Honeycomb RhI Flakes with High Environmental Stability for Optoelectronics.

The emerging 2D layered transition metal trihalides (MX ) have attracted extremely high interest given their exceptional structural and physical properties. Continuing to extend the library of 2D MX 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 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 flakes display n-type semiconducting behavior with competitive mobility of 2.5 cm V s and ON/OFF current ratio of 4 × 10 . Importantly, the outstanding responsivity of 11.5 A W and high specific detectivity of 2 × 10 Jones are recorded from the RhI photodetectors under 980 nm illumination at room temperature in air. These findings indicate a variety of potential applications of atomically thin RhI flakes in future 2D-material-based electronic and optoelectronic devices.