Enhancing Operational Lifetime of Blue Organic Light‐Emitting Diodes Through Targeted Deuteration of Host Materials

ABSTRACT The development of blue organic light‐emitting diodes (OLEDs) with longevity remains a significant challenge. Using deuterated materials has been established as a highly effective, universal method to improve the operational stability of blue OLEDs. However, the intrinsic mechanisms of the deuterium effect on device lifetime, as well as the relationship between the specific deuteration sites within the molecular structure and operational stability, have not been fully elucidated. In this work, we focused on two anthracene‐based blue host materials with linear (9‐phenyl‐10‐(4‐phenylnaphthalen‐1‐yl)anthracene, PNA) and angular (7‐phenyl‐1‐(10‐phenylanthracen‐9‐yl)dibenzofuran, PADF) molecular structures. Through targeted deuteration of distinct phenyl groups, combined with device degradation studies and molecular dynamics simulations, we demonstrated that deuterating the phenyl group in closer proximity to adjacent molecules yields a disproportionately large lifetime enhancement, achieving 77% to 80% of the lifetime of fully deuterated hosts at a much lower deuteration ratio. The position‐dependent isotope effect on device lifetime provides a strategic guideline for designing cost‐effective, deuterated OLED materials through minimal, targeted deuterium substitutions.