In a recent study, researchers have demonstrated ultra-stable breakdown resistance in the two-dimensional (2D) perovskite antiferroelectric (AFE) (2-MBA)₂CsPb₂Br₇ (2-MBA = 2-methylbutylammonium) by regulating cage-confined atomic displacement.

The material exhibited an electric breakdown field strength of up to ~175 kV/cm and fatigue endurance exceeding 10⁶ cycles, which the researchers attributed to confinement-dependent atomic displacement.

The study, led by Prof. SUN Zhihua and Prof. LUO Junhua from the Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences (CAS), was published in Angewandte Chemie International Edition.

Molecular AFEs, characterized by antiparallel dipole configurations in neighboring lattices, are promising candidates for high-precision digital displacement sensors and energy-storage capacitors. However, their energy-storage applications are limited by low maximum applied field amplitudes and inadequate long-term cycling stability. Designing molecular AFEs with superior breakdown resistance remains challenging because the atomic-level origin of AFE ordering is not yet fully understood.

To address this challenge, the researchers explored cage-confined atomic displacement as a means of regulating motif motion and improving breakdown resistance.

In (2-MBA)₂CsPb₂Br₇, the confinement-dependent atomic displacement resulted in strong antifatigue performance, including an electric breakdown field strength of up to ~175 kV/cm and fatigue endurance exceeding 10⁶ cycles. According to the researchers, these values are among the highest reported for molecular AFEs and even surpass those of purely inorganic oxides.

To investigate the underlying mechanism, the researchers combined energy-barrier calculations with in situ solid-state nuclear magnetic resonance (NMR) spectroscopy to examine the displacive dynamics and their role in breakdown resistance.

In contrast to order-disordering dynamics, the researchers found that the high displacement energy barrier (E_a= 2.91 eV) of cage-confined Cs⁺ cations led to increases in the Curie temperature and forward coercive field.

According to the researchers, the findings provide a feasible principle for designing new electrically ordered materials by precisely manipulating cage-confined dynamics.

Illustration of the research: stable breakdown resistant molecular antiferroelectric triggered by confinement-dependent atomic displacement. (Image by FJIRSM)