Stokes shifts of small ZnSe clusters from first-principles calculations

ABSTRACT

The large Stokes shifts of II-VI semiconductor quantum dots favour their application in bioimaging. Using a cluster model, we revealed that ZnSe clusters have large Stokes shifts at small cluster sizes by means of density functional theory calculations. Both the optical absorption and emission wavelengths of the clusters are size-dependent. While some trends were noted for the absorption spectra, the emission wavelength varies in a complicated way, leading to large fluctuations in their Stokes shifts with cluster size. These fluctuations, as well as their variations with solvent, were rationalised in terms of changes in their geometrical and electronic structures from size to size, and from ground- to excited-state.

KEYWORDS:

• Nanocluster
• first-principles calculation
• Stokes shift
• electronic structure

Acknowledgments

The authors thank the financial support from National Natural Science Foundation of China (No. 21373140) and National High Technology Research and Development Program of China (No. 2015AA034202). Part of the calculations was carried out at the State Key Laboratory of Physical Chemistry of Solid Surfaces in Xiamen University and National Supercomputing Center in Shenzhen. All authors thank the referee for constructive and helpful comments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

National Natural Science Foundation of China [grant number 21373140]; National High Technology Research and Development Program of China [grant number 2015AA034202].