Core/shell CdSe/ZnS quantum dots (QDs) are synthesized by thermal deposition using cadmium oxide and selenium as precursors for a hot lauric acid and hexadecylamine trioctylphosphine oxide hybrid. The CdSe/ZnS QDs show high photoluminescence efficiency, with a quantum yield greater than 48% and sizetunable emission wavelengths ranging from 500 to 620 nm. A diode that emits white light with color coordinates of (0.311, 0.321) and luminous efficiency of 46.7 lm/W at 20 mA, as standardized by the Commission Internationale de L’Eclairage or International Commission on Illumination, is fabricated by combining a blue indium-gallium nitride (InGaN) chip with multi-CdSe/ZnS QDs.