Optical properties of Cu nanocomposite glass obtained via CuO and SnO co-doping

Prospective applications of plasmonic nanocomposites in photonic and optoelectronic devices demand innovative means of material syntheses, as well as a comprehensive understanding of the influence of material composition and processing on resulting properties. In this work, it is shown that a phosphate glass matrix prepared with stoichiometric amounts of CuO and SnO dopants by the melting technique may well be effective for the precipitation of Cu nanoparticles (NPs) upon heat treatment (HT). Optical absorption and photoluminescence (PL) spectroscopy, including emission decay dynamics, are employed in the characterization of the melt-quenched glass, and for investigating the influence of HT on material optical properties. The as-prepared material appeared highly luminescent; the data suggests contributions from both twofold-coordinated tin centers and Cu⁺ ions to light emission. The PL depends strongly on excitation wavelength; e.g. excitation at 260 nm shows a blue-white emission for which a significant contribution from tin is indicated, whereas excitation at 360 nm produces an orange emission in association with Cu⁺ ions. Thermal processing results in the chemical reduction of ionic copper via Sn²⁺ ultimately producing Cu NPs in the matrix, as evidenced by the appearance of the surface plasmon resonance around 574 nm. As a result, Cu⁺ PL decreases and the emission band shows a dip due to reabsorption by Cu NPs in resonance.