An above-room-temperature ferroelectric organo-metal halide perovskite: (3-pyrrolinium)(CdCl₃)

Molecular Dynamics of Flexible Polar Cations in a Variable Confined Space: Toward Exceptional Two-Step Nonlinear Optical Switches

The changeable molecular dynamics of flexible polar cations in the variable confined space between inorganic chains brings about a new type of two-step nonlinear optical (NLO) switch with genuine "off-on-off" second harmonic generation (SHG) conversion between one NLO-active state and two NLO-inactive states.

Symmetry breaking in molecular ferroelectrics

Symmetry breaking occurs between the high-temperature, high-symmetry paraelectric phase and the low-temperature, low-symmetry ferroelectric phase along with a reduction in the number of symmetry elements, obeying the Curie symmetry principle and relating to the ferroelectricity.

Sequential structural transitions with distinct dielectric responses in a layered perovskite organic-inorganic hybrid material: [C4H9N]2[PbBr4]

A novel organic-inorganic hybrid layered perovskite-type compound of the general formula A2BX4, bis(IBA)tetrabromolead(II) (1, IBA = isobutyl-ammonium cation), has been successfully synthesized and grown as flake-like crystals, and undergoes two reversible solid-state phase transitions at 315 K and 250 K, and has been systematically characterized using differential scanning calorimetry measurements, variable-temperature structural analyses, variable-temperature powder X-ray diffraction measurements and dielectric measurements. 1 exhibits a remarkable temperature-dependent dielectric behavior, which could be switched between high and low dielectric states above room temperature, and a broad peak exists below room temperature. The most striking dielectric property is the remarkable anisotropy along the various crystallographic axes. All of these demonstrate its potential application as a high temperature switchable molecular dielectric and low temperature phase transition material.

Interfacing Solution-Grown C60 and (3-Pyrrolinium)(CdCl3 ) Single Crystals for High-Mobility Transistor-Based Memory Devices

Aligned ferroelectric single crystals of (3-pyrrolinium)(CdCl₃ ) can be prepared from solution on top of aligned semiconducting C₆₀ single crystals using an orthogonal solvent. Memory devices based on these ferroelectric/semiconductor bilayered heterojunctions exhibit much larger hysteresis compared with that of only C₆₀ single crystals. More importantly, the introduction of the ferroelectric layer induces the memory window without dramatically reducing the charge mobility.

The First Organic-Inorganic Hybrid Luminescent Multiferroic: (Pyrrolidinium)MnBr3

A hybrid organic-inorganic compound, (pyrrolidinium)MnBr3 , distinguished from rare earth (RE)-doped inorganic perovskites, is discovered as a new member of the ferroelectrics family, having excellent luminescent properties and relatively large spontaneous polarization of 6 μC cm(-2) , as well as a weak ferromagnetism at about 2.4 K. With a quantum yield of >28% and emission lifetime >0.1 ms, such multiferroic photoluminescence is a suitable candidate for future applications in luminescence materials, photovoltaics, and magneto-optoelectronic devices.

An extended Tolerance Factor approach for organic-inorganic perovskites

Goldschmidt's concept of ionic Tolerance Factors was recently shown to be a valuable guideline for the preparation of new compounds within the field of organic-inorganic perovskites. Here, we extend this approach and calculate Tolerance Factors for over 2500 amine-metal-anion permutations of the periodic table. The results suggest the potential existence of more than 600 undiscovered hybrid perovskites including alkaline earth metal and lanthanide based materials.

A lead-halide perovskite molecular ferroelectric semiconductor

Inorganic semiconductor ferroelectrics such as BiFeO₃ have shown great potential in photovoltaic and other applications. Currently, semiconducting properties and the corresponding application in optoelectronic devices of hybrid organo-plumbate or stannate are a hot topic of academic research; more and more of such hybrids have been synthesized. Structurally, these hybrids are suitable for exploration of ferroelectricity. Therefore, the design of molecular ferroelectric semiconductors based on these hybrids provides a possibility to obtain new or high-performance semiconductor ferroelectrics. Here we investigated Pb-layered perovskites, and found the layer perovskite (benzylammonium)₂PbCl₄ is ferroelectric with semiconducting behaviours. It has a larger ferroelectric spontaneous polarization P_s=13 μC cm⁻² and a higher Curie temperature T_c=438 K with a band gap of 3.65 eV. This finding throws light on the new properties of the hybrid organo-plumbate or stannate compounds and provides a new way to develop new semiconductor ferroelectrics.

Lead-halide perovskite compounds have seen a considerable interest for their optoelectronic properties. Here, the authors discover a ferroelectric halide perovskite compound as an alternative pathway towards designing semiconductor ferroelectrics.

Phase transitions and dielectric properties of a hexagonal ABX3 perovskite-type organic–inorganic hybrid compound: [C3H4NS][CdBr3]

The perovskite-type hybrid thiazolium tribromocadmate(ii) exhibits two phase transitions at 180 and 146 K, accompanied by remarkable dielectric responses.

Insight into the molecular dynamics of guest cations confined in deformable azido coordination frameworks

The guest molecular dynamics confined in deformable azido coordination frameworks are revealed, one of which features unvaried/varied E_a during its two structural phase transitions.