Effect of Li+ doping on the luminescence performance of a novel KAlSiO4:Tb3+ green-emitting phosphor

Abstract

A new green-emitting phosphor, KAlSiO₄:1.5 mol% Tb³⁺, x mol% Li⁺, was prepared via a high-temperature solid-phase method, and its crystal structure, diffuse reflectance spectrum, and luminescence were studied. The results show that the Li⁺ doping shifts the strongest diffraction peak to a high angle direction, reducing grain size by 11.4%. The entry of Li₂CO₃ improves the luminescence performance of KAlSiO₄:1.5 mol% Tb³⁺. At a Li⁺ concentration of 1.5 mol%, the sample has strong absorption in the ultraviolet light range from 250 to 400 nm. The luminous intensity of the sample at 550 nm approximately quadruples after Li⁺ doping. Additionally, the colour purity of the sample and the internal quantum yield increase to 83.3% and 42%, respectively. The sample changes colour with time when exposed to air without an obvious fading phenomenon. The emission intensity at 200 °C is 95.1% of its value at room temperature, indicating that the phosphor has excellent thermal stability when x = 1.5. These results show the feasibility of using the silicate phosphor for generating the green light component of white light-emitting diodes for solid-state lighting.