Understand two-dimensional perovskite nanosheets from individual and collective perspectives

Two-dimensional (2D) perovskite nanosheets have attracted great attention in recent years due to their unique morphological advantages and high qualifications in constructing miniature optoelectronic devices. However, there remains unexplored aspects regarding the structural evolution during spacer decoupling in nanosheet formation and the recoupling process in heterostructure assembly, which limits the understanding of the nanosheet structure-property relationship. Here, based on the advances and limitations of nanosheet preparations, we recommend further optimization of the synthesis method to achieve quality and prosperity for the whole family (including quasi-2D and Dion-Jacobson phases). Due to structural relaxation stem from extreme reduction of thickness, we propose to explore the microstructural evolution of 2D perovskite nanosheets, e.g. through high-resolution microscopy and spring-mass modeling to understand the different lattice arrangements and vibrational modes of nanosheets compared to bulk materials. Finally, we discuss the preparation and application of heterostructures based on 2D perovskite nanosheets and emphasize the structural rearrangement during van der Waals interface assembly in heterostructures. We hope this work will improve researcher's understanding of structure-property relationship of 2D perovskite nanosheets and accelerate research progress in this field.