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SrS:Ce/ZnS:Mn-A di-band phosphor for near-UV and blue LED-converted white-light emitting diodes |
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| Authors: | P Thiyagarajan M Kottaisamy |
| Institution: | a Material Science Research Center, Indian Institute of Technology Madras, Chennai 600 036, India b Department of Physics, Indian Institute of Technology Madras, Chennai 600 036, India c Materials Research Laboratory, Kalasalingam University, Krishnan Kovil, TN, India |
| Abstract: | The SrS:Ce/ZnS:Mn phosphor blends with various combination viz 75:25, 50:50 and 25:75 were assign to generate the white-light emission using near-UV and blue-light emitting diodes (LED) as an excitation source. The SrS:Ce exhibits strong absorption at 427 nm and the corresponding intense emission occurs at 480 and 540 nm due to electron transition from 5d(2D)−4f(2F5/2, 7/2) of Ce3+ ion as a result of spin-orbit coupling. The ZnS:Mn excited under same wavelength shows broad emission band with λmax=582 nm originates due to 3d (4G−6S) level of Mn2+. Photoluminescence studies of phosphor blend excited using near-UV to blue light confirms the emitted radiation varies from cool to warm white light in the range 430-600 nm, applicable to LED lightings. The CIE chromaticity coordinate values measured using SrS:Ce/ZnS:Mn phosphor blend-coated 430 nm LED pumped phosphors in the ratio 75:25, 50:50 and 25:75 are found to be (0.235, 0.125), (0.280, 0.190) and (0.285, 0.250), respectively. |
| Keywords: | 78 55 &minus m 71 35 Cc 71 70 Ej |
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