Gas−Liquid−Solid Phase Transition Model for Two-Dimensional Nanocrystal Self-Assembly on Graphite

Tang, Jing; Ge, Guanglu; Brus, L. E.

doi:10.1021/jp014559c

Cited by 85 publications

(99 citation statements)

References 25 publications

(61 reference statements)

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“…With proper parameter scaling 57 we find that the results are independent of the nanoparticle size, in agreement with experiments. 21 The size of the simulation box is 256 × 256 × 11 with periodic boundary conditions in the x-y plane. Since the lower layer is filled with substrate, nanoparticle and liquid can fill the top 10 layers only.…”

Section: Resultsmentioning

confidence: 99%

“…[43][44][45][46] Another example is the formation of disks, ribbons, and cracks recently observed by Brus and co-workers. 15,16,21 These experiments utilize a thin solution that contains semiconductor nanocrystals passivated by an organic surface ligand. The solution wets the surface of the substrate, effectively forming a two-dimensional film.…”

Section: Introductionmentioning

confidence: 99%

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Self-Assembly of Nanoparticles in Three-Dimensions: Formation of Stalagmites

2005

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We develop a coarse-grained lattice gas model to describe drying-mediated self-assembly of nanoparticles in three dimensions. Our model is an extension of the model developed by Rabani et al. [Nature 2003, 426, 271] in two dimensions. We show that when liquid evaporation occurs layer by layer and solvation forces are strong, the resulting morphologies agree well with the predictions of the 2D model. We discuss scenarios in which the full 3D treatment is necessary and predict the formation of nanostalagmites.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-Assembly of Nanoparticles in Three-Dimensions: Formation of Stalagmites

2005

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“…It is the combination of these two effects of the organic material that enable the monolayer formation and self-assembly to occur during the solvent drying time. Once phase separation has occurred, the QDs are mobile on the organic underlayer surface, [13,20] and self-assemble into hcp arrays as they seek their equilibrium conformation, coarsening via a combination of …”

Section: Role Of Organic Underlayermentioning

confidence: 99%

“…QD monolayers arranged onto organic thin films are a unique platform for the study of basic physical properties of materials, for example allowing investigation of coarsening mechanisms on the individual adatom (in this case a single-QD) level. [13,14] The fabrication of a monolayer sheet of close-packed QDs by phase separation during spin-casting is in essence a very simple process, as depicted in Figure 1. The process relies upon the solvation of both the organically capped semiconductor QDs and the organic material to be used as an underlayer in a compatible solvent system.…”

Section: Introductionmentioning

confidence: 99%

Large-Area Ordered Quantum-Dot Monolayers via Phase Separation During Spin-Casting

et al. 2005

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We investigate a new method for forming large‐area (> cm2) ordered monolayers of colloidal nanocrystal quantum dots (QDs). The QD thin films are formed in a single step by spin‐casting a mixed solution of aromatic organic materials and aliphatically capped QDs. The two different materials phase separate during solvent drying, and for a predefined set of conditions the QDs can assemble into hexagonally close‐packed crystalline domains. We demonstrate the robustness and flexibility of this phase‐separation process, as well as how the properties of the resulting films can be controlled in a precise and repeatable manner. Solution concentration, solvent ratio, QD size distribution, and QD aspect ratio affect the morphology of the cast thin‐film structure. Controlling all of these factors allows the creation of colloidal‐crystal domains that are square micrometers in size, containing tens of thousands of individual nanocrystals per grain. Such fabrication of large‐area, engineered layers of nanoscale materials brings the beneficial properties of inorganic QDs into the realm of nanotechnology. For example, this technique has already enabled significant improvements in the performance of QD light‐emitting devices.

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“…In a good solvent, surfaceadsorbed PVP can swell up to 20 nm in thickness, counteracting the strong van der Waals (vdW) forces between large facets, which can exceed thousands of kT per particle pair (21). In colloidal systems where particle-substrate interactions are small, solvent drying triggers a phase separation by increasing the interactions between particles because the original solvent is replaced by a poor solvent such as air (30). We assembled Ag octahedra (a = 300 nm) from a dilute solution of ethanol (∼0.05 μg/μL) by dropping it on a clean glass (SiO 2 ) coverslip that had been passivated with tridecafluoro-1,1,2,2-tetrahydrooctyl-1-trichlorosilane (Materials and Methods).…”

Section: Resultsmentioning

confidence: 99%

Oriented assembly of polyhedral plasmonic nanoparticle clusters

Henzie

Andrews

Ling

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

122

118

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Shaped colloids can be used as nanoscale building blocks for the construction of composite, functional materials that are completely assembled from the bottom up. Assemblies of noble metal nanostructures have unique optical properties that depend on key structural features requiring precise control of both position and connectivity spanning nanometer to micrometer length scales. Identifying and optimizing structures that strongly couple to light is important for understanding the behavior of surface plasmons in small nanoparticle clusters, and can result in highly sensitive chemical and biochemical sensors using surface-enhanced Raman spectroscopy (SERS). We use experiment and simulation to examine the local surface plasmon resonances of different arrangements of Ag polyhedral clusters. High-resolution transmission electron microscopy shows that monodisperse, atomically smooth Ag polyhedra can selfassemble into uniform interparticle gaps that result in reproducible SERS enhancement factors from assembly to assembly. We introduce a large-scale, gravity-driven assembly method that can generate arbitrary nanoparticle clusters based on the size and shape of a patterned template. These templates enable the systematic examination of different cluster arrangements and provide a means of constructing scalable and reliable SERS sensors.nanocrystal | self-assembly | plasmonics | nanopatterning T he ability to control the arbitrary position, orientation, and connectivity of colloidal building blocks with nanoscale precision is an objective of materials research that is critical for advances in fields including electronics, energy harvesting/conversion, optics, and biosensing (1-4). Additionally, many barriers in our understanding of fundamental nanoscale phenomena are frequently overcome by ever more precise tools to manipulate the processes and organization of matter across extended and multiple-length scales (5, 6). The impact of new tools is particularly apparent in the field of plasmonics, which uses the collective excitations of free electrons in nanoscale metallic structures and periodically structured composites to control and manipulate light at deeply subwavelength scales (7-9). Experiment and simulation show that the subtle differences in the size, geometry, and spacing of metal nanostructures strongly impact their optical properties (10-13). However, to accurately and reproducibly fabricate structures using top-down tools is limited by the challenge of controlling nanoscale materials dimensions that depend on the crystallinity and surface roughness of materials (14-16).Noble metal nanoparticles can be synthesized in a variety of shapes with exceptional monodispersity (17, 18) and self-assembled into complex, ordered structures (19-21). The outcome of the assembly process depends on particle shape, size, relevant particle interactions, and external driving forces (22). Because their surfaces are atomically smooth, polyhedral nanocrystals can form interparticle gaps with distinct, flat interfaces that are below 2 ...

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Gas−Liquid−Solid Phase Transition Model for Two-Dimensional Nanocrystal Self-Assembly on Graphite

Cited by 85 publications

References 25 publications

Self-Assembly of Nanoparticles in Three-Dimensions: Formation of Stalagmites

Self-Assembly of Nanoparticles in Three-Dimensions: Formation of Stalagmites

Large-Area Ordered Quantum-Dot Monolayers via Phase Separation During Spin-Casting

Oriented assembly of polyhedral plasmonic nanoparticle clusters

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