Preface: Two dimensional (2D) hybrid organic-inorganic perovskites

摘要： 2D hybrid organic-inorganic perovskites (HOIPs) have been intensively investigated over the past 30 years before the rise of photovoltaic 3D hybrid perovskites. Along with the increasing research interest on 2D materials, they have attracted much attention. On the one hand, 2D hybrid perovskites possess much improved photo- and chemical stability over their 3D counterparts. On the other hand, the delicate interplay of multiple atomic bonding forces in the crystal lattice enables them to exhibit extraordinary properties that traditional inorganic 2D materials are unable to show. More importantly, the chemical and structural diversity of 2D HOIPs offers greater opportunities to fine-tune and engineer properties and functionalities compared with their 3D counterparts.