2D Self-Bundled CdS Nanorods with Micrometer Dimension in the Absence of an External Directing Process

Abstract

In the absence of an external direction-controlling process, exclusive self-bundled arrays of CdS nanorods are formed using a facile solution-based method involving trioctylphosphine (TOP) and tetradecylphosphonic acids (TDPA) as cosurfactants. CdS self-bundled arrays with an area of as large as 2.0 microm(2) could be obtained. A detailed mechanistic investigation leads us to conclude that the matching in nanorod concentration, intrinsic properties of CdS, and the hydrocarbon chains of the surfactants between adjacent CdS rods play key roles in the self-assembly. In sharp contrast to the defect dominant emission in solutions, the self-bundled CdS nanorods exhibit optical emission nearly free from the defect-states, demonstrating their potential for applications in luminescence and photovoltaic devices.

Mesocrystals—Ordered Nanoparticle Superstructures

“…[28] Even without electric field, ordering is possible if surfactants with three or four alkane chains were used for the stabilization of CdS which facilitate corralling by hydrocarbon interaction. [29] Above a critical particle concentration, simple drying led to 2D mesocrystals.…”

“…Upon capping CdS with tri-n-octylphosphine (TOP) and tetradecylphosphonic acid (TDPA), they obtained 2D self-bundled CdS nanorods with an area as large as 2.0 mm 2 . [29] TEM studies revealed self-assemblies of CdS nanorods with outer edges of leaning bundles and an inner part of hexagonal packing perpendicular to the substrate. Evaporation-induced corralling of nanorods normal to the substrate, might serve as a nucleation site.…”

Mesocrystal-embedded functional oxide systems

“…[3,4] Due to their structural nature, the mesoscopically well-ordered crystals can exhibit unique properties and functionalities that cannot be seen in the parent bulk materials. Typical examples of mesocrystals can be found in various materials as diverse as metal oxides, [5][6][7][8][9] II/IV semiconductors, [10,11] complex oxides, [12,13] fluorides, [14] phosphates, [15] organic molecular systems, [16,17] etc. To date, considerable efforts have been made to develop synthesis mechanisms, to acquire new members of the mesocrystal family, and to tailor their tantalizing functionalities.…”

Water Dispersible Semiconductor Nanorod Assemblies Via a Facile Phase Transfer and Their Application as Fluorescent Biomarkers

“…[3][4][5][6][7][8][9][10] Nanorods have been directed into perpendicularly ordered assemblies either by using external electric fields or by evaporation control at solid/liquid or liquid/air interfaces. [11][12][13][14] The aspect ratio and polydispersity of the rods in addition to solvent-evaporation dynamics plays a key role in achieving vertical alignment and close packing from solution. In effect, the gradual packing of randomly dispersed nanorods into a reducing solvent volume allows attractive dipole-dipole and Van der Walls forces between ligand capped nanorods to dominate the assembly behaviour at a substrate.…”