Power-Dependent Hybrid Photoluminescence Emission of Ag Nanowires on an Ag Film

Nobel metal nanostructures, such as silver nanowires (AgNWs), have attracted considerable attention due to their extraordinary capability to manipulate light-matter interactions at the nanoscale and promising applications in various areas. However, the underlying mechanism of photoluminescence (PL) emission of AgNWs on a metal film (NWoF structure) is still under debate. Here, we provided an exhaustive investigation of the PL behaviors of AgNWs by performing substrate-dependent PL imaging, as well as power-dependent PL spectra and photoblinking dynamics of single AgNWs on an Ag film with Al2O3 as a dielectric space. The similar PL spectra among suspension AgNWs, crossed AgNWs on Si/SiO2 substrate, and single AgNWs on the Ag films confirmed that PL emission from NWoF structures is originated from AgNWs, rather than Ag films. Three PL peaks from AgNWs on the Ag film have been attributed to the photoactive Ag nanoclusters, the radiative recombination of intraband transitions, and the possible gap plasmonic modes, respectively, which have been evidenced by analysis of power-dependent PL spectra and photoblinking dynamics. These findings may provide new insight into the PL mechanisms of AgNWs and offer inspiration to develop customized plasmonic applications.