Introducing Ferroelasticity into 1D Hybrid Lead Halide Semiconductor by Halogen Substitution Strategy.

Organic-inorganic hybrid lead halide perovskites (OLHPs), represented by (CH NH )PbI , are one of the research focus due to their exceptional performance in optoelectronic applications, and ferroelastic domain walls are benign to their charge carrier transport that is confirmed recently. Among them, the 1D OLHPs feature better stability against desorption and moisture, but related 1D ones possessing ferroelasticity are rarely investigated and reported so far. In this work, the 1D ferroelastic semiconductor (N-iodomethyl-N-methyl-morpholinium)PbI ((IDMML)PbI ) is prepared successfully by introducing successively halogenate atoms from Cl, Br to I into the organic cation of the prototype (N,N-dimethylmorpholinium)PbI ((DMML)PbI ).

Nicotinic acid bromide: a simple organic salt optical-electrical ferroelastic with high .

A new ferroelastic organic salt nicotinic acid bromide (N-Br) was connected by hydrogen bonding with nicotinic acid cations a halogen substitution strategy. It exhibits a ferroelastic phase transition from 2/ to 1̄ with 2/1̄ Aizu notation with a high Curie temperature () of 402 K. Moreover, optical regulation from blue light to white light was achieved by halogen substitution.

A nickel(ii)-based one-dimensional organic-inorganic halide perovskite ferroelectric with the highest Curie temperature.

Organic-inorganic halide perovskites (OIHPs) are very eye-catching due to their chemical tunability and rich physical properties such as ferroelectricity, magnetism, photovoltaic properties and photoluminescence. However, no nickel-based OIHP ferroelectrics have been reported so far. Here, we designed an ABX OIHP ferroelectric (3-pyrrolinium)NiCl, where the 3-pyrrolinium cations are located on the voids surrounded by one-dimensional chains composed of NiCl-face-sharing octahedra hydrogen bonding interactions.

Halogen Engineering To Realize Regulable Multipolar Axes, Nonlinear Optical Response, and Piezoelectricity in Plastic Ferroelectrics.

Compared with uniaxial molecular ferroelectrics, multiaxial ferroelectrics have better application prospects because they are no longer subject to the single-crystal form and have been pursued in recent years. Halogen engineering refers to the adjustment of halogens in materials at the atomic level, which can not only explore multiaxial ferroelectrics but also help to improve piezoelectrics, recently. In this work, we successfully synthesized and characterized three multiaxial plastic ferroelectrics through the precise molecular design from I to Cl, confirming the increase of the number of polar axes of ferroelectrics from 3 to 6, the increase of second-harmonic generation density from 2.

Metal ion induced dual switchable dielectric and luminescent properties in hybrid halides.

A new multi-functional organic-inorganic hybrid compound was successfully obtained by regulating metal halides. Apart from excellent luminescence properties, in particular, the introduction of a Mn halide successfully achieved a dual-switchable dielectric property, which could lead to very interesting exploration in sensors.

Integrated Reversible Thermochromism, High T , Dielectric Switch and Narrow Band Gap in One Multifunctional Ferroic.

Organic-inorganic Hybrid (OIH) materials for multifunctional switchable applications have attracted enormous attention in recent years due to their excellent optoelectronic properties and good structural tunability. However, it still remains challenging to fabricate one simple OIH compound with multi-functionals properties, such as dielectric switching, thermochromic properties, semiconductor characteristics and ferroelasticity. Under this context, we successfully synthesized [2-(2-fluorophenyl)ethan-1- ammonium] SnBr (compound 1), which has a higher phase transition temperature of 427.

Competitive Dual-Emission-Induced Thermochromic Luminescence in Organic-Metal Halides.

Lead-free Halides, especially Mn-based ones, are preferred as hotspots in the exploration of photoluminescent materials. However, there are few reports on sensitive reversible thermochromism and switchable dual emission originating from self-trapped exciton emission in pure Mn-Based materials. Here, we report a new Mn-based hybrid material [TMPA]MnI (TMPA = trimethylphenylammonium), which shows two emission peaks at 545 and 660 nm benefitting from the d-d orbital transition of Mn and the generation of self-trapped excitons, respectively.

The construction of a two-dimensional organic-inorganic hybrid double perovskite ferroelastic with a high and narrow band gap.

