Dynamic Alignment and Polarized Emission of Semiconductor Nanoplatelets in a Liquid Crystal

Osuj-Kagan-Murray figure on Switchable Polarization

The image shows bright and dark states in polarized optical microscope images corresponding to different orientations of CdSe nanoplatelets which are aligned by a magnetic field. The alignment direction is “horizontal” in the top case, and “vertical” in the bottom case. As a result, the emission through polarizers changes from bright to dark (or dark to bright).

This work demonstrates the potential of liquid crystals as a versatile medium for controlling the orientation of anisotropic optically-active nanomaterials.

High stability dispersions of CdSe/ZnS nanoplatelets were realized in a composite system consisting of a liquid crystal polymer and labile small molecule mesogens. The orientation of the LC director is controlled by a magnetic field, and the LC director orientation in turn controls the orientation of the nanoplatelets. Switching the field direction results in a rapid change of orientation of the nanoplatelets, which is visualized in polarized optical microscope images.

Such dynamic alignment of optically-active nanomaterials may enable the development of programmable materials for photonic applications. The methodology developed here can be applied to the design of anisotropic nanomaterial composites for a broad set of related nanomaterials.

Kim, D., Ndaya, D., Bosire, R., Masese, F. K., Li, W., Thompson, S. M., Kagan, C. R., Murray, C. B., Kasi, R. M., Osuji, C. O. Nature Communications, 13, 2507 (2022); DOI: 10.1038/s41467-022-30200-2