Query:  from Colloidal Semiconductor Quantum Rods

Candidate papers:

abstract: Colloidal quantum rods of cadmium selenide (CdSe) exhibit linearly polarized emission. Empirical pseudopotential calculations predict that slightly elongated CdSe nanocrystals have polarized emission along the long axis, unlike spherical dots, which emit plane polarized light. Single molecule luminescence spectroscopy measurements on CdSe quantum rods with an aspect ratio between 1 and 30 confirm a sharp transition from nonpolarized to purely linearly polarized emission at an aspect ratio of 2. Linearly polarized luminescent chromophores are highly desirable in a variety of applications.
author_names: Jiangtao Hu

Liang-shi Li

Weidong Yang

Liberato Manna

Lin-wang Wang

A Paul Alivisatos
title: Linearly Polarized Emission from Colloidal Semiconductor Quantum Rods
venue: Science
year: 2001

abstract: Quasi one dimensional (1D) semiconductor nanocrystals manifest linearly polarized emission, reduced lasing threshold, and improved charge transport compared with their counterparts such as spherical quantum dots. Present investigations of colloidal semiconductor quantum rods are mainly based on cadmium chalcogenide systems because of their facile synthetic accessibility. However, it is still a big challenge to fabricate quasi 1D zinc chalcogenide nanocrystals with controlled aspect ratios. Here we report a general strategy for synthesizing zinc chalcogenide quantum rods via a colloidal chemical synthetic approach. Unlike the most common growth mechanisms of quasi 1D colloidal nanocrystals such as monomer attachment and particle coalescence, the synthesis of zinc chalcogenide quantum rods is performed by a ripening process starting from their respective ultrathin nanowires through thermodynamically driven material diffusion. We anticipate that this strategy is general and could be applied to other systems to construct quasi 1D nanostructures. Moreover, the presence of cadmium free (or "green" zinc chalcogenide quantum rods synthesized through this strategy provides a desirable platform for eco friendly photocatalysis, optoelectronic devices, biolabeling, and other applications.
author_names: Guohua Jia

Uri Banin
title: A general strategy for synthesizing colloidal semiconductor zinc chalcogenide quantum rods.
venue: Journal of the American Chemical Society
year: 2014

abstract: Colloidal semiconductor nanocrystals, also known as "quantum dots" (QDs) represent an example of a disruptive technology for display and lighting applications. Their high luminescence efficiency and tunable, narrow emission are nearly ideal for achieving saturated colors and enriching the display or TV color gamut. Our contribution will discuss the next generation of inorganic nanostructures with electronic structure optimized for achieving emission characteristics beyond traditional near spherical QDs. For example, nano heterostructures with spherical CdSe QDs epitaxially integrated into CdS quantum rods combine high luminescence efficiency with giant extinction coefficients, large Stokes shifts, and linearly polarized emission. Such a set of characteristics can be ideal for LCD backlighting. The other class of emitters includes colloidal quantum wells (QWs) whose ensemble luminescence is significantly narrower than emission spectra of the best QD samples. Moreover, we show that colloidal QWs produce amplified spontaneous emission (ASE) with pump fluence thresholds as low as 6 mJ/cm2 and gain as high as 600 cm 1, on par with the best values for any solution processed material.
author_names: Chunxing She

Igor Fedin

Michael A Boles

Dmitriy S Dolzhnikov

Richard D Schaller

Matthew Pelton

Dmitri V Talapin
title: 12.2: Invited Paper: Colloidal Quantum Rods and Wells for Lighting and Lasing Applications
year: 2014

abstract: Atomically thin layers of transition metal dichalcogenides semiconductors, such as MoS2, exhibit strong and circularly polarized light emission due to inherent crystal symmetries, pronounced spin orbit coupling and out of plane dielectric and spatialconfinement. While the layer by layer confinement is well understood, the impact of in plane quantization in their optical spectrum is far behind. Here, we report the novel optical properties of atomically thin MoS2 colloidal semiconductor nanocrystals. Besides the spatial confinement effect leading to their blue wavelength emission, the high quality of our MoS2 nanocrystals is revealed by narrow photoluminescence, which allows us to resolve multiple optically active transitions, originating from quantum confined excitons (coupled electron hole pairs) Surprisingly, in stark contrast to monolayer MoS2, the luminescence of the lowest energy levels is linearly polarized and persists up to room temperature that could be exploited in a variety of light emitting applications.
author_names: Andres Granados del Aguila

