High-Temperature Antiferroelectric of Lead Iodide Hybrid Perovskites

Antiferroelectrics, characterized
by the natural polarization-electric
field (P–E) double hysteresis
loops, has been developed as a promising branch for energy storage.
Here, we present the first antiferroelectric in the booming family
of lead iodide hybrid perovskites, (BA)2(EA)2Pb3I10 (1, where BA = n-butylammonium and EA = ethylammonium), which exhibits
one of the highest Curie temperatures (∼363 K) for the majority
of known molecular systems. Strikingly, its high-temperature antiferroelectricity,
triggered by an antipolar alignment of adjacent dipoles, is confirmed
by the characteristic double P–E hysteresis loops, thus enabling remarkable energy storage efficiencies
in the range of 65%–83%. This merit is almost comparable to
those of many inorganic counterparts, suggesting the great potential
of 1 for energy storage. Another fascinating attribute
is that 1 also acts as a room-temperature biaxial ferroelectric
with spontaneous polarization of 5.6 μC·cm–2. As far as we know, this study on the high-temperature antiferroelectric,
along with room-temperature biaxial ferroelectricity, is unprecedented
for the versatile lead iodide hybrid perovskites, which sheds light
on the design of new electric-ordered materials and facilitates their
application of high-performance devices.