Mechanical Strain-Modulated Multifunctional Pr-Doped BaTiO₃Thin Film for Luminescence Sensing and Piezoelectric Energy-Harvesting Applications

Piezoelectric materials with tunable photoluminescence have gained widespread attention for their application in optical communications and optoelectronic sensing devices. This has provided new opportunities to explore the possibility of developing flexible piezoelectric devices with both piezoelectricity and photoluminescence for multifunctional applications. In this study, we prepared a crystalline Pr-doped perovskite BaTiO3 (BPTO) film on a flexible mica substrate using the radio-frequency (RF) sputtering technique. The photoluminescence intensity remarkably increased by about 210% when external mechanical stress was applied to the film. This remarkable increase in photoluminescence is attributed to lattice distortion and a decrease in crystal symmetry. The BPTO film also exhibited reversible and high-endurance behavior even after 103 fatigue bending cycles. Moreover, the BPTO film was utilized as a piezoelectric nanogenerator device, which demonstrated a maximum output voltage of about 2.68 V when external stress was applied through palm tapping. The nanogenerator device yielded an instantaneous output power of 1.80 μW with an external load resistance of 0.8 MΩ. These versatile and robust properties of the BPTO film demonstrate its potential for future development of lead-free self-powered optoelectronic sensing applications, such as artificial intelligence and biomedical devices.