Bypassing Pre‐Photoactivation in High‐Barrier Polyamide for Robust and Scalable Organic Persistent Luminescence

ABSTRACT The critical trade‐off between ambient stability and moisture/oxygen barrier properties has long hindered the practical application of organic persistent luminescent (OPL) polymers, particularly for rapid‐response photoluminescence in demanding environments. Such limitations are manifested in direct‐doping systems, which suffer from humidity‐induced mechanical deterioration and sluggish excitation kinetics. Here, we overcome this fundamental limitation by molecularly locking chromophores within a poly( m‐ xylene adipamide) (MXD6) matrix via melt doping. The engineered OPL composites leverage MXD6's exceptional barrier (oxygen transmission rate (OTR): 0.68 cm 3 ·m −2 ·day −1 ·bar −1 ; water vapor transmission rate (WVTR): 5.3 g·m −2 ·day −1 ) to achieve efficient multicolor afterglow with high quantum yields ( Φ afterglow = 30.6%) and long lifetimes (5.6 s), operating stably without pre‐photoactivation. Remarkably, they retain >90% of afterglow efficiency after 30 days of continuous water immersion. Integrated experimental and computational studies reveal that multiple disordered hydrogen bonding simultaneously rigidify the polymer matrix and interlock chromophores, establishing an oxygen and water barrier for triple excitons. This strategy enables meter‐scale homogeneous fibers and transparent films that validate industrial viability for versatile luminescent devices. This work offers a universal paradigm for ambient‐stable OPL polymers, solving the stability‐barrier trade‐off to unlock rapid‐response luminescence in demanding environmental applications.