Realization of warm white light and energy transfer studies of Dy3+/Eu3+ co-doped Li2O-PbO-Al2O3-B2O3 glasses for lighting applications

The spectroscopic exploration of Dy3+/Eu3+ co-doped Li2O-PbO-Al2O3-B2O3 (LiPbA1B) glasses have been performed through absorption, photoluminescence, colour coordinates, correlated colour temperatures (CCT) and decay spectral profiles. The bonding parameters, energy band gaps and nephelauxetic ratios are discussed by using optical absorption spectra. The luminescence of Dy3+/Eu3+ co-doped glasses was tuned from cool white to warm white light under different selected ultraviolet excitation wavelengths such as 348 nm, 365 nm, 384 nm and 393 nm. The F-4(9/2) -> H-6(13/2), H-6(15)/2 transition of Dy3+ and D-5(0) -> F-7(2) transition of Eu3+ are responsible for the generation of warm white light from the as-prepared glasses. Dexter theory revealed the dipole-dipole (d-d) mechanism could be the foremost channel responsible for non-radiative energy transfer among Dy3+ (sensitizer) and Eu3+ (activator) constellations. The colour coordinates (x, y) of the as-synthesized co-doped glasses under 348 nm excitation confers the good white emission. The lifetime diminutions with increase in Eu3+ ions concentration and maximum energy transfer efficiency (eta(T) = 12.25%) was observed for glass 0.5 mol% Dy3+ and 5 mol% Eu3+ co-doped LiPbAlB glass (glass DE5). The aforementioned results suggest that the Dy3+/Eu3+ co-doped LiPbA1B glasses driven by UV LEDs might be suitable for the fabrication of cool/warm white as well as reddish-orange lighting devices.