Fluorescence or Phosphorescence? The Metallic Composition of the Nanocluster Kernel Does Matter

It remains challenging to manipulate the nature of photoluminescence as either fluorescence or phosphorescence for a correlated cluster series. In this work, two correlated nanoclusters, Au₅ Ag₁₁ (SR)₈ (DPPOE)₂ and Pt₁ Ag₁₆ (SR)₈ (DPPOE)₂ with comparable structure features, were synthesized and structurally determined. These two alloy nanoclusters displayed distinct photoluminescent nature-the Au₅ Ag₁₁ nanocluster is fluorescent, whereas the Pt₁ Ag₁₆ nanocluster is phosphorescent. The decay processes of the excited electrons in these two nanoclusters have been explicitly mapped out by both experimental and theoretical approaches, disclosing the mechanisms of their fluorescence and phosphorescence. Specifically, the metallic compositions of the nanocluster kernels mattered in determining their photoluminescent nature. The results herein provide an intriguing nanomodel that enables us to grasp the origin of photoluminescence at the atomic level, which further paves the way for fabricating novel nanoclusters or cluster-based nanomaterials with customized photophysical properties.