Tunable Luminescent Properties and Concentration-Dependent, Site-Preferable Distribution of Eu²⁺ Ions in Silicate Glass for White LEDs Applications

Abstract

The design of luminescent materials with widely and continuously tunable excitation and emission is still a challenge in the field of advanced optical applications. In this paper, we reported a Eu²⁺-doped SiO₂-Li₂O-SrO-Al₂O₃-K₂O-P₂O₅ (abbreviated as SLSAKP:Eu²⁺) silicate luminescent glass. Interestingly, it can give an intense tunable emission from cyan (474 nm) to yellowish-green (538 nm) simply by changing excitation wavelength and adjusting the concentration of Eu²⁺ ions. The absorption spectra, photoluminescence excitation (PLE) and emission (PL) spectra, and decay curves reveal that there are rich and distinguishable local cation sites in SLSAKP glasses and that Eu²⁺ ions show preferable site distribution at different concentrations, which offer the possibility to engineer the local site environment available for Eu²⁺ ions. Luminescent glasses based color and white LED devices were successfully fabricated by combining the as-synthesized glass and a 385 nm n-UV LED or 450 nm blue LED chip, which demonstrates the potential application of the site engineering of luminescent glasses in advanced solid-state lighting in the future