Lead halide perovskites have demonstrated outstanding performance in photovoltaics, photodetectors, radiation detectors and light-emitting diodes. However, the electromechanical properties, which are the main application of inorganic perovskites, have rarely been explored for lead halide perovskites. Here, we report the discovery of a large electrostrictive response in methylammonium lead triiodide (MAPbI₃) single crystals. Under an electric field of 3.7 V µm⁻¹, MAPbI₃ shows a large compressive strain of 1%, corresponding to a mechanical energy density of 0.74 J cm⁻³, comparable to that of human muscles. The influences of piezoelectricity, thermal expansion, intrinsic electrostrictive effect, Maxwell stress, ferroelectricity, local polar fluctuation and methylammonium cation ordering on this electromechanical response are excluded. We speculate, using density functional theory, that electrostriction of MAPbI₃ probably originates from lattice deformation due to formation of additional defects under applied bias. The discovery of large electrostriction in lead iodide perovskites may lead to new potential applications in actuators, sonar and micro-electromechanical systems and aid the understanding of other field-dependent material properties.

卤化钙钛矿已在光伏，光电探测器，辐射探测器和发光二极管中表现出出色的性能。然而，机电性能是无机钙钛矿的主要用途，很少有人研究卤化钙钛矿。在这里，我们报告发现在甲基碘化三碘化铅（MAPbI ₃）单晶中有较大的电致伸缩响应。在3.7 V µm ^-1的电场下，MAPbI ₃表现出1％的大压缩应变，对应于0.74 J cm ^{- 3}的机械能密度，相当于人类的肌肉。排除了压电性，热膨胀，固有电致伸缩效应，麦克斯韦应力，铁电性，局部极性波动和甲基铵阳离子有序性对该机电响应的影响。我们使用密度泛函理论推测，MAPbI _3的电致伸缩可能源自晶格变形，这是由于在施加偏压下形成了其他缺陷所致。碘化铅钙钛矿中大电致伸缩的发现可能会导致在致动器，声纳和微机电系统中出现新的潜在应用，并有助于理解其他与场有关的材料特性。