Sheng Liu

T Anh Thu Do

Zhuangchai Lai

Thu Ha Tran

Sean Ryan Krupp

Zhi-Rui Gong

Hua Zhang

Wang Yao

Qihua Xiong
title: Linearly Polarized Luminescence of Atomically Thin MoS2 Semiconductor Nanocrystals.
venue: ACS nano
year: 2019

abstract: Spectroscopy of single colloidal quantum dots (QDs) especially at cryogenic temperature, helps to understand the inherent properties of nanocrystals that are often hidden in ensemble level studies. This applies in particular to InP based QDs, which attract increasing interest as Cd free alternative nanocrystals yet were hardly investigated at the single QD level. Here, we discuss the photoluminescence properties of single InP/ZnSe QDs, both at room temperature and at cryogenic temperature. While ensemble level measurements feature a luminescent linewidth of around 50 nm, we find that emission spectrum of single InP/ZnSe QDs can have a linewidth as narrow as 14 nm (50 meV) Hence, the relatively broad emission line that characterizes ensembles of InP based QDs is by no means an intrinsic material property. In addition, we found that InP/ZnSe QDs combine a nearly blinking free emission with a high purity single photon emission (g(0)<0.03) also well beyond the saturation intensity.[1] Cryogenic single QD spectra, on the other hand, consist of zero phonon lines that can be as narrow as 40 meV. Polarization resolved spectra point to a linearly polarized spectral doublet from the bright exciton. At lower excitation intensities, jitter was negligible and spectra could be integrated for tens of seconds without erasing the doublet splitting of 1.2 meV. At higher excitation intensities, jitter becomes more severe and switching between emission from the exciton doublet and the trion singlet can be observed. This indicates that spectral jitter finds its origin in changes of the local electric field caused by the temporal trapping of one charge carrier. In summary, we find conclude that single InP QDs have emission characteristics similar to the extensively studied CdSe based QDs. Moreover, the narrow emission lines, limited jitter and fluorescence intermittency of single InP/ZnSe QDs holds great promise to further explore these materials as a solutionprocessable single photon emitter and improve the ensemble level characteristics of these materials.
author_names: Vigneshwaran Chandrasekaran

Lorenzo Scarpelli

Francesco Masia

Dorian Dupont

Mickael D Tessier

Pieter Geiregat

Iwan Moreels

Wolgang Langbein

Zeger Hens
title: Spectral dynamics of linearly polarized bright exciton in InP/ZnSe colloidal quantum dots
year: 2018

abstract: Polarizers provide convenience in generating polarized light, meanwhile their adoption raises problems of extra weight, cost, and energy loss. Aiming to realize polarizer free polarized light sources, herein, we present a plasmonic approach to achieve direct generation of linearly polarized optical waves at the nanometer scale. Periodic slot nanoantenna arrays are fabricated, which are driven by the transition dipole moments of luminescent semiconductor quantum dots. By harnessing interactions between quantum dots and scattered fields from the nanoantennas, spontaneous emission with a high degree of linear polarization is achieved from such hybrid antenna system with polarization perpendicular to antenna slot. We also demonstrate that the polarization is engineerable in aspects of both spectrum and magnitude by tailoring plasmonic resonance of the antenna arrays. Our findings will establish a basis for the development of innovative polarized light emitting devices, which are useful in optical displays, spectroscopic techniques, optical telecommunications, and so forth.
author_names: Mengxin Ren

Mo Chen

Wei Wu

Lihui Zhang

Junku Liu

Biao Pi

Xinzheng Zhang

Qunqing Li

Shoushan Fan

Jingjun Xu
title: Linearly polarized light emission from quantum dots with plasmonic nanoantenna arrays.
venue: Nano letters
year: 2015

abstract: Semiconductor heterostructure nanocrystals, especially with core/shell architectures, are important for numerous applications. Here we show that by decreasing the shell growth rate the morphology of ZnS shells on ZnSe quantum rods can be tuned from flat to islands like, which decreases the interfacial strain energy. Further reduced growth speed, approaching the thermodynamic limit, leads to coherent shell growth forming unique helical shell morphology. This reveals a template free mechanism for induced chirality at the nanoscale. The helical morphology minimizes the sum of the strain and surface energy and maintains band gap emission due to its coherent core/shell interface without traps, unlike the other morphologies. Reaching the thermodynamic controlled growth regime for colloidal semiconductor core/shell nanocrystals thus offers morphologies with clear impact on their applicative potential.Core/shell semiconductor nanocrystals have advantageous optoelectronic properties, which depend on the shell architecture. Here the authors show that by reducing the growth rate of ZnS shells on ZnSe nanorods the shell morphology can be tuned from flat to islands like to helical
author_names: Botao Ji

