Cumulative Impact of Ligands on the Optical Properties of Ag₂₁ Nanoclusters: Insights into the Relaxation Dynamics

Abstract

Considerable progress has been made in the synthesis and structural characterization of metal nanoclusters (NCs), but the ligandinduced electron−phonon coupling-dependent ultrafast carrier dynamics is still in its infancy. Here, we have employed a new synthetic strategy for the preparation of Ag 21 (CHT) 5 (DPPB) NCs with 7% photoluminescence (PL) quantum yield (QY). Such high QY is discovered to evolve from the intracluster interactions between 1,4-bis(diphenylphosphino)butane (DPPB) and cyclohexanethiol (CHT) ligands. These Ag 21 NCs exhibit significantly strong electron−phonon interactions (average phonon energy of ∼76 meV), originating from the combining effect of the metal core and surface of the NCs. Global analysis of the transient absorption kinetic data reveals that Ag 21 (CHT) 5 (DPPB) NCs involve a three-state relaxation process�core-state relaxation (8.65 ps), core to shell relaxation (617.8 ps), and slower relaxation to the ground state (>1 ns). This work reports new atomically precise Ag NCs with high PL quantum yield, providing a model for the excited-state relaxation dynamics.

Recent advances in synthesis and properties of silver nanoclusters

“…80 Intracluster interactions among thiolate and diphosphine ligands of Ag 21 clusters have been shown to enhance the PLQY up to 7%. 81…”