An Organic-Inorganic Hybrid Pyrrolidinium Ferroelectric Based on Solvent Selective Effect

Abstract

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.

Lead-Free Hybrid Organic–Inorganic Ferroelectric: (3,3-Difluoropyrrolidinium)2ZnCl4·H2O

“…32 In addition, Jiao et al also reported a H/F-substituted HOIF (C 4 H 8 NF 2 ) 2 CdCl 4 , in which two different solvents were used to obtain a ferroelectric and a non-ferroelectric. 33 At present, the number of zinc-based ferroelectrics is still relatively small. Inspired by these studies, we used 3,3-difluoropyrrolidine hydrochloride and ZnCl 2 to obtain a (3,3-difluoropyrrolidine) 2 ZnCl 4 •H 2 O (DFZC) crystal by the solution evaporation method with water as a solvent.…”

“…Another example is that Wu et al synthesized zinc-based chiral hybrid organic–inorganic RMPZnS 2 and SMP 2 ZnS 3 single crystals, in which the RMPZnS 2 crystal is ferroelectric . In addition, Jiao et al also reported a H/F-substituted HOIF (C 4 H 8 NF 2 ) 2 CdCl 4 , in which two different solvents were used to obtain a ferroelectric and a non-ferroelectric . At present, the number of zinc-based ferroelectrics is still relatively small.…”

H/F Substitution on the Spacer Cations Leads to 1D-to-2D Increment of the Pyrrolidinium-Containing Lead Iodide Hybrid Perovskites

“…However, very little attention was paid on the effect of difluoride substitution on the spacer cations of 1D chain HOIPs. In fact, difluoride substitution on the 1D HOIPs has a chance to result in the dimensional increment to 2D HOIPs, such as (3,3-difluoropyrrolidine) 2 CdCl 4 , (4,4-DFHHA) 2 PbI 4 , and (4,4-DFPD) 2 PbI 4 . The expansion of the Pb–I network from 1D to 2D for lead iodide HOIPs usually leads to the band gap reduction, which is of great importance for their photoelectric feature. , …”

Solvent Selective Effect Occurs in Iodinated Adamantanone Ferroelectrics

“…[ 1 , 2 , 3 ] Combined with their excellent pyroelectric, piezoelectric, and other physical properties, ferroelectrics represented by the inorganic ceramics such as barium titanate (BTO) and lead zirconate titanate (PZT) have been widely used for electronic applications, such as transducers, memories, actuators, and sensors. [ 4 , 5 , 6 , 7 ] Facing the challenges of the environment, energy, and cost, the focus of materials science has gradually but firmly shifted from inorganic and organic–inorganic systems to organic ones. [ 8 ] Recently, interest in organic ferroelectrics is increasing because of their superiority of lightweight, good degradability, easy solution processing, low acoustic impedance (matches with human bodies), satisfying biocompatibility, and environmental friendliness.…”