End-to-End Alignment of Nanorods in Thin Films

Thorkelsson, Kari; Nelson, James H.; Alivisatos, A. Paul; Xu, Ting

doi:10.1021/nl402862b

Cited by 72 publications

(96 citation statements)

References 49 publications

(95 reference statements)

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“…22,23 Perhaps the simplest small anisotropic objects are nanorods, and their behavior in block copolymer films has been considered in Refs. [24][25][26][27][28][29][30][31][32][33][34][35][36], which are mainly short communications just focused into the visualization of the morphology of the prepared composites. In any case the number of 4 publications dealing with anisotropic nanoparticles in block copolymers is vanishingly small compared with the total number of publications on block copolymer nanocomposites over the past decade.…”

Section: Introductionmentioning

confidence: 99%

“…In the existing studies, the host matrices are limited to the diblock copolymers of PS with PMMA, 24,[27][28][29][30][31] P2VP, 26,36 and modified P4VP, 25,[32][33][34][35] doped with nanorods made of Au, [24][25][26] ZnO, 27 CdSe, [28][29][30][31][32][33][34] CuPt, 35 and Fe 2 P 36 and covered by low-or high-molecular mass ligands providing their selective localization in a particular block copolymer domain. At the present stage, controlling such a selectivity and preventing nanorod aggregation are considered to be the main results.…”

Section: Introductionmentioning

confidence: 99%

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Ordering of anisotropic nanoparticles in diblock copolymer lamellae: Simulations with dissipative particle dynamics and a molecular theory

Berezkin

Kudryavtsev

Gorkunov

et al. 2017

The Journal of Chemical Physics

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Short title: Ordering of anisotropic nanoparticles: Simulations and theory a) Corresponding author. Electronic mail: yar@ips.ac.ru 2 ABSTRACT Local distribution and orientation of anisotropic nanoparticles in microphase-separated symmetric diblock copolymers has been simulated using dissipative particle dynamics and analyzed with a molecular theory. It has been demonstrated that nanoparticles are characterized by a non-trivial orientational ordering in the lamellar phase due to their anisotropic interactions with isotropic monomer units. In the simulations, the maximum concentration and degree of ordering are attained for nonselective nanorods near the domain boundary. In this case the nanorods have a certain tendency to align parallel to the interface in the boundary region and perpendicular to it inside the domains. Similar orientation ordering of spherical nanoparticles located at the lamellar interface is predicted by the molecular theory which takes into account that the nanoparticles interact with monomer units via both isotropic and anisotropic potentials. Computer simulations enable one to study the effects of the nanorod concentration, length, stiffness, and selectivity of their interactions with the copolymer components on the phase stability and orientational order of nanoparticles. If the volume fraction of the nanorods is lower than 0.1, they have no effect on the copolymer transition from the disordered state into a lamellar microstructure. Increasing nanorod concentration or nanorod length results in clustering of the nanorods and eventually leads to a macrophase separation, whereas the copolymer preserves its lamellar morphology. Segregated nanorods of length close to the width of the diblock copolymer domains are stacked side by side into smectic layers that fill domain space. Thus, spontaneous organization and orientation of nanorods leads to a spatial modulation of anisotropic composite properties creating an opportunity to align block copolymers by external fields which may be important for various applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ordering of anisotropic nanoparticles in diblock copolymer lamellae: Simulations with dissipative particle dynamics and a molecular theory

Berezkin

Kudryavtsev

Gorkunov

et al. 2017

The Journal of Chemical Physics

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“…The fluorescence polarization of a number of single DRshas been measured but not for aligned ones. [5,6,24,25] In order to obtain a macroscopic organization and orientation ofsingle nanorods onto a substrate, the use of anisotropic matrices working as hard or soft templatesoffers a promising experimental alternative, as shown for polymer matrices [26][27] , which can be stretched [5,28] ,as for DNA molecules [29] andcarbonnanotubes. [30] 4 An increasing number of works is alsodevoted to the use of anisotropic matrices made ofliquid crystals.…”

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confidence: 99%

Alignment of Rod‐Shaped Single‐Photon Emitters Driven by Line Defects in Liquid Crystals

