Bifunctional hybrid persistent luminescent materials with optical and magnetic response

Persistent luminescent materials have attracted significant interest due to their unique afterglow emission and duration. These properties have been studied for decades but the potential applications of such materials are limited. In this work we introduce the concept of bi-functional hybrid materials combining optical and magnetic properties. Persistent phosphor crystals CaAl 2 O 4 : Eu 2+ , Nd 3+ (CAO) were combined with various loadings of polyethyleneimine (PEI) functionalized Fe 3 O 4 magnetic nanoparticles using Tylose (ty) as a binder, leading to hybrid materials CAO@ty@[PEI@Fe 3 O 4 ] ( 1 – 4 ) with optical/magnetic bifunctionality. Persistent phosphor crystals CaAl 2 O 4 : Eu 2+ , Nd 3+ (CAO) were combined with various loadings of polyethyleneimine (PEI) functionalized Fe 3 O 4 magnetic nanoparticles using Tylose (ty) as a binder, leading to four (i.e., 1–4) hybrid materials CAO@ty@[PEI@Fe 3 O 4 ] (1–4) with optical/magnetic bifunctionality, differing in their content of PEI-functionalized Fe 3 O 4 nanoparticles. Study of the structural, optical and magnetic properties confirmed that the addition of Fe 3 O 4 nanoparticles does not affect the structure and hence the luminescence details of the CAO crystal, however the luminescence intensity decreases systematically with increasing the Fe 3 O 4 mass loading. In addition, photoluminescence studies revealed a distinct afterglow emission peak centered at ∼440 nm, attributed to Eu 2+ . Magnetic studies demonstrated superparamagnetic behavior, with reduced magnetization due to Fe 3 O 4 @PEI mass loading. The bifunctional hybrid persistent phosphors 1 – 4 exhibited synergistic luminescent and magnetic properties, paving the way for applications in bioimaging, sensors, and multifunctional materials. • Hybrid materials with persistent luminescence (CaAl 2 O 4 :Eu 2+ , Nd 3+ ) and superparamagnetism (Fe 3 O 4 @PEI) were successfully synthesized. • CaAl 2 O 4 :Eu 2+ , Nd 3+ retained its luminescence and afterglow post-functionalization. with strong afterglow peak at ∼440 nm. • Superparamagnetic behavior was observed in all hybrid phosphors, with magnetization decreasing in proportion to Fe 3 O 4 loading. • These bifunctional materials exhibit potential for advanced applications in bioimaging, sensing, and multifunctional devices.