Kinetically Trapped High-Density Interstitial Mn²⁺ Enables Concentration-Quenching-Free Persistent Luminescence in...

Long-persistent luminescence materials commonly suffer from concentration quenching at high dopant levels, limiting simultaneous optimization of luminescent centers and trap states. Herein, we report a kinetically controlled room-temperature strategy for high-density interstitial Mn²⁺ doping in CsCdCl₃ perovskites. Using cetyltrimethylammonium bromide  as both bromine source and crystallization modulator, rapid nucleation kinetically traps Mn²⁺ ions at interstitial sites within a Br-expanded lattice, bypassing thermodynamically favored substitutional incorporation. This nonequilibrium doping configuration effectively suppresses Mn²⁺ aggregation and breaks the concentration-quenching limit of conventional substitutional doping, enabling efficient emission even at 20% Mn²⁺ loading. The cooperative halide-interstitial doping further establishes a hierarchical trap landscape with optimized carrier trapping and release behavior. Consequently, the material exhibits a near-unity photoluminescence quantum yield of 94.2%, ultralong persistent luminescence exceeding 4000 s, continuously tunable afterglow emission, and anomalous thermally enhanced luminescence over 77-407 K. The synthesis is completed within 20 s at room temperature and is readily scalable to gram-level production. Multifunctional applications including optical thermometry, rewritable information storage, and dynamic anti-counterfeiting are further demonstrated.