Tailoring La doping concentration for superior ferroelectric and energy storage performance in Bi₂WO₆ thin films

Bi-layered perovskite ferroelectric thin films like Bi₂WO₆ (BWO) typically suffer from low remanent polarization, limiting their application in non-volatile memory. However, their excellent leakage current and fatigue resistance make them promising candidates for energy storage. This study uniquely investigates the impact of La doping on the ferroelectric and energy storage properties of BWO thin films, with La concentrations ranging from 0 to 12 mol%. The BWO thin films, deposited on (200) Pt/TiO₂/SiO₂/Si substrates, displayed mixed a- and c-oriented crystallinity, with optimal improvements at 9 mol% La. This enhanced crystallinity, coupled with the layered perovskite structure, led to superior leakage current characteristics and significant improvements in remanent and saturation polarizations in ferroelectric properties. Notably, the 9 mol% La-doped BWO thin films achieved the highest energy storage density of approximately 91.8 J/cm³ and an efficiency of about 68.6 %, demonstrating their potential for advanced energy storage technologies.