First-Principles Prediction of 2D Semiconductors MAN₃ (M = V, Nb, Ta; A = Si, Ge) from the MA₂N₄ Family: Implication for Optoelectronics Applications

Renowned for their outstanding structural and electronic properties, two-dimensional (2D) polar materials are highly regarded as promising candidates for advanced optoelectronics and catalysis applications. Herein, based on the design principle of valence charge balance and layer stacking, we successfully designed 22 stable 2D polar monolayers with intrinsic built-in electric fields. The predicted monolayer, i.e., 2D MAN₃, originates from the MA₂N₄ (M= V, Nb, Ta; A = Si, Ge) and has been widely studied in recent years. All of these monolayers exhibit semiconductor properties, with half displaying a direct band feature. Additionally, 2D MAN₃ monolayer shows remarkable hole mobility (∼10⁴ cm² V^–1 s^–1) and optical absorption. Furthermore, the band edges of these monolayers not only facilitate the establishment of diverse interface contacts but also meet the requirements for photovoltaic water splitting. Our work not only significantly expands the MAN₃ family but also provides valuable insights for its future research on optoelectronic applications.