Recent Advances in Narrow Emission Bandwidth Materials for Application in Organic Light-Emitting Diodes

The preparation of narrow emission bandwidth materials is crucial for the development of advanced organic light-emitting diodes (OLEDs). In this review article, state-of-the-art methodologies used for the preparation of narrow bandwidth emitters with high color purity are summarized, and favorable design strategies are rationally organized. Currently used OLEDs have some issues, such as device stabilization that must be resolved, and color purity should also be considered. Given the recent exponential growth in the number and types of narrowband emissive organic emitters and organometallic complexes exhibiting multiple-resonance thermally activated delayed fluorescence and metal-to-ligand charge transfer characteristics, there is an urgent need to establish key technology descriptors for OLEDs with high color purity. In this review, recent developments in boron, fused indolocarbazole, carbonyl, phosphine oxide, and organometallic complexes that exhibit narrow emission spectra are described, and future directions to advance the performance of such devices are suggested.