Ni2+-doped CsPbI3 perovskite nanocrystals with near-unity photoluminescence quantum yield and superior structure stability for red light-emitting devices

Room temperature phase instability of cubic CsPbI 3 perovskite nanocrystals is one of the notorious limitations for practical applications in optoelectronic fields. Herein, the incorporation of Ni 2+ ions into CsPbI 3 lattice was successfully achieved by a modified hot-injection method using nickel acetate as doping precursor. The as-prepared Ni 2+ (3.3 mol%): CsPbI 3 nanocrystals exhibited an improved, near-unity (95%~100%) photoluminescence quantum yield owing to the enhanced radiative decay rate and the decreased non-radiative decay rate. Additionally, Ni-doping was demonstrated to stabilize CsPbI 3 lattice and the Ni 2+ : CsPbI 3 film and colloidal solution can retain their red luminescence up to 15 days and 7 months in atmosphere, respectively. First-principle calculations verified that the significantly improved optical performance and stability of Ni 2+ : CsPbI 3 nanocrystals arose primarily from the increased formation energy due to the successful doping of Ni 2+ in CsPbI 3 . Benefiting from such an effective doping strategy, the as-prepared Ni 2+ -doped CsPbI 3 perovskite nanocrystals can function well as efficient red-light emitter toward the fabrication of high-performance perovskite LED with a peak external quantum efficiency of ~7%.