Tailored Anthracene–Naphthobenzofuran Hosts for Enhanced Efficiency and Operational Stability in Blue Fluorescence OLEDs

ABSTRACT Anthracene based fluorescent host materials continue to play a pivotal role in advancing device efficiency and lifetime. Especially when synergized with state‐of‐the‐art narrowband fluorescent emitters. In this context, we developed two anthracene naphthobenzofuran‐based host materials, NBFPAn and NBFNAn , through rational molecular engineering. Their planar yet sterically optimized structures effectively suppress intermolecular π–π stacking, minimizing excimer formation, and facilitating efficient singlet energy transfer to the dopant. The doped host films with multi‐resonance TADF emitter m‐t‐DABNA, the host films exhibit PLQYs of 84.2% ( NBFPAn ) and 93.9% ( NBFNAn ), along with high horizontal transition dipole orientations (Θ) of 83.8% and 88.2%, respectively. Additionally, both hosts exhibit excellent thermal and morphological stability, with decomposition temperatures (T d ) above 355°C and 381°C for NBFPAn and NBFNAn respectively, supporting reliable vacuum deposition. Devices employing these hosts achieve deep blue emission of λ em 463 nm, with EQE max of 10.5% and 8.56% for NBFPAn and NBFNAn, respectively. Notably, the NBFPAn based device exhibits an extended lifetime (LT 90 ) of 45 h at 1000 cd m −2 . This work underscores the critical role of molecular engineering toward simultaneously enhancing device efficiency and operational lifetime through optimizing exciton dynamics, charge transports for next‐generation high‐performance blue OLEDs.