A high-temperature double perovskite molecule-based antiferroelectric with excellent anti-breakdown capacity for...

Halide double perovskites have recently emerged as an environmentally green candidate toward electronic and optoelectronic applications owing to their non-toxicity and versatile physical merits, whereas study on high-temperature antiferroelectric (AFE) with excellent anti-breakdown property remains a huge blank in this booming family. Herein, we present the first high-temperature AFE of the lead-free halide double perovskites, (CHMA)₂CsAgBiBr₇ (1, where CHMA⁺ is cyclohexylmethylammonium), by incorporating a flexible organic spacer cation. The typical double P-E hysteresis loops and J-E curves reveal its concrete high-temperature AFE behaviors, giving large polarizations of ~4.2 μC/cm² and a high Curie temperature of 378 K. Such merits are on the highest level of molecular AFE materials. Particularly, the dynamic motional ordering of CHMA⁺ cation contributes to the formation of antipolar alignment and high electric breakdown field strength up to ~205 kV/cm with fatigue endurance over 10⁴ cycles, almost outperforming the vast majority of molecule counterparts. This is the first demonstration of high-temperature AFE properties in the halide double perovskites, which will promote the exploration of new "green" candidates for anti-breakdown energy storage capacitor.