Advantageous Occupation of Europium(III) in the B Site of Double-Perovskite Ca<sub>2</sub>BB′O<sub>6</sub> (B = Y, Gd, La; B′ = Sb, Nb) Frameworks for White-Light-Emitting Diodes
Yongbin Hua, Weiguang Ran, Jae Su Yu
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.