Engineers have created 23 all-organic perovskites, one of which offers ferroelectric properties comparable to the widely used inorganic perovskite ferroelectrics BaTiO3 (BTO), a new study reports. The creation of a family of metal-free ferroelectric perovskites that exhibits non-toxic and mechanically flexible properties holds great potential for the next generation of flexible, soft robotic and biomedical devices. Inorganic perovskites like BTO have long been used in applications, ranging from capacitors and sensors to digital data storage and displays. Despite this wide-spread application, however, they are often difficult and expensive to manufacture, and the toxic heavy metals they contain raise significant environmental concerns. As such, the development of organic-based ferroelectrics offers a promising alternative for materials science and technology applications. Driven by the need for energy-efficient, economically inexpensive and environmentally friendly materials, Heng-Yun Ye and colleagues used a molecular design strategy and a large selection of organic cations to design a new family of metal-free ferroelectric perovskites using different combinations of halogens and organic molecules. Their findings demonstrate the viability of high-performance organic ferroelectric perovskites. Of the 23 they synthesized, one - MDABCO-NH4I3 - shows great promise, demonstrating both high spontaneous polarization and ferroelectric properties similar to BTO. Also, beyond the ferroelectric traits, organic perovskites can be synthesized at room temperatures and might be optimized for other properties or made with other organic molecules, the authors report. In a related perspective, Wei Li and Li-jun Ji write, "the marriage between symmetry and hydrogen bonding in these elegant metal-free compounds extends the fields of both perovskites and ferroelectrics to a brand-new realm."
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Journal
Science