Tunable polarization-drived superior energy storage performance in PbZrO₃ thin films

Antiferroelectric PbZrO₃ (AFE PZO) films have great potential to be used as the energy storage dielectrics due to the unique electric field (E)-induced phase transition character. However, the phase transition process always accompanies a polarization (P) hysteresis effect that induces the large energy loss (W_loss) and lowers the breakdown strength (E_BDS), leading to the inferior energy storage density (W_rec) as well as low efficiency. In this work, the synergistic strategies by doping smaller ions of Li⁺–Al³⁺ to substitute Pb²⁺ and lowering the annealing temperature (T) from 700 to 550 ℃ are proposed to change the microstructures and tune the polarization characters of PZO films, except to dramatically improve the energy storage performances. The prepared Pb_(1−x)(Li_0.5Al_0.5)_xZrO₃ (P_(1−x)(L_0.5A_0.5)_xZO) films exhibit ferroelectric (FE)-like rather than AFE character once the doping content of Li⁺–Al³⁺ ions reaches 6 mol%, accompanying a significant improvement of W_rec of 49.09 J/cm³, but the energy storage efficiency (η) is only 47.94% due to the long-correlation of FE domains. Accordingly, the low-temperature annealing is carried out to reduce the crystalline degree and the P loss. P_0.94(L_0.5A_0.5)_0.06ZO films annealed at 550 ℃ deliver a linear-like polarization behavior rather than FE-like behavior annealed at 700 ℃, and the lowered remanent polarization (P_r) as well as improved E_BDS (4814 kV/cm) results in the superior W_rec of 58.7 J/cm³ and efficiency of 79.16%, simultaneously possessing excellent frequency and temperature stability and good electric fatigue tolerance.