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.

We report the synthesis and characterization of (Ph 4 P) 2 SbCl 5 , a novel ionically bonded organic metal halide hybrid with a zero-dimensional (0D) structure at the molecular level. By cocrystallization of tetraphenylphosphonium (Ph 4 P + ) and antimony (Sb 3+ ) chloride salts, (Ph 4 P) 2 SbCl 5 bulk single crystals can be prepared in high yield, which exhibit a highly efficient broadband red emission peaked at 648 nm with a photoluminescence quantum efficiency (PLQE) of around 87%. Density functional theory (DFT) calculations reveal the origin of emission as phosphorescence from the excitons localized at SbCl 5 2− with strong excited-state structural distortion. Interestingly, (Ph 4 P) 2 SbCl 5 bulk crystals with a PLQE of around 100% can be prepared via a rapid crystal growth process within minutes, followed by a spontaneous structural transformation. It was found that the rapid growth process yielded a yellow emitting kinetically favored metastable product containing solvent molecules, which turned into the red emitting thermodynamically stable product slowly at room temperature or quickly upon thermal treatment.

The rich chemistry of organic-inorganic metal halide hybrids has enabled the development of a variety of crystalline structures with controlled morphological and molecular dimensionalities. Here we report for the first time a single crystalline assembly of metal halide clusters, (CNH)(PbCl)PbCl, in which lead chloride tetrahedrons (PbCl) and face-sharing lead chloride trimer clusters (PbCl) cocrystallize with organic cations (CNH) to form a periodical zero-dimensional (0D) structure at the molecular level. Blue light emission peaked at 470 nm with a photoluminescence quantum efficiency (PLQE) of around 83% was realized for this single crystalline hybrid material, which is attributed to the individual lead chloride clusters. Our discovery of single crystalline assembly of metal halide clusters paves a new path to functional cluster assemblies with highly tunable structures and remarkable properties.

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.

Organic−inorganic metal halide hybrids have emerged as a new class of materials with fascinating optical and electronic properties. The exceptional structure tunability has enabled the development of materials with various dimensionalities at the molecular level, from threedimensional (3D) to 2D, 1D, and 0D. Here, we report a new 1D lead chloride hybrid, C 4 N 2 H 14 PbCl 4 , which exhibits unusual inverse excitation-dependent broadband emission from bluish-green to yellow. Density functional theory calculations were performed to better understand the mechanism of this excitation-dependent broadband emission. This 1D hybrid material is found to have two emission centers, corresponding to the self-trapped excitons (STEs) and vacancy-bound excitons. The excitation-dependent emission is due to different populations of these two types of excitons generated at different excitation wavelengths. This work shows the rich chemistry and physics of organic− inorganic metal halide hybrids and paves the way to achieving novel light emitters with excitation-dependent broadband emissions at room temperature.

Zero-dimensional (0D) organic metal halide hybrids are an emerging class of light emitting materials with exceptional photoluminescence quantum efficiencies (PLQEs), thanks to their perfect "host−guest" structures with light emitting metal halide species periodically "embedded" in a wide band gap organic cationic matrix through ionic bonds. However, achieving efficient blue emissions is challenging for this class of materials, as structural distortions of metal halides often lead to large Stokes shifts. Here we report a highly luminescent blue emitting 0D organic lead bromide, (C 13 H 19 N 4 ) 2 PbBr 4 , with a peak emission of 460 nm (2.70 eV), a full width at half maximum (FWHM) of 66 nm (0.40 eV), a Stokes shift of 111 nm (0.85 eV), and a PLQE of ∼40%. Single crystal structure analysis shows that individual PbBr 4 2− species adopt a nearseesaw structure, which are coordinated to benzyl-hexamethylenetetrammonium (C 13 H 19 N 4 + ) organic cations. The relatively small Stokes shift as compared to those of previously reported 0D organic metal halide hybrids are attributed to the low chemical reactivity of Pb 6s 2 lone pairs and the rigid organic cationic matrix. (C 13 H 19 N 4 ) 2 PbBr 4 also shows exceptional stability in air with little-to-no change of properties for more than a year in ambient conditions.