Hierarchical Energetic Coherence and Interfacial Robustness Enable 44.3% EQE Deep-Blue Hyperfluorescent OLEDs

Abstract

Here we demonstrate that integrating hierarchical energy-level coherence with robust interfacial photophysics enables simultaneous optimization of charge injection, charge transport, and charge recombination in hyperfluorescent (HF) blue-emitting organic light-emitting diodes (OLEDs). A self-assembled hybrid hole-injection layer forms a vertically stratified, dipole-induced interface, and an HF emitting layer (EML) that is composed of a fast triplet-upconverting sensitizer, a high-triplet-energy host, and a narrowband thermally activated delayed fluorescence (TADF) emitter achieves efficient triplet harvesting and singlet-mediated energy transfer. This hierarchical framework ensures smooth charge-carrier propagation, balanced recombination, and strong suppression of interfacial exciton quenching, thereby preserving efficient triplet recirculation even in multilayer architectures. As a result, the blue HF OLED attains a high external quantum efficiency of 44.3%, a narrow emission bandwidth of 19 nm, deep-blue CIE coordinates of (0.104, 0.173), and improved operational stability.