YScSi₄N₆C:Ce³⁺—A Broad Cyan-Emitting Phosphor To Weaken the Cyan Cavity in Full-Spectrum White Light-Emitting Diodes

Abstract

On the basis of a rough rule of thumb that the difference in ionic radius for the interstitial cationic pair may affect the structure of some nitride and carbonitride compounds, a novel carbonitride phosphor, YScSi₄N₆C:Ce³⁺, was successfully designed. The crystal structure (space group P6₃mc (No. 186), a = b = 5.9109(8) Å, c = 9.67701(9) Å, α = β = 90°, γ = 120°) was characterized by single-crystal synchrotron X-ray diffraction and further confirmed by powder X-ray diffraction and refined with Rietveld methods. Ce³⁺-doped YScSi₄N₆C shows a broad excitation band ranging from 280 to 425 nm and a broad cyan emission band peaking at about 469 nm upon excitation by near-UV light (400 nm). The mechanism of thermal quenching for this phosphor was also investigated. In addition, a white light-emitting diode (w-LED) was prepared by coating a near-UV chip (λ_em = 405 nm) with YScSi₄N₆C:Ce³⁺, β-sialon:Eu²⁺ (green), and CaAlSiN₃:Eu²⁺ (red) phosphors. It emitted a well-distributed warm white light with high color rendering index (CRI) of 94.7 and a correlated color temperature (CCT) of 4159 K. The special color rendering index R12 of the obtained white light was as high as 88. All of the results indicate that this novel phosphor can compensate for the cyan cavity and has potential applications in the full-spectrum lighting field.