ZnxCd1-xS quantum dots-based white light-emitting diodes

In this study, two kinds of colloidal ternary semiconductor white light-emitting quantum dots (WQDs), Zn0.5Cd0.5S and Zn0.8Cd0.2S, are prepared and used as nanophosphors in a UV light-emitting diode (UV-LED) pumping device. When the weight ratio of Zn0.5Cd0.5S WQDs is 9.1 wt. % in silicone and the drive current is set at 20 mA, the chromaticity coordinates (CIE), correlated color temperature (CCT), color rendering index (CRI), and luminous efficiency are (0.43,0.37), 2830 K, 90, and 0.94 lm/W, respectively. On the other hand, under the same weight ratio in silicone, the CIE, CCT, CRI, and luminous efficiency of Zn0.8Cd0.2S WQDs are (0.36,0.33), 4240 K, 86, and 4.12 lm/W, respectively. Based on the above results, we can conclude that WQDs-based LED can be obtained by controlling the compositions of ZnxCd1-xS QDs due to the coexistence of band-edge and surface state emission. (C) 2013 Optical Society of America