Tm3+-Doped Ca2Ga2SiO7 Phosphor as Blue-Emitting Candidate for Tricolor w-LED Application

Abstract

In this work, a batch of Tm³⁺-doped Ca₂Ga₂SiO₇ phosphors was successfully synthesized via the conventional solid-state reaction method and systematically investigated for structural and photoluminescence properties. X-ray diffraction results confirmed the formation of a single-phase tetrahedral structure of Ca₂Ga₂SiO₇ with a P421m space group and no detectable impurity phase, indicating successful incorporation of Tm³⁺ ions into the host lattice. Under near-ultraviolet excitation of 355 nm, the phosphors exhibited intense blue emission centered at 455 nm. The emission peak is attributed to the ¹D₂ → ³F₄ transition of Tm³⁺ ions. The concentration-dependent study revealed an optimal dopant level of 1.0 mol% of Tm³⁺, beyond which concentration quenching occurs. The chromaticity coordinates of the optimized phosphor fall in the ideal blue region of the CIE 1931 diagram, confirming its potential to emit white light when combined with red and green phosphors. Decay time analysis showed a reduction in lifetime with increasing dopant concentration, suggesting energy transfer between neighboring Tm³⁺ ions. The results demonstrate that Ca₂Ga₂SiO₇:Tm³⁺ is a promising candidate for next-generation solid-state lighting applications.