Sunlight‐Activated Eu²⁺‐Doped Red Persistent Luminescence Material for Night‐Vision Signage, Anti‐Counterfeiting and Location Detection

Abstract Persistent luminescence materials have been widely studied due to their excellent optical properties. However, they can only be activated by UV light; in other words, the charging method for these phosphors is limited. In fact, materials that can continuously emit light when exposed to sunlight are highly sought after for their potential to reduce energy consumption. Warm‐colored persistent luminescence materials are particularly useful for information storage, security marking, and preventing counterfeiting. Nevertheless, creating effective warm‐color persistent luminescence materials that are activated by sunlight remains a challenging task. To address this issue, novel daylight‐activated red persistent luminescence materials, Gd 3‐ x Ca x ‐0.02 GaO 6 :0.02Eu 2+ ( x = 0.3 ‐ 0.7) are explored. The material can be effectively activated by sunlight under all weather conditions, as well as by bright light from indoor lamps, mobile phone screens, and any form of visible light. Moreover, it possesses excellent water resistance. The process of electron trapping and release within the material is investigated through thermoluminescence experiments, photoluminescence spectra, and persistent luminescence spectra. Importantly, this phosphor has been demonstrated for various applications, including night vision marking, anti‐counterfeiting, optical information storage, and positioning, among others.