查看文章

The observation of low-energy edge photoluminescence and its beneficial effect on the solar cell efficiency of Ruddlesden–Popper perovskites has unleashed an intensive research effort to reveal its origin. This effort, however, has been met with more challenges as the underlying material structure has still not been identified; new modelings and observations also do not seem to converge. Using two-dimensional (2D) (BA)₂(MA)₂Pb₃Br₁₀ as an example, we show that three-dimensional (3D) MAPbBr₃ is formed due to the loss of BA on the edge. This self-formed MAPbBr₃ can explain the reported edge emission under various conditions, while the reported intriguing optoelectronic properties such as fast exciton trapping from the interior 2D perovskite, rapid exciton dissociation, and long carrier lifetime can be understood via the self-formed 2D/3D lateral perovskite heterostructure. The 3D perovskite is identified by …