Enabling Excitation-Wavelength and Temperature-Responsive Chromatic Indicators via the Integration of Dual Luminescent Centers

Abstract

Owing to their vibrant chromatic representation and distinctive optical characteristics, stimuli-responsive multicolor luminescent materials have attracted heightened interest within the domains of information security and intelligent systems. Nonetheless, developing phosphors that exhibit stimuli responsiveness, especially those with luminescence influenced by both temperature variations and excitation wavelengths, continues to pose considerable difficulties. In this study, we present a multicolor luminescent compound derived from tridymite-structured CaGa₂O₄ codoped with Bi³⁺ and Eu³⁺. Significantly, this Bi³⁺/Eu³⁺ coactivated phosphor demonstrates responsiveness to thermal variations and excitation wavelengths, along with exceptional chromatic tunability ranging from yellow to orange red. The observed tunability of the color is attributed to the distinct thermal quenching behaviors associated with Bi³⁺ and Eu³⁺ emitters. Thermoluminescence profiles, in conjunction with persistent luminescence decay analysis and photostimulated luminescence, elucidate the distribution and photoactive nature of these traps. Finally, we illustrate potential applications in visual thermometry and information display using CaGa₂O₄:Bi³⁺, Eu³⁺-based luminescent ink. This study not only provides strategic insights for the development of inorganic phosphors with adjustable emission spectra and stimuli-responsive properties but also underscores significant potential in fields such as information security, thermal distribution visualization, anticounterfeiting, and smart platforms.