Luminescence properties of Eu2+- and Ce3+-doped CaAl2S4 and application in white LEDs

✍ Scribed by Ruijin Yu; Jing Wang; Jianhui Zhang; Haibin Yuan; Qiang Su

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 620 KB
• Volume: 181
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2007.12.038

✦ Synopsis

The Eu 2+ -and Ce 3+ -doped CaAl 2 S 4 phosphors were comparatively synthesized by conventional solid-state reaction and the evacuated sealed quartz ampoule. The X-ray diffraction (XRD) patterns show that the sample with better crystalline quality was prepared by the evacuated sealed quartz ampoule, resulting in the enhancement of the emission intensity of Eu 2+ ion by a factor of 1.7. The intensive green LEDs were also fabricated by combining CaAl 2 S 4 :Eu 2+ with near-ultraviolet InGaN chips (l em ¼ 395 nm). The dependence of as-fabricated green LEDs on forward-bias currents shows that it presents good chromaticity stability and luminance saturation, indicating that CaAl 2 S 4 :Eu 2+ is a promising green-emitting phosphor for a near-UV InGaN-based LED. In addition, the optical properties of CaAl 2 S 4 :Ce 3+ were systematically investigated by means of diffuse reflectance, photoluminescence excitation and emission, concentrating quenching and the decay curve.