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Scintillators are utilized for X-ray detection in many important fields ranging from homeland security to health care. Developing low-cost, high-performance scintillation materials to address the issues of existing commercially available ones is of great interest. Recently, organic metal halide hybrids have emerged as highly promising luminescent materials with excellent optical properties and low-temperature solution processability. Herein, we report a zero-dimensional organic metal halide hybrid, (PPN)2SbCl5 (PPN = bis­(triphenylphosphoranylidene)­ammonium cation), as an X-ray scintillation material with high light yield and exceptional environmental stability. Our study shows that (PPN)2SbCl5 single crystals prepared by solution growth exhibit visible photoluminescence with a quantum efficiency of 98.1%. When excited by X-rays, (PPN)2SbCl5 single crystals exhibit radioluminescence with a near-perfect linearity over a large range of X-ray dose rates and a light yield of ∼49000 ph MeV–1, which is comparable to that of a commercial CsI­(Tl) scintillator (∼54000 ph MeV–1). Moreover, the detection limit of (PPN)2SbCl5 (191.4 nGyair s–1) is much lower than the required value for regular medical diagnostics (5.5 μGyair s–1). (PPN)2SbCl5 single crystals also display remarkable stability, with little-to-no change in properties after storage under ambient conditions for 2 years.

Organic metal halide hybrids with zero-dimensional (0D) structure at the molecular level, or single-crystalline bulk assemblies of metal halides, are an emerging class of light-emitting materials with high photoluminescence quantum efficiencies (PLQEs) and color tunability. Here we report the synthesis and characterization of a new single-crystalline bulk assembly of metal halide clusters, (bmpy) 9 [ZnCl 4 ] 2 [Pb 3 Cl 11 ] (bmpy: 1-butyl-1-methylpyrrolidinium), which exhibits green emission peaked at 512 nm with a remarkable near-unity PLQE at room temperature. Detailed structural and photophysical studies suggest that there are two emitting states in [Pb 3 Cl 11 ] 5− clusters, whose populations are strongly dependent on the surrounding molecular environment that controls the excitedstate structural distortion of [Pb 3 Cl 11 ] 5− clusters. High chemical-and photostability have also been demonstrated in this new material.

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Tin halide perovskites and perovskite-related materials have emerged as promising lead-free hybrid materials for various optoelectronic applications. While remarkable progress has been achieved in the development of organic tin halide hybrids with diverse structures and controlled dimensionalities at the molecular level, some controversial results that have been reported recently need to be addressed. For instance, different photophysical properties have been reported for two-dimensional (2D) (PEA)2SnBr4 (PEA = phenylethylammonium) by several groups with distinct emission peaks at around 468 and 550 nm. Here we report our efforts in the synthesis of phenylethylammonium tin bromide hybrids with zero-dimensional (0D) and 2D structures, and characterizations of their structural and photophysical properties. 0D [(PEA)4SnBr6]­[(PEA)­Br]2[CCl2H2]2 was found to exhibit strong yellow emission peak at 566 nm with a photoluminescence quantum efficiency (PLQE) of ∼90%, while 2D (PEA)2SnBr4 had weak emission peak at 470 nm with a PLQE of <0.1%. Interestingly, 0D [(PEA)4SnBr6]­[(PEA)­Br]2[CCl2H2]2 can be converted into 2D (PEA)2SnBr4 upon drying, which would return to 0D [(PEA)4SnBr6]­[(PEA)­Br]2[CCl2H2]2 upon addition of dichloromethane. Powder X-ray diffraction results confirmed the reversible transformation between 0D and 2D structures. Density functional theory calculations showed that excitons in 0D [(PEA)4SnBr6]­[(PEA)­Br]2[CCl2H2]2 are highly localized, resulting in a strongly Stokes shifted broadband emission, while delocalized electronic states in 2D (PEA)2SnBr4 result in weaker exciton binding, a higher exciton mobility, and a higher nonradiative decay.