Single‐Emitter White OLEDs via Microcavity Spectral Engineering

Abstract White organic light‐emitting diodes (WOLEDs) are promising candidates for next‐generation lighting and display technologies. However, conventional WOLED fabrication often relies on complex doping schemes or multiple color stacked emitting layers, complicating device design, and fabrication. Here, a simple approach for fabricating ITO‐free WOLEDs with a single‐component, using a planar aluminium microcavity, is presented. By engineering the cavity and surface plasmon polariton modes around the emission resonance of the high‐efficiency blue thermally activated delayed fluorescence emitter DMAC‐DPS, electroluminescence that is spectrally broadened to white light, with a tunable color temperature ranging from 3790 to 5050 K, is achieved. The WOLEDs are top‐emitting and reach an external quantum efficiency of >5%. The results are supported by optical simulations and transient emission measurements, providing insights into the emission kinetics.