Manganese‐Doping‐Induced Quantum Confinement within Host Perovskite Nanocrystals through Ruddlesden–Popper Defects

The concept of doping Mn(2+) ions into II–VI semiconductor nanocrystals (NCs) was recently extended to perovskite NCs. To date, most studies on Mn(2+) doped NCs focus on enhancing the emission related to the Mn(2+) dopant via an energy transfer mechanism. Herein, we found that the doping of Mn(2+) ions into CsPbCl(3) NCs not only results in a Mn(2+)‐related orange emission, but also strongly influences the excitonic properties of the host NCs. We observe for the first time that Mn(2+) 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(2+) ions improves the size distribution of the NCs, which results in a prominent excitonic peak. However, with increasing the Mn(2+) 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.