Rational design of one-dimensional hybrid organic-inorganic perovskites with room-temperature ferroelectricity and strong piezoelectricity

Rational design of ferroelectric/piezoelectric materials is still a big challenge due to our incomplete understanding of the underlying phase-transition mechanisms. Herein, by using first-principles calculations, three prototypes of one-dimensional (1D) hybrid organic-inorganic perovskites (HOIPs) as benchmarks are investigated, from which an approach to measure their ferroelectricity/piezoelectric-related key parameters is developed. Specifically, the ferroelectric transition temperature can be assessed by the computed energies and polarizations, and the piezoelectricity can be evaluated by the change of lattice parameters β during the phase transition. Based on this computational approach, we have examined a series of organic cations to design new 1D HOIPs via conscious chemical modification. Among them, seven potential candidates with excellent ferroelectricity or piezoelectricity are identified, especially for two of them, trimethyl(2,2,2-trifluoroethyl)ammonium trichloromanganese(II) (TMTFE-MnCl₃) and diethylmethyl(2-fluoroethyl)ammonium trichloromanganese(II) (DEMFE-MnCl₃). We predict that the TMTFE-MnCl₃ and DEMFE-MnCl₃ crystals outperform all previously reported 1D ferroelectric HOIPs in terms of high spontaneous polarization, high phase transition temperature, and strong piezoelectricity. The newly proposed design strategy for 1D HOIPs with room-temperature ferroelectricity or strong piezoelectricity can be validated for broader applications if both outstanding ferroelectric/piezoelectric perovskites can be synthesized and confirmed in the laboratory.