上海科技大学知识管理系统

High-resolution transmission electron microscopy (HRTEM) is a widely-used technique for atomic-scale characterization. However, the conventional dose of HRTEM can destroy beam-sensitive materials such as organic-inorganic halide perovskites. CH3NH3PbI3 (MAPbI(3)), a typical perovskite, will be easily damaged after irradiated with the dose of similar to 10(2) e-/& Aring;(2). Low-dose imaging techniques can protect the specimen but it is difficult to achieve an image which is both directly interpreted and atomically clear. Exit wave reconstruction (EWR), as one of phase retrieval methods, can recover an interpretable phase image at the atomic scale but its signal-to-noise ratio (SNR) is limited by low electron doses. Here, we improve the iterative wave function reconstruction (IWFR) method and present a soft-thresholding L-1-IWFR. Results from both simulated and experimental focal-series dataset at the extremely low dose show that L-1-IWFR improves the SNR effectively and has better performance on low-dose datasets than IWFR. Combined with low-dose imaging techniques and various alignment strategies, an atomically clear image of CH3NH3PbI3 (MAPbI(3)) is successfully achieved at the total dose of similar to 45 e(-)/& Aring;(2).