In the past years, light-emitting devices (LEDs) based on erbium (Er)-doped insulators or wide-bandgap semiconductors have received intensive attention because the intra-4f transition ( ⁴I _13/2→ ⁴I _15/2) of Er ³⁺ions at ～ 1540 nm has potential applications in the optical interconnection for silicon-based circuits. The LEDs with rare-earth (RE)-doped SiO _x( x≤ 2) or SiN _x( x≤ 4/3) films have been well investigated as the silicon-compatible emitters. However, they suffer difficulty in injecting current and easing fatigue. In this context, the LEDs with RE-doped oxide semiconductors have been extensively investigated out of research interest in recent years. Among the oxide semiconductors, TiO ₂is a desirable host for RE-doping because it is transparent for visible and infrared light, and cost-effective, and has considerably high RE solubility. In our previous work (Zhu C, Lü C Y, Gao Z F, Wang C X, Li D S, Ma X Y, Yang D R 2015 Appl. Phys. Lett. 107131103), we have realized erbium (Er)-related visible and near-infrared (～ 1540 nm) electroluminescence (EL) from the LED with a structure of ITO/TiO ₂:Er/SiO ₂/n ⁺-Si, in which TiO ₂:Er refers to the Er-doped TiO ₂film as the light-emitting layer. In this work, we co-dope ytterbium (Yb) into the TiO ₂:Er film in the aforementioned LED to significantly enhance the Er-related visible and near-infrared EL. It is revealed that a certain amount of Yb co-doping enables the TiO ₂:Er film to transform its crystal phase from anatase to rutile. Such a phase transformation reduces the symmetry of crystal field surrounding the Er ³⁺ions incorporated into the TiO ₂host. Moreover, the substitution of over-sized Yb ³⁺ions for Ti ⁴⁺ions in the TiO ₂host leads to the distortion of the crystal field around the Er ³⁺ions. The aforementioned symmetry-reduction and distortion of the crystal field increase the probabilities of the intra-4f transitions of Er ³⁺ions. Due to the aforementioned reason, the Yb co-doping into the TiO ₂:Er film remarkably enhances the EL from the corresponding LED. It is believed that the strategy of Yb-codoping can be adopted to enhance the EL from the LEDs with other RE-doped TiO ₂films.