Effect of Ag nanoparticles growth on the downconversion emissions of erbium in TeO2-Nb2O5-ZnO-Ag2O glass system

TeO2 based glasses containing silver and doped by erbium ions were synthesized via the melting-quenching process. These glasses were subjected to an annealing treatment during different times above the glass tem-perature transition Tg. Transmission electron microscope (TEM) and X-ray diffraction (XRD) revealed the growth of silver nanoparticles inside the tellurite glass host. Raman analysis was conducted to examine the structural characteristics of the glass systems and to detect any effects brought by the heat-treatment. Using 488 nm excitation, the down-conversion luminescence properties of erbium ions were studied and the processes impli-cated in the near-infrared emission (NIR) at 1530 nm were analysed. It was found that the heat-treatment enhanced the Raman signal and the downconversion emission of Er3+ ions. Especially, annealing for long time (at 440 degrees C) resulted in an improvement of NIR emission intensity to the detriment of green emissions, as well as a considerable enhancement in the quantum yield and measured lifetime of the 1530 nm emission. The results indicate that the proposed glasses could be appropriate down-converting materials for improving the spectral response of some photovoltaic (PV) cells having bandgaps in the range 0.7-0.9eV.