An effective Fe(II) doping strategy for stable and highly photoluminescent CsPbBrI2 nanocrystals

Doping metal ions into a perovskite lattice is an effective strategy for tailoring the intrinsic properties of perovskite nanocrystals (NCs). Herein, strong red-emitting and highly ambient and light stable Fe2+-doped CsPbBrI2 NCs with a maximum photoluminescence quantum yield (PLQY) of 92.1% were obtained. Systematic investigation of Fe2+ doping on the stability and the luminescence performance of CsPbBrI2 NCs was performed. Owing to the smaller ionic size compared to Pb2+, Fe2+ induced the lattice contraction and shortened the bond length of Pb–X, which suppressed the distortion of [PbX6]4− octahedra, thus improving the stability of CsPbBrI2 NCs. The champion sample could maintain up to 86% emission under the ambient conditions for 5 weeks. Besides, the incorporation of Fe2+ suppressed the formation of halide vacancies and optimized the relaxation process of CsPbBrI2, thereby contributing to the enhancement of PLQY. This facile Fe2+ doping method provides an effective strategy to synthesize stable and highly photoluminescent red perovskite materials.