Isotropic-liquid crystalline phase diagram of a CdSe nanorod solution

Li, Liang Shi; Marjańska, Małgorzata; Park, Gregory H. J.; Pines, Alexander; Alivisatos, A. Paul

doi:10.1063/1.1640331

Cited by 45 publications

(56 citation statements)

References 28 publications

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“…due to solvent evaporation), because the gain in positional entropy on alignment (associated with reducing the total excluded volume) more than compensates for the loss in rotational entropy 24 . Li et al have observed similar liquid-crystalline behavior for CdSe nanorods 25 , which have analogous physical properties to the CdS nanorods used in the present study. In Li's work, the isotropic-nematic phase boundary was found to be weakly temperature dependent over the range considered (some of this data is plotted in Figure 3a for comparison), indicating that the entropically driven ordering may be opposed by enthalpic interactions that become less important at higher temperature.…”

supporting

confidence: 80%

Device-Scale Perpendicular Alignment of Colloidal Nanorods

Baker¹,

Widmer‐Cooper²,

et al. 2009

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The self-assembly of nanocrystals enables new classes of materials whose properties are controlled by the periodicities of the assembly, as well as by the size, shape and composition of the nanocrystals. While selfassembly of spherical nanoparticles has advanced significantly in the last decade, assembly of rod-shaped nanocrystals has seen limited progress due to the requirement of orientational order. Here, the parameters critically relevant to self-assembly are systematically quantified using a combination of diffraction and theoretical modeling; these highlight the importance of kinetics on orientational order. Through dryingmediated self-assembly we achieve unprecedented control over orientational order (up to 96% vertically oriented rods on 1cm 2 areas) on a wide range of substrates (ITO, PEDOT:PSS, Si 3 N 4 ). This opens new avenues for nanocrystal-based devices competitive with thin film devices, as problems of granularity can be tackled through crystallographic orientational control over macroscopic areas.Colloidal nanocrystals offer a potential route to realizing low-cost solution-processed electronic devices. In particular, with their size-tunable properties, single-crystallinity, and inexpensive synthesis, semiconductor nanoparticles could enable improved optoelectronic devices. To date, however, the performance of nanoparticle devices has been limited, in large part, by the number of interfaces that charge carriers encounter before they can be collected; each interface presents an opportunity for recombination and subsequent charge loss or

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confidence: 80%

Device-Scale Perpendicular Alignment of Colloidal Nanorods

Baker¹,

Widmer‐Cooper²,

et al. 2009

Self Cite

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“…Beside van der Waals interactions, the effects of electrostatic interactions were studied. 38,39 Furthermore, attractive interactions between the spherocylinders by depletion forces were considered by Bolhuis et al 40 Attractive interactions support the parallel orientation of the rods, so that the anisotropic phase starts to appear already at lower volume fractions as observed by Li et al 35 Bolhuis and…”

Section: Phase Transition Compared To Theory and Experimentsmentioning

confidence: 92%

“…34 Lower volume fractions for phase transitions are calculated by other groups. [35][36][37][38][39][40] In this study we combine in situ SAXS to study structure formation with ex situ SEM-based image analysis and Raman analysis. This allows us to tailor highly ordered nematic thin films by influencing the relative impact of the resulting evaporationinduced convective flow and externally applied shear forces.…”

Section: Introductionmentioning

confidence: 99%

From evaporation-induced self-assembly to shear-induced alignment

et al. 2016

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The functionality of compact nanostructured thin films depends critically on the degree of order and hence on the underlying ordering mechanisms during film formation. For dip coating of rigid nanorods the counteracting mechanisms, evaporation-induced self-assembly (EISA) and shear-induced alignment (SIA) have recently been identified as competing ordering mechanisms. Here, we show how to achieve highly ordered and homogeneous thin films by controlling EISA and SIA in dip coating. Therefore we identify the influences of the process parameters including temperature, initial volume fraction and nanorod aspect ratio on evaporation-induced convective flow and externally applied shear forces and evaluate the resulting films. The impact of evaporation and shear can be distinguished by analysing film thickness, surface order and bulk order by careful in situ SAXS, Raman and SEM-based image analysis. For the first time we derive processing guidelines for the controlled application of EISA and SIA towards highly ordered thin nematic films.

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“…Peng et al [98] demonstrated that by controlling the growth kinetics the shapes of the resulting cadmium selenide nanoparticles can be tuned to vary from a nearly spherical morphology to a rod-like one, with aspect ratios as large as 10 to 1. Li et al [99,100] observed the formation of a nematic LC phase in suspensions of these CdSe semiconductor nanorods. Smectic-like LC structures mediated by drying-induced self-assembly on a TEM grid were observed for CdSe nanorods by Li & Alivisatos [101] and for CdSe/CdS heteronanorods by Carbone et al [97], while Talapin et al [102] took the drying-induced selfassembly method one step further to produce highly luminescent smectic three-dimensional structures of CdSe and CdSe/CdS.…”

Section: (A) Novel Colloidal Liquid Crystal Phases In External Fieldsmentioning

confidence: 99%

Liquid crystal phase transitions in suspensions of mineral colloids: new life from old roots

Lekkerkerker

Vroege

2013

Phil. Trans. R. Soc. A.

127

104

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A review is given of the field of mineral colloidal liquid crystals: liquid crystal phases formed by individual mineral particles within colloidal suspensions. Starting from their discovery in the 1920s, we discuss developments on the levels of both fundamentals and applications. We conclude by highlighting some promising results from recent years, which may point the way towards future developments.

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Isotropic-liquid crystalline phase diagram of a CdSe nanorod solution

Cited by 45 publications

References 28 publications

Device-Scale Perpendicular Alignment of Colloidal Nanorods

Device-Scale Perpendicular Alignment of Colloidal Nanorods

From evaporation-induced self-assembly to shear-induced alignment

Liquid crystal phase transitions in suspensions of mineral colloids: new life from old roots

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