Getting a charge out of hybrid perovskites.

Until now, metal–organic hybrid perovskites (MOHPs) have been known mainly for their remarkable electronic (1–3) and optical properties, generating immense interest worldwide and offering the potential to realize the goal of highly efficient and inexpensive solar power conversion (1, 4, 5) as well as a wide variety of other optoelectronic applications (6, 7). In an exciting development that promises to electrify the already hot field of MOHPs, Rakita et al. (8) for the first time demonstrate unambiguously that a tetragonal trihalide perovskite is ferroelectric, associated with a spontaneous and reconfigurable ion ordering. This opens the door for the realization of multiple functionalities derived from ferroelectric behavior and a wide range of devices that can be enabled by the juxtaposition of ferroelectricity and the excellent semiconducting and electronic structure properties of MOHPs.