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

Abstract

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.