Enhancing NIR emission of Yb3+ by silver nanoclusters in oxyfluoride glass

Oxyfluoride glass comprising Yb3+ ions and Ag nanoclusters was prepared via a melt-quenching method. The molecule-like Ag clusters (ML-Ag) in the glass displayed broad absorption and emission bands in the ultraviolet (UV) and visible spectral regions, respectively. The luminescence quantum yield (QY) was determined to be higher than 90%. We observed energy transfer from ML-Ag nanoclusters to Yb3+ ions as evidenced by time resolved luminescence spectra, which resulted in a four-fold enhancement in NIR emission of Yb3+. The luminescence enhancement effect described here would be applied to boost the efficiency of solar cells by converting high energy UV photons into NIR photons that better match the absorption of photovoltaic devices.