Effect of BFO layer position on energy storage properties of STO/BFO thin films

Heterostructure is highly effective to improve the energy storage properties of the thin films for one phase provides large polarization and the other phase maintains high electrical breakdown strength. In this paper, the two-layered and the sandwich-structured BFO/STO thin films were prepared by a sol–gel method, respectively. The influence of BFO layer positions on the electrical properties was investigated. The results show that compared with the two-layered film, the breakdown strength of the sandwiched film is increased by 29.2% to 2.431 MV/cm, the energy storage density is significantly improved. The recoverable energy storage density is 29.5 J/cm 3 with an efficiency of 54.8%. Its dielectric properties at 10 kHz are: the dielectric constant is 111, the dielectric loss is 0.036 and the capacitance-temperature variation from room temperature to 145 °C is lower than 15%. It indicates that the sandwich structure is superior to the two-layered film since the former shows more interface which is beneficial to inhibit electronic tree growth.