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A computational investigation is presented, in conjunction with synthesis and experimental characterization, into the structural, electronic, and optical properties of layered two‐dimensional organic lead bromide perovskites. Materials based on the chiral (R/S)‐4‐fluoro‐α‐methylbenzylammonium (R/S‐FMBA), which have been shown to lead to bright room‐temperature circularly polarized luminescence, are contrasted with the similar achiral 4‐fluorobenzylammonium (FBA). Using density functional theory (DFT) with van der Waals (vdW) corrections, relaxed structures (compared with X‐ray diffraction, XRD) and optical absorption spectra (compared with experiments) are studied, as well as band structure and orbital character of transitions. A Python code is developed and provided to calculate octahedral distortions and compare DFT and XRD results, finding that vdW corrections are important for accuracy and that DFT overestimates octahedral tilt angles. (FMBA)₂PbBr₄shows among the largest tilt angle differences (often termed ) reported, 14°–15°, indicating strong inversion symmetry‐breaking, which enables its chiral emission. A large resulting Dresselhaus spin‐splitting effect is found. The lowest‐energy optical transitions involve the perovskite only and are polarized within the layer. This work furthers understanding of structure‐property relations with applications to optoelectronics and spintronics. 

Abstract Low dimensional (LD) organic metal halide hybrids (OMHHs) have recently emerged as new generation functional materials with exceptional structural and property tunability. Despite the remarkable advances in the development of LD OMHHs, optical properties have been the major functionality extensively investigated for most of LD OMHHs developed to date, while other properties, such as magnetic and electronic properties, remain significantly under‐explored. Here, we report for the first time the characterization of the magnetic and electronic properties of a 1D OMHH, organic‐copper (II) chloride hybrid (C₈H₂₂N₂)Cu₂Cl₆. Owing to the antiferromagnetic coupling between Cu atoms through chloride bridges in 1D [Cu₂Cl₆²⁻]_∞chains, (C₈H₂₂N₂)Cu₂Cl₆is found to exhibit antiferromagnetic ordering with a Néel temperature of 24 K. The two‐terminal (2T) electrical measurement on a (C₈H₂₂N₂)Cu₂Cl₆single crystal reveals its insulating nature. This work shows the potential of LD OMHHs as a highly tunable quantum material platform for spintronics. 

Organic metal halide hybrids with low-dimensional structures at the molecular level have received great attention recently for their exceptional structural tunability and unique photophysical properties. Here we report for the first time the synthesis and characterization of a one-dimensional (1D) organic metal halide hybrid, which contains metal halide nanoribbons with a width of three octahedral units. It is found that this material with a chemical formula C 8 H 28 N 5 Pb 3 Cl 11 shows a dual emission with a photoluminescence quantum efficiency (PLQE) of around 25%. Photophysical studies and density functional theory (DFT) calculations suggest the coexisting of delocalized free excitons and localized self-trapped excitons in metal halide nanoribbons leading to the dual emission. 

1D organic metal halide hybrids (OMHHs) exhibit strongly anisotropic optical properties, highly efficient light emission, and large Stokes shift, holding promise for novel photodetection and lighting applications. However, the fundamental mechanisms governing their unique optical properties and in particular the impacts of surface effects are not understood. Herein, 1D C4N2H14PbBr4 by polarization-dependent time-averaged and time-resolved photoluminescence (TRPL) spectroscopy, as a function of photoexcitation energy, is investigated. Surprisingly, it is found that the emission under photoexcitation polarized parallel to the 1D metal halide chains can be either stronger or weaker than that under perpendicular polarization, depending on the excitation energy. The excitation-energy-dependent anisotropic emission is attributed to fast surface recombination, supported by first-principles calculations of optical absorption in this material. The fast surface recombination is directly confirmed by TRPL measurements, when the excitation is polarized parallel to the chains. The comprehensive studies provide a more complete picture for a deeper understanding of the optical anisotropy in 1D OMHHs.