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

Abstract

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.

Circularly Polarized Luminescence Induced by Hydrogen‐Bonding Networks in a One‐Dimensional Hybrid Manganese(II) Chloride

“…Circularly polarized light is of strong interest in diverse optoelectronic fields, including information encryption, security inks, tomographic scanning, and optical sensors. [1][2][3][4] Chiral luminescent materials can directly emit left-or righthanded circularly polarized luminescence (CPL), significantly minimizing energy losses and facilitating device miniaturization. Over the years, organic small molecules, polymers, inorganic nanostructures, and liquid crystal complexes have been the main sources of CPL-active materials.…”

Polymeric polyiodo-chlorotellurates(iv): new supramolecular hybrids in halometalate chemistry

“…Metal halide complexes, or halometalates (HMs), are classical objects of coordination chemistry. Being known for many decades, 1–8 they find application in photocatalysis, 9–13 optical devices, 14–16 photodetectors, 17,18 X-ray imaging 19–21 etc. Due to the increasing energy demand, the search for new energy sources has stimulated the development of new photovoltaic materials.…”