Improving the UV–Vis light-harvesting of Er3+ using Mn4+ as a sensitizer in Li2TiO3 host

Abstract

A series of Li2TiO3 phosphors, both singly doped with Mn4+ and codoped with Mn4+ and Er3+, were synthesized using a solid-state reaction at high temperatures. In the Li2TiO3:Mn4+/Er3+ system, Mn4+ ions have the ability to absorb UV–Vis photons within the range of 250–600 nm. Subsequently, an energy transfer process occurs between Mn4+ and Er3+ ions, resulting in the emission of near-infrared light originating from Er3+ ions. When excited by light at 365 nm, the Li2TiO3:Mn4+-Er3+ phosphors demonstrated a strong emission in the far-red region, peaking at 682 nm, which corresponds to the 2E→4A2 transition of Mn4+ ions. Additionally, an emission at 1555 nm was observed, associated with the 4I13/2→4I15/2 transition of Er3+ ions. The discussion of the energy transfer from Mn4+ to Er3+ involves the investigation of variations in Er3+ doping and the lifetime values of Mn4+. The absorption of Mn4+ in the UV–Vis range and the subsequent energy transfer to Er3+ ions suggest that these materials could be utilized as spectral converters, enhancing the UV–Vis absorption efficiency of luminescent materials based on Er3+.