In order to incorporate nanostructures into functional devices, it is imperative to create an effective, reproducible, and economic method to manipulate the systematic arrangement of nanostructures patterning, alignment, and orientation on a substrate. Two dimensional array (2D) of metal nanoparticles (MNPs) are of great interest in the field of energy, optoelectronics, and biosensing because of their intrinsic optical properties such as localized surface plasmon resonance. Top-down techniques such as electron beam lithography and vapor deposition are commonly used to fabricate highly ordered 2D array of MNPs. Though these techniques offer superior flexibility and precision in arranging MNPs directly on a substrate, they are complex and expensive. We developed a method to fabricate highly ordered 2D arrays of dimers of MNPs with different compositions, sizes, and shapes directly on a substrate in a controlled manner.  This method involves i) the assembly of MNPs into 2D array with hexagonal packing directly on a substrate via solvent evaporation process, ii) the selective removal of thiol ligands from the top surface of MNPs by selective etching process without deteriorating the 2D array, and iii) the subsequent assembly of other MNPs on top of the 2D array through functional linkers or electrostatic interactions. MNPs with different sizes can be readily integrated into the arrays to produce dimers with controlled symmetry. The distance between dimer islands can be precisely controlled by tuning the ligands on the MNP surface. This is a simple, and low-cost, general method for generating high-quality arrays without the need of sophisticated and expensive instruments. Scanning electron microscopy and atomic force microscopy were used to study the morphology of the nanostructures as well as the topology of the 2D array of MNP dimers. This highly ordered array of dimers may find applications in surface-enhanced Raman scattering signal detection, photovoltaic devices, and photonic crystals.

Assembly of 2D highly-ordered arrays of nanoparticle dimers directly on a substrate

248th National Meeting (2014)

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