Studying the structural and optical properties of Er³⁺ doped TiO₂ powders synthesized by the sol-gel process

Abstract

A series of TiO2:xEr powders (with x from 0% to 1% at.) was synthesised by a simple sol–gel process. The structural and optical properties were studied in detail using diffusion reflection spectroscopy, x-ray diffraction, Raman spectroscopy, high-resolution transmission electron microscopy, and energy-dispersive x-ray spectroscopy, to systematically determine the band edge, morphology, and structural properties of both undoped and Er-doped TiO2 samples. Notably, the introduction of Er dopants in the TiO2 matrix results in a decrease in both the band gap and crystallite size as well as the anatase phase of host matrix TiO2 remained in the anatase phase even at 800 °C. The heat treatment temperature has an insignificant effect on the green/red emission ratio of Er ions. However, this ratio strongly depends on excitation wavelengths corresponding to down-conversion and up-conversion processes. The colour emission of TiO2:Er is easily tunable from green to yellow under different excitations. The emission mechanism of TiO2:Er is proposed based on spectroscopy techniques. These findings reveal that the TiO2:Er powders are potential materials for labelling and photocatalyst applications.

A light emitting device with TiO2:Er3+/ZnO heterostructure for enhanced near-infrared electroluminescence

“…In this study, under a 325 nm laser excitation, the PL peaks originates from the energy transfer (ET) from TiO 2 to Er 3+ ions, leading to the characteristic emission peaks in Er 3+ ions, which has been discussed in our previous work based on the results of photoluminescence excitation spectra [16]. The splitting peaks observed in PL spectra can be attributed to Stark splitting of the energy levels, which is caused by the special crystalline local environment around Er 3+ ions in the TiO 2 host [22,25]. The EL process is a little bit complicated.…”