Self-assembled zinc oxide (ZnO) and indium-doping zinc oxide (ZnO:In) nanorod thin films were synthesized on quartz substrates without catalyst in aqueous solution by sol-gel method. The samples were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), Raman-scattering spectroscopy, room-temperature photoluminescence (PL) spectra, and temperature-dependent PL spectra measurements. XRD and Raman spectra illustrated that there were no single In2O3 phase in ZnO lattice after indium doping. The PL spectra of ZnO showed a strong UV emission band located at 394 nm and a very weak visible emission associated with deep-level defects. Indium incorporation induced the shift of optical band gap, quenching of the near-band-edge photoluminescence and enhanced LO mode multiphonon resonant Raman scattering in ZnO crystals at different temperatures. Abnormal temperature dependence of UV emission integrated intensity of ZnO and ZnO:In samples is observed. The local state emission peak of ZnO:In samples at 3.37 eV is observed in low-temperature PL spectra. The near-band-edge emission peak at room temperature was a mixture of excitons and impurity-related transitions for both of two samples.

Cuprous oxide films were successfully electrodeposited onto three different substrates through the reduction of copper lactate in alkaline solution at pH = 10. The substrates include indium tin oxide film coated glass, n-Si wafer with (001) orientation and Au film evaporated onto Si substrate. The substrate effects on the structural and optical properties of the electrodeposited films are investigated by in situ voltammetry, current versus time transient measurement, ex situ x-ray diffraction, scanning electron microscopy, UV-vis transmittance and reflectance and photoluminescence techniques. The results indicate that the choice of substrate can strongly affect the film morphology, structure and optical properties.

Yb/Al/P-co-doped silica glasses with different P/Al ratios were prepared using the sol-gel method combined with high-temperature sintering. The evolution of composition-dependent color centers caused by X-ray irradiation in these glasses was correlated with their structural changes, which are controlled by the P/Al ratio. Nuclear magnetic resonance (NMR) and Raman spectra have been used to characterize the glass network structure, and advanced pulse electron paramagnetic resonance (EPR) has been employed to study the local coordination atomic structures of Yb ions in pristine glasses as a function of the P/Al ratio. Si- (Si-E'), Al- (Al-E', Al-ODC, AlOHC), P- (P, P, POHC), and Yb-related (Yb) color centers in irradiated glasses have been observed and explained by optical absorption and continuous wave-EPR spectroscopies. The formation mechanisms of these centers, the structural models of glasses, and the relationship between them were proposed. Direct evidence confirms that the formation of Yb ions induced by radiation is highly dependent on the coordination environment of Yb ions in glasses. In addition, the glass network structure significantly affects the generation of oxygen hole color centers (AlOHCs/POHCs) caused by radiation. These results are useful in understanding the microstructural origin and the suppression mechanism of the radiodarkening effect by phosphorus co-doping in Yb-doped silica fibers.

Zinc oxide nanocrystalline films with (002) preferred orientation and intense ultravoilet (UV) emission were prepared by oxidation of zinc-implanted silica at 700°C for 2 h in oxygen ambient. A TEM micrograph showed that ZnO nanocrystalline films with a thickness of about 90 nm were formed on the surface of the Zn-implanted silica substrate. The quality and excitonic properties of the ZnO nanocrystalline films were studied through absorption spectra at room temperature and photoluminescence (PL) spectra in the temperature range from 79 to 300 K. At room temperature, a strong free excitonic emission peak at 377 nm with a very weak deep-level emission can be observed. The intensity ratio of the UV near-band-edge emission to the deep-level emission can reach up to 40. The temperature-dependent PL indicated that the UV near-band-edge emission in the temperature range 79–187 K can be attributed to a free exciton (FE), a bound exciton and the one longitudinal-optical phonon replica of FE lines. The presence of a strong emission of FE lines at 79 K suggested that high-purity ZnO nanocrystalline films have been obtained.

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earth (RE) ion-doped materials have been developed as significant gain matrices due to their high photoluminescence quantum yield (PLQY) and multiple-wavelength luminescence. [4,5] Recent decades have witnessed extensive investigations in doping methods and network structure design to obtain more efficient gain materials. [6,7] However, the requirements for high luminescence efficiency and excellent thermodynamic stability of optical materials are always contradictory, greatly restricting their applications in, e.g., high-temperature, high-humidity, and high-power laser pumping environments. Generally, the luminescence efficiency of an optical material is inversely proportional to the multiphonon nonradiative transition probability (W p ) of the intermediate state energy level for RE ions. [8] The luminescence process, especially for the upconversion (UC) process, is normally associated with a large number of intermediate state energy levels. Furthermore, its value (W p ) depends on the maximum phonon energy (ћω) of the elastic structure of condensed matter, and it increases dramatically with increasing ћω (as described in Equations (S1)-(S3) of the Supporting Information). [9] Traditionally, one class of soft material with extremely low ћω values, including fluorides, chalcogenides, and halogenides, has been widely Optical gain materials are of fundamental importance for various applications, such as lasers, lighting, optical communication, microscopy, and spectroscopy. However, the requirements for high luminescence efficiency and excellent thermodynamic stability of materials are always contradictory. As a result, wide applications of optical materials in high-temperature, high-humidity, and high-power laser-irradiated environments are restricted. Here, a facile approach based on phase-separation engineering is proposed to modulate the thermodynamic stability and enhance the luminescence efficiency of optical gain materials. It is shown that the thermodynamic stability and luminescence efficiency of the phase-separated fluorosilicate (FS) gain glass are both enhanced dramatically when the SiO 2 concentration is optimized. Owing to the confinement effect of phase-separation network structure on active ions, the upconversion (UC) luminescence efficiency of the designed glass is 150 times higher than that of traditional FS glasses and even seven times higher than that of ZBLAN (ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF) glass, which is the most commonly used material for UC fiber lasing applications. These intriguing properties of the glass indicate that phase-separation engineering not only provides a powerful solution to conquer the conventional contradiction between thermodynamic stability and luminescence efficiency but also offers significant opportunities for manufacturing a wide range of optical composites with multiple functions.

Yttrium-doped ZnO thin films were deposited on silica glass substrates by the sol–gel method. The structural, electrical and optical properties of yttrium-doped ZnO thin films were investigated systematically and in detail. All the thin films have a preferred (0 0 2) orientation. When compared with the electrical resistivity values of films without annealing treatment, the values of films annealed in the reducing atmosphere were decreased by about three orders of magnitude. The lowest electrical resistivity value was 6.75 × 10−3 Ω cm, which was obtained in the 0.5 at% yttrium-doped ZnO thin film annealed in nitrogen with 5% hydrogen at 500 °C. In room-temperature photoluminescence (PL) spectra, two PL emission peaks are found in the pure ZnO thin film; one is the near-band-edge (NBE) emission at 3.22 eV and the other is a green emission at about 2.38 eV. Nevertheless, the green emission is not found in the PL of the yttrium-doped ZnO thin films. The low-temperature PL spectrum of the undoped ZnO thin film at 83 K is split into well-resolved free and bound excition emission peaks in the ultraviolet region, but the NBE emission of the 5 at% yttrium-doped ZnO thin film at 83 K has only one broad emission peak.

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