Crystal and Band-Gap Engineering of One-Dimensional Antimony/Bismuth-Based Organic-Inorganic Hybrids

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.

One-Dimensional Organic-Inorganic Lead Bromide Hybrids with Excitation-Dependent White-Light Emission Templated by Pyridinium Derivatives

Organic-inorganic hybrid metal halides have attracted widespread attention due to their excellent tunability and versatility. Here, we have selected pyridinium derivatives with different substituent groups or substitution positions as the organic templating cations and obtained six 1D chain-like structures. They are divided into three types: type I (single chain), type II (double chain), and type III (triple chain), with tunable optical band gaps and emission properties. Among them, only (2,4-LD)PbBr₃ (2,4-LD = 2,4-lutidine) shows an exciton-dependent emission phenomenon, ranging from strong yellow-white to weak red-white light. By comparing its photoluminescence spectrum with that of its bromate (2,4-LD)Br, it is found that the strong yellow-white emission at 534 nm mainly came from the organic component. Furthermore, through a comparison of the fluorescence spectra and lifetimes of (2,4-LD)PbBr₃ and (2-MP)PbBr₃ (2-MP = 2-methylpyridine) with similar structures at different temperatures, we confirm that the tunable emission of (2,4-LD)PbBr₃ comes from different photoluminescent sources corresponding to organic cations and self-trapped excitons. Density functional theory calculations further reveal that (2,4-LD)PbBr₃ has a stronger interaction between organic and inorganic components compared to (2-MP)PbBr₃. This work highlights the importance of organic templating cations in hybrid metal halides and the new functionalities associated with them.

Unusual isostructural Br/I substitution effect on the crystal structure and optical properties of hybrid halobismuthates

The gradual change of the optical properties of solid solutions by variation of the halogen composition is shown.

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.

Recent advances on structural, thermal, vibrational, optical, phase transitions, and catalysis properties of alkylenediammonium halogenometallate materials (Metal: Bi, Sb, Halogen: Cl, Br, I)

This paper aims to review recent advances on synthesis, crystal structures, thermal, spectroscopic, phase transitions, optical, dielectric, and catalysis properties of hydrate and anhydrous alkylenediammonium halogenometallates materials (Metal: Bi, Sb, Halogen: Cl, Br, I). These hybrid materials present rich structural diversities based on octahedra forming infinite zero dimensional, 1-dimensional chains, 2-dimensional layers, discrete bioctahedra, and discrete tetramer units. The effect, contribution and importance of hydrogen bonding N–H … X (X: Cl, Br, I) are reviewed in terms of solid state relationship. Particularly, a comparative study is made on hydrate and anyhdrous aliphatic chlorobismuthates with alkylenediammonium +NH3(CH2) n NH3 + based on structural data and V/Z variation with (CH2) n chains (n = 2–8, 12), and variation of BiCl6 3− Raman frequencies modes versus (CH2) n chains (n = 3–8). Hydrate salts with (n = 3, 12) consist of isolated BiCl6 3− anions and two water molecules, against others ones with isolated anionic chains [BiCl5 2−] n or Bi2Cl10 4− dimers, formed by distorted octahedra BiCl6 3− sharing corners, vices or edges. The reviewed optical and electronic band gaps suggested interesting compounds with band gaps (1.85–2.4 eV), as suitable materials in optoelectronic properties, photoactive layer in solution-processed photovoltaics, and bio-imaging or photovoltaic applications. It was concluded that iodobismuthate salts have generally the lowest bands gap, compared to that of bromo and chlorobismuthate slats. Catalysis proprieties are reviewed n fast (RhB) degradation under dark conditions for (C4N2H7)4Bi2Cl10, (C5H9N2)BiI4, and {(H-BPA)4·[(BiI6)I13]·2I3} n , and in organic salts synthesis under solvent-free conditions. Herein NH3(CH2) n NH3BiCl5 (n = 5–7) salts were used as highly efficient catalysts, which is a novel tendency in chlorobismuthate researchs in the green chemistry field.

