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Piezoelectricity, one of the most desirable properties of non-centrosymmetric crystalline materials, has long been blooming in academic research, industrial manufacturing, and daily applications owing to its unique electromechanical transformation capability. Compared with inorganic piezoelectric ceramics dominating the market, molecule-based piezoelectric materials exhibit advantages of light weight, mechanical flexibility, and environment friendliness and have attracted widespread interest recently. However, investigations on molecular materials with large piezoelectric coefficients are mainly focused on organic–inorganic hybrids, while pure organic homochiral piezoelectrics holding large piezoelectric coefficients remain scarce. Herein, by precise molecular modification on (S)-2-methylpiperazin-1-ium perchlorate ([(S)-MPP][ClO4]) with polar cyanomethyl groups, a homochiral pure organic compound (3S)-3-methyl-1,4-di(cyanomethyl)piperazin-1-ium perchlorate [DCM-(S)-MPP][ClO4] with large d22 of 18 pC/N was achieved, along with changes in the space group from nonpolar to polar, giving rise to second harmonic generation and phase transition behaviors. The modification strategy proposed here will benefit piezoelectricity enhancement in more chiral compounds, promoting their application potential in biological medicine, flexible devices, and green chemistry. [ABSTRACT FROM AUTHOR]

What is the most favorite and original chemistry developed in your research group? We originally proposed the design principle for molecular ferroelectrics: ferroelectrochemistry, including quasi‐spherical theory, the introduction of homochirality, and H/F substitution. Ferroelectrochemistry changed the blind search for molecular ferroelectrics into targeted chemical design, which will develop into a new discipline. How do you get into this specific field? Could you please share some experiences with our readers? I have been devoted to the field of molecular ferroelectrics for more than 20 years. In the early stage, I worked on non‐centrosymmetric metal‐organic complexes, which are potential molecular ferroelectrics. This laid a foundation for my further study of molecular ferroelectrics. Non‐centrosymmetric crystal symmetry is only one of the necessary requirements for ferroelectrics, which must adopt one of the 10 polar crystallographic point groups and should also generally undergo symmetry‐breaking phase transitions. Due to the lack of a feasible method, the discovery of molecular ferroelectrics has long depended on blindly searching. This process is like finding a needle in a haystack. After years of exploration in this field, I fully understood the Landau phase transition phenomenological theory, Curie symmetry, and Neumann principle from a chemical perspective, and proposed the design principle for molecular ferroelectrics: ferroelectrochemistry, transforming the discovery of molecular ferroelectrics from blind search to targeted chemical design. Never give up no matter how much difficulty you have met, because maybe there is an opportunity the next second. What is the most important personality for scientific research? Curiosity, divergent thinking, perseverance, team spirit, and gratitude. How do you supervise your students? Emphasis on independent problem‐solving abilities. Encourage students to read professional books frequently while doing research. What are your hobbies? What's your favorite book(s)? Jogging, reading, and swimming. My favorite book is The Journey to the West. Comprehensive Summary: Molecular ferroelectrics have attracted tremendous attention in the past decades due to their excellent ferroelectric performance and superiorities of easy processability, mechanical flexibility, and good biocompatibility. However, the discovery of molecular ferroelectrics is a great challenge and has long relied on blind search. This situation changed recently, with the development of ferroelectrochemistry proposed by our group. As a major design approach in ferroelectrochemistry, introducing homochirality, which facilitates the crystallization of materials in polar crystallographic point groups, greatly improves the probability of being ferroelectrics. Various new molecular ferroelectrics with splendid properties have been precisely synthesized by using this efficient and universal strategy. In this review, we summarize the advances in the chemical design of molecular ferroelectrics through the strategy of introducing homochirality. Key Scientists: [ABSTRACT FROM AUTHOR]

Here, we synthesized a series of cholesteryl-based compounds, whose phases and their transformation can be modulated by temperature and the chain length of the fluoroalkyl moieties. To our knowledge, this is the first time that the phase transition could be modulated with perfluoroalkyl tail engineering in organic single-component ferroelectric crystals. [ABSTRACT FROM AUTHOR]

