Fluorophores emitting in the NIR-IIb wavelength range (1.5 micron - 1.7 micron) 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 emitting at 1.7 microns through the interband transition. Growth of a thick shell led to a drastic increase in the photoluminescence quantum yield, with a value of 55% 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 >6% 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
@article{arxiv.2301.10364,
title = {Bright Fluorophores in the Second Near-Infrared Window: HgSe/CdSe Quantum Dots},
author = {Ananth Kamath and Richard D. Schaller and Philippe Guyot-Sionnest},
journal= {arXiv preprint arXiv:2301.10364},
year = {2023}
}