Manganese-Doping-Induced Quantum Confinement within Host Perovskite Nanocrystals through Ruddlesden-Popper Defects.

The concept of doping Mn ions into II-VI semiconductor nanocrystals (NCs) was recently extended to perovskite NCs. To date, most studies on Mn doped NCs focus on enhancing the emission related to the Mn dopant via an energy transfer mechanism. Herein, we found that the doping of Mn ions into CsPbCl NCs not only results in a Mn -related orange emission, but also strongly influences the excitonic properties of the host NCs. We observe for the first time that Mn doping leads to the formation of Ruddlesden-Popper (R.P.) defects and thus induces quantum confinement within the host NCs. We find that a slight doping with Mn ions improves the size distribution of the NCs, which results in a prominent excitonic peak. However, with increasing the Mn concentration, the number of R.P. planes increases leading to smaller single-crystal domains. The thus enhanced confinement and crystal inhomogeneity cause a gradual blue shift and broadening of the excitonic transition, respectively.