Organic–inorganic metal halides (OIMHs) have attracted immense attention in recent decades due to their diverse physical properties, such as optoelectronic properties, photoluminescence, magnetism, and ferroelectricity. Besides these fascinating physical properties, OIMHs have also received much interest for their phase transitions. Muconic acid has captured extensive interest owing to the presence of cis,cis-form (Z,Z) and trans,trans-form (E,E) isomers. However, there have been no reports on muconic acid derivative OIMHs with phase transitions. In this work, we successfully synthesized the first muconic acid derivative OIMHs (Z,Z)- and (E,E)-[BPHD]ZnCl4 (BPHD = N1,N6-bis(piperidine-1-yl) hexa-2,4-diene diamide). Both of them crystallized in the monoclinic space group P21/c at room temperature. Notably, (Z,Z)-[BPHD]ZnCl4 does not exhibit phase transition behavior, while (E,E)-[BPHD]ZnCl4 has a high-temperature phase transition of up to 449.4 K, which is higher than that of the majority of OIMH phase transition compounds. Furthermore, the high-temperature structural analysis of (E,E)-[BPHD]ZnCl4 discloses that its high-temperature phase transition originates from the order–disorder transition of the piperidine groups of one (E,E)-[BPHD]2+ cation and the swing motion of the piperidine groups of another (E,E)-[BPHD]2+ cation. This work expands the family of OIMHs and provides a new platform for designing high-temperature phase transition OIMHs. [ABSTRACT FROM AUTHOR]

Thermally triggered spatial symmetry breaking in traditional ferroelectrics has been extensively studied for manipulation of the ferroelectricity. However, photoinduced molecular orbital breaking, which is promising for optical control of ferroelectric polarization, has been rarely explored. Herein, for the first time, we synthesized a homochiral fulgide organic ferroelectric crystal (E)‐(R)‐3‐methyl‐3‐cyclohexylidene‐4‐(diphenylmethylene)dihydro‐2,5‐furandione (1), which exhibits both ferroelectricity and photoisomerization. Significantly, 1 shows a photoinduced reversible change in its molecular orbitals from the 3 π molecular orbitals in the open‐ring isomer to 2 π and 1 σ molecular orbitals in the closed‐ring isomer, which enables reversible ferroelectric domain switching by optical manipulation. To our knowledge, this is the first report revealing the manipulation of ferroelectric polarization in homochiral ferroelectric crystal by photoinduced breaking of molecular orbitals. This finding sheds light on the exploration of molecular orbital breaking in ferroelectrics for optical manipulation of ferroelectricity. [ABSTRACT FROM AUTHOR]

Bismuth(III) iodide perovskites have attracted great attention as lead-free hybrid semiconductors, but they mainly show zero- and one-dimensional structures. Herein, we report the first two-dimensional chiral perovskite-like bismuth(III) iodide hybrid [(S)-3-aminopyrrolidinium I]2Bi2/3I4 (1) with a high phase transition temperature of 408.8 K, higher than most of the reported chiral lead-free hybrid semiconductors. [ABSTRACT FROM AUTHOR]

Inorganic ferroelectrics have long dominated research and applications, taking advantage of high piezoelectric performance in bulk polycrystalline ceramic forms. Molecular ferroelectrics have attracted growing interest because of their environmental friendliness, easy processing, lightweight, and good biocompatibility, while realizing the considerable piezoelectricity in their bulk polycrystalline forms remains a great challenge. Herein, for the first time, through ring enlargement, a molecular ferroelectric 1‐azabicyclo[3.2.1]octonium perrhenate ([3.2.1‐abco]ReO4) with a large piezoelectric coefficient d33 up to 118 pC/N in the polycrystalline pellet form is designed, which is higher than that of the parent 1‐azabicyclo[2.2.1]heptanium perrhenate ([2.2.1–abch]ReO4, 90 pC/N) and those of most molecular ferroelectrics in polycrystalline or even single crystal forms. The ring enlargement reduces the molecular strain for easier molecular deformation, which contributes to the higher piezoelectric response in [3.2.1‐abco]ReO4. This work opens up a new avenue for exploring high piezoelectric polycrystalline molecular ferroelectrics with great potential in piezoelectric applications. [ABSTRACT FROM AUTHOR]

