Preparation of Ca2HfSi4O12:Ce3+, Tb3+ green phosphor with high quantum efficiency and luminous thermal stability for WLED application

Abstract

A novel green-emitting phosphor, Ca₂HfSi₄O₁₂:Ce³⁺, Tb³⁺ (CHSO:Ce³⁺, Tb³⁺), was successfully fabricated via a conventional solid-state reaction under high-temperature conditions. The phosphor shows two broad excitation bands (200–400 nm), which can be attributed to the characteristic 4f → 5d electronic transitions of Ce³⁺ ions. As an efficient sensitizer, Ce³⁺ transfers absorbed ultraviolet energy to Tb³⁺ ions, resulting in a strong green luminescence peaking at 543 nm when excited at 330 nm. The optimized composition, CHSO:0.02Ce³⁺, 0.035Tb³⁺, exhibits high internal quantum efficiency (IQE) of 88.65% and external quantum efficiency (EQE) of 54.0% under 330 nm excitation, together with excellent luminous thermal stability, maintaining 90% of its emission intensity at 393 K. White light-emitting diodes (WLEDs) were assembled using CHSO:Ce³⁺, Tb³⁺ in conjunction with a 310 nm UV chip and commercial blue BaMgAl₁₀O₁₇:Eu²⁺ and red (Ca, Sr)AlSiN₃:Eu²⁺ phosphors, yielding a high color rendering index (Ra = 90.2) and a correlated color temperature of 5157 K. These findings highlight CHSO:Ce³⁺, Tb³⁺ as an efficient and thermally stable green phosphor with significant potential for UV-pumped WLED applications.