Chiroptical Metamaterials

Professor: Richard Robinson

Project Description: Concurrent advances in additive manufacturing techniques and the availability of colloidal nanomaterials with precisely programmable size, shape and composition alongside have opened up an immensely fertile and intriguing opportunity space for the creation of metamaterials with unprecedented properties that are not attainable in naturally occurring objects. Chirality is a curious property of materials that cannot be superimposed on their mirror image using rotations and translations. Beyond chirality at the molecular scale (as recognized by the 2021 Nobel prize in chemistry), recent observations of chirality in multi-scale materials have captivated scientists and engineers as a platform to understand the emergence of chirality and as a way to develop chiroptical metamaterials with potential applications in sensing, photochemistry, and spintronics. Recent studies by the Robinson / Hanrath collaboration have lead to the discovery strong and tunable chiroptical properties (i.e., circular polarization) in multi-scale materials derived from the self-assembly of magic-sized semiconductor quantum dots into fibers and filaments. Preliminary experiments suggest that rheological stresses during the formation of the thin films play a role in determining the chirality of the self-assembled structures. This project will explore direct-write 3D printing of quantum dot inks to create chiroptical metamaterials. The goals of the project are to establish the relationship between printing conditions (i.e., shear, evaporation rate) and the chirality of the printed materials. The ability to create multi-scale chiroptical structures by 3D printing will also allow us to create programmable metamaterials spanning control over structure from nanometer to centimeter. The student involved in this project will learn about quantum dot synthesis, 3D printing, and various materials characterization techniques including atomic force microscopy, electron microscopy and circular polarization spectroscopy.