Luminescent Properties of Eu3+-Doped Hybrid SiO₂-PMMA Material for Photonic Applications

Hybrid organic-inorganic materials are of great interest for various applications. Here, we report on the synthesis and optical characterization of silica-PMMA samples with different Eu³⁺ molar concentrations. The optical properties of this material make it suitable for photonic applications. The samples were prepared using the sol-gel method, mixing tetraethyl orthosilicate (TEOS) as a silica glass precursor and methyl methacrylate (PMMA) as a polymer component. Europium nitrate pentahydrate was then added in six different molar concentrations (0.0, 0.1, 0.25, 0.5, 0.75, and 1%) to obtain as many different samples of the material. The absorption spectra were obtained applying the Kubelka–Munk formula to the diffuse reflectance spectra of the samples, all in the wavelength range between 240 and 2500 nm. The emission and excitation measurements were made in the visible range. Five bands could be identified in the emission spectra, related to electronic transitions of the ion Eu³⁺ (⁴D₀→⁷F_i, i from 0 to 4). In the excitation spectra, the following bands were detected: ⁷F₀→⁵G₃ (379 nm), ⁷F₀→⁵G₂ (380 nm), ⁷F₀→⁵L₆ (392 nm), ⁷F₀→⁵D₃ (407 nm), ⁷F₀→⁵D₂ (462 nm), and ⁷F₀→⁵D₁ (530 nm). The emission decay times were measured for the different samples and showed an inverse dependence with the Eu³⁺ concentration.

Low temperature photoluminescence characteristics of chemically synthesized indium doped zinc oxide nanostructures

Photoluminescence (PL) emission and excitation (EPL) spectra of un-doped and indium (1%) doped 1D zinc oxide nanostructures are studied at different temperatures. The nanostructures reveal a blue emission band attributed to localized donor states. Indium doping enhances the blue emission. While at low temperatures (< 50 K) PL spectra are dominated by the emission attributed to the recombination of excitons bound to neutral donors (D(0),X), at higher temperatures (>100 K), defect related emissions in the visible range dominate over the excitonic emission. Temperature dependence measurements on the doped sample reveal that (D(0),X) emission energies obey the Varshni's formula with fitting constants alpha = 8.4 +/- 0.3 x 10(-4) eV/K and beta = 650 +/- 40 K. The (D(0),X) emission intensity decays exponentially with temperature.