Chiral ferroelectric crystals with intriguing features have attracted great interest and many with point or axial chirality based on the stereocarbon have been successively developed in recent years. However, ferroelectric crystals with stereogenic heteroatomic chirality have never been documented so far. Here, we discover and report a pair of enantiomeric stereogenic sulfur‐chiral single‐component organic ferroelectric crystals, Rs‐tert‐butanesulfinamide (Rs‐tBuSA) and Ss‐tert‐butanesulfinamide (Ss‐tBuSA) through the deep understanding of the chemical design of molecular ferroelectric crystals. Both enantiomers adopt chiral‐polar point group 2 (C2) and exhibit mirror‐image relationships. They undergo high‐temperature 432F2‐type plastic ferroelectric phase transition around 348 K. The ferroelectricity has been well confirmed by ferroelectric hysteresis loops and domains. Polarized light microscopy records the evolution of the ferroelastic domains, according with the fact that the 432F2‐type phase transition is both ferroelectric and ferroelastic. The very soft characteristics with low elastic modulus and hardness reveals their excellent mechanical flexibility. This finding indicates the first stereosulfur chiral molecular ferroelectric crystals, opening up new fertile ground for exploring molecular ferroelectric crystals with great application prospects. [ABSTRACT FROM AUTHOR]

Chiral organic–inorganic hybrid semiconductors (COIHSs) dominated by lead halides have recently gained tremendous interest. Here, we report a lead-free photoluminescent COIHS [R-3-hydroxylpiperidinium]2SbCl5 with a bandgap of 3.14 eV. It shows a ferroelastic phase transition at 341 K accompanied by a switchable second-harmonic generation response and presents clear ferroelastic domains, which are rarely found in lead-free COIHSs. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskites (OIHPs) have gained tremendous interest for their rich functional properties. However, the coexistence of more than one of ferroelectricity, ferromagnetism and ferroelasticity has been rarely found in OIHPs. Herein, we report a two‐dimensional Cr2+‐based OIHP, [3,3‐difluorocyclobutylammonium]2CrCl4 ([DFCBA]2CrCl4), which shows both ferroelectricity and ferromagnetism. It undergoes a 4/mmmFm type ferroelectric phase transition at a temperature as high as 387 K and shows multiaxial ferroelectricity with a saturate polarization of 2.1 μC cm−2. It acts as a soft ferromagnet with a Curie temperature of 32.6 K. This work throws light on the exploration of OIHPs with the coexistence of ferroelectricity and ferromagnetism for applications in future multifunctional smart devices. [ABSTRACT FROM AUTHOR]

Ferroelectrics usually exhibit temperature‐triggered structural changes, which play crucial roles in controlling their physical properties. However, although light is very striking as a non‐contact, non‐destructive, and remotely controlled external stimuli, ferroelectric crystals with light‐triggered structural changes are very rare, which holds promise for optical control of ferroelectric properties. Here, an organic molecular ferroelectric, N‐salicylidene‐2,3,4,5,6‐pentafluoroaniline (SA‐PFA), which shows light‐triggered structural change of reversible photoisomerization between cis‐enol and trans‐keto configuration is reported. SA‐PFA presents clear ferroelectricity with the saturate polarization of 0.84 μC cm−2, larger than those of some typical organic ferroelectrics with thermodynamically structural changes. Benefit from the reversible photoisomerization, the dielectric real part of SA‐PFA can be reversibly switched by light. More strikingly, the photoisomerization enables SA‐PFA to show reversible optically induced ferroelectric polarization switching. Such intriguing behaviors make SPFA a potential candidate for application in next‐generation photo‐controlled ferroelectric devices. This work sheds light on further exploration of more excellent molecular ferroelectrics with light‐triggered structural changes for optical control of ferroelectric properties. [ABSTRACT FROM AUTHOR]

