14 September 2005 A novel green phosphor for three band white LEDs
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Current technology of lighting is Solid state lighting using LED's (SSL-LED). The aim of the present study is to find the critical concentration of Eu2+ for high emission intensity and also the role of Ce3+ co-doping on the absorption and emission properties in the host BaMgSiO4. Photoluminescence emission of Eu2+ in BaMgSiO4 when excited with 370 nm shows a broad band in the region 450 to 550 nm with a maximum at 502 nm and a shoulder at ~480 nm and one more band at ~ 400nm. The three emissions are due to Eu2+ in three different Ba sites in the lattice. Studies on Ba1 xEuxMgSiO4 [x = 0.0025 - 0.1 in steps of 0.0025] show that the emission intensity is maximum for x = 0.075 and a decrease in emission intensity is observed for higher x values. Ce3+ luminescence is studied for the first time in BaMgSiO4. Ce3+ emission occurs as a broad band with maximum at 430 nm when excited with 356 nm. The Eu2+ excitation that occurs in the region 250 - 420 nm covers both the Ce3+ absorption and emission. Hence Ce3+ to Eu2+ energy transfer is possible in BaMgSiO4. In the case of Ba0.99 xEu0.01CexMgSiO4 [ x = 0.0025 - 0.1 ], it is observed that the emission intensity of Eu2+ increases with increasing Ce3+ content up to 0.01. This result proves the energy transfer from Ce3+ to Eu2+. Thus, the co-doping of Ce3+ also enhances the absorption of Eu2+ in the near UV to blue region where the LED emission occurs. BaMgSiO4:Eu2+, Ce3+ with bright green emission can find potential application as a green phosphor for SSL-LED technology.
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Sivakumar Vaidyanathan, Sivakumar Vaidyanathan, Varadaraju Upadhyayula, Varadaraju Upadhyayula, } "A novel green phosphor for three band white LEDs", Proc. SPIE 5941, Fifth International Conference on Solid State Lighting, 594110 (14 September 2005); doi: 10.1117/12.614299; https://doi.org/10.1117/12.614299

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