Near-planar light outcoupling structures with a finite lateral dimension for ultra-efficient and crosstalk-free OLED displays

Abstract The stratified structure of organic light-emitting diodes (OLEDs) is bound to confine a substantial portion of light within substrates or organic layers, limiting light outcoupling to air. Macroscale half-ball lenses can extract most of the light trapped in substrates, but their bulky protrusion undermines the planar advantages of OLEDs. Microlens arrays (MLAs), typically only tens of micrometers in height, preserve planarity well but offer only modest improvements in light outcoupling, particularly with a finite lateral dimension. Here we present a systematic approach to enhancing outcoupling efficiency while maintaining the near-planarity of OLEDs. The proposed method addresses the limited prompt light extraction of conventional MLAs – responsible for their modest performance enhancements – by jointly tailoring the OLED stack and the topography of near-planar outcoupling structures. With this approach, we demonstrate OLEDs with external quantum efficiency and current efficiency of 48.0% and 192 cd/A, respectively – far surpassing the 35.6% and 102 cd/A of a bare OLED and the 35.4% and 150 cd/A of MLA-attached OLEDs. Overcoming the trade-offs among intrusiveness, aperture ratio, and performance, our work offers an effective design strategy for ultra-efficient OLEDs and other light-emitting devices, opening up a route to in-pixel light outcoupling structures for crosstalk-free displays.