Effective Sensitization of Eu3+ with Ce3+ by suppression of metal-to-metal charge transfer in composite structured TbF3 fluoride particles

Abstract

Sensitization of Eu3+ with Ce3+ suffers from low emission intensities due to the well-known metal-to-metal charge transfer (MMCT), which effectively quenches the luminescence process. By separating sensitizer and activator spatially, reduced MMCT quenching and thus higher luminescence intensities can be expected. We chose TbF3 as host material, since it is well-known that Tb3+ acts as a mediator in the energy transfer (ET) between Ce3+ and Eu3+. Respective phosphor particles were prepared via precipitation synthesis. X-ray powder diffraction was used to determine the phase purity of the synthesized samples. Emission spectra, excitation spectra and diffuse reflectance spectra were measured to record the photoluminescence properties. Fluorescence lifetime measurements were performed to contrast the decay behavior between the co-doped and the composite approach. Especially by comparison of the emission spectra between the composite particles and the single co-doped phosphor particles it could be demonstrated that the composite approach significantly increases the luminescence intensities due to the spatial separation of Ce3+ and Eu3+.