White emission from CdSe/ZnSe nanoparticles combining with 400, 430 and 460nm InGaN LED

White light emitting diodes (LEDs) were fabricated combining InGaN LED chip as the excitation source and CdSe/ZnSe as the phosphor. CdSe/ZnSe nanoparticles were synthesized via wet chemical method using CdO, zinc stearate, TOP Se as precursors. 4.5 and 5.3 nm diameter CdSe/ZnSe nanoparticles with emission peak at 540 and 620nm, respectively, were obtained. CdSe nanoparticle phosphors were coated onto the 460, 430 and 400nm LED chips to fabricate white LEDs. As the shorter wavelength of LED chip was applied to excitation source, the luminous efficiency of white LED was enhanced. The luminous efficiencies of 400, 430, and 460nm excitation white LEDs were 2.15, 3.96 and 6.57 lm/W, respectively at 20 mA. The corresponding CIE-1931 coordinates were (0.34, 0.30), (0.30, 0.32), and (0.31, 0.29). The color rendering index (CRI) of white LED showed similar values ; 65.1, 65.5, and 66.2.