Strong red emission in lead-free ferroelectric Pr3+-doped Na0.5Bi0.5TiO3 thin films without the need of charge compensation

We report on the strong red emission properties of lead-free perovskite ferroelectric Pr3+-doped Na0.5Bi0.5TiO3 (NBT: Pr3+) thin films without the need of charge compensation. The thin films were prepared by a chemical solution deposition method combined with a rapid thermal annealing process at 700 °C. The strong red emission assigned to prominent 1D2→3H4 transitions of the Pr3+ ions at 611 nm was observed together with a very weak blue-green emission, indicating the commercial use potential of the lead-free perovskite NBT: Pr3+ ferroelectric thin film materials. The energy transfer from the host lattice to the Pr3+ ions should be responsible for the strong red emission, while the weak blue-green emission might be due to the quenching of 3P0 induced by a low-lying Pr3+/Ti4+↔Pr4+/Ti3+ intervalence charge transfer state. The lead-free NBT: Pr3+ thin films also exhibit good ferroelectric and dielectric properties.