Giant Bulk Photostriction and Accurate Photomechanical Actuation in Hybrid Perovskites

It is well known that a material may be strained by mechanical, thermal, electric, magnetic, and light stimuli, and this effect has been extensively utilized in industries. However, the observed photostrictive effect usually occurs in the very thin surface layer and the photostriction of most bulk materials has been too small to be applied in a device until now. Here, a giant bulk photostriction is achieved, evidenced by the measured linear strain ε ≈ 0.72–0.43% for MAPbI₃ single crystal plates of 0.05–0.5 mm in thickness under the 532 nm illumination. More importantly, the MAPbI₃ single crystals also exhibit accurate photomechanical actuation functionality and the actuator can precisely adjust the displacement from hundreds of pm to tens of μm or the angle of a hard mirror from ≈10⁻⁶ to 0.2 degree. The present work not only unveils the huge bulk photostriction in lead halide perovskite single crystals but also demonstrates a wireless photomechanical actuator which is much simpler and smaller than conventional piezoelectric actuators. © 2021 Wiley-VCH GmbH