Honeycomb RhI<sub>3</sub> Flakes with High Environmental Stability for Optoelectronics.

Wang, Fakun; Zhang, Zhuang; Zhang, Yue; Nie, Anmin; Zhao, Wei; Wang, Dong; Huang, Fuqiang; Zhai, Tianyou · Adv Mater · 2020

basic_science · Level V

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Abstract

The emerging 2D layered transition metal trihalides (MX<sub>3</sub> ) have attracted extremely high interest given their exceptional structural and physical properties. Continuing to extend the library of 2D MX<sub>3</sub> is essential for exploring new physical phenomena and enabling new functionality. Herein, the optical and electrical properties and the photodetection behavior of atomically thin RhI<sub>3</sub> flakes exfoliated from bulk crystals are reported. This compound exhibits superior air and thermal stability, as well as thickness-dependent bandgap from 1.1 (18L) to 1.4 eV (2L). Field-effect transistors based on the few-layer RhI<sub>3</sub> flakes display n-type semiconducting behavior with competitive mobility of 2.5 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup> and ON/OFF current ratio of 4 × 10<sup>4</sup> . Importantly, the outstanding responsivity of 11.5 A W<sup>-1</sup> and high specific detectivity of 2 × 10<sup>10</sup> Jones are recorded from the RhI<sub>3</sub> photodetectors under 980 nm illumination at room temperature in air. These findings indicate a variety of potential applications of atomically thin RhI<sub>3</sub> flakes in future 2D-material-based electronic and optoelectronic devices.