Multicolor emission in silica sol-gel materials co-doped with Tb3+ and Eu3+ for near-UV photonic devices

In this work, the luminescence properties of silica materials singly- and doubly-doped with Tb3+ and Eu3+ ions derived by low-temperature sol-gel technique were investigated. The optical properties of prepared samples were evaluated based on photoluminescence excitation (PLE) and emission spectra (PL) as well as luminescence decay analysis. The PL measurements of investigated Tb3+/Eu3+ co-doped systems were conducted using different excitation wavelengths. Prepared sol-gel materials exhibit bright multicolor, wavelength-tunable luminescence under near-UV illumination. Indicated emission is originated from electronic transitions within 4f(6) and 4f(8) manifolds of Eu3+ and Tb3+, respectively. Additionally, based on recorded decay curves, the luminescence lifetimes (tau(m)) for the D-5(0) state of Eu3+ and the D-5(4) level of Tb3+ were also evaluated. Obtained results indicated that co-doping with Tb3+ ions led to prolongation of luminescence lifetime of the D-5(0) state of Eu3+ up to similar to 24% due to Tb3+ -> Eu3+ energy transfer process. The interpretation of obtained results may suggests the potential usage of fabricated Tb3+/Eu3+ co-doped sol-gel materials in optical devices operating under near-UV excitation.