High Br Content CsPb(Cl Br) Perovskite Nanocrystals with Strong Mn Emission through Diverse Cation/Anion Exchange Engineering.

The unification of tunable band edge (BE) emission and strong Mn doping luminescence in all-inorganic cesium lead halide perovskite nanocrystals (NCs) CsPbX (X = Cl and Br) is of fundamental importance in fine tuning their optical properties. Herein, we demonstrate that benefiting from the differentiation of the cation/anion exchange rate, ZnBr and preformed CsPbCl: xMn NCs can be used to obtain high Br content Cs(PbZn )(Cl Br): xMn perovskite NCs with strong Mn emission, and the Mn substitution ratio can reach about 22%. More specifically, the fast anion exchange could be realized by the soluble halide precursors, leading to anion exchange within a few seconds as observed from the strong BE emission evolution, whereas the cation exchange instead generally required at least a few hours; moreover, their exchange mechanism and dynamics process have been evaluated. The Mn emission intensity could be further varied by controlling the replacement of Mn by Zn with prolonged ion exchange reaction time. White light emission of the doped perovskite NCs via this cation/anion synergistic exchange strategy has been realized, which was also successfully demonstrated in a prototype white light-emitting diode (LED) device based on a commercially available 365 nm LED chip.