Yossef E Panfil

Nir Waiskopf

Sergei Remennik

Inna Popov

Uri Banin
title: Strain controlled shell morphology on quantum rods
venue: Nature Communications
year: 2019

abstract: Semiconductor quantum dots (QDs) have been demonstrated viable for the emission of single photons on demand during the past decade. However, the synthesis of QDs emitting photons with pre defined a
author_names: Anders Lundskog

Chih-Wei Hsu

K F Karlsson

Supaluck Amloy

Daniel Nilsson

Urban Forsberg

P O Holtz

Erik Janzen
title: Direct generation of linearly polarized photon emission with designated orientations from site controlled InGaN quantum dots
year: 2014

abstract: The polarized emission of colloidal quantum dots from II VI and perovskite semiconductors were investigated thoroughly, revealing information about the optical transitions in these materials and their potential use in various opto electronic or spintronic applications. The studies included recording of the micro photoluminescence of individual nanostructures at cryogenic temperatures, with or without the influence of an external magnetic field. The experimental conditions enabled detection of circular and/or linear polarized emission to elucidate the exciton manifolds, angular momentum of the emitting states, Lande g factors, single exciton and bi exciton binding energies, the excitons' effective Bohr radii, and the unique influence of the Rashba effect. The study advances the understanding of other phenomena such as electron hole dissociation, long diffusion lengths, and spin coherence, facilitating appropriate design of optical and spin based devices.
author_names: Maya Isarov

Liang Z Tan

Jenya Tilchin

Freddy T Rabouw

Maryna I Bodnarchuk

Relinde J A van Dijk-Moes

R Carmi

Yahel Barak

Alyssa Kostadinov

Itay Meir

Daniel Vanmaekelbergh

Maksym V Kovalenko

Andrew M Rappe

Efrat Lifshitz
title: Polarized emission in II VI and perovskite colloidal quantum dots
year: 2017

abstract: Semiconductor nanorods can emit linear polarized light at efficiencies over 80% Polarization of light in these systems, confirmed through single rod spectroscopy, can be explained on the basis of the anisotropy of the transition dipole moment and dielectric confinement effects. Here we report emission polarization in macroscopic semiconductor polymer composite films containing CdSe/CdS nanorods and colloidal CdSe nanoplatelets. Anisotropic nanocrystals dispersed in polymer films of poly butyl co isobutyl methacrylate (PBiBMA) can be stretched mechanically in order to obtain unidirectionally aligned arrays. A high degree of alignment, corresponding to an orientation factor of 0.87, was achieved and large areas demonstrated polarized emission, with the contrast ratio I/I 5.6, making these films viable candidates for use in liquid crystal display (LCD) devices. To some surprise, we observed significant optical anisotropy and emission polarization for 2D CdSe nanoplatelets with the electronic structure of quantum wells. The aligned nanorod arrays serve as optical funnels, absorbing unpolarized light and re emitting light from deep green to red with quantum efficiencies over 90% and high degree of linear polarization. Our results conclusively demonstrate the benefits of anisotropic nanostructures for LCD backlighting. The polymer films with aligned CdSe/CdS dot in rod and rod in rod nanostructures show more than 2 fold enhancement of brightness compared to the emitter layers with randomly oriented nanostructures. This effect can be explained as the combination of linearly polarized luminescence and directional emission from individual nanostructures.
author_names: Patrick D Cunningham

Joao B Souza

Igor Fedin

Chunxing She

Byeongdu Lee

Dmitri V Talapin
title: Assessment of Anisotropic Semiconductor Nanorod and Nanoplatelet Heterostructures with Polarized Emission for Liquid Crystal Display Technology.
venue: ACS nano
year: 2016