Honeycomb RhI3 Flakes with High Environmental Stability for Optoelectronics.

The emerging 2D layered transition metal trihalides (MX3 ) have attracted extremely high interest given their exceptional structural and physical properties. Continuing to extend the library of 2D MX3 is essential for exploring new physical phenomena and enabling new functionality. Herein, the optical and electrical properties and the photodetection behavior of atomically thin RhI3 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 RhI3 flakes display n-type semiconducting behavior with competitive mobility of 2.5 cm2 V-1 s-1 and ON/OFF current ratio of 4 × 104 . Importantly, the outstanding responsivity of 11.5 A W-1 and high specific detectivity of 2 × 1010 Jones are recorded from the RhI3 photodetectors under 980 nm illumination at room temperature in air. These findings indicate a variety of potential applications of atomically thin RhI3 flakes in future 2D-material-based electronic and optoelectronic devices.