“…It also allows in situ real-time monitoring and characterization of material growth and evolution processes,s urface dynamics,a nd surface chemistry.Scanning tunneling spectroscopy can precisely reveal the electronic structures of the surface at the atomic scale.F urthermore,S TM can be combined with many other ultrahigh vacuum (UHV) techniques to provide comprehensive characterization of the sample surface.C ompared with transmission electron microscopy (another powerful technique with the capability of atomic-resolution imaging), STM experiments can be considered non-invasive and the sample preparation is relatively straightforward. However,S TM requires an atomically smooth and conductive surface and asharp metallic tip.Although STM can offer crucial insights into the fundamental understanding of materials ultimately at the atomic scale, [15] STM studies on perovskite materials are still relatively rare,p resumably because of the technical difficulty in obtaining an immaculate and atomically flat sample surface. [13a, 16] Recent findings indicate that the surface trap states in the perovskite layer can strongly influence the performance of the solar cell devices; [7b,17] however, the chemical and physical properties of atomic-scale defects and surface and interface properties are not well-understood.…”