High quantum-yield CdSexS1-x/ZnS core/shell quantum dots for warm white light-emitting diodes with good color rendering

Composition-controllable ternary CdSexS1-x quantum dots (QDs) with multiple emission colors were obtained via a hot-injection-like method at a relatively low injection temperature (230 degrees C) in octadecene. Then highly fluorescent CdSexS1-x/ZnS core/shell (CS) QDs were synthesized by a facile single-molecular precursor approach. The fluorescent quantum yield of the resulting green (lambda(cm) = 523 nm), yellow (lambda(cm) = 565 nm) and red (lambda(cm) = 621 nm) emission of CS QDs in toluene reached up to 85%, 55% and 39%, respectively. Moreover, a QDs white light-emitting diode (QDs-WLED) was fabricated by hybridizing green-, yellow- and red-emitting CdSexS1-x/ZnS CS QDs/epoxy composites on a blue InGaN chip. The resulting four-band RYGB QDs-WLED showed good performance with CIE-1931 coordinates of (0.4137, 0.3955), an R-a of 81, and a T-c of 3360 K at 30 mA, which indicated the combination of multiple-color QDs with high fluorescence QYs in LEDs as a promising approach to obtain warm WLEDs with good color rendering.