A new green phosphor of SrAl2O4:Eu2+,Ce3+,Li+ for alternating current driven light-emitting diodes

New phosphors are desired to overcoming the flickering luminescence of alternating current light-emitting diodes (AC-LEDs) by compensating dark duration with appropriately persistent luminescence. Here, the phosphor of SrAl2O4:Eu2+,Ce3+,Li+ was developed for this application. The phosphor was synthesized with solid-state reaction method by using H3BO3 as flux. The XRD patterns show that the impurity phase of Sr4Al14O25 which always formed together with SrAl2O4 during reaction was suppressed by using Ce. The charger defects caused by the non-equivalent substitution of Sr2+ with Ce3+ were compensated with Li+. Thus, the luminescence intensity of SrAl2O4:Eu2+ was enhanced significantly by co-doping Ce3+ and Li+. The fluorescence lifetime of the phosphor is about 36.5 ms. The energy dispersive spectra (EDS) assisted with scanning electron microscope (SEM) pictures reveal that Ce ions mainly distribute along grain boundary.

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► This work focuses on exploring new phosphors of SrAl2O4:Eu2+,Ce3+,Li+ for AC LEDs.
► The work provides a new route to synthesize the pure phase of SrAl2O4.
► The formation of the impurity phase of Sr4Al14O25 was suppressed by using Ce3+.
► Charger defects were compensated by using Li+.
► The luminescence intensity was enhanced significantly by co-doping Ce3+ and Li+.