Zinc-blende CdSe, CdS, and CdSe/CdS core/shell nanocrystals with a structure-matched shape (cube-shaped, edge length ≤30 nm) are synthesized via a universal scheme. With the edge length up to five times larger than exciton diameter of the bulk semiconductors, the nanocrystals exhibit novel properties in the weakly confined size regime, such as near-unity single exciton and biexciton photoluminescence (PL) quantum yields, single-nanocrystal PL nonblinking, mixed PL decay dynamics of exciton and free carriers with sub-microsecond monoexponential decay lifetime, and stable yet extremely narrow PL full width at half maximum (FWHM < 0.1 meV) at 1.8 K. Their monodisperse edge length, shape, and facet structure enable demonstration of unexpected yet size-dependent PL properties at room temperature, including unusually broad and abnormally size-dependent PL FWHM (∼100 meV), nonmonotonic size dependence of PL peak energy, and dual-peak single-exciton PL. Calculations suggest that these unusual properties should be originated from the band-edge electron/hole states of the dynamic-exciton, whose exciton binding energy is too small to hold the photogenerated electron-hole pair as a bonded Wannier exciton in a weakly confined nanocrystal.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/jacs.2c05151 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Interaction Renormalization and Validity of Kinetic Equations for Turbulent States.
Phys Rev Lett
December 2024
Weizmann Institute of Science, Rehovot 7610001, Israel.
We consider turbulence of waves interacting weakly via four-wave scattering (sea waves, plasma waves, spin waves, etc.). In the first order in the interaction, a closed kinetic equation has stationary solutions describing turbulent cascades.
View Article and Find Full Text PDFA deep understanding of the mechanical properties of weakly cemented sandstones in coal-bearing strata is crucial for ensuring the safety of coal mining operations. This study addresses this problem by investigating the deformation characteristics of such rocks through triaxial compression tests, and a novel piecewise constitutive model was developed, integrating the Double-strain Hoek model (TPHM) and statistical damage theory. The outcomes highlight several key findings: (1) The experiments revealed a distinct compaction stage in weakly cemented sandstone, which becomes shorter with an increase in confining pressure, highlighting a significant mechanical property of these rocks.
View Article and Find Full Text PDFCollective Interactions of Quantum-Confined Excitons in Halide Perovskite Nanocrystal Superlattices.
ACS Nano
December 2024
Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
Collective optical properties can emerge from an ordered ensemble of emitters due to interactions between the individual units. Superlattices of halide perovskite nanocrystals exhibit collective light emission, influenced by dipole-dipole interactions between simultaneously excited nanocrystals. This coupling changes both the emission energy and rate compared to the emission of uncoupled nanocrystals.
View Article and Find Full Text PDFHeavy-boundary mode patterning and dynamics of topological phonons in polymer chains and supramolecular lattices on surfaces.
Nat Commun
December 2024
Department of Physics & IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany.
In topological band theory, phonon boundary modes consequence of a topologically non-trivial band structure feature desirable properties for atomically-precise technologies, such as robustness against defects, waveguiding, and one-way transport. These topological phonon boundary modes remain to be studied both theoretically and experimentally in synthetic materials, such as polymers and supramolecular assemblies at the atomistic level under thermal fluctuations. Here we show by means of molecular simulations, that surface-confined Su-Schrieffer-Heeger (SSH) phonon analogue models express robust topological phonon boundary modes at heavy boundaries and under thermal fluctuations.
View Article and Find Full Text PDFThe Effect of Salinity on the Dielectric Permittivity of Nanoconfined Geofluids.
ACS Earth Space Chem
November 2024
Department of Earth Sciences, Utrecht University, Utrecht 3584 CB, The Netherlands.
Article Synopsis
- Nanoporosity in geological formations allows for the movement and interaction of fluids and minerals, leading to unique properties of water confined within these tiny spaces.
- In nanopores, the dielectric constant of water behaves differently, showing variations in permittivity based on its orientation relative to the pore walls, particularly when mixed with salts.
- This study uses molecular dynamics simulations to explore how saline water’s dielectric properties change in calcite nanopores, finding that salinity has a minimal impact, thus allowing the application of pure water properties for understanding geochemical behaviors in natural nanoporous environments.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!