LAUSR

2D materials, due to their ultrathin dangling‐bond‐free configuration and excellent electrostatic control, have potential as possible Si‐alternative building blocks for future competitive devices. Exploring 2D electronic materials with suitable band gap and high mobility is key to designing ultra‐scaled devices. The electronic properties and device performance of sub‐10 nm 2D Sb2Te2Se are studied by ab initio quantum‐transport simulations. The results show that 2D Sb2Te2Se, a stable system, possesses an indirect bandgap of 1.01 eV and high electron mobility exceeding 103 cm2 V−1 s−1. Through comparing with the ballistic quantum transports of Sb2Te2Se, the n‐metal‐oxide‐semiconductor field‐effect transistor (MOSFET) exhibits better device performance than p‐MOSFET. In particular, not only can the on‐current of n‐MOSFET with gate length Lg = 9 nm reach as high as 1660 µA µm−1, but its other figures of merit including gate capacity (0.72 fF µm−1), delay time (0.31 ps), and power dissipation (0.37 fJ µm−1) also satisfy the International Technology Roadmap for Semiconductors 2020 requirements. Therefore, 2D Sb2Te2Se could become a potential electronic material for next‐generation nanodevices.