Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) are recent members of the 2D materials family with wide tunability, highly dynamic structural features, and excellent physical properties. Ultrathin 2D HOIPs and their heterostructures with other 2D materials have been exploited for study of physical phenomena and device applications. The in-plane mechanical properties of 2D ultrathin HOIPs are critical for understanding the coupling between mechanical and other physical fields and for integrated devices applications. Here we report the in-plane mechanical properties of ultrathin freestanding 2D lead iodide perovskite membranes and their dependence on the membrane thickness. The in-plane Young’s moduli of 2D HOIPs are smaller than that of conventional covalently bonded 2D materials. As the thickness increases from monolayer to three-layer, both the Young’s modulus and breaking strength decrease, while three-layer and four-layer 2D HOIPs have almost identical in-plane mechanical properties. These thickness-dependent mechanical properties can be attributed to interlayer slippage during deformation. Our results show that ultrathin 2D HOIPs exhibit outstanding breaking strength/Young’s modulus ratio compared to many other widely used engineering materials and polymeric flexible substrates, which renders them suitable for application into flexible electronic devices.

中文翻译：

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超薄二维杂化有机-无机钙钛矿的拉伸和断裂

二维（2D）杂化有机-无机钙钛矿（HOIPs）是2D材料家族的最新成员，具有广泛的可调性，高度动态的结构特征和出色的物理性能。超薄2D HOIP及其与其他2D材料的异质结构已被用于研究物理现象和设备应用。2D超薄HOIP的面内机械特性对于理解机械领域和其他物理领域之间的耦合以及集成设备应用至关重要。在这里，我们报告了超薄的独立式二维碘化铅钙钛矿膜的平面内机械性能及其对膜厚度的依赖性。2D HOIP的面内杨氏模量小于常规的共价键合2D材料的杨氏模量。随着厚度从单层增加到三层，杨氏模量和断裂强度都降低，而三层和四层2D HOIP具有几乎相同的面内机械性能。这些取决于厚度的机械性能可归因于变形期间的层间滑动。我们的结果表明，与许多其他广泛使用的工程材料和聚合物柔性基板相比，超薄2D HOIP具有出色的断裂强度/杨氏模量比，这使其适用于柔性电子设备。