A New Blue-Emitting Oxohalide Phosphor Sr₄OCl₆:Eu²⁺ for Thermally Stable, Efficient White-Light-Emitting Devices under Near-UV

Abstract

New blue-emitting Sr4OCl6:Eu2+ (SOC:Eu2+) phosphor was prepared by solid-state reaction. Structural properties including phase purity were analyzed through Rietveld analysis, using X-ray powder diffraction. The photoluminescence (PL) property of the SOC:Eu2+ phosphor was explored, for its successful application in the white light-emitting devices (WLED) industry. The SOC:Eu2+ phosphor exhibits broad excitation spectra ranging from 250 to 425 nm, and an intense broad blue emission band centered at 446 nm under λex = 370 nm. The optimum concentration of Eu2+ in Sr4–xEuxOCl6 was found with x = 0.02 (0.5 mol %). The temperature-dependent PL studies have been investigated, and the phosphor exhibits strong thermal quenching resistance, retaining the luminance of ∼91% at 200 °C. The WLED device was fabricated by integrating the blue-emitting Sr3.98Eu0.02OCl6 with commercial red- and green-emitting phosphor, excited with near UV LED chip (λex = 395 nm), and shows excellent CIE chromaticity coordinates (x = 0.32, y = 0.33). The structural stability of the host, good thermal stability, and excellent CIE coordinates suggest that SOC:Eu2+ is a promising blue component for application in the white LED industry.