Magnetic Field Alignment and Optical Anisotropy of MoS2 Nanosheets Dispersed in a Liquid Crystal Polymer

Uri R Gabinet; Changyeon Lee; Na Kyung Kim; Martin Hulman; Sarah M Thompson; Cherie R Kagan; Chinedum O Osuji

doi:10.1021/acs.jpclett.2c01819

Magnetic Field Alignment and Optical Anisotropy of MoS₂ Nanosheets Dispersed in a Liquid Crystal Polymer

J Phys Chem Lett. 2022 Sep 1;13(34):7994-8001. doi: 10.1021/acs.jpclett.2c01819. Epub 2022 Aug 19.

Authors

Uri R Gabinet^{1

2}, Changyeon Lee¹, Na Kyung Kim¹, Martin Hulman³, Sarah M Thompson⁴, Cherie R Kagan^{4

5

6}, Chinedum O Osuji^{1

2}

Affiliations

¹ Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
² Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States.
³ Institute of Electrical Engineering, Slovak Academy of Sciences, 84104 Bratislava, Slovakia.
⁴ Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
⁵ Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
⁶ Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.

PMID: 35984767
DOI: 10.1021/acs.jpclett.2c01819

Abstract

Molybdenum disulfide (MoS₂) nanosheets exhibit anisotropic optical and electronic properties, stemming from their shape and electronic structure. Unveiling this anisotropy for study and usage in materials and devices requires the ability to control the orientation of dispersed nanosheets, but to date this has proved a challenging proposition. Here, we demonstrate magnetic field driven alignment of MoS₂ nanosheets in a liquid crystal (LC) polymer and unveil the optical properties of the resulting anisotropic assembly. Nanosheet optical anisotropy is observed spectroscopically by Raman and direction-dependent photoluminescence (PL) measurements. Resulting data indicate significantly lower PL emission due to optical excitation with electric field oscillation out of plane, parallel to the MoS₂ c-axis, than that associated with perpendicular excitation, with the dichroic ratio I_perp/I_par = 3. The approach developed here provides a useful route to elucidate anisotropic optical properties of MoS₂ nanosheets and to utilize such properties in new materials and devices.