Unprecedented Ferroelectric–Antiferroelectric–Paraelectric Phase Transitions Discovered in an Organic–Inorganic Hybrid Perovskite

As a promising candidate for energy storage capacitors, antiferroelectric (AFE) materials have attracted great concern due to their congenital advantages of large energy storage ability from double polarization versus electric field (P–E) hysteresis characteristics in contrast to ferroelectrics and linear dielectrics. However, antiferroelectricity has only been discovered in inorganic oxides and some hydrogen-bonded molecular systems. In view of the structural diversity and unique physical properties of organic–inorganic hybrid system, it remains a great opportunity to introduce antiferroelectricity into organic–inorganic hybrid perovskites. Here, we report that polarizable antiparallel dipole arrays can be realized in an organic–inorganic hybrid perovskite, (3-pyrrolinium)CdBr3, which not only exhibits an excellent ferroelectric property (with a high spontaneous polarization of 7.0 μC/cm2), but also presents a striking AFE characteristic revealed by clear double P–E hysteresis loops. To the best of our knowledge, it is the first time that such successive ferroelectric–antiferroelectric–paraelectric phase transitions have been discovered in organic–inorganic perovskites. Besides, a giant dielectric constant of 1600 even at high frequency of 1000 kHz and a bulk electrocaloric effect with entropy change of 1.18 J K–1 kg–1 under 7.41 kV/cm are also observed during the phase transition. Apparently, the combined striking AFE characteristic and giant dielectric constant make (3-pyrrolinium)CdBr3 a promising candidate for next generation high-energy-storage capacitors.