High-efficiency dielectric capacitors based on BaTi_0.5Hf_0.5O₃ films

Film dielectric capacitors enabled with large breakdown field strength and high energy density play a key role for compact and integrated power systems. Nevertheless, the energy storage efficiency is always sacrificed as we tried to increase the energy density. This trade-off between energy density and efficiency means significant energy dissipation and thermal effects, which will lead to a deterioration of the reliability and lifetime of the dielectric capacitors. In the present work, we design a crystalline–amorphous structure based on BaTi_0.5Hf_0.5O₃ films, in which the nano-sized crystalline BaTi_0.5Hf_0.5O₃ matrix contributes to a relatively large polarization, while the amorphous phase is beneficial to the enhanced breakdown field strength and lowered polarization–electric field hysteresis. Thus, such structure simultaneously leads to a high energy storage efficiency of 90.6% and a relatively high energy density of 53 J·cm⁻³, as well as excellent antifatigue properties. This work provides a feasible route to realize outstanding energy storage performance in dielectric capacitors. Graphical abstract: [Figure not available: see fulltext.]