TiO 2 as Trap Sensitizer for Enhanced Persistent Luminescence in ZnGa 2 O 4 :Cr 3 + Nanoparticles

Abstract

ABSTRACT Enhancing the charging efficiency of persistent luminescence materials remains a key challenge for their practical implementation. Here, we report a hybrid strategy based on coupling ZnGa 2 O 4 :Cr 3 + nanoparticles with TiO 2 through a porous SiO 2 interlayer to promote interfacial charge transfer and improve energy storage. The resulting architecture exhibits a twofold increase in both steady‐state and afterglow intensity under UV excitation. Through excitation‐dependent spectroscopy, we show that TiO 2 ‐mediated excitation modifies the population pathway of Cr 3 + centers, leading to enhanced vibronic emission characteristic of Cr 3+ in a distorted environment. Kinetic analysis using a rate equation model reveals that the hybrid system features an increased excitation rate, the activation of additional trapping states, and a reduced sensitivity to optically stimulated detrapping, demonstrating that TiO 2 sensitization not only enhances carrier generation but also mitigates intrinsic loss processes during charging. These results establish interfacial engineering as a powerful approach to decouple light absorption from energy storage and to control trapping–detrapping processes, opening new pathways for the design of high‐performance persistent phosphors.