Designing of Eu2+-activated single-phase white-emitting phosphor through modifying cationic sites for high color rendering full-spectrum illumination

Single-phase full-spectrum white-emitting phosphors with individual activator are of great significance for avoiding unnecessary energy loss and realizing high luminescence efficiency. Herein, a novel Na₂Ca₁₇Al₂(PO₄)₁₄:Eu²⁺ phosphor is designed and the strategy of cation substitution is functioned in regulating the luminescence. The Na₂Ca₁₇Al₂(PO₄)₁₄:Eu²⁺ phosphor could realize basic full-spectrum emission under the excitation of 335 nm, but the lack of red-light component and the CIE color coordinates of (0.2291, 0.2302) can not meet the requirements for white light-emitting diodes (WLEDs). With partial or even full replacement of Na⁺ in the host with Li⁺ ions, the red-light component in the emission is efficiently improved and each emitting color reaches the appropriate proportion, achieving the cold white light at (0.3330, 0.3179). By further regulating the excitation wavelength, Li₂Ca₁₇Al₂(PO₄)₁₄:Eu²⁺ phosphor finally exhibits bright warm white emission with the color coordinates of (0.3551, 0.3448) upon 360 nm excitation and the internal quantum efficiency is 33.2%. It is due to the substitution of Na⁺ by Li⁺ ions that contributes to the redistribution of Eu²⁺ in different crystal sites and regulates the photoluminescence of this phosphor, further realizing the full-spectrum white light emission. The fabricated two WLED devices by this material with near ultraviolet chips show outstanding color rendering index of 92.7 and 96.8, respectively, revealing that this material has a promising prospect in the field of full-spectrum illumination.