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Bi-doped Y2O3 phosphor thin films were fabricated by RF magnetron sputtering and their photoluminescence (PL) emission characteristics were systematically investigated depending on substrate temperature, film thickness, and Bi3 + ion concentration. Visible PL emission via 3P1➔1S0 transition of Bi3 + ions could be observed by ultraviolet light excitation and its intensity was increased with increasing the substrate temperature and the film thickness. This is due to enhancement of the film crystallinity with increasing substrate temperature and film thickness and due to interaction volume increase with increasing the film thickness. However, PL intensity had the maximum value with Bi3 + ion concentration of 1.09 at.% owing to concentration quenching effect. These films showed high transmittance of above 95% in the visible and near-infrared region and had refractive index of 1.87 ~ 1.97 depending on the wavelength. These results show the potential of Bi-doped Y2O3 phosphor thin films not only as a spectrum converting layer but also as an antireflective coating layer in crystalline Si solar cells, considering that refractive index of the Bi-doped Y2O3 film is nearly similar to that of silicon nitride film.

We report the deposition of tungsten oxide (WO3) thin films on fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO) glass substrates by using a room-temperature deposition system based on low-vacuum air-spray for the fabrication of inorganic electrochromic windows. The structure of the WO3 films was characterized using X-ray diffraction, and the surface morphology and film thickness were investigated using scanning electron microscopy and atomic force microscopy. The color of the prepared WO3 films changed from slight yellow to dark blue under applied voltages, demonstrating electrochromism. The WO3 film coated FTO glass exhibited a large electrochromic contrast of up to 50% at a wavelength of 800 nm. The electrochemical properties of the films were examined using cyclic voltammetry and chronocoulometry.