Small Organic Molecular-Based Hybrid Halides with High Photoluminescence Quenching Temperature

Organic-inorganic metal halides (OIMHs) exhibit excellent photoelectric properties; however, their high-temperature light-emission stability requires further improvement. Here, we report three isostructural OIMHs (C₂H₈N)₄InCl₇, (C₂H₈N)₄SbCl₇, and (C₂H₈N)₄SbBr₇ (C₂H₈N⁺ = dimethylammonium). They are all crystallized in the P2₁2₁2 space group with a zero-dimensional (0D) structure, with orange-red photoluminescence (PL) under 365 nm UV excitation. Among them, (C₂H₈N)₄InCl₇ exhibits the strongest PL with a photoluminescence quantum yield (PLQY) of 13.9% at room temperature. Optical property measurements and density functional theory unveil that the luminescence of (C₂H₈N)₄InCl₇ at 405 and 620 nm is due to free exciton and self-trapped exciton emission, respectively. It is worth noting that (C₂H₈N)₄InCl₇ shows a high PL quenching temperature, maintaining 50% of its room-temperature PL intensity at 425 K, which is rare in OIHMs. This is much higher than the application temperature of phosphors in practical solid-state lighting applications (363-383 K). In this temperature range, the luminous intensity of (C₂H₈N)₄InCl₇ exceeds 60% of that at room temperature. The high PL quenching temperature observed in (C₂H₈N)₄InCl₇ indicates the potential of OIMHs for applications in phosphor-converted light-emitting diodes.

Synthesis and first-principles study of structural, electronic and optical properties of tetragonal hybrid halobismuthathes [Py2(XK)]2[Bi2Br10−xIx]

Tuning the optical properties of solid solutions by variation of the halogen composition.

Assembling Polyiodides and Iodobismuthates Using a Template Effect of a Cyclic Diammonium Cation and Formation of a Low-Gap Hybrid Iodobismuthate with High Thermal Stability

Exploiting a template effect of 1,4-diazacycloheptane (also known as homopiperazine, Hpipe), four new hybrid iodides, (HpipeH₂)₂Bi₂I₁₀·2H₂O, (HpipeH₂)I(I₃), (HpipeH₂)₃I₆·H₂O, and (HpipeH₂)₃(H₃O)I₇, were prepared and their crystal structures were solved using single crystal X-ray diffraction data. All four solid-state crystal structures feature the HpipeH₂²⁺ cation alternating with Bi₂I₁₀^4–, I₃^–, or I^– anions and solvent water or H₃O⁺ cation. HpipeH₂²⁺ assembles anionic and neutral building blocks into polymer structures by forming four strong (N)H···I and (N)H···O hydrogen bonds per cation, with the H···I distances ranging from 2.44 to 2.93 Å and H···O distances of 1.88–1.89 Å. These hydrogen bonds strongly affect the properties of compounds; in particular, in the case of (HpipeH₂)₂Bi₂I₁₀·2H₂O, they ensure narrowing of the band gap down to 1.8 eV and provide high thermal stability up to 240 °C, remarkable for a hydrated molecular solid.

Non-transient thermo-/photochromism of iodobismuthate hybrids directed by solvated metal cations

Two iodobismuthate-based organic-inorganic hybrids, [M(DMSO)₈][Bi₂I₉] (M = La (1), Bi (2)), have been successfully designed and synthesized by using solvated metal cations as structure-directing agents (SDAs). 1 displays transient high-temperature thermochromism, which is similar to that of the characteristic low-temperature thermochromic properties of bulk bismuth iodide and iodobismuthate hybrids. In contrast, 2 exhibits distinguishing non-transient thermochromic properties stimulated by the different temperature ranges of the thermal treatments. More importantly, a comparison of the optical inertness of 1 and 2 also reveals novel photochromic behavior. The completely different thermo-/photo-responsive properties of 1 and 2 are mainly ascribed to the different binding abilities of the central metal cations with DMSO molecules, which cause a distinct transformation of the inorganic moiety and consequent modulation of band gaps.

A chiral lead-free photoactive hybrid material with a narrow bandgap

A chiral lead-free hybrid of (C₅H₁₁N₃)SbI₅ was synthesized that exhibits a narrow bandgap, typical semiconducting behavior and notable photoresponse.

Effect of positional isomers on the photochromic behaviors of bipyridyltriazolium chloroantimonate hybrids

Two chloroantimonates with isomeric bipyridyltriazoliums exhibit distinct photochromic behaviors, of which 1 is the first reported photochromic chloroantimonate hybrid.