Realization of warm white light from Ce-Eu-Tb doped zinc fluoroboro silicate glass for lighting applications

Highlights: • Eu is present substantially in Eu²⁺ state as compared to Eu³⁺state. • Redox reaction between Ce and Eu is observed. • Electron transfer from Ce .→ Eu ions has been identified. • Effective energy transfer from Tb³⁺ to Eu³⁺ ions. • Warm white light (x = 0.38, y = 0.39; CCT∼ 4116 K) realized from triply doped glasses. Luminescence characteristics and energy transfer dynamics have been studied in a series of Ce-Eu co-doped and Ce-Eu-Tb triply doped zinc fluoroboro silicate glasses to achieve white light generation for LED applications. In this host, Eu ions are found to exist substantially in divalent state (Eu²⁺) rather than in trivalent state (Eu³⁺) which has been verified through XPS studies. Further presence of Ce³⁺ in co-doped samples aids in the reduction process of Eu³⁺→Eu²⁺. In Ce-Eu co-doped glass series, the Ce³⁺ sensitized luminescence realized from Eu³⁺ has been ascribed to the electron transfer process between Ce³⁺ and Eu³⁺. Inclusion of Tb³⁺ resulted in enhancement of Eu³⁺ emission in triply doped glasses due to effective energy transfer from Tb³⁺ to Eu³⁺. Chromaticity co-ordinates calculated using CIE diagram resulted in realization of warm white light (x = 0.38, y = 0.39; CCT∼ 4116 K) from the triply doped glasses under excitation at 378 nm which can prove to be beneficial for lighting living rooms.