Flexible Na0.5Bi0.5(Ti,Fe)O3–BiFeO3–SrTiO3 solid-solution thin film with high polarization linearity and stability for dielectric energy storage via artificial aging process

Flexible thin-film dielectric capacitors have attracted significant attention among researchers under the current trend of integration and portability in electronic devices. In this work, lead-free relaxor ferroelectric 0.85Na0.5Bi0.5(Ti0.97Fe0.03)O3- 0.10BiFeO3-0.05SrTiO3 (NBFT-BFO-STO) solid-solution thin film is synthesized via sol-gel method onto Pt/Mica to obtain NBFT-BFO-STO dielectric capacitor. Artificial aging process is taken for modulating polarization behavior via defect engineering. Higher polarization linearity is noted, reflected by the increased discrepancy in maximum polarization and remanent polarization (Pm–Pr), higher breakdown strength (EBD) and delayed saturation polarization (ΔP/Pm). Accordingly, the highest values of Wrec and η, reaching 23.61 J/cm3 and 75.48% respectively, are obtained at 20 kHz, which are approximately raised by 59.0% and 26.0%, respectively, compared with the fresh state. Excellent thermal stability and anti-fatigue characteristics are obtained with minimal changes of <1.15%, <1.18%, <0.25% for Wrec, W and η, respectively in the range of 50–150 °C and <2.05%, <2.14%, <1.06%, respectively after 108 switching cycles. The interaction mechanisms for artificial aging process on the polarization response are explored based on Rayleigh Law and Finite-element simulation for exploring electric flux density and Von Mises stress. These findings provide a new route to modulate polarization behavior of NBT-based thin film for dielectric energy storage application.