Color-tunable upconversion luminescence of Yb ³⁺, Er³⁺, and Tm³⁺ tri-doped ferroelectric BaTiO₃ materials

Abstract

Tunable upconversion (UC) multicolor luminescence is observed from Yb³⁺, Er³⁺, and Tm³⁺ tri-doped ferroelectric BaTiO₃ (BTO) materials. By control of dopant concentrations, the lanthanide-doped BTO powders are capable of generating various UC spectra and color tunability. A white-light emission is achieved through an optimal design. Strong UC luminescence is also observed in the lanthanide-doped BTO thin-films grown on Pt/TiO₂/SiO₂/Si substrate, which can retain well-defined hysteresis loops with a remnant polarization (2Pr) of 17.8 μC/cm² . These findings open the possibility of lanthanide-doped BTO as multifunctional materials, in which both luminescent and ferroelectric properties co-exist.