Multi‐functionalized lead‐free organic‐inorganic hybrid ferroelectrics have recently realized diverse applications especially for optoelectronics and photovoltaics. Herein, the chiral Zn‐based organic−inorganic hybrids are discovered: [(R)‐(−)‐2‐methylpiperazine‐1,4‐diium][Zn(H2O)6]•(SO4)2 (RMPZnS2, space group P21) and [(S)‐(+)‐2‐methylpiperazine‐1,4‐diium]2[Zn(H2O)6]•(SO4)3 (SMP2ZnS3, space group P21212). Through experimental and computational investigations, it is found that RMPZnS2 is a ferroelectric with considerable large polarization value (P ≈ 9.5 µC cm−2) along b–axis, and its ferroelectric‐paraelectric phase transition is switched by rotation of organic cations. Meanwhile, it also possesses a fascinating photovoltaic effect driven by the polar charges at solar‐blind UV region, endowing it with the potential of self‐driven photodetection. In addition, white‐light emissions of the RMPZnS2 and SMP2ZnS3 are observed. The enhanced luminescence by heating is especially suitable for the application in white light‐emitting diodes. Overall, these chiral emission ferroelectrics at the supramolecular level will largely expand their applications in multidisciplinary fields.

Organic-inorganic hybrid ferroelectrics (OIHFs) have fueled enormous interest benefiting from their less environmental pollution, performance-tailored functionality, low product costs as well as tunability of structures. However, the lack of material synthesis approaches and diverse targeted molecular design is a stumbling block for designing novel OIHFs rationally. Here, we report a unique organic-inorganic hybrid ferroelectric (3,3-difluoropyrrolidine)2CdCl4 1 and another novel nonferroelectric crystal (3,3-difluoropyrrolidine)2Cd2Cl6 2 by changing various crystallization solvents. Significantly, 1 presents a ferroelectric phase transition behavior at ∼367 K, and the distinct symmetry breaking, i.e., mmmFm, sets up a biaxial ferroelectric with four equivalent directions of polarization, which has a P r ∼ 0.77 μC/cm2. Systematic studies prove that ferroelectricity can be ascribed to the synergistic effects of the distortion of the inorganic anion skeleton and the ordering of organic cations. This work reveals the potential of constructing novel ferroelectrics based on the solvent selective effect and pyrrolidinium as organic cations.

No abstract