A facile route to violet- to orange-emitting CdxZn1−xSe alloy nanocrystals via cation exchange reaction

The most advanced CdSe-based binary semiconductor system does not work well for emission in the short wavelength spectral region from 420 to 500?nm, which is of special interest for the preparation of nanocrystal-based blue LEDs and white light generation. CdxZn1?xSe alloy nanocrystals are proven to be an attractive alternative as their emission color can be tuned from the UV spectral region (ZnSe) to the red region (CdSe) by changing the composition of the Zn/Cd ratio in the alloy. Herein we report a facile and 'green' alloying approach for the preparation of highly luminescent CdxZn1?xSe nanocrystals via cation exchange reaction of the pre-prepared ZnSe nanocrystals with Cd2+ at intermediate temperatures. Through this new synthetic strategy, high-quality alloy QDs with different desired emission wavelengths or colors (ranging from 370 to 600?nm) can be made reproducibly and precisely by varying the predetermined amounts of the reaction precursors.