Crystal Phase Transitions in the Shell of PbS/CdS Core/Shell Nanocrystals Influences Photoluminescence Intensity.
Rainer T. Lechner,Gerhard Fritz-Popovski,Maksym Yarema,Wolfgang Heiss,Armin Hoell,Tobias U. Schülli,Daniel Primetzhofer,M. Eibelhuber,Oskar Paris +8 more
TLDR
It is demonstrated that the photoluminescence emission of PbS nanocrystals can be drastically enhanced by the formation of a CdS shell and related to two different transition mechanisms for changing from the metastable rock salt phase to the equilibrium zinc blende phase depending on the shell thickness.Abstract:
We reveal the existence of two different crystalline phases, i.e., the metastable rock salt and the equilibrium zinc blende phase within the CdS-shell of PbS/CdS core/shell nanocrystals formed by cationic exchange. The chemical composition profile of the core/shell nanocrystals with different dimensions is determined by means of anomalous small-angle X-ray scattering with subnanometer resolution and is compared to X-ray diffraction analysis. We demonstrate that the photoluminescence emission of PbS nanocrystals can be drastically enhanced by the formation of a CdS shell. Especially, the ratio of the two crystalline phases in the shell significantly influences the photoluminescence enhancement. The highest emission was achieved for chemically pure CdS shells below 1 nm thickness with a dominant metastable rock salt phase fraction matching the crystal structure of the PbS core. The metastable phase fraction decreases with increasing shell thickness and increasing exchange times. The photoluminescence intens...read more
Citations
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Forging Colloidal Nanostructures via Cation Exchange Reactions
Luca De Trizio,Liberato Manna +1 more
TL;DR: This review provides an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange and gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions as they are currently understood.
PatentDOI
Hybrid molecule-nanocrystal photon upconversion across the visible and near-infrared
TL;DR: In this article, CdSe and PbSe semiconductor nanocrystals are combined with molecular emitters to upconvert photons in both the visible and near infrared spectral regions.
References
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Journal ArticleDOI
Shape-Controlled Synthesis of Gold and Silver Nanoparticles
Yugang Sun,Younan Xia +1 more
TL;DR: Monodisperse samples of silver nanocubes were synthesized in large quantities by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP), characterized by a slightly truncated shape bounded by {100, {110}, and {111} facets.
BookDOI
Transmission Electron Microscopy
TL;DR: The client would like to get a larger, approximately 3 cm in diameter, well fixed tissue sample, together with a detailed report of the clinical presentation, gross, and microscopic lesions, along with the submission of samples prepared in a similar manner by the client for processing.
Journal ArticleDOI
Synthesis and Characterization of Monodisperse Nanocrystals and Close-Packed Nanocrystal Assemblies
TL;DR: In this article, solution phase syntheses and size-selective separation methods to prepare semiconductor and metal nanocrystals, tunable in size from ∼1 to 20 nm and monodisperse to ≤ 5%, are presented.