Programmable afterglow tuning in monodisperse SiO₂ microparticles through spatially confined emitter doping

Developing monodisperse microparticles with tailored afterglow properties is crucial for optoelectronic applications, achieving afterglow tuning in uniform microsized platforms remains a significant challenge. Here, we present programmable afterglow tuning in monodisperse SiO₂ MPs through spatially confined emitter doping, creating core@shell@shell SiO₂ MPs. By repeatedly performing pseudomorphic transformation, we achieve spatially confined doping of 4-phenylpyridine, 4,4'-bipyridine, and 1,8-naphthalimide into different layers. This method enables afterglow color output from blue to cyan and orange by shifting main excitation from 250 to 350 nm. It also allows tuning of afterglow lifetime and quantum yields of the dopants by gradually enhancing dopant-matrix interactions through repeating hydrothermal reactions. Additionally, altering the doping positions further controls the optical properties due to a combined screen effect by the outer SiO₂ matrix and dopants. Our approach enables the creation of a versatile library of optically active SiO₂ MPs with finely tuned properties, paving the way for advanced photonic crystal platforms for optical encoding and spontaneous emission regulation.