Intercalated Architecture of the Ca 2 A 2 Z 5 Monolayer with High Electron Mobilities and High Power Conversion Efficiencies

The exploration of novel two-dimensional (2D) materials with a direct band gap and high mobility has attracted huge attention due to their potential application in electronic and optoelectronic devices. Here, we propose a feasible way to construct multiatomic monolayer Ca A Z (A = Al and Ga and Z = S, Se, and Te) by first-principles calculations. Our results indicated that the energies of α -phase Ca A Z are slightly lower than those of experimentally synthesized α -phase-like Ca A Z monolayers with excellent structural stability. Moreover, the α - and α -phase Ca A Z monolayers possess not only direct band gaps but also high electron mobilities (up to ∼10 cm V s ), demonstrating an intriguing range of visible light absorption. Importantly, α - and α -phase Ca Ga Se monolayers are good donor materials, and the corresponding Ca Ga Se /ZrSe type-II heterostructures exhibit desirable power conversion efficiencies of 22.4% and 22.9%, respectively. Our findings provide a feasible way to explore new 2D materials and offer several Ca A Z candidate monolayers for the application of high-performance solar cells.