Enhancement of energy storage density achieved in Bi-modified SrTiO3 thin films by introducing a TiO2 layer

Dielectric Sr0.88Bi0.08TiO3 (SBT) and Sr0.88Bi0.08TiO3/TiO2 (SBT/TiO) thin films were fabricated via sol-gel and spin-coating method with various annealing temperatures ranging from 450 degrees C to 600 degrees C. The XRD results show that the SBT thin films can crystallize at a lower temperature due to introducing a TiO2 layer. The SEM results reveal that the annealing temperatures have impact on the surface morphology. Moreover, the absorbed water was closely related with annealing temperature. When the temperature rises to 550 degrees C, the reduction of absorbed water limited the formation of the aluminum oxide insulating layer between the Al electrode and the thin films, decreasing the breakdown strength. The finite element simulation showed the effect of the aluminum oxide insulating layer on enhancing the dielectric breakdown strength of the samples. The excellent energy storage performance was achieved in the SBT/TiO films annealed at 450 degrees C with the recoverable energy storage density of 31.3 J/cm(3) and ultrahigh efficiency of 96%, which is almost 2 times that of SBT thin films (12.4 J/cm(3)). Additionally, the samples possess a high dielectric constant (107) and a low dissipation factor (similar to 0.035) at 1 MHz. Therefore, This work could provide a novel and simple way to develop high-performance dielectric capacitor devices. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Dielectric Sr0.88Bi0.08TiO3 (SBT) and Sr0.88Bi0.08TiO3/TiO2 (SBT/TiO) thin films were fabricated through sol-gel and spin-coating methods at different annealing temperatures. The results show that adding a TiO2 layer allows SBT thin films to crystallize at lower temperatures, affecting surface morphology. Absorbed water content is reduced at higher temperatures, impacting breakdown strength, while finite element simulation highlights the role of an aluminum oxide insulating layer in enhancing dielectric breakdown strength. SBT/TiO films annealed at 450°C exhibit superior energy storage performance compared to SBT thin films, suggesting a promising strategy for developing high-performance dielectric capacitor devices.