Synergistic Modulation of Multimodal Luminescence in Self-Activated Phosphors for Advanced Anticounterfeiting and X-ray Imaging

Self-activated luminescent materials, characterized by low-cost and industrial-scale manufacturability, have demonstrated significant potential in anticounterfeiting and X-ray imaging applications. However, their development is hindered by a single emission response mode and low scintillation luminescence intensity. In this work, we demonstrate that the self-activated CaGa4O7 (CGO) matrix with excellent defect tolerance exhibits three response modes (persistent luminescence (PersL), photochromism, and time-dependent luminescence) and X-ray excited luminescence properties. Then, we adopt lone-pair Pb2+ cations with a larger ionic size to substitute Ca2+ (CGO:Pb2+), which causes a contrasting change in the concentrations of the two defect types and enables synergistic modulation of the PersL decay time, the degree of photochromism, and the variation rate of time-dependent luminescence, outperforming currently reported self-activated luminescent materials. Furthermore, the incorporation of Pb2+ enhances X-ray absorption efficiency, yielding a 4-fold increase in X-ray excited luminescence intensity compared with pristine CGO, demonstrating high sensitivity in detecting tissue structures. These findings establish CGO:Pb2+ as a promising candidate for dual anticounterfeiting and X-ray imaging applications, providing fundamental design principles for developing advanced self-activated luminescent materials and paving the way for multifunctional optical applications.