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 mu C/cm(2)), 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 741 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.