Assembling Nanoparticle Arrays at Fluid Interfaces

Columbia University, New York NY

Investigators

Abstract

CBET - 1603043 PI: Herman, Irving P. One route to making new materials for electronics, sensors, solar cells and other devices is to assemble nanoparticles into ordered structures. This project will develop new ways of assembling nanoparticles into two-dimensional monolayers at interfaces between liquid and air. The project will use iron oxide nanoparticles and semiconductor nanocrystals, which are often used in important technological applications. To control and tune the assembly process, the nanoparticles will be coated with chemical compounds that influence interactions among the particles. The effect of the compounds on the formation of a particle monolayer, the distances between particles within the monolayer, and characteristics of the resulting monolayer will be investigated using a variety of methods. The approaches in the project are general, so results should apply to the formation of a wide range of two-dimensional assemblies on liquid surfaces, which can then be transferred to solid surfaces. The resulting materials can be used in technologies involving light and electrical conduction. The project will provide opportunities for students at all academic levels to participate in research, and participants in the project will host materials and engineering demonstrations for children and adults in the Harlem STM Expo. This goal of this project is to use a combination of modeling and new experimental approaches to enable the rational design of ordered two-dimensional nanoparticle monolayers that takes full advantage of the unique and tunable properties of nanoparticles. A new route to monolayer formation using miscible liquids will be explored to determine if structures can be formed that cannot be obtained with standard methods. Nanoparticles capped with ligands will be synthesized and characterized by x-ray diffraction, absorption spectra and transmission electron microscopy. The size of the nanoparticle core, polydispersity, and ligand composition will be determined. Real time microscopy will be used to track the formation of the nanoparticles into monolayers at interfaces. Since physical coupling of nanoparticles can be linked to their electronic coupling, electrical and optical measurements of the fabricated structures will be conducted and correlated with details of the fabrication procedures. Modeling will be used to examine the evolution of nanoparticle ordering at interfaces and the dynamics and properties of the resulting structures as surrounding liquid evaporates. Finally, methods of transferring the resulting nanoparticle layer to a solid substrate, while monitoring monolayer properties, will be developed.