With prosperity, decay, and another spring, molecular ferroelectrics have passed a hundred years since Valasek first discovered ferroelectricity in the molecular compound Rochelle salt. Recently, the proposal of ferroelectrochemistry has injected new vigor into this century-old research field. It should be highlighted that piezoresponse force microscopy (PFM) technique, as a non-destructive imaging and manipulation method for ferroelectric domains at the nanoscale, can significantly speed up the design rate of molecular ferroelectrics as well as enhance the ferroelectric and piezoelectric performances relying on domain engineering. Herein, we provide a brief review of the contribution of the PFM technique toward assisting the design and performance optimization of molecular ferroelectrics. Relying on the relationship between ferroelectric domains and crystallography, together with other physical characteristics such as domain switching and piezoelectricity, we believe that the PFM technique can be effectively applied to assist the design of high-performance molecular ferroelectrics equipped with multifunctionality, and thereby facilitate their practical utilization in optics, electronics, magnetics, thermotics, and mechanics among others. [ABSTRACT FROM AUTHOR]

With the capability to manipulate the built‐in field in solar cells, ferroelectricity is found to be a promising attribute for harvesting solar energy in solar cell devices by influencing associated device parameters. Researchers have devoted themselves to the exploration of ferroelectric materials that simultaneously possess strong light absorption and good electric transport properties for a long time. Here, it is presented a novel and facile approach of combining state‐of‐art light absorption and electric transport properties with ferroelectricity by the incorporation of room temperature 1D ferroelectric perovskite with 3D organic–inorganic hybrid perovskite (OIHP). The 1D/3D mixed OIHP films are found to exhibit evident ferroelectric properties. It is notable that the poling of the 1D/3D mixed ferroelectric OIHP solar cell can increase the average Voc can be increased from 1.13 to 1.16 V, the average PCE from 20.7% to 21.5%. A maximum power conversion efficiency of 22.7%, along with an enhanced fill factor of over 80% and open‐circuit voltage of 1.19 V, can be achieved in the champion device. The enhancement is by virtue of reduced surface recombination by ferroelectricity‐induced modification of the built‐in field. The maximum power point tracking measurement substantiates the retention of ferroelectric‐polarization during the continued operation. [ABSTRACT FROM AUTHOR]

The well-developed design strategy of molecular modification for assembling molecular ferroelectrics mainly focuses on the cations. Herein, by homochiral anionic modification of the non-ferroelectric (quinuclidinium)(HSO4), we designed high-temperature multiaxial organic enantiomeric ferroelectrics, (quinuclidinium)(L - and D -camphorsulfonate). This work paves a new road for precisely constructing excellent molecular ferroelectrics. [ABSTRACT FROM AUTHOR]

Objective: Bladder urothelial carcinoma (BUC) is a common urological malignancy with molecular heterogeneity. However, the genetic feature of Chinese BUC patients is still not well-identified. Methods: We performed deep sequencing by a large panel (450 genes) on 22 BUC samples and using matched normal bladder tissue as control. Genomic alterations (GAs), pathways and Tumor Mutation Burden (TMB) were investigated. Results: The frequencies of GAs (TERT , 54.5%; CREBBP , 27.3%; GATA3 , 22.7%; BRAF , 18.2%; TEK , 18.2% and GLI1 , 18.2%) were significantly higher in Chinese than Western BUC patients. Other GAs' frequencies were in accordance with previous study (TP53 , 50.0%; KDM6A , 31.8%; KMT2D , 22.7%; etc.). Besides, we detected gene amplification in ERBB2, FRS2, FAS , etc. The gene fusion/rearrangement took place in the chromosome 11, 12, 14, 17, 19, 22, and Y. Other than cell cycle and PI3K-AKT-mTOR, mutated genes were more associated with the transcription factor, chromatin modification signaling pathways. Interestingly, the TMB value was significantly higher in the BUC patients at stages T1–T2 than T3–T4 (P = 0.025). Conclusion: Deep genomic sequencing of BUC can provide new clues on the unique GAs of Chinese patients and assist in therapeutic decision. [ABSTRACT FROM AUTHOR]

