Post-processing emission color design of NaBaPO4: Eu tricolor phosphor via photoinduced emission center formation

Inorganic phosphors activated by specific chemical species exhibit unchangeable unique emissions under the electrostatic influences from the surroundings of the species. Under this background, there is a growing interest in multicolor phosphors whose emission color can be controlled through simple post-processing. This capability enables the generation of a wide range of emission colors from a single phosphor as desired, which enhances the versatility of phosphors. In this study, the change in emission color in Eu-doped NaBaPO 4 induced by post-phototreatment is investigated. NaBaPO 4 : Eu 3+ exhibits a Eu 3+ -derived orange emission under 254-nm light. This emission color is altered to blue or bright purple upon photostimulation. This change results from the varying intensities of three different-color (orange, blue, yellow) emission in response to photostimulation wavelengths. To elucidate the mechanism, the electron states of NaBaPO 4 : Eu are analyzed using electron spin resonance (ESR) spectroscopy. Finally, the ability to rewrite the emission color of this phosphor is demonstrated, showcasing its potential for dynamic color manipulation. • Emission from NaBaPO 4 :Eu changes from orange to blue upon exposure to UV stimulation. • Emission from NaBaPO 4 :Eu changes to bright purple upon exposure to CuKα stimulation. • Photostimulation induces Eu-related emission species, Eu 2+ and Eu 3+ -e - . • Eu-related emission species are induced via CT transition or interband excitation. • Photostimulation process may induce novel emission species from existing phosphors.