Near-Infrared Quantum Dot Emission Enhanced by Stabilized Self-Assembled J‑Aggregate Antennas

• Published in: Nano letters Vol. 17; no. 12; pp. 7665 - 7674
• Main Authors: Freyria, Francesca S, Cordero, José M, Caram, Justin R, Doria, Sandra, Dodin, Amro, Chen, Yue, Willard, Adam P, Bawendi, Moungi G
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.12.2017
• Subjects: solar (photovoltaic), solid state lighting, photosynthesis (natural and artificial), charge transport, optics, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing); water-soluble QDs; NIR PbS QDs; antenna effect; excitons; hybrid materials; FRET; J-aggregates
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.7b03735

Enhancing photoluminescent emission (PL) in the near-infrared–infrared (NIR–IR) spectral region has broad applications from solar energy conversion to biological imaging. We show that self-assembled molecular dye J-aggregates (light-harvesting nanotubes, LHNs) can increase the PL emission of NIR PbS quantum dots (QDs) in both liquid and solid media more than 8-fold, promoted primarily by a long-range antenna effect and efficient Förster resonance energy transfer (FRET) from donor to acceptor. To create this composite material and preserve the optical properties of the nanocrystals, we performed an in situ ligand substitution followed by a functionalization reaction using click-chemistry. This resulted in PbS QDs soluble in an aqueous environment compatible with the molecular J-aggregates (LHNs). Theoretical and experimental results demonstrate that long-range diffusive exciton transport in LHNs enables efficient energy transfer to low concentrations of QDs despite there being no direct binding between molecular donors and QD acceptors. This suggests a broad application space for mixed light harvesting and photophysically active nanocomposite materials based on self-assembling molecular aggregates.