A relatively fast, easy and inexpensive technique for inducing nanorods – rod-shaped semiconductor nanocrystals – to self-assemble into one-, two- and even three-dimensional macroscopic structures has been developed by a team of researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab). This technique should enable more effective use of nanorods in solar cells, magnetic storage devices and sensors. It should also help boost the electrical and mechanical properties of nanorod-polymer composites.
Leading this project was Ting Xu, a polymer scientist who holds joint appointments with Berkeley Lab’s Materials Sciences Division and the University of California (UC) Berkeley’s Departments of Materials Sciences and Engineering, and Chemistry. Xu and her research group used block copolymers – long sequences or “blocks” of one type of monomer bound to blocks of another type of monomer – as a platform to guide the self-assembly of nanorods into complex structures and hierarchical patterns. Block copolymers have an innate ability to self-assemble into well-defined arrays of nano-sized structures over macroscopic distances.
“Ours is a simple and versatile technique for controlling the orientation of nanorods within block copolymers,” Xu says. “By varying the morphology of the block copolymers and the chemical nature of the nanorods, we can provide the controlled self-assembly in nanorods and nanorod-based nanocomposites that is critical for their use in the fabrication of optical and electronic devices.”
Xu is the corresponding author of a paper describing this research that has been published in the journal Nano Letters under the title “Direct Nanorod Assembly Using Block Copolymer-Based Supramolecules.” Co-authoring the paper were Kari Thorkelsson, Alexander Mastroianni and Peter Ercius.
Nanorods – particles of matter a thousand times smaller than the stuff of today’s microtechnologies – display highly coveted optical, electronic and other properties not found in macroscopic materials. To fully realize their vast technological promise, however, nanorods must be able to assemble themselves into complex structures and hierarchical patterns, similar to what nature routinely accomplishes with proteins.
Xu and her group are now investigating the self-assembly of semiconductor nanocrystals that take the shapes of cubes or tetrapods, both of which have important potential applications for photovoltaic and other technologies.
This story is reprinted from material from Berkeley Lab, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.