2D NbOI<sub>2</sub> : A Chiral Semiconductor with Highly In-Plane Anisotropic Electrical and Optical Properties.

Fang, Yuqiang; Wang, Fakun; Wang, Ruiqi; Zhai, Tianyou; Huang, Fuqiang · Adv Mater · 2021

basic_science · Level V

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Abstract

Exploring in-plane anisotropic 2D materials is of great significance to the fundamental studies and further development of polarizationsensitive optoelectronics. Herein, chiral niobium oxide diiodide (NbOI<sub>2</sub> ) is introduced into the intriguing anisotropic 2D family with the experimental demonstration of anisotropic optical and electrical properties. 2D NbOI<sub>2</sub> crystals exhibit highly anisotropic dispersed band structures around the Fermi surface and strong in-plane anisotropy of phonon vibrations owing to the different bonding modes of Nb atoms along the b- and c-axes. Consequently, the anisotropic factors of optical absorbance and photoresponsivity in 2D NbOI<sub>2</sub> crystals reach up to 1.75 and 1.7, respectively. These anisotropic properties make 2D NbOI<sub>2</sub> an interesting platform for novel polarization-sensitive optoelectronic applications.