Molecular design and device engineering of stable blue hyperfluorescent organic light-emitting diodes

Improving the stability of pure blue narrowband organic light-emitting diodes (OLEDs) has become increasingly important due to stringent NTSC/BT.2020 color requirements. Despite major commercial progress, achieving deep-blue emission with both high efficiency and long operational lifetime remains challenging. Hyperfluorescence (HF), in which phosphorescent or thermally activated delayed fluorescence (TADF) sensitizers transfer harvested excitons to narrowband fluorophores, provides a promising pathway toward unity exciton utilization, reduced roll-off, and ultra-narrowband electroluminescence. Recent developments in high-performance hyperfluorescent-based sensitizers, rigid multi-resonant narrowband emitters, and finely tuned host-guest systems have significantly enhanced device stability. Progress in molecular engineering, mitigation of nonradiative losses, precise management of excited-state processes, and refined device architectures have further enhanced overall device performance. This article reviews emerging material classes, photophysical mechanisms, engineering strategies, and outlines remaining challenges and future directions for realizing commercially viable, efficient, and stable pure-blue HF-OLED technologies. This Review focuses on stable, pure-blue hyperfluorescent organic light-emitting diodes, including emerging material classes, photophysical mechanisms, engineering strategies, and outlines challenges and future directions for achieving commercial viability.