Extremly high stabilities and mobilities in monolayer XYO2 (X=Li, Na; Y=Al, Ga, In) for solar cells

Two-dimensional (2D) materials with high mobility and suitable direct band gap can be candidates for photoelectric materials. However, some ideal 2D photoelectric materials are easily oxidized in ambient conditions. Herein, we have systematically explored a new 2D ternary layered material by first-principles calculations, named XYO2 (X=Li, Na; Y=Al, Ga, In). These XYO2 monolayers possess desirable direct band gaps, revealing fine optical adsorption efficiency due to the adsorption spectra covering visible and ultraviolet light. Importantly, NaAlO2 host extremely high carrier mobilities of ∼104cm2V−1s−1, close to that of phosphorene. Furthermore, NaAlO2 shows outstanding power conversion efficiency of up to 22.8%, meaning that it is a suitable potential donor material. Our results propose potential candidates in the application of photoelectric materials. In addition, LiAlO2 monolayer with a desirable band gap alignment, can be a possible effective photocatalyst for water splitting within the ultraviolet range.