Blue light excitable red emitting ZnO and its blend for high CRI white light emitting diodes applications

Red emitting ZnO at the excitation of blue light has been prepared from zinc acetate-urea precursor by sol-gel combustion method. X-ray diffraction studies confirm that the obtained material is in hexagonal wurtzite structure. The photo-luminescent studies reveal that the ZnO is excitable at a wide range of wave length from near UV and blue light. However, at blue light excitation, it shows a strong broad band emission than the near UV excitation, and it starts from 475 nm to 650 nm with an emission maximum of 540 nm. The diffused reflectance spectra show a strong absorption of light from 240 nm to 500 nm. At blue LED excitation (465 nm), it emits a bright broad band red emission with an emission maximum of 625 nm with a CIE chromaticity value of (x = 0.65, y = 0.37). The di band phosphor blend containing red emitting ZnO and yellow emitting YAG:Ce3+ shows warm white light emission at the excitation of blue LED (465 nm) with CIE chromaticity (x = 0.51, y = 0.31) as well as CRI of 96 and CCT of 1986K. All the results indicate that the synthesized ZnO is a promising phosphor material for the applications of WLEDs.