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Updated: Jul 31, 2025

Compact Quantum Dots for Single-molecule Imaging
Published on: October 9, 2012
Bright Fluorophores in the Second Near-Infrared Window: HgSe/CdSe Quantum Dots
Ananth Kamath1, Richard D Schaller2,3, Philippe Guyot-Sionnest1
1Department of Chemistry and the James Franck Institute, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States.
Abstract:
Fluorophores emitting in the NIR-IIb wavelength range (1.5-1.7 μm) show great potential for bioimaging due to their large tissue penetration. However, current fluorophores suffer from poor emission with quantum yields ∼2% in aqueous solvents. In this work, we report the synthesis of HgSe/CdSe core/shell quantum dots (QDs) emitting at 1.7 μm through the interband transition. Growth of a thick shell led to a drastic increase in the photoluminescence quantum yield, with a value of 63% in nonpolar solvents. The quantum yields of our QDs and other reported QDs are explained well by a model of Forster resonance energy transfer to ligands and solvent molecules. The model predicts a quantum yield >12% when these HgSe/CdSe QDs are solubilized in water. Our work demonstrates the importance of a thick type-I shell to obtain bright emission in the NIR-IIb region.
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