Significance of Ni Doping in CsPbX3 Nanocrystals via Postsynthesis Cation-Anion Coexchange

In this work, a novel dynamic cation exchange driven by an anion exchange procedure was used for incorporating Ni dopants into the Pb-site of CsPbBr₃ and CsPb(BrCl)₃ perovskite nanocrystals under ambient conditions. Ni doping has significant merits in tuning the optical properties and introducing magnetic functionality. Moreover, Ni doping provides chemical and photochemical stability to a host phase with consequent importance for solar cell applications. The present work describes a thorough investigation of the Ni incorporation mechanism via structural, compositional, and optical characterizations. The results indicated the essential need for cation-anion coexchange, enabling control of the Ni concentration from <1% to about 12%, with uniform distribution across the host lattice. In addition, the doping improved the photoluminescence quantum yields beyond those of the undoped nanocrystals. The observations were corroborated by the density functional theory (DFT), confirming that the incorporation of Ni is energetically favorable.