Pelliser

Manceau

Lethiec

et al. 2015

Adv Funct Materials

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We use arrays of liquid crystal defects, linear smectic dislocations, to trap semi-conductor CdSe/CdS dot-in-rods which behave as single photon emitters. We combine measurements of the emission diagram together with measurements of the emitted polarization of the single emitters. We show that the dot-inrods are confined parallel to the linear defects to allow for a minimization of the disorder energy associated with the dislocation cores. We demonstrate that the electric dipoles associated with the dotin-rods, tilted with respect to the rods, remain oriented in the plane including the smectic linear defects and being perpendicular to the substrate, most likely due to the dipole/dipole interactions between the dipoles of the liquid crystal molecules and the dot-in-rods ones. Using smectic dislocations, we can consequently orient nanorods along a unique direction for a given substrate, independently of the ligands' nature, without any induced aggregation, leading as well to a fixed azimuthal orientation for the associated dot-in-rods' dipoles. These results open the way for a fine control of nanoparticle anisotropic optical properties, in particular a fine control of single photon emission polarization.Control of single photon emitters is a major objective in the field of nanophotonics.[1] The synthesis of colloidal semiconductor inorganic nanocrystals having specific light-emission properties has been providing important advances in this field. In particular, recent developments in synthesis methodologies, fully compatible with standard nanofabrication technologies have enabled a superior 3 control on nanocrystals composition and morphology.Rod-shaped nanocrystals showing pronounced polarization, behaving as emitting linear dipoles, have been obtained. [2][3][4] The encapsulation of a spherical core into a rod-like shell [5] resulted in non-blinking inorganic single photon emitters, [6] hereafter referred to as dot-in-rods (DRs). Moreover it has been recently shown that, by increasing the thickness of the shell, it is possible to greatly suppress photoluminescence blinking and to improve DRs overall photo-stability, while keeping a low probability of multi-photon emission. [7] Such features are of primary importance when nanocrystalsare used in applications demanding a control of photons'polarization, such as coupling with complex photonic cavities [8][9] or quantum cryptography.[10] The control of the polarization of the emitted light also requires the capacity to control the particle orientation. Howevertechnologies aimed at guiding nanocrystal orientation at the single particle level are still poorly discussed in literature.Alignednanoparticleshave been obtained through mechanical rubbing, [11] short-range interactions [12][13] or patterned substrates. [14] Liquid crystal-like structures, composed of alarge number of elongated nanocrystalsassembled in multi-layers have also been evidenced on both solid substrates [15][16][17][18] and water films. [18][19][20] Orientation and positional ordering of CdS and CdSe...

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“…These properties of QDs make them the most promising type of fluorescent dopants for the development of nanohybrid composites based on different types of polymer matrices. Among the main lines of research in this field, noteworthy are the development of techniques for highly homogeneous aligned distribution of QDs in different organic matrices [5][6][7][8][9] , designing of light conversion devices [10][11][12] , and sensing approaches 13,14 . Significant efforts have been made to engineer hybrid nanophotonic materials from different types of liquid crystals and QDs 15,16 .…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Optical Properties of Composites Consisting of Nanoporous Stretched Polypropylene Doped with Liquid Crystals and Quantum Dots at a High Concentration

Mochalov¹,

Bobrovsky²,

Solovyeva³

et al. 2016

Orient. J. Chem

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Unique properties of nanohybrid composites based on different types of porous polymer matrices doped with fluorescent nanoparticles (quantum dots, QDs) are determined by the combination of the mechanical properties of the host matrix (flexibility, chemical stability, etc.) and a high luminescence intensity and extreme stability of QDs. Here, we report on the preparation, optical and microstructural characterization of a nanoporous stretched polypropylene matrix embedded with CdSe/ZnS QDs as fluorescent dopants at a high concentration. The microstructure and optical properties of two types films based on QD-polymer composites and liquid crystals are described. The distribution of QDs in the composite films and their morphology was determined. The annealing of the nanoporous composite films leads to shrinking of the pores and encapsulation of QDs, which results in a domain-like structure. The resulting flexible, stable and highly luminescent materials may be applied to obtain the highly luminescent diodes, the light converter devices and the display systems.

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End-to-End Alignment of Nanorods in Thin Films

Cited by 72 publications

References 49 publications

Ordering of anisotropic nanoparticles in diblock copolymer lamellae: Simulations with dissipative particle dynamics and a molecular theory

Ordering of anisotropic nanoparticles in diblock copolymer lamellae: Simulations with dissipative particle dynamics and a molecular theory

Alignment of Rod‐Shaped Single‐Photon Emitters Driven by Line Defects in Liquid Crystals

Microstructure and Optical Properties of Composites Consisting of Nanoporous Stretched Polypropylene Doped with Liquid Crystals and Quantum Dots at a High Concentration

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