A Family of Two-Dimensional Quaternary Compounds A₂BXY₂ (A = K, Na; B = Li, Na; X = Al, Ga, In; Y = P, As, Sb) for Optoelectronics Applications

Expanding material types and developing two-dimensional (2D) semiconductor materials with high performance have been hotspots in the field. In this research, it is found that the 12 existing semiconductors A 2 BXY 2 (A = K, Na; B = Li, Na; X = Al, Ga, In; Y = P, As, Sb) have a pronounced layered structure. We predict their 2D structures and properties, using first-principles calculations. Lower exfoliation energies confirm the feasibility of mechanical exfoliation from their bulk phases and that the 2D structures can be stabilized independently at room temperature. Interestingly, A 2 BXY 2 has an anionic tetrahedral one-dimensional chain or two-dimensional mesh structure of [XY 2 ] 3– composed of elements III–V. All A 2 BXY 2 monolayers exhibit direct or indirect band gap features (0.78–1.94 eV). More encouragingly, the A 2 BXY 2 monolayers possess ultrahigh carrier mobilities (∼10 5 cm 2 V –1 s –1 ) at room temperature. Furthermore, the results based on the nonequilibrium Green’s function indicate that 2D A 2 BXY 2 exhibits a high ON/OFF ratio (∼10 4 ). To sum up, the A 2 BXY 2 family is an outstanding promising candidate for optoelectronics application.