Langmuir−Blodgettry of Nanocrystals and Nanowires

Abstract

Although nanocrystals and nanowires have proliferated new scientific avenues in the study of their physics and chemistries, the bottom-up assembly of these small-scale building blocks remains a formidable challenge for device fabrication and processing. An attractive nanoscale assembly strategy should be cheap, fast, defect tolerant, compatible with a variety of materials, and parallel in nature, ideally utilizing the self-assembly to generate the core of a device, such as a memory chip or optical display. Langmuir-Blodgett (LB) assembly is a good candidate for arranging vast numbers of nanostructures on solid surfaces. In the LB technique, uniaxial compression of a nanocrystal or nanowire monolayer floating on an aqueous subphase causes the nanostructures to assemble and pack over a large area. The ordered monolayer can then be transferred to a solid surface en masse and with fidelity. In this Account, we present the Langmuir-Blodgett technique as a low-cost method for the massively parallel, controlled organization of nanostructures. The isothermal compression of fluid-supported nanoparticles or nanowires is unique in its ability to achieve control over nanoscale assembly by tuning a macroscopic property such as surface pressure. Under optimized conditions (e.g., surface pressure, substrate hydrophobicity, and pulling speed), it allows continuous variation of particle density, spacing, and even arrangement. For practical application and device fabrication, LB compression is ideal for forming highly dense assemblies of nanowires and nanocrystals over unprecedented surface areas. In addition, the dewetting properties of LB monolayers can be used to further achieve patterning within the range of micrometers to tens of nanometers without a predefined template. The LB method should allow for easy integration of nanomaterials into current manufacturing schemes, in addition to fast device prototyping and multiplexing capability.

Metal nanoparticle field-effect transistor

“…Devices founded on new principles with promising new functions, higher performance, or reduced production costs should anyhow be reliable, large-scale producible, and CMOS compatible [32]. One branch of material synthesis which fulfills these requirements is colloidal chemistry [33].…”

Infrared external reflection spectra of Janus gold nanoparticle monolayers prepared at the air–water interface

“…The construction of 2D arrays of nanoparticles (NPs) is of great importance owing to their potential applications in electronic, magnetic, and optical devices [1][2][3]. Gold nanoparticle (AuNP) monolayers at the air-water interface have recently attracted widespread attention because of their tunable lateral surface density and ability to form 3D assemblies via the Langmuir-Blodgett method [4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Capillary Assembly of Silicon Nanowires Using the Removable Topographical Patterns

“…[1][2][3][4][5] To take advantage of their unique physical properties, however, uniform assembly of these nanostructures in largescale with desired patterns is highly necessitated. Several reports have demonstrated methods to assemble NWs into desired structures, including the electric/magnetic field assisted assembly method, 6,7) fluidic flow as-sembly method, [8][9] stick-slip motion method, 10,11) Langmuir-Blodgett method, [12][13][14][15] contact printing method, 16,17) and selection adhesion method. [18][19][20] Although such aforementioned methods have shown considerable progresses in assembling SiNWs into desired positions, they generally require unconventional facilities and sophisticated treatments which can be major problematic in cost-effectiveness and simplicity of the fabrication process.…”