Mechanical Properties of a 2D Lead-Halide Perovskite, (C6H5CH2NH3)2PbCl4, by Nanoindentation and First-Principles Calculations

Two-dimensional (2D) hybrid lead halide perovskites have been extensively regarded as most promising candidates for application in solar cells and other optoelectronic devices. Although the power conversion efficiencies and environmental stability of 2D hybrid lead halide perovskites have rapidly improved, mechanical property studies of these materials are scarce. However, it contributes to fabricating mechanically stable or flexible devices. Herein, we report the mechanical properties of a 2D layered lead halide hybrid (C6H5CH2NH3)2PbCl4 by nanoindentation and first-principles calculations. The detailed discussion of the structure–property relationship demonstrates that the mechanical properties of (C6H5CH2NH3)2PbCl4 are anisotropic, and the organic components and van der Waals interactions between layers play a significant role in the structural stability of the 2D structure. Furthermore, the results of theoretical calculations suggest that 2D hybrid halide perovskites with an increase in the number of inorganic layers exhibit diminishing ductility when subjected to very large deformation. We further deduce that the substitution of organic parts with stiff and multifunctional organic components will lead to improved stability and carrier mobility of the perovskite solar cell absorber layer. These explorations shed light on routes to fabricate stable (flexible) and high-performance devices.