Alloyed (Cd,Zn)(Se,S) quantum dots : an efficient synthesis for full optical tunability

Semiconductor quantum dots (QDs) are luminescent nanocrystals offering bright and narrow emissions from UV to near-infrared. As a result, they find numerous applications as light emitters in a wide range of technologies, from photonics to biotechnologies. However, tuning the emission color is usually done by varying the size of the nanocrystals, what can be problematic for their integration in electronic and optoelectronic devices. To overcome this limitation, the syntheses of alloyed QDs, such as ternary Cd(Se,Te), have been developed in the past years. These systems allow a fine tuning of the emission color by varying the composition of the alloy without changing the size of the QDs. We recently developed a new approach for the synthesis of CdSe and ZnSe QDs based on a heterogeneous Se precursor. This fast synthesis with high reaction yield allows the production of high quality nanocrystals at large scale. In this contribution, we will show how this new approach can be extended to the synthesis of homogeneously alloyed Cd(Se,S), Zn(Se,S) but also (Cd,Zn)(Se,S) QDs thanks to the equivalent reactivity of the Se and S precursors towards the Cd and Zn precursors. The optical properties of the alloyed QDs will be fully described, with a particular attention to the dependence of the band gap on their composition. Finally, the interest of tuning the bang gap for the design of new heteronanostructures will also be highlighted through the growth of shells on the alloyed QDs.

Publication year:2013

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