A semiconducting molecular ferroelectric with a bandgap much lower than that of BiFeO3

Ferroelectrics have been attracting increasing attention as good candidates for multifunctional materials because of their fascinating properties. However, their large bandgap has been a roadblock limiting their application in optoelectronics and photovoltaics, among other applications. Hybrid ferroelectrics have the potential to combine the advantages of both molecular materials and ferroelectrics. In this context, we designed a hybrid ferroelectric: (2-(ammoniomethyl)pyridinium)SbI5. It shows an above-room-temperature Curie temperature (Tc=360 K), a large spontaneous polarization (Ps=4 μC cm−2) and a small bandgap (2.03 eV) that is much smaller than the recently reported 2.7–3.65 eV for the lead-halide perovskite ferroelectrics. The implementation of ferroelectricity in hybrid semiconducting materials may be a feasible way to realize high-performance ferroelectric optoelectronic and photovoltaic devices. NPG Asia Materials (2017) 9, e342; doi:10.1038/am.2016.193; published online 20 January 2017