Abstract Motivated by the fascinating properties of both two-dimensional transition metal dichalcogenide quantum dots (TMD QDs) and Janus TMD monolayers, we theoretically explore the equilibrium structures of free-standing Janus MoSSe QDs in which atomic asymmetry of chalcogen is introduced. Two distinct types of spontaneous curling are observed by molecular dynamics simulations, and the curling behavior depends on the size of QD. The bowl-like (tube-like) curling occurs in relatively small (large) MoSSe QDs with different shapes (hexagon and triangle) and edge types (zigzag and armchair). The transition between these two curling types occurs at the sizes of around 10 nm and 13 nm for hexagonal and triangular shapes, respectively. By applying equivalent misfit strains into two adjacent sublayers, finite element analysis reproduces similar curling behavior. This confirms the relaxation of intrinsic strain in Janus structure acting as the predominant driving force of spontaneous curling. In addition, the curvatures of Janus TMD QDs increase from MoSSe to MoSeTe to MoSTe, indicating the positive correlation between the curling and misfit.

中文翻译：

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独立二维 Janus MoSSe 量子点的内在应变诱导卷曲

摘要 受二维过渡金属二硫属化物量子点 (TMD QD) 和 Janus TMD 单层的迷人特性的启发，我们从理论上探索了独立的 Janus MoSSe QD 的平衡结构，其中引入了硫属元素的原子不对称性。通过分子动力学模拟观察到两种不同类型的自发卷曲，卷曲行为取决于 QD 的大小。碗状（管状）卷曲发生在具有不同形状（六边形和三角形）和边缘类型（锯齿形和扶手椅）的相对较小（大）MoSSe QD 中。对于六边形和三角形，这两种卷曲类型之间的过渡分别发生在大约 10 nm 和 13 nm 的大小处。通过将等效的错配应变应用到两个相邻的子层中，有限元分析再现了类似的卷曲行为。这证实了作为自发卷曲的主要驱动力的 Janus 结构中固有应变的松弛。此外，Janus TMD QD 的曲率从 MoSSe 到 MoSeTe 再到 MoSTe，表明卷曲和失配之间呈正相关。