Europium(ii)-activated oxonitridosilicate yellow phosphor with excellent quantum efficiency and thermal stability – a robust spectral conversion material for highly efficient and reliable white LEDs

Abstract

Knowing the physicochemical properties of a material is of great importance to design and utilize it in a suitable way. In this paper, we conduct a comprehensive survey of photoluminescence spectra, localized cathodoluminescence, temperature-dependent luminescence efficiency, and applications of Eu²⁺-doped Sr_0.5Ba_0.5Si₂O₂N₂ in solid-state lighting. This phosphor exhibits a broad emission band with a maximum at 560–580 nm and a full-width at half maximum of 92–103 nm upon blue light excitation, whereas a dual-band emission (i.e., 470 nm and 550 nm) is observed under electron beam irradiation due to perhaps the intergrowth of BaSi₂O₂N₂:Eu²⁺ and Sr_0.5+σBa_0.5−σSi₂O₂N₂:Eu²⁺ in each phosphor particle. Under 450 nm blue light irradiation, this yellow phosphor exhibits excellent luminescence properties with absorption, internal and external efficiencies of 83.2, 87.7 and 72.6%, respectively. Furthermore, it also possesses high thermal stability, with the quantum efficiency being decreased by only 4.2% at 150 °C and a high quenching temperature of 450 °C. High-efficiency white LEDs using the title phosphor have a luminous efficacy, color temperature and color rendition of ∼120 lm W⁻¹, 6000 K and 61, respectively, validating its suitability for use in solid-state white lighting.