Temperature-dependent physical switching materials have been of wide concern for materials chemists. Among them, switchable dielectric perovskite materials have shown huge application potential in the fields of sensing, information storage, and electronics. In particular, for better practical application, obtaining dual-phase-change switching materials with a high phase transition temperature (Tc) is still a worthwhile issue to study. In this work, we synthesized chiral hybrid organic inorganic perovskites, namely, (R)-, (S)- and (rac)-N,N-dimethyl-3-fluoropyrrolidinium (DMFP) CdCl3. The enantiomeric compound undergoes a dual phase transition with a Tc of 460 K and 367 K. Tc significantly increased by 28 K from 411 K of (N,N-dimethyl pyrrolidinium) (DMP) CdCl3 to 439 K of (rac)-DMFP CdCl3. Besides, (R) and (S)-DMFP CdCl3 are the first example of chiral perovskites that show dual Tc with robust switching dielectric characteristics. This work could be a pathway for designing multifunctional chiral perovskite-type switchable materials. [ABSTRACT FROM AUTHOR]

Organic–inorganic metal halide ferroelectric semiconductors are mainly lead halide ones, suffering from the presence of toxic lead. Herein, we report a lead-free bismuth iodide ferroelectric semiconductor [1,4-butanediammonium]BiI5, showing a high Curie temperature of 365 K and a small band gap of 1.95 eV, smaller than those of most lead halide counterparts. [ABSTRACT FROM AUTHOR]

Previously, organic-ionic crystal phase transition materials have mainly focused on mono- or divalent organic amine cations, while higher valent amine cations have rarely been introduced. Here, we have selected a ring-shaped trivalent organic amine, triethylenetriamine, in order to construct a high-Tc phase transition material, triethylenetriammonium trichloride ([HTETA]3+ 3[Cl]−). [ABSTRACT FROM AUTHOR]

The nonradiative recombination of electrons and holes has been identified as the main cause of energy loss in hybrid organic–inorganic perovskite solar cells (PSCs). Sufficient built‐in field and defect passivation can facilitate effective separation of electron–hole pairs to address the crucial issues. For the first time, we introduce a homochiral molecular ferroelectric into a PSC to enlarge the built‐in electric field of the perovskite film, thereby facilitating effective charge separation and transportation. As a consequence of similarities in ionic structure, the molecular ferroelectric component of the PSC passivates the defects in the active perovskite layers, thereby inducing an approximately eightfold enhancement in photoluminescence intensity and reducing electron trap‐state density. The photovoltaic molecular ferroelectric PSCs achieve a power conversion efficiency as high as 21.78 %. [ABSTRACT FROM AUTHOR]

Through the strategy of F/H substitution, we precisely designed the highest-Tc (phase transition temperature) organic enantiomeric ferroelectrics, (R)- and (S)-(N,N-dimethyl-3-fluoropyrrolidinium) iodide, of which the Tc reaches up to 470 K, far beyond those of other enantiomeric ferroelectrics and also the commercial ferroelectric BaTiO3. [ABSTRACT FROM AUTHOR]

Switchable materials play an invaluable role in signal processing and encryption of smart devices. The development of multifunctional materials that exhibit switching characteristics in multiple physical channels has attracted widespread attention. Now, two chiral thermochromic ferroelastic crystals (S‐CTA)2CuCl4 and (R‐CTA)2CuCl4 (CTA=3‐chloro‐2‐hydroxypropyltrimethylammonium) have been prepared with switchable properties in dielectricity, conductivity, second harmonic generation (SHG), piezoelectricity, ferroelasticity, chiral, and thermochromic properties. Compared with traditional phase‐transition materials with switching features, thermochromism brings additional spectral encryption possibilities for future information processing. To the best of our knowledge, this is the first chiral thermochromic ferroelastic that exhibits switching properties in seven physical channels. This work is expected to promote further exploration of multifunctional molecular switchable materials. [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]

