Giant Electrostriction in Halide Perovskites Revisited With Double‐Modulation Interferometry

A reported giant electrostrictive effect in halide perovskites has attracted interest for its physical origin and for potential applications in actuation and sensing. However, despite the reported exceptionally large magnitude of the effect, systematic experimental investigation remains limited. In this work, the electromechanical response of methylammonium lead halide perovskites (MAPbX 3 ; X═I, Br, Cl) in the form of powder‐pressed pellets, MAPbBr 3 single crystals, and MAPbI 3 thin films is investigated using a high‐resolution double‐modulation interferometer. Reference measurements using a commercial electrostrictive polymer confirm that the setup resolves sub‐nanometer electromechanical displacements. In contrast to previous reports of giant electrostrictive compression in halide perovskites, no such intrinsic compressive electrostriction is observed in any of the samples. Instead, an expansion at twice the driving frequency is detected. Analysis of the frequency dependence and step response indicates that the expansion arises primarily from thermal expansion caused by Ohmic currents that lead to Joule heating.