Mn doping as a simple strategy for improving energy storage in BaBi4Ti4O15 thin films

To obtain high energy storage density in ferroelectric films, polarization and breakdown field E-b are two crucial factors. The inversely coupled relationship between polarization and E-b is commonly observed and it remains a challenge to realize high E-b without deteriorating polarization. Selecting a suitable element doping should largely enhance the E-b since of the optimization of microstructures as well as the decrease in defects, meanwhile the doping should induce extra polarization contribution from lattice distortion. In this work, we reported that E-b can be largely enhanced via Mn doping in BaBi4Ti4O15 thin films due to grain refining, densification, and oxygen vacancy reduction. Interestingly, the polarization is not deteriorated since of the Mn doping effect induced extra polarization from the lattice distortion. Consequently, an ultrahigh energy storage density of 96 J/cm(3) with a high efficiency of 76.6% was achieved in BaBi4Ti3.95Mn0.05O15 thin films with excellent stability and reliability. This work will provide a simple and effective route to improve the energy storage in dielectric capacitors.