Imaging Electron Beam-Sensitive Twisted Hybrid Perovskite Bilayers at One-Angstrom Resolution

Twisted halide perovskite bilayers, a type of moiré material, show square moiré patterns with exciting optical properties. Atomic-scale structure analysis and its correlation with properties are difficult to achieve due to the extreme sensitivity of organic-inorganic halide perovskites to the illuminated electron beam in conventional/scanning transmission electron microscopy. Here, we developed a low-dose exit wave reconstruction methodology with a real-space resolution of one angstrom at ∼50 e/Ų, which recovers the phase information on the moiré fringes in CH₃NH₃PbI₃ (MAPbI₃) twisted perovskite bilayers at atomic scale, enabling detailed structural analysis of defects and corresponding strain distribution in such moiré materials. This work provides an atomic-level understanding of electron beam-sensitive twisted bilayer materials.