Perovskite Ferroelectrics Go Metal Free

Ferroelectric materials, which have spontaneous electric polarization that can be switched with an external electric field, have applications as capacitors, sensors, and data-storage devices ( 1 ). Since the discovery of high-performance BaTiO3 and LiNbO3, ferroelectric perovskite oxides have dominated industrial applications ( 2 ). However, these ceramics are expensive to produce as high-quality thin films, and they often contain heavy metals such as Pb2+, which raises health and environmental concerns. Replacing heavy metals with organic components in the perovskite lattice was considered an alternative ( 3 ), but hybrid organic–inorganic perovskites have not shown comparable ferroelectricity and stability ( 4 ). On page 151 of this issue, Ye et al. ( 5 ) report metal-free perovskites that can compete with ferroelectric oxides (see the figure).