Luminescent Properties of Eu 3+-Doped Hybrid SiO₂-PMMA Material for Photonic Applications

Micromachines (Basel). 2018 Sep 1;9(9):441. doi: 10.3390/mi9090441.

Abstract

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→⁷Fi, 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.

Keywords: europium; hybrid materials; luminescence; microdevices.