Single crystalline zero-dimensional organic metal halide hybrids have been developed.

Organic-inorganic hybrid metal halide perovskites have emerged as a highly promising class of light emitters, which can be used as phosphors for optically pumped white light-emitting diodes (WLEDs). By controlling the structural dimensionality, metal halide perovskites can exhibit tunable narrow and broadband emissions from the free-exciton and self-trapped excited states, respectively. Here, we report a highly efficient broadband yellow light emitter based on zero-dimensional tin mixed-halide perovskite (CNHBr)SnBrI (x = 3). This rare-earth-free ionically bonded crystalline material possesses a perfect host-dopant structure, in which the light-emitting metal halide species (SnBrI, x = 3) are completely isolated from each other and embedded in the wide band gap organic matrix composed of CNHBr. The strongly Stokes-shifted broadband yellow emission that peaked at 582 nm from this phosphor, which is a result of excited state structural reorganization, has an extremely large full width at half-maximum of 126 nm and a high photoluminescence quantum efficiency of ∼85% at room temperature. UV-pumped WLEDs fabricated using this yellow emitter together with a commercial europium-doped barium magnesium aluminate blue phosphor (BaMgAlO:Eu) can exhibit high color rendering indexes of up to 85.

The susceptibility of zeolites to hot liquid water may hamper their full utilization in aqueous phase processes, such as those involved in biomass conversion and upgrading reactions. Interactions of zeolites with water strongly depend on the presence of hydrophilic moieties including Brønsted acid sites (BAS), extraframework cations, and silanol defects, which facilitate wetting of the surface. However, it is not clear which of these moieties are responsible for the susceptibility of zeolites to liquid water. Previous studies have offered contradictory explanations because the role of each of these characteristics has not been investigated independently. In this work, a systematic comparison has been attempted by relating crystallinity losses to the variation of each of the five zeolite characteristics that may influence their stability in liquid water, including number of BAS, Si-O-Si bonds, framework type, silanol defects, and extraframework Al. In this study, we have systematically monitored the crystallinity changes of a series of HY, H-ZSM-5, and H-β zeolite samples with varying Si/Al ratio, density of BAS, zeolite structure, and density of silanol defects upon exposure to liquid water at 200 °C. The results of this comparison unambiguously indicate that the density of silanol defects plays the most crucial role in determining susceptibility of zeolites to hot liquid water. By functionalizing the silanol defects with organosilanes, the hydrophobicity of defective zeolite is increased and the tolerance to hot liquid water is significantly enhanced.

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.

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.