Advantageous Occupation of Europium(III) in the B Site of Double-Perovskite Ca2BB′O6 (B = Y, Gd, La; B′ = Sb, Nb) Frameworks for White-Light-Emitting Diodes

Abstract

At present, rare-earth-activated perovskite-type materials have attracted lots of interest from researchers owing to their excellent advantages of unique electron properties and stable structure. This present work was designed to synthesize, investigate, and compare the photoluminescence properties in europium(III) (Eu³⁺)-activated Ca₂BB′O₆ (B = Y, Gd, and La; B′ = Sb and Nb) double-perovskite (A₂BB′O₆) luminescent materials. The doped Eu³⁺ ions substitute the B sites of Y³⁺, Gd³⁺, and La³⁺ ions, which are distributed to the equilibrium valence state and exhibit little difference in ion radius among them. All the resultant samples have a monoclinic structure, and the B sites strongly affect the space group in double-perovskite Ca₂BB′O₆ frameworks. Additionally, the emission intensity, thermal stability, decay curve, color purity, quantum yield (QY), etc. were determined. The Ca₂BNbO₆:Eu³⁺ (B = Y, Gd, and La) frameworks have good QYs (>42%), which are promising for white-light-emitting diodes (WLEDs). Besides, the red-emitting Ca₂BB′O₆:Eu³⁺–polydimethylsiloxane (PDMS) and white-emitting CYN0.1Eu³⁺–commercial phosphors (CP)–PDMS films were fabricated. Eventually, the packaged WLEDs based on the Ca₂BNbO₆:Eu³⁺ (B = Y, Gd, and La) powders and a novel white-emitting structure based on the CYN:0.1Eu³⁺–CP–PDMS film were confirmed to have suitable color rendering index and correlated color temperature values for indoor illumination.