Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics, Southeast University, Nanjing 211189, P.R. China.
Ordered Matter Science Research Center, Nanchang University, Nanchang 330031, P.R. China.
Science. 2018 Jul 13;361(6398):151-155. doi: 10.1126/science.aas9330. Epub 2018 Jul 12.
Inorganic perovskite ferroelectrics are widely used in nonvolatile memory elements, capacitors, and sensors because of their excellent ferroelectric and other properties. Organic ferroelectrics are desirable for their mechanical flexibility, low weight, environmentally friendly processing, and low processing temperatures. Although almost a century has passed since the first ferroelectric, Rochelle salt, was discovered, examples of highly desirable organic perovskite ferroelectrics are lacking. We found a family of metal-free organic perovskite ferroelectrics with the characteristic three-dimensional structure, among which MDABCO (-methyl--diazabicyclo[2.2.2]octonium)-ammonium triiodide has a spontaneous polarization of 22 microcoulombs per square centimeter [close to that of barium titanate (BTO)], a high phase transition temperature of 448 kelvins (above that of BTO), and eight possible polarization directions. These attributes make it attractive for use in flexible devices, soft robotics, biomedical devices, and other applications.
无机钙钛矿铁电体因其优异的铁电和其他性能而被广泛应用于非易失性存储元件、电容器和传感器。有机铁电体因其机械柔韧性、低重量、环保加工和低温加工而受到青睐。尽管自第一个铁电体罗谢尔盐被发现以来已经过去了近一个世纪，但缺乏理想的有机钙钛矿铁电体的例子。我们发现了一类具有特征三维结构的无金属有机钙钛矿铁电体，其中 MDABCO(-甲基--二氮杂二环[2.2.2]辛基)-铵三碘化盐具有 22 微库仑/平方厘米的自发极化[接近钛酸钡 (BTO)]，448 开尔文的高相转变温度（高于 BTO）和 8 个可能的极化方向。这些特性使其成为柔性器件、软机器人、生物医学器件和其他应用的理想选择。
