A site-selection multi-element co-doping strategy in three-layered bismuth-based layered perovskite-like structure ferroelectrics leads to large energy storage capability

Abstract

Improving the energy storage density of dielectric capacitors, which are widely used in power electronic devices, is a continuous challenge. In this work, a site-selection multi-element co-doping strategy was used by doping Pr atoms at the A-site and then doping Mn atoms at the B-site in bismuth-based layered perovskite-like structure prototype ferroelectrics Bi4Ti3O12 due to its large polarization and high Curie temperature. On the one hand, the substitution of Bi3+ with Pr3+ at the A-site introduces significant cation disorder, which disrupts the long-range ferroelectric order, consequently leading to a reduction in remnant polarization. On the other hand, the substitution of Ti4+ by Mn4+ at the B-site results in delayed polarization saturation due to the different electronic configurations between d3 Mn4+ and d0 Ti4+. In addition, the leakage current of the thin film exhibits a continuous decrease with doping concentration, which can be attributed to microstructural modifications including reduced grain size and the formation of amorphous regions, consequently leading to an enhanced breakdown field. Finally, a recoverable energy storage density of 42.1 J cm−3 and an efficiency of 69.9% were obtained for the BPT film, and a recoverable energy storage density of 81.8 J cm−3 and an efficiency of 73% were achieved in the BPTM film. The enhanced energy storage density can be attributed to the synergistic effect of co-doping of A- and B-sites on polarization and breakdown. Besides, the doped films have excellent frequency, temperature, and cycling stability. This work provides a guide to substantially enhance dielectric energy storage by a site-selection multi-element co-doping strategy.