Two-dimensional (2D) hybrid double perovskites have attracted extensive research interest for their fascinating physical properties, such as ferroelectricity, X-ray detection, light response and so on. In addition, ferroelastics, as an important branch of ferroic materials, exhibits wide prospects in mechanical switches, shape memory and templating electronic nanostructures. Here, we designed a 2D phase-transition double perovskite ferroelastic through a structurally progressive strategy.

Dehydration-activated structural phase transition in a two-dimensional hybrid double perovskite.

As a feasible lead-free scheme, organic-inorganic hybrid double perovskites show many excellent properties, including ferroelectricity, ferroelasticity, self-powered circularly polarized light detection and so on. In this work, the solid-to-solid structural phase transition of a two-dimensional hybrid double perovskite (CHA)CuBiI was successfully activated the dehydration of (CHA)CuBiI·HO, which was proven by differential scanning calorimetry (DSC) and temperature-dependent dielectric measurements. Using variable-temperature single-crystal X-ray diffractometry, the cause behind the phase transition of (CHA)CuBiI was determined to be the overall coordination of distortion and movement of the inorganic skeleton and thermal deformation of the cationic structure.

Metal ion modulation triggers dielectric double switching and green fluorescence in AMX-type compounds.

Multifunctional switching materials show great potential for applications in sensors, smart switches, and other fields due to their ability to integrate different physical channels in one single device. However, multifunctional responsive materials with multiple switching and luminescence properties have rarely been reported. Here, we report three organic-inorganic hybrids: [TMAA][CoCl] (compound 1), [TMAA][CdBr] (compound 2) and [TMAA][MnCl] (compound 3).

In Situ Observation of Ferroelastic Domain and Phase Transition in a Three-Dimensional Molecular Crystal.

Massive efforts have been devoted to designing molecular ferroic materials by molecular modification. For molecular ferroelastic, previous work is focused on the temperature-dependent ferroelastic domains, however, few are related to controlling the ferroelastic domain by the stress. Inspired by the "quasi-spherical theory" and fluorination effect, we designed a more flexible (MedabcoF) (MedabcoF=1-fluoro-4-methyl-1,4-diazoniabicyclo[2.

A-site cation with high vibrational motion in ABX perovskite effectively induces dielectric phase transition.

Organic-inorganic hybrid ABX perovskite (OIHPs) with phase transition have considerable application potential in multifunctional devices for their structural tunability and excellent photo/electric performance. Because the interaction between molecules during the crystallization process is difficult to predict and control, exploring targeted chemical design methods to synthesize phase change materials has been an interesting and challenging problem. As per the synergistic effect of anion and cation, we assemble a cation with high vibrational activity and an inorganic anion with large voids to successfully design a one-dimensional OIHPs phase change material.

Methylation Design Strategy to Trigger a Dual Dielectric Switch and Improve the Phase Transition Temperature.

Phase transitions of hybrid materials have aroused widespread concern and call for an in-depth study on its structure design, because the structure and characteristics are closely related, which promote potential applications in the field of temperature sensors, dielectric switches, and actuators. However, designing materials with multiple phase transitions and a high phase transition temperature (Tr) remains a huge challenge. In order to deal with this key hurdle, we tried to regulate the structural components and successfully synthesized [MASD][CdCl] (, MASD = 8-methyl-5-azoniaspiro[4,5]decane), which displays multiple phase transitions occurring at 273.

Unique Design Strategy for Dual Phase Transition That Successfully Validates Dual Switch Implementation in the Dielectric Material.

Dual phase transition/switch materials are a critical cornerstone of information storage and sensing. However, they are difficult to design successfully, and compared with materials showing single-switchable phase transitions, the dual ones retain many challenges by far. Therefore, the significance of a general strategy is far greater than an accidental success.

A modified molecular framework derived highly efficient Mn-Co-carbon cathode for a flexible Zn-air battery.

A controllable Co doping strategy is introduced to significantly activate more catalytic sites for Mn-based materials and anchor Co-Mn nanoparticles on the N-doped carbon nanotube (N-CNT) substrates. The as-synthesized CoMnO/N-CNTs exhibit excellent ORR catalytic performance with large limited current density and positive half-wave potential, even outperforming the Pt/C catalysts. The outstanding ORR activity allows the CoMnO/N-CNTs to directly serve as the cathode electrode in a liquid/solid state Zn-air battery, demonstrating large power density and robust stability.