  Ferroelectric materials with up-conversion luminescence (UCL) properties have
potential opto-electric applications for display and sensing etc. Here, we
demonstrate strong green UCL and enhanced electrical properties in Er3+-doped
Na0.5Bi0.5TiO3 thin films. The thin films are prepared via using a modified
chemical solution deposition method. These thin films are phase-pure and
crystallized in perovskite structure. The largest remnant polarization (Pr) and
highest dielectric constant are obtained from Na0.5Bi0.49Er0.01TiO3 thin films,
and their values are 0.22 C/m2 and 1166, respectively. Meanwhile, strong green
UCL at 525 nm and 548 nm are observed in Er3+-doped thin films. They are
attributed to 2H11/2 to 4I15/2 and 4S3/2 to 4I15/2 transitions of Er3+ ions.
These thin films have potentials in optoelectrical device applications.
