The Electronic Relaxation Dynamics and Electron-Vibration Coupling of Assembled Metal Nanoclusters

Abstract

The electronic relaxation dynamics and electron–phonon vibration of assembled metal nanoclusters (MNCs) are important to understand for photonic applications. We employed an effective approach to enhance the emission intensity via self-assembly and examined electron-vibration coupling via photoluminescence (PL) measurements with varying temperatures. A Cu16(TBBT)12(DPPE)2 nanocluster (Cu NCs) capped with 4-tert-butylbenzene thiol (TBBT) and 1,2-bis(diphenylphosphino)ethane (DPPE) has been synthesized via a bottom-up approach. Assembly formation increases PL intensity by 45 times relative to isolated Cu NCs at RT, yielding an absolute QY of 5.7%. Temperature-dependent PL and time-resolved decay were measured for isolated Cu NCs and their assembly from 80 to 300 K. The vibrational energy was determined to increase from 31.37 to 40.28 meV, and the electron-vibration coupling constants decreased from 3.9 to 2.18 for Cu NCs and the assembled structure, respectively. The high vibrational energy indicates that the Cu(1)-S surface motif is involved rather than the Cu core. Eventually, the electron-vibration coupling constants decreased from 3.9 to 2.18 for Cu nanoclusters and the assembled structure, respectively.