Development of thermally stable, single-phased CaAl4O7:Dy3+ phosphor and a study on their down-conversion features for lighting applications

Abstract

This investigation underscores the structural, optical and temperature-dependent photoluminescence characteristics of CaAl₄O₇:Dy³⁺-doped phosphor synthesized via microwave-assisted combustion synthesis route for the first time. The sample crystallizes in monoclinic structure affirmed by XRD analysis. Morphological behaviour was conducted via SEM analysis. The existence of functional groups was validated through FTIR study. Bandgap of the optimized sample was established as 4.11 eV from the UV–VIS absorbance spectra. The emission spectra possessed characteristic peaks of Dy³⁺ ion around 485 nm (blue), 576 nm (yellow) upon suitable excitation at 347 nm. The concentration of Dy³⁺ ion at x  = 0.03 was established to be optimal. The CIE chromaticity co-ordinate of (x = 0.347, y = 0.427), correlated color temperature of 5109 K and color purity of 32.87 % were inferred. The PL decay time for CaAl₄O₇:Dy³⁺(x = 0.03) phosphor was obtained as 0.31 ms. Excellent thermal stability of the sample was established from the temperature-dependent PL analysis. To assess the lighting ability of the phosphor, phosphor-in-glass (P-i-G) material was fabricated. Superior luminous efficacy (428 lm/W) and luminous efficiency (62.66 %) were established for the fabricated P-i-G. The outcome vividly declares the potency of the CaAl₄O₇:Dy³⁺phosphor as a promising contender for n-UV excited phosphors for wLED applications.