT Organic light‐emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) are an attractive alternative to phosphorescent OLEDs to harvest triplet excitons. However, a quantitative device model is still lacking. Here, we present an optoelectronic device model that fully predicts the performance of single‐layer TADF OLEDs without any adjustable parameter. All input parameters have been independently obtained from charge‐transport characterization, optical constants, and photoluminescence measurements. The electrical characteristics of the OLED are first simulated with a drift‐diffusion solver, followed by the determination of the position‐ and voltage‐dependent exciton densities based on kinetic rates determined from photoluminescence experiments, and finally combined with an optical‐outcoupling model. The integrated optoelectronic model is validated with single‐layer OLEDs based on the TADF emitter 9,10‐bis(4‐(9H‐carbazol‐9‐yl)−2,6‐dimethylphenyl)−9,10‐diboraanthracene (CzDBA), quantitatively describing the external quantum efficiency and its roll‐off for different layer thicknesses and temperatures.