A DFT study of defects in SnO monolayer and their interaction with O2 molecule

Progress on two-dimensional binary oxide materials

Two-dimensional van der Waals (2D vdW) materials have attracted much attention because of their unique electronic and optical properties. Since the successful isolation of graphene in 2004, many interesting 2D materials have emerged, including elemental olefins (silicene, germanene, etc.), transition metal chalcogenides, transition metal carbides (nitrides), hexagonal boron, etc. On the other hand, 2D binary oxide materials are an important group in the 2D family owing to their high structural diversity, low cost, high stability, and strong adjustability. This review systematically summarizes the research progress on 2D binary oxide materials. We discuss their composition and structure in terms of vdW and non-vdW categories in detail, followed by a discussion of their synthesis methods. In particular, we focus on strategies to tailor the properties of 2D oxides and their emerging applications in different fields. Finally, the challenges and future developments of 2D binary oxides are provided.

Layer-dependent electronic and optical properties of tin monoxide: a potential candidate in photovoltaic applications

Tunable band gaps make two-dimensional (2D) SnO a promising candidate for a wide variety of applications in optoelectronic devices. In this work, we calculated the structural, electronic, and optical properties of monolayer and mutilayer SnO up to seven layers based on density functional theory. We found that the band gaps of SnO can vary from 0.61 eV to 4.05 eV as the layer number of SnO decreases from seven to one, which is mainly because of the interlayer coupling effect. The interlayer coupling ensures improved carrier transport properties between neighbouring layers, which can benefit the performance of 2D SnO in photovoltaic applications. In particular, a suitable band gap of 1.20 eV for solar cell applications is obtained in trilayer SnO, and the predicted theoretical efficiency of solar cells with trilayer SnO as the active material achieves a high value exceeding 16%, which is relatively high for 2D materials.