Enhanced Circular Dichroism and Polarized Emission in an Achiral, Low Band Gap Bismuth Iodide Perovskite Derivative

Lead halide perovskites and related main-group halogenido metalates offer unique semiconductor properties and diverse applications in photovoltaics, solid-state lighting, and photocatalysis. Recent advances in incorporating chiral organic cations have led to the emergence of chiral metal-halide semiconductors with intriguing properties, such as chiroptical activity and chirality-induced spin selectivity, enabling the generation and detection of circularly polarized light and spin-polarized electrons for applications in spintronics and quantum information. However, understanding the structural origin of chiroptical activity remains challenging due to macroscopic factors and experimental limitations. In this work, we present an achiral perovskite derivative [Cu2(pyz)3(MeCN)2][Bi3I11] (CuBiI; pyz = pyrazine; MeCN = acetonitrile), which exhibits remarkable circular dichroism (CD) attributed to the material's noncentrosymmetric nature. CuBiI features a unique structure as a poly-threaded iodido bismuthate, with [Bi3I11]2- chains threaded through a cationic two-dimensional coordination polymer. The material possesses a low, direct optical band gap of 1.70 eV. Notably, single crystals display both linear and circular optical activity with a large anisotropy factor of up to 0.16. Surprisingly, despite the absence of chiral building blocks, CuBiI exhibits a significant degree of circularly polarized photoluminescence, reaching 4.9%. This value is comparable to the results achieved by incorporating chiral organic molecules into perovskites, typically ranging from 3-10% at zero magnetic field. Our findings provide insights into the macroscopic origin of CD and offer design guidelines for the development of materials with high chiroptical activity.

Influence of interaction between organic cation and inorganic unit in bi-based hybrid perovskites for photoelectronic properties

With the increase of the passion on lead-free perovskites, more and more endeavor focused on halobismuthates. Here, we have introduced the p-iodoaniline and p-phenylenediamine into Bi-based hybrid materials, and two photoactive iodobismuthate named p-phenylenediamine iodobismuthate (PDABI) and p-iodoaniline iodobismuthate (PIDBI) were prepared. Their single structures, band gaps, thermostability and other properties were explored. The structure results revealed that they all have 1D BiI₄ ^- anion chains with edge-shared BiI₆ octahedron. The DFT result revealed that PIDBI had an inherent interaction between the I substituent in p-iodoaniline cation and the Bi atom in inorganic BiI₄ ^- anion chains. The photodetector assembled by PDABI and PIDBI revealed that the interaction provided by symmetric p-phenylenediamine has a positive effect on PIDBI's optoelectronic properties compared to the role of asymmetric p-iodoaniline in PDABI.

Preparation of Bismuth Tungstate Nanomaterials with Different Morphologies and Their Effect on Exercise Rehabilitation of Patients with Lumbar Disc Herniation

It is understood that the effect of exercise rehabilitation drugs in patients with lumbar disc herniation is poor. Some studies have shown that bismuth tungstate nanomaterials with certain morphology can treat the exercise rehabilitation of patients with lumbar disc herniation. In order to help patients with lumbar disc herniation to a certain extent, in this paper, bismuth tungstate nanomaterials with different structures and morphologies were prepared by hydrothermal method, and viscous tungsten nanomaterials with different structures and morphologies were prepared by adjusting the pH value of the solution and the concentration of CTAB. In this paper, the structure and morphology of tungsten samples with different structure and morphology were characterized by CTAB X-ray (XRD) deflection and FESEM. It was found that the morphology of the samples changed after adding 0.02 mol/L surfactant CTAB in the reaction system, and when the concentration of CTAB was 0.04 mol/L, the nanotubes were stacked together under the action of surfactant. When the concentration of CTAB increased to 0.06 mol/L, the self-assembled nanocomposites tended to be petal like.

Bismuth(III) Iodide Complexes with 1-Ethyl-4-Dimethylaminopyridinium: Structure, Thermal Stability, and Optical Properties

Abstract

Polynuclear bismuth(III) iodide complexes with 1-ethyl-4-dimethylaminopyridinium (1-EtDMAP)4[Bi8I28] (1) and (1-EtDMAP)BiI4 (2) have been obtained by the reactions of bismuth(III) iodide with an organic iodide salt cations in organic solvents and characterized by X-ray diffraction. The optical properties and thermal stability of the obtained compounds have been studied.

Guanidinium sulfates as directors of noncentrosymmetric structures

Guanidinium sulfate hydrogen bonding networks are found to have a remarkable tendency to crystallize in noncentrosymmetric, chiral, and polar frameworks.

Semiconducting crystalline inorganic-organic hybrid metal halide nanochains

One-dimensional (1D) inorganic-organic metal halide hybrids at the molecular level, which can be considered as arrays of nanochains isolated by organic components, have shown remarkable optical and electric properties. This review summarizes their reported structural types and shows how to modify their band gaps and optical and electric properties.

11/15/17 Complexes as Molecular Models for Metal Halide Double Perovskite Materials

Thirteen neutral complexes [E _xM _yX _z(PPh₃) _n(L) _m] (E = Bi, Sb; M = Cu, Ag; X = Cl, Br, I; L = solvent) featuring three different motifs were prepared and characterized regarding their structure, stability, and absorption spectra. While not identical in structural motif, the compounds can serve as models for the influence of the composition E/M/X on the optical properties of double perovskites A₂EMX₆ (A = Cs, CH₃NH₃).

Diimidazolium Halobismuthates [Dim]2[Bi2X10] (X = Cl-, Br-, or I-): A New Class of Thermochromic and Photoluminescent Materials

We present a novel family of polyhalide salts of Bi(III) with the general formula [Dim]₂[Bi₂X₁₀], where Dim²⁺ is the diimidazolium cation (C₉H₁₄N₄)²⁺ and X is Cl^-, Br^-, or I^-. Single-phase materials are easily obtained by means of a mild solution chemistry method performed at room temperature. This [Dim]₂[Bi₂X₁₀] family exhibits a crystal structure based on halobismuthate [Bi₂X₁₀]^4- dimers, built by distorted {BiX₆} octahedra interconnected by edge sharing, and sandwiched between two diimidazolium cations. The optical band gaps displayed by these materials (1.9-3.2 eV) allow their classification as semiconductors. Additionally, the three halides display photoluminescence with emission in the visible range. The behavior of [Dim]₂[Bi₂I₁₀] is particularly interesting, as it shows an optical band gap of 1.9 eV, a broad band photoluminescence emission, and a relatively long emission lifetime of 190 ns. Moreover, the iodide and bromide compounds also exhibit a reversible solid state thermochromism, being the first example of a bromobismuthate with this property. The diimidazolium cations play an important structural role by stabilizing the crystal structure and balancing the charges of the [Bi₂X₁₀]^4- dimers. Furthermore, density functional theory calculations suggest that they play a key role in the thermochromic behavior. Therefore, compounds [Dim]₂[Bi₂X₁₀] (X = Cl^-, Br^-, or I^-) represent a very versatile family in which the optical band gap can be tuned by changing the halide or temperature. This makes them promising new materials for different optoelectronic applications, in particular for obtaining new solar absorbers.

Reversible solid-state thermochromism of a 2D organic–inorganic hybrid perovskite structure based on iodoplumbate and 2-aminomethyl-pyridine

An organic–inorganic hybrid solid [(PyCH₂NH₃)₆][Pb₅I₂₂]·3H₂O with a 2D inorganic layer exhibited a reversible color change from orange to red at 80 °C in the solid state.