Tunable luminescence of Tb3+ doped SiO2-TiO2-PDMS hybrid ORMOSILs

Abstract

A new class of SiO2-TiO2-PDMS hybrid ORMOSILs doped with Tb3+ ions were synthesized by non-hydrolytic sol-gel method. The host matrix was developed from both organic and inorganic constituents and when doped with Tb3+ making it suitable for a wide range of optical applications. The X-ray Diffraction (XRD) analysis confirmed the amorphous nature of the samples. The Fourier Transform Infra-Red (FTIR) analysis confirmed the unaltered chemical structure of the samples while the Thermogravimetric (TG) analysis established its thermal stability. The photoluminescence (PL) analysis demonstrated that the Tb3+ doped samples emit blue light along with the characteristic Tb3+ emission when excited at 276 nm. This confirms the existence of a host to Tb3+ energy transfer pathway in the doped sample. These samples were also excited at 352, 369, 378 and 487 nm wavelengths which give similar emission spectra, but with increasing emission intensity. The Judd-Ofelt (JO) intensity parameters and the radiative properties of 5D4→7F3, 4, 5 transitions were also evaluated from the emission spectra. High values obtained for branching ratio and stimulated emission cross-section for the 5D4→7F5 transition make the material suitable for optical amplification. Furthermore, the CIE co-ordinates were calculated and found that color tuning is possible from blue to green region with Tb3+ doped SiO2-TiO2-PDMS ORMOSILs when excited at different wavelengths.