Bound Exciton Complexes in Near-Infrared Emitting Quantum Shells
Dulanjan Harankahage, Divesh Nazar, Korneel Molkens, Mykhailo V. Bondarchuk, Christopher M. Hicks, Andrew A. Marder, Michael Montemurri, Adam Roach, Ivo Tanghe, Liangfeng Sun, Richard D. Schaller, Benjamin T. Diroll, Anton V. Malko, Alexander N. Tarnovsky, Dries van Thourhout
TL;DR
Researchers developed quantum shells that emit near-infrared light efficiently by suppressing harmful recombination processes and observing new exciton behaviors.
Contribution
The study introduces quantum shells that suppress Auger recombination and exhibit bound exciton complexes at room temperature.
Findings
CdS/HgS/CdS quantum shells show tunable NIR emission with high photoluminescence quantum yields.
CdS/HgCdSe/ZnS quantum shells display photoinduced absorption due to bound multiexciton complexes.
Bound exciton complexes enable long-lived sub-bandgap states and potential nonlinear photonic applications.
Abstract
Near-infrared (NIR) light sources based on colloidal semiconductor nanocrystals (NCs) represent a scalable, low-cost alternative to epitaxial semiconductor platforms. However, their performance remains hindered by rapid Auger recombination, a problem that is particularly pronounced in narrow-bandgap materials. Here, we report on CdS/HgS/CdS and CdS/HgCdSe/ZnS quantum shells (QSs), a class of spherical quantum wells specifically engineered for a suppression of nonradiative Auger processes. Fabricated QSs exhibit tunable NIR emission with photoluminescence quantum yields reaching ∼60% below 1000 nm and up to 30% near 1300 nm. Optical gain and stimulated emission were observed in CdS/HgS/CdS QSs. In contrast, CdS/HgCdSe/ZnS QSs displayed a photoinduced absorption in lieu of optical gain despite demonstrating a comparatively stronger Auger suppression. Transient absorption spectroscopy…
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Taxonomy
TopicsQuantum Dots Synthesis And Properties · Nonlinear Optical Materials Studies · Photonic Crystals and Applications