Enhancing the white light emission of SrAl2O4:Ce3+ phosphors by codoping with Li+ ions. Issue 14 (1st November 2016) - Diaz-Torres, L.A.
Abstract: The structural, morphological and luminescent properties of SrAl2 O4 :Ce 3+ (SAO:Ce) phosphors doped with Ce 3+ concentrations from 0.5 at% up to 7 at% and synthesized by combustion synthesis are reported. The morphology of the particles changes from coalesced grains (with average size of 121 nm) for a cerium concentration of 0.5 at% to needle-like shape when the cerium concentration is above 1% (with an average length of 1–2 µm). XRD patterns also show a change in the crystalline structure from monoclinic to hexagonal when the Li ion is introduced to improve the luminescent properties. The sample doped with 0.5 at% of Ce 3+ presents the highest white luminescence. When this sample was codoped with 0.2 at% of Li +, there was an increase of 100% in the white light emission. The luminance values of the samples with and without Li +, under UV-LED excitation (365 nm commercial Star LED) were 1630 cd/m 2 and 3760 cd/m 2, respectively. That is, the luminance enhancement achieved by lithium co-doping was 130%. Thus, our results indicate that Li codoped SrAl2 O4 :Ce 3+ phosphors could be useful for applications in displays and solid state lighting.