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Ferroelastic materials with high phase transition temperature have broad application prospects in information conversion and storage, shape memory, energy conversion, hyperelasticity, etc. However, most of the current reports focus on inorganic ferroelastic materials. Inorganic ferroelastic materials have the disadvantages of high energy consumption and harmful metals, which limit their application in practical work. In contrast, organic ferroelastic materials have the advantages of structural adjustability, environmental protection, easy processing, low cost, mechanical flexibility, and so on, which have great development potential in new ferroelastic materials. Here, we have successfully designed and synthesized a pair of homochiral enantiomers [(R/S)‐4‐fluorobenzoic acid‐2‐amino‐2‐phenylethanol] (R‐ and S‐F) using the chemical design strategy of H/F substitution. Compared with the non‐F substitution [(R/S)‐benzoic acid‐2‐amino‐2‐phenylethanol] (R‐ and S‐H), they undergo 2F1‐type ferroelastic phase transitions at 370 K. Notably, the ferroelastic domains of R/S‐F can be controlled through two physical channels that are temperature and stress, showing great potential in dual‐channel switches. [ABSTRACT FROM AUTHOR]

Organosilicons have been used extensively in aerospace, electronics, food, medicine and other fields, due to their low viscosity, hydrophobicity, corrosion resistance, non‐toxic, and physiologically inert features. Despite extensive interest, however, organosilicon ferroelectric crystals have never been found. Here, by using the chemical design strategy, we successfully obtained a molecular ferroelectric D‐chiro‐inositol‐SiMe3 with polar P43 symmetry, whose spontaneous polarization can be electrically switchable on thin film. The introduction of organosilicon groups endows the thin films with excellent softness, ductility and flexibility (extremely low hardness of 72.8 MPa and small elastic modulus of 5.04 GPa) that are desirable for biomedical and human‐compatible applications. As the first case of organosilicon ferroelectric crystal to date, this work offers a new structural paradigm for molecular ferroelectrics, and highlights their potential for flexible bio‐electronic applications. [ABSTRACT FROM AUTHOR]

Organic ferroelectrics, as a type of crystalline compound, are generally solution processing. However, for most crystalline compounds, the changing of solvent would not influence the crystalline phase, let alone their physical performance. Here, the solvent selective effect occurs in the iodinated adamantanone ferroelectrics. By changing the solvent with different polarities, the ferroelectric crystals can be induced in two different phases, which is unprecedented to the knowledge. More strikingly, this solvent‐induced transformation could realize the physical performance optimization in the orthorhombic phase (orth‐I‐OA, obtained from ethanol) with a stronger second harmonic generation (SHG) response, greater piezoelectric coefficient d33 of 5 pC N−1, and larger spontaneous polarization (Ps) of 3.43 µC cm−2 than those of monoclinic one (mono‐I‐OA, obtained from ethyl acetate). Such an intriguing phenomenon might be closely related to solvent polarity. Based on the quantitative and qualitative analyses, the similar interaction energies of these two phases suggest that their transformation could be easily realized via changing the solvent. This work provides new insights into the chemical design and performance optimization of organic ferroelectrics. [ABSTRACT FROM AUTHOR]

Organic ferroelectrics are flexible, lightweight, and bio‐friendly, promising for bio‐harmonized electronic devices, while their ferroelectric lithography remains relatively unexplored. Here, by introducing homochirality and ZE photoisomerization, we obtained a pair of organic enantiomorphic ferroelectrics, di(benzylamino)‐substituted derivatives of muconic acids, the first ferroelectrics in the muconic family. Their ferroelectric and chiral features were confirmed by the polarization–electric field hysteresis loops and circular dichroism spectra, respectively. Piezoresponse force microscopy measurements demonstrate that the desired domain structure can be precisely achieved by applying a local electric field on a predefined pattern in their thin films. Moreover, thermogravimetric analyses reveal that their ferroelectricity can persist up to above 550 K. The precise pattern lithography and excellent thermal stability make them competitive candidates for ferroelectric lithography. [ABSTRACT FROM AUTHOR]

Molecular ferroelectrics have attracted considerable interests because of their easy and environmentally friendly processing, low acoustical impedance and mechanical flexibility. Herein, a molecular thermochromic ferroelectric, N,N′‐dimethyl‐1,4‐diazoniabicyclo[2.2.2]octonium tetrachlorocuprate(II) ([DMe‐DABCO]CuCl4) is reported, which shows both excellent ferroelectricity and intriguing thermochromism. [DMe‐DABCO]CuCl4 undergoes a ferroelectric phase transition from Pca21 to Pbcm at a significantly high Curie temperature of 413 K, accompanied by a color change from yellow to red that is due to the remarkable deformation of [CuCl4]2− tetrahedron, where the ferroelectric and paraelectric phases correspond to yellow and red, respectively. Combined with multiple bistable physical properties, [DMe‐DABCO]CuCl4 would be a promising candidate for next‐generation smart devices, and should inspire further exploration of multifunctional molecular ferroelectrics. [ABSTRACT FROM AUTHOR]

A new asymmetric capacitor concept is proposed providing high energy storage capacity for only one charging direction. Size‐selective microporous carbons (w<0.9 nm) with narrow pore size distribution are demonstrated to exclusively electrosorb small anions (BF4−) but size‐exclude larger cations (TBA+ or TPA+), while the counter electrode, an ordered mesoporous carbon (w>2 nm), gives access to both ions. This architecture exclusively charges in one direction with high rectification ratios (RR=12), representing a novel capacitive analogue of semiconductor‐based diodes ("CAPode"). By precise pore size control of microporous carbons (0.6 nm, 0.8 nm and 1.0 nm) combined with an ordered mesoporous counter electrode (CMK‐3, 4.8 nm) electrolyte cation sieving and unidirectional charging is demonstrated by analyzing the device charge‐discharge response and monitoring individual electrodes of the device via in situ NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Narrow band gaps and excellent ferroelectricity are intrinsically paradoxical in ferroelectrics as the leakage current caused by an increase in the number of thermally excited carriers will lead to a deterioration of ferroelectricity. A new molecular ferroelectric, hexane-1,6-diammonium pentaiodobismuth (HDA-BiI5), was now developed through band gap engineering of organic-inorganic hybrid materials. It features an intrinsic band gap of 1.89 eV, and thus represents the first molecular ferroelectric with a band gap of less than 2.0 eV. Simultaneously, low-temperature solution processing was successfully applied to fabricate high-quality ferroelectric thin films based on HDA-BiI5, for which high-precision controllable domain flips were realized. Owing to its narrow band gap and excellent ferroelectricity, HDA-BiI5 can be considered as a milestone in the exploitation of molecular ferroelectrics, with promising applications in high-density data storage and photovoltaic conversion. [ABSTRACT FROM AUTHOR]