Chiral Switchable Low-Dimensional Perovskite Ferroelectrics.

Low-dimensional hybrid organic-inorganic perovskites (HOIPs) possess more localized electronic states and narrower conduction and valence bands to promote self-trapping of excitons and stronger exciton emission; therefore, they are widely used as building blocks for various applications in the fields of optoelectronics, photovoltaics, light-emitting diodes, luminescence, fluorescence, and so forth. Despite the past decades of intensive study, the discovered low-dimensional chiral HOIPs are rare as of the 1D chiral HOIP single crystals reported in 2003, as well as the low-dimensional chiral HOIP ferroelectrics are particularly scarce since the first chiral two-dimensional (2D) and/or one-dimensional (1D) HOIP ferroelectrics reported. Herein, two new low-dimensional HOIPs with the same conformational formula [R-MPA]CdCl (R-MPA = ()-(-)-1-methyl-3-phenylpropylamine) were successfully synthetized by means of regulating the stoichiometric proportion of R-MPA and CdCl in two ways of 1:1 () and 2:1 (). By combining single-crystal X-ray diffraction, circular dichroism (CD) spectroscopy, differential scanning calorimetry, temperature-dependent dielectric constant, temperature-dependent second-harmonic generation (SHG) effect, polarization-dependent SHG response, and - hysteresis loop, we reveal that is a 1D nonchiral molecular ferroelectric and is the first zero-dimensional (0D) chiral ferroelectric with distinct CD signals; meanwhile, exhibits increased properties of high-, large dielectric constant, SHG isotropy, and ferroelectricity than that of . These results not only shed light on the high tunability of the low-dimensional HOIP ferroelectrics but also open up an avenue to explore multifunctional chiral ferroelectrics.