Optimization of energy storage performance in (La, Mn) co-doped SrTiO3 thin film through grain engineering

Lead-free dielectric capacitors have become a topic of great interest in response to the ever-increasing demand for high-performance and environmentally friend energy devices. As SrTiO 3 (STO) is paraelectrics, the extremely low spontaneous polarization limits the development of its energy storage applications. In this paper, the microstructure and ferroelectric properties of STO are adjusted by grain engineering to expand its application in energy storage. STO, SrTi 1-x Mn x O 3 (STM x , x = 0.01 and 0.04) and Sr 1-y La y TiMn 0.01 O 3 (SL y TM 0.01 , y = 0.01, 0.02, 0.03 and 0.04) thin films are synthesized by the sol-gel method and thoroughly investigated on the effects of A-site (La) and B-site (Mn) co-doping effects on the crystalline phase, morphology, dielectric, ferroelectric and energy storage characteristics of STO thin film. The results indicate that the SL 0.01 TM 0.01 thin film exhibits a breakdown electric field of 3666.2 kV/cm. The SL 0.02 M 0.01 thin film exhibits excellent frequency stability and low dielectric loss (<0.01) with an energy storage density of 29.5 J/cm 3 and an efficiency of 83.7 % at 2600 kV/cm. Moreover, the sample shows good frequency stability (400–2800 Hz) and thermal stability (20−140 °C). These findings indicate the potential of (Mn, La) co-doped SrTiO 3 thin film for dielectric capacitor energy storage field applications.