Since the first perovskite CaTiO3 was discovered in 1839, the development of perovskite has a history of 180 years. The emergence of solar cells (CH3NH3)PbI3 has set off the trend of hybrid organic–inorganic perovskite (HOIP) materials. Since then, various HOIPs have sprung up and been widely used in various material devices. Among them, HOIP ferroelectrics have gained widespread attention. However, antiperovskite, as a twin brother of perovskite, has been neglected although it has similar structure with perovskite. Here, we successfully found that [C3H7FN]3[SnCl6]Cl has a three‐dimensional (3D) antiperovskite structure with the formula M3AB. Importantly, the compound exhibits obvious ferroelectric properties with an Aizu notation of 622F6 at 391 K. To the best of our knowledge, this is the first 3D hybrid organic–inorganic antiperovskite ferroelectric, which will greatly promote the development of antiperovskite families with more superior physical properties. [ABSTRACT FROM AUTHOR]

Molecular optical‐dielectric duple bistable switches are photoelectric (dielectric and fluorescent) multifunctional materials that can simultaneously convert optical and electrical signals in one device for seamless integration. However, exploring optical‐dielectric duple channels of dielectric and photoluminescence is still a bigger challenge than single dielectric or photoluminescence bistable ones, which are hardly reported but probably will be heavily researched owing to the new generation artificial intelligence development needs in the future. Herein, a new optical‐dielectric duple bistable switches material, [(CH3)3NCH2CH3]2MnCl4 (I), was obtained by a simple method for volatilization of solvents. Variable temperature single crystal X‐ray analysis indicates that material I has a reversible bistable structure (order‐disorder structure phase transition) corresponding to switching "ON′′ and "OFF′′. Unlike the single dielectric bistable structures that were previously reported, material I also own bistable features in terms of fluorescence property. This material enriches the specific examples of photoelectric duple function switch materials and facilitates the development of required devices. [ABSTRACT FROM AUTHOR]

In this paper, three zero-dimensional organic–inorganic hybrid compounds [(CH3)3S]2[CdBr4] (1), [(CH3)3S]2[MnBr4] (2) and [(CH3)3S]2[ZnBr4] (3) were synthesized. The phase transition behavior of 1, 2 and 3 was well characterized by differential scanning calorimetry (DSC) and variable temperature single crystal diffraction measurements. The phase transition temperature of 1, 2 and 3 was at ca. 315 K in the heating process. The vigorous ordered–disordered reorientation and displacement motion of [(Me3)3S]+ and [MBr4]2− of 1, 2 and 3 induce the structural phase transition from the centrosymmetric (CS) space group Pnma to the non-centrosymmetric (NCS) space group P212121. The apparent second-harmonic generation (SHG) switching responses further confirm this CS to NCS symmetry breaking. Moreover, dielectric studies illustrate that 1, 2 and 3 display distinctly switchable dielectric behavior, revealing their potential application in dielectric switches. This finding suggests that sulfonium-based organic–inorganic hybrids can be used to build phase transition materials, broadening the way for exploring dielectric and nonlinear optical (NLO) switching materials. [ABSTRACT FROM AUTHOR]

A novel organic–inorganic ABX3 perovskite-type material with specific hydrogen bonding interactions, N,N-dimethylethanolammonium trichlorocadmate ([DMEA]CdCl3), has been synthesized as a phase transition material. It is notable that the DMEA cations are arranged to form one-dimensional chains connected by hydrogen bonds at room temperature, which are very sparse in other perovskite-type compounds. The strong intermolecular interactions have made the phase transition temperature of the material reach up to 429 K, as confirmed by differential scanning calorimetry measurements, variable-temperature structural analyses, and dielectric measurements. The origin of the symmetry-breaking phase transition is associated with the motion or reorientation of the DMEA cations, accompanied by the crystal structures from orthorhombic Pnma to monoclinic P21/c with the temperature decreases. The finding of [DMEA]CdCl3 with unprecedented hydrogen bonding interactions has opened a new avenue to design novel phase transition materials with higher transition temperatures. [ABSTRACT FROM AUTHOR]