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  1. Abstract

    Organic metal halide hybrids (OMHHs) have attracted great research attention owing to their exceptional structure and property tunability. Using appropriate organic and inorganic metal halide components, OMHHs with controlled dimensionalities at the molecular level, from 3D to 2D, 1D, and 0D structures, can be obtained. In 0D OMHHs, anionic metal halide polyhedrons are surrounded and completely isolated by organic cations to form single crystalline “host–guest” structures. These ionically bonded organic–inorganic hybrid systems often exhibit the intrinsic properties of individual metal halide species, for instance, highly efficient Stokes‐shifted broadband emissions. In this progress report, the recent advances in the development and study of luminescent 0D OMHHs are discussed: from synthetic structural control to fundamental understanding of the structure–property relationship and device integration.

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  2. Abstract

    Scintillation based X-ray detection has received great attention for its application in a wide range of areas from security to healthcare. Here, we report highly efficient X-ray scintillators with state-of-the-art performance based on an organic metal halide, ethylenebis-triphenylphosphonium manganese (II) bromide ((C38H34P2)MnBr4), which can be prepared using a facile solution growth method at room temperature to form inch sized single crystals. This zero-dimensional organic metal halide hybrid exhibits green emission peaked at 517 nm with a photoluminescence quantum efficiency of ~ 95%. Its X-ray scintillation properties are characterized with an excellent linear response to X-ray dose rate, a high light yield of ~ 80,000 photon MeV−1, and a low detection limit of 72.8 nGy s−1. X-ray imaging tests show that scintillators based on (C38H34P2)MnBr4powders provide an excellent visualization tool for X-ray radiography, and high resolution flexible scintillators can be fabricated by blending (C38H34P2)MnBr4powders with polydimethylsiloxane.

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  3. Abstract

    The photophysical tuning is reported for a series of tetraphenylphosphonium (TPP) metal halide hybrids containing distinct metal halides, TPP2MXn(MXn=SbCl5, MnCl4, ZnCl4, ZnCl2Br2, ZnBr4), from efficient phosphorescence to ultralong afterglow. The afterglow properties of TPP+cations could be suspended for the hybrids containing low band gap emissive metal halide species, such as SbCl52−and MnCl42−, but significantly enhanced for the hybrids containing wide band gap non‐emissive ZnCl42−. Structural and photophysical studies reveal that the enhanced afterglow is attributed to stronger π–π stacking and intermolecular electronic coupling between TPP+cations in TPP2ZnCl4than in the pristine organic ionic compound TPPCl. Moreover, the afterglow in TPP2ZnX4can be tuned by controlling the halide composition, with the change from Cl to Br resulting in a shorter afterglow due to the heavy atom effect.

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  4. Abstract

    Mechanochemical synthesis has emerged as a facile method for the preparation of a wide range of organic, inorganic, and polymeric materials. Here, we report the use of mechanochemical synthesis for the preparation of ionically bonded organic metal halide hybrids with a zero‐dimensional (0D) structure at the molecular level. (Ph4P)2SbCl5and (Ph4P)2MnCl4were synthesized by grinding appropriate ratios of organic halide salt Ph4PCl with inorganic metal halide salts SbCl3and MnCl2, respectively. The structural and photophysical properties of mechanochemically synthesized (Ph4P)2SbCl5and (Ph4P)2MnCl4were characterized, which are almost identical to those of single crystals prepared by slow solution growth. By reacting Ph4PCl with both SbCl3and MnCl2, we have been able to produce a mixture of two 0D organic metal halide hybrids that exhibit a dual emission covering a wide range of the spectrum with Commission Internationale de l'Eclairage (CIE) coordinates of (0.4898, 0.4800). Our work has clearly established mechanochemical synthesis as an effective method to produce ionically bonded organic‐inorganic hybrids.

