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We investigate the influence of X-ray and gamma-ray irradiation on the photophysical properties of sub-monolayer CdTe/CdS quantum dots (QDs) immobilized in porous silica (PSiO2) scaffolds. The highly luminescent QD-PSiO2 thin films allow…

Mesoscale and Nanoscale Physics · Physics 2015-08-25 Girija Gaur , Dmitry S. Koktysh , Daniel M. Fleetwood , Robert A. Weller , Robert A. Reed , Bridget R. Rogers , Sharon M. Weiss

We propose the concept of valley coherence and superradiance in the reciprocal space and show that it leads to an $N$-fold decrease of the bright exciton radiative lifetime in quantum dots (QDs) of an $N$-valley semiconductor. Next we…

Mesoscale and Nanoscale Physics · Physics 2022-09-21 S. V. Goupalov , E. L. Ivchenko , M. O. Nestoklon

Unique optical properties of colloidal semiconductor quantum dots (QDs), arising from quantum mechanical confinement of charge within these structures, present a versatile testbed for the study of how high electric fields affect the…

Intermittent photoluminescence of colloidal core/shell semiconductor nanocrystals of spherical and branched shape was studied under CW-laser excitation. Luminescent multichannel registration system was applied for the fluorescence detection…

Optics · Physics 2011-12-13 A. G. Vitukhnovsky , M. M. Kovalev , V. V. Lidsky , E. M. Khokhlov

Colloidal quantum dots (cQDs) are now a mature nanomaterial with optical properties customizable through varying size and composition. However, their use in optical devices is limited as they are not widely available in convenient forms…

Heavy metal-free quantum-dot light-emitting devices (QD-LEDs) have demonstrated remarkable brightness, saturated color, and high efficiencies across a broad spectral range. However, in contrast to organic LEDs (OLEDs), QD-LED operational…

We report optical studies of quantum dot excitons in individual suspended carbon nanotubes at cryogenic temperatures. Narrow optical linewidths, strongly suppressed spectral wandering, and photoluminescence lifetimes in the range of…

Mesoscale and Nanoscale Physics · Physics 2014-10-03 Matthias S. Hofmann , Jan T. Glückert , Alexander Högele

We investigate the time-resolved photocurrent response of CdSe quantum dot (QD) thin films sensitized with zinc beta-tetraaminophthalocyanine (Zn4APc) on three different substrates, namely silicon with 230 nm SiO2 dielectric, glass as well…

Mesoscale and Nanoscale Physics · Physics 2021-09-07 Christine Schedel , Fabian Strauß , Krishan Kumar , Andre Maier , Kai M. Wurst , Patrick Michel , Marcus Scheele

We probe the extent to which dislocations reduce carrier lifetimes and alter luminescence and growth morphology in InAs quantum dots (QD) grown on silicon. These heterostructures are key ingredients to achieving a highly reliable…

In this work, we report on the exciton radiative lifetimes of graphitic carbon nitride monolayers in the triazine- (gC$_3$N$_4$-t) and heptazine-based (gC$_3$N$_4$-h) forms, as obtained by means of ground- plus excited-state ab initio…

Materials Science · Physics 2021-04-05 Michele Re Fiorentin , Francesca Risplendi , Maurizia Palummo , Giancarlo Cicero

The design of some optical devices such as semiconductor optical amplifiers for telecommunication applications requires polarization-insensitive optical emission at the long wavelengths (1300-1550 nm). Self-assembled InAs/GaAs quantum dots…

Materials Science · Physics 2015-05-20 Muhammad Usman , Susannah Heck , Edmund Clarke , Peter Spencer , Hoon Ryu , Ray Murray , Gerhard Klimeck

The geometrical structure and photoexcitation properties of Zn27-nCdnO27C42 complexes are investigated by density functional theory (DFT) and time-dependent DFT calculations at the PBE0/6-31G*/SDD level of theory. The cohesive energy and…

Materials Science · Physics 2023-08-16 Ivan Shtepliuk

Colloidal semiconductor nanocrystals are promising building blocks for optoelectronics due to their solution processability, spectral tunability, and ability to self-assemble into complex architectures. However, their use in lasing…

Thin films of colloidal semiconductor CdSe quantum-dots (QDs) and a styrene/maleic anhydride copolymer were prepared by the Langmuir-Blodgett technique and their photoluminescence was characterized by confocal fluorescence lifetime…

Previous single-particle spectroscopic studies of colloidal quantum dots have indicated a significant spread in biexciton lifetimes across an ensemble of nominally identical nanocrystals. It has been speculated that in addition to…

Materials Science · Physics 2013-09-24 Young-Shin Park , Wan Ki Bae , Lazaro A. Padilha , Jeffrey M. Pietryga , Victor I. Klimov

By combining an atomistic valence-force field approach and calculations based on the effective-mass approximation we investigate the influence of strain effects on the band alignment and general excitonic properties of core/shell CdSe/CdS…

Mesoscale and Nanoscale Physics · Physics 2019-02-25 Sven-Hendrik Lohmann , Philip Harder , Felix Bourier , Christian Strelow , Alf Mews , Tobias Kipp

Photoluminescence of a single CdSe quantum dot embedded in a ZnSe nanowire has been investigated. It has been found that the dark exciton has a strong influence on the optical properties. The most visible influence is the strongly reduced…

Cadmium selenide nanocrystal quantum dots (NC-QDs) are site-selectively synthesized by sequential ion beam implantation of selenium and cadmium ions in a SiO2 matrix through sub-micron apertures followed by a rapid thermal annealing step.…

Mesoscale and Nanoscale Physics · Physics 2022-12-13 H. Moritz Mangold , Helmut Karl , Hubert J. Krenner

The dynamics of exciton recombination in an ensemble of indirect band-gap (In,Al)As/AlAs quantum dots with type-I band alignment is studied. The lifetime of confined excitons which are indirect in momentum-space is mainly influenced by the…

Design, epitaxial growth, and resonant spectroscopy of CdSe Quantum Dots (QDs) embedded in an innovative (Zn,Cd)Se barrier are presented. The (Zn,Cd)Se barrier enables shifting of QDs energy emission down to 1.87 eV, that is below the…

Mesoscale and Nanoscale Physics · Physics 2016-04-20 J. Piwowar , W. Pacuski , T. Smoleński , M. Goryca , A. Bogucki , A. Golnik , M. Nawrocki , P. Kossacki , J. Suffczyński
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