Despite broad applications in imaging, energy conversion, and telecommunications, few nanoscale moieties emit light efficiently in the shortwave infrared (SWIR, 1000–2000 nm or 1.24–0.62 eV). We report quantum-confined mercury chalcogenide (HgX, where X = Se or Te) nanoplatelets (NPLs) can be induced to emit bright (QY > 30%) and tunable (900–1500+ nm) infrared emission from attached quantum dot (QD) “defect” states. We demonstrate near unity energy transfer from NPL to these QDs, which completely quench NPL emission and emit with a high QY through the SWIR. This QD defect emission is kinetically tunable, enabling controlled midgap emission from NPLs. Spectrally resolved photoluminescence demonstrates energy-dependent lifetimes, with radiative rates 10–20 times faster than those of their PbX analogues in the same spectral window. Coupled with their high quantum yield, midgap emission HgX dots on HgX NPLs provide a potential platform for novel optoelectronics in the SWIR.
We demonstrate the preparation of mesoscale semiconductor (II–VI) nanoplatelets (NPLs) for the first time using colloidal seeded growth. These nanoplatelets are quantum-confined and atomically precise but grown to a length scale compatible with conventional optical imaging and microscopic manipulation (even reaching >1 μm2) offering an opportunity to bridge the application space between nanocrystals and two-dimensional (2D) materials. Using CdTe as a model system, we develop a seeded growth procedure, show the parameters that control extension, and apply them to a variety of thicknesses and compositions. In situ spectroscopy demonstrates that addition onto the nanoplatelet seeds is not continuous and likely occurs through ripening. Finally, we use correlative optical and electron microscopy to demonstrate that at large sizes, photoluminescence (PL) mapping of the entire structure can be resolved including spatial inhomogeneities. Overall, these results show that nanoplatelets can be compared to 2D semiconductors while maintaining the advantages of scalable colloidal synthesis, thickness tunability, and solution processability.
Colloidally grown (II-VI) semiconductor nanoplatelets display significantly smaller lateral dimensions than their mechanically exfoliated 2D van der Waal (vdW) semiconductor counterparts. Here, we show that a seeded growth procedure allows us to significantly extend the lateral area of atomically precise nanoplatelets to the mesoscale (>1 μm^2). Using CdTe nanoplatelets as a model system, we optimize reaction parameters to expand a variety of nanoplatelets with different thickness and compositions. In situ spectroscopy results demonstrate that large NPLs grow through a mechanism of lateral ripening of seeds. Correlative optical spectroscopy and electron microscopy measurements show that the photoluminescence displays resolvable spatial inhomogeneities, similar to 2D semiconductors. Overall, these mesoscale nanoplatelets can be analogized to vdW semiconductors, with the added advantages of scalable colloidal synthesis, thickness tunability and solution processability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.