YAG and CdSe/ZnSe nanoparticles hybrid phosphor for white LED with high color rendering index

Phosphor conversion white LED was developed using a 460 nm InGaN LED chip as an excitation source and yellow emitting Ce-activated YAG as the phosphor. YAG:Ce phosphor was obtained through solid state reaction (SSR) at 1500 degrees C, and spray pyrolysis (SP) at 900 degrees C. The SSR and SP prepared YAG:Ce had strong excitation peaks at 460 nm, and broad band emissions from 540 nm to 580 nm due to d-f transition of the Ce ion. The fabricated white LED using SSR-YAG:Ce and SP-YAG:Ce showed a luminous efficiency of 65.8 lm W-1 with CRI of 65.1, and 92.1 lm W-1 with CRI of 67.7 at 20 mA, respectively. For high CRI values, CdSe/ZnSe nanoparticles emitting at 622 nm were prepared via the wet chemical method. The high CRI values of the white LED were achieved by efficient energy transfer from YAG:Ce to CdSe/ZnSe nanoparticles in hybrid phosphor system. The luminous efficiency of the hybrid phosphor white LED was 77.1 lm W-1 and this device showed an excellent CRI of 92.3 at 20 mA. The CIE of the white LED was varied from (0.34, 0.31) to (0.35, 0.31) when the applied currents increased from 20 to 60 mA. (C) 2010 Elsevier B.V. All rights reserved.