Superior energy storage performance in lead-free SrTiO3 films via ion doping and crystalline optimization
SrTiO 3 paraelectric materials exhibit significant potential to be used as lead-free energy storage dielectrics due to their distinctive linear-like polarization behavior. Nonetheless, the application in advanced thin-film capacitors is challenging due to their low polarization strength and structural anomalies, which reduce the breakdown field strength and diminish the energy storage density. This study proposes a synergistic approach that integrates ion doping with the optimization of thermal treatment to enhance the energy storage capabilities of SrTiO 3 thin films. Initially, Mn 2+ doping in SrTiO 3 films mitigates oxygen vacancies and forms Mn 2+ -V O •• defect dipoles, thereby refining the polarization behavior and reducing the leakage current density. Subsequently, the crystalline degree of SrTi 0.99 Mn 0.01 O 3 thin films can be regulated by adjusting the annealing temperature. The optimal breakdown field strength of the resultant SrTi 0.99 Mn 0.01 O 3 films reaches 4681 kV/cm with a 1 mol% Mn 2+ doping level, enhancing the recoverable energy storage density ( W rec ) to 32.17 J/cm 3 . Furthermore, the recoverable energy storage density of SrTi 0.99 Mn 0.01 O 3 films escalates to 36.62 J/cm 3 with an efficiency of 80.28 %, upon reducing the annealing temperature to 625 °C. Moreover, SrTi 0.99 Mn 0.01 O 3 films demonstrate superior thermal stability, frequency stability, and electrical fatigue resistance, underscoring their potential as efficacious materials for film capacitor applications.
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