Synthesis of New Melilite Structured Blue Phosphor for UV LED

Abstract

Solid-state LED lighting has been in the spotlight due to its high efficient, energy savings, and eco-friendly nature. Conventional blue LED based white lighting in combination with yellow phosphors showed high luminous efficiency (>30 lm/W) but have serious issue of poor color rendering index (65) due to weak red emission. As an alternative, UV based white LEDs has been under intensive research due to its high color rendering index (99), excellent conversion efficiency and a wide emission band ranging 350 to 700 nm. In this study, a blue-emitting melilite phosphor was developed with wide absorption in the near-UV by solid-solution. The synthesized blue phosphor has wide absorption band with a maxima at 420 nm. The emission wavelength was tunable in the window of 470 to 505 nm. The structural and optical characteristics were investigated using X-ray diffraction, Rietveld refinement, photoluminescence, thermal quenching and decay time. Finally white LED was fabricated using the optimized melilite blue phosphor in combination with commercial green and red phosphor under 420 nm LED chip. The results indicate melilite blue phosphor could be promising blue component for UV based white LEDs. Fig1. Normalized excitation and emission spectra of the Sr4-x-y Ca ­x Ba y MgAl2Si3O14:Eu2+ Figure 1