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  5. Abstract

    Organic metal halide hybrids have attracted tremendous research interests owing to their outstanding optical and electronic properties suitable for various applications, including photovoltaics, light‐emitting diodes, and photodetectors. Recently, the multifunctionality of this class of materials has been further explored beyond their optical and electronic properties. Here, for the first time the microwave electromagnetic properties of a 1D organic metal halide hybrid, (C6H13N4)3Pb2Br7, a single crystalline bulk assembly of organic metal halide nanotubes, are reported. Good microwave absorption performance with a large reflection loss value of −18.5 dB and a threshold bandwidth of 1.0 GHz is discovered for this material, suggesting its potential as a new microwave absorber. This work reveals a new functionality of organic metal halide hybrids and provides a new material class for microwave absorption application studies.

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  6. Abstract

    Zero‐dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)4PbMn0.69Sn0.31Br8, in which the organic cationN‐benzylhexamethylenetetrammonium (HMTA+, C13H19N4+) cocrystallizes with PbBr42−, MnBr42−, and SnBr42−. The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single‐crystalline “host–guest” system to exhibit emissions from multiple “guest” metal halide species simultaneously. The combination of these emissions led to near‐perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm‐ to cool‐white emissions could be generated by controlling the excitation wavelength.

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  7. Abstract

    The family of molecular level low‐dimensional organic metal halide hybrids has expanded significantly over the last few years. Here a new type of 1D metal halide structure is reported, in which metal halide octahedra form a corrugated double‐chain structure via nonplanar edge‐sharing. This material with a chemical formula of C5H16N2Pb2Br6exhibits a broadband yellow emission under ultraviolet light excitation with a photoluminescence quantum efficiency of around 10%. The light‐yellow emission is considered to be attributed to self‐trapping excitons. Theoretical calculations show that the unique alignment of the octahedra leads to small band dispersion and large exciton binding energy. Together with previously reported 1D metal halide wires and tubes, this new bulk assembly of 1D metal halides suggests the potential to develop a library of bulk assemblies of metal halides with controlled structures and compositions.

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  8. Abstract

    Perovskite light‐emitting diodes (LEDs) have recently attracted great research interest for their narrow emissions and solution processability. Remarkable progress has been achieved in green perovskite LEDs in recent years, but not blue or red ones. Here, highly efficient and spectrally stable red perovskite LEDs with quasi‐2D perovskite/poly(ethylene oxide) (PEO) composite thin films as the light‐emitting layer are reported. By controlling the molar ratios of organic salt (benzylammonium iodide) to inorganic salts (cesium iodide and lead iodide), luminescent quasi‐2D perovskite thin films are obtained with tunable emission colors from red to deep red. The perovskite/polymer composite approach enables quasi‐2D perovskite/PEO composite thin films to possess much higher photoluminescence quantum efficiencies and smoothness than their neat quasi‐2D perovskite counterparts. Electrically driven LEDs with emissions peaked at 638, 664, 680, and 690 nm have been fabricated to exhibit high brightness and external quantum efficiencies (EQEs). For instance, the perovskite LED with an emission peaked at 680 nm exhibits a brightness of 1392 cd m−2and an EQE of 6.23%. Moreover, exceptional electroluminescence spectral stability under continuous device operation has been achieved for these red perovskite LEDs.

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  9. Abstract

    The synthesis and characterization is reported of (C9NH20)2SnBr4, a novel organic metal halide hybrid with a zero‐dimensional (0D) structure, in which individual seesaw‐shaped tin (II) bromide anions (SnBr42−) are co‐crystallized with 1‐butyl‐1‐methylpyrrolidinium cations (C9NH20+). Upon photoexcitation, the bulk crystals exhibit a highly efficient broadband deep‐red emission peaked at 695 nm, with a large Stokes shift of 332 nm and a high quantum efficiency of around 46 %. The unique photophysical properties of this hybrid material are attributed to two major factors: 1) the 0D structure allowing the bulk crystals to exhibit the intrinsic properties of individual SnBr42−species, and 2) the seesaw structure enabling a pronounced excited state structural deformation as confirmed by density functional theory (DFT) calculations.

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