Copper Halides Research Articles

Solution-Processable Copper Halide Based Hybrid Materials Consisting of Cationic Ligands with Different Coordination Modes

Using cationic ligands containing both aromatic and aliphatic coordination sites, we have synthesized and structurally characterized five new CuX-based hybrid materials consisting of anionic inorganic motifs that also form coordinate bonds with the cationic organic ligands. As a result of the unique bonding nature at the inorganic/organic interfaces, these compounds demonstrate strong resistance toward heat and can be readily processed in solution. They emit light in the visible region ranging from cyan to yellow color, with the highest photoluminescence quantum yield (PLQY) reaching 71%. The influence of the different coordination modes of the ligands on their emission behavior was investigated employing both experimental and theoretical methods, which have provided insight in understanding structure-property relationships in these materials and guidelines for tuning and enhancing their chemical and physical properties.

Highly Effective Hybrid Copper(I) Iodide Cluster Emitter with Negative Thermal Quenched Phosphorescence for X-Ray Imaging.

The low efficiency triplet emission of hybrid copper(I) iodide clusters is a critical obstacle to their further practical optoelectronic application. Herein, we present an efficient hybrid copper(I) iodide cluster emitter (DBA)4 Cu4 I4 , where the cooperation of excited state structure reorganization and the metallophilicity interaction enables ultra-bright triplet yellow-orange emission with a photoluminescence quantum yield over 94.9 %, and the phonon-assisted de-trapping process of exciton induces the negative thermal quenching effect at 80-300 K. We also investigate the potential of this emitter for X-ray imaging. The (DBA)4 Cu4 I4 wafer demonstrates a light yield higher than 104 photons MeV-1 and a high spatial resolution of ≈5.0 lp mm-1 , showing great potential in practical X-ray imaging applications. Our new copper(I) iodide cluster emitter can serve as a model for investigating the thermodynamic mechanism of photoluminescence in hybrid copper(I) halide phosphorescence materials.

Highly Effective Hybrid Copper(I) Iodide Cluster Emitter with Negative Thermal Quenched Phosphorescence for X‐Ray Imaging

AbstractThe low efficiency triplet emission of hybrid copper(I) iodide clusters is a critical obstacle to their further practical optoelectronic application. Herein, we present an efficient hybrid copper(I) iodide cluster emitter (DBA)4Cu4I4, where the cooperation of excited state structure reorganization and the metallophilicity interaction enables ultra‐bright triplet yellow‐orange emission with a photoluminescence quantum yield over 94.9 %, and the phonon‐assisted de‐trapping process of exciton induces the negative thermal quenching effect at 80–300 K. We also investigate the potential of this emitter for X‐ray imaging. The (DBA)4Cu4I4 wafer demonstrates a light yield higher than 104 photons MeV−1 and a high spatial resolution of ≈5.0 lp mm−1, showing great potential in practical X‐ray imaging applications. Our new copper(I) iodide cluster emitter can serve as a model for investigating the thermodynamic mechanism of photoluminescence in hybrid copper(I) halide phosphorescence materials.

Cover Feature: Synthesis of Efficient and Stable Tetrabutylammonium Copper Halides with Dual Emissions for Warm White Light‐Emitting Diodes (Chem. Eur. J. 10/2023)

Cover Feature: Synthesis of Efficient and Stable Tetrabutylammonium Copper Halides with Dual Emissions for Warm White Light‐Emitting Diodes (Chem. Eur. J. 10/2023)

Synthesis of Efficient and Stable Tetrabutylammonium Copper Halides with Dual Emissions for Warm White Light-Emitting Diodes.

In order to achieve high color rendering index (CRI) and low correlated color temperature (CCT) indoor lighting, single component phosphors with broadband dual emission emission are high demanded for white light emitting diodes (WLEDs). However, phosphors with such fluorescent properties are rare at present. Herein, we report a facile solid-state chemical method for the synthesis of single-component phosphor with broadband emission and large Stokes shift that can meet the requirements of future white light sources. These new tetrabutylammonium copper halides phosphors have excellent warm white emission characteristics, and their luminescence peaks located at 494 nm and 654 nm, respectively. The optimized photoluminescence (PL) quantum yield can reach 93.7%. The typical CIE coordinate of the as-fabricated WLED is at (0.3620, 0.3731) with CRI of 89 and low CCT of 4516 K.

Organic–Inorganic Hybrid Alkali Copper Iodides for Bright Emission across the Visible Spectrum

Organic–inorganic hybrid metal halides are well known for their structural flexibility and high photoluminescence quantum yield (PLQY), showing great potential for optical applications. In this work, we demonstrate the synthesis of a series of alkali copper(I) iodide (ACuI)-based (A = Na, K, Rb, and Cs) organic–inorganic hybrid materials with different structures and emission peaks by adjustment of the alkali atoms and organic molecules. These compounds possess strong PL with emission peaks in the range of 530–660 nm, the highest PLQY of 91% was achieved for KCuI2(C4H8OS)2, and their different emissions originate from distinct charge-transfer processes. Green, yellow, and red light-emitting diodes (LEDs) can be fabricated by using these materials, and a white LED based on all-copper iodide phosphors is demonstrated with a high color rendering index of 93 by utilizing a mixture of blue-emissive Cs3Cu2I5 and yellow-emissive Rb2Cu2I4(C4H8OS)3 powders. This work provides a new strategy for the development of hybrid copper halides with composition-tunable structures and high performance and demonstrates that this series of (ACuI)-based compounds could be candidates for emission applications, including lighting or display.

Zn (II)‐Doped Cesium Copper Halide Nanocrystals with High Quantum Yield and Colloidal Stability for High‐Resolution X‑Ray Imaging

AbstractScintillators are essential for high‐energy radiation detection in a variety of potential applications. However, due to complex fabrication processes and nanocrystal homogeneity, conventional scintillators are challenging to meet the need for cost‐effective, environmentally friendly, and flexible X‐ray detection. Here, monodisperse nanocrystals (NCs) with small grain size and colloidal stability are obtained by adjusting the doping concentration of Zn2+ ions and controlling the morphology uniformity of Cs3Cu2I5 NCs. The photoluminescence quantum yield (PLQY) for the optimal doping concentration is as high as 92.8%, which is a 28.5% improvement compared to nondoped NCs. Density functional theory calculations reveal that the Zn2+ dopant inclines to occupy Cu sites and the I‐rich condition suppresses the formation of I vacancy, enriching the excited electron density at the band‐edge to enhance the self‐trapped exciton emission. Moreover, high luminescence performance and flexible X‐ray scintillator films are prepared using Zn2+‐doped Cs3Cu2I5 NCs, with a spatial resolution of up to 15.7 lp mm–1. This work provides an effective strategy for the development of environmentally friendly, low‐cost, and efficient blue‐emitting 0D all‐inorganic metal halides, as well as shows their great potential for high‐performance flexible lead‐free and low‐toxicity X‐ray detector applications.

Structural and Luminescence Properties of Cu(I)X-Quinoxaline under High Pressure (X = Br, I)

A study of high-pressure single-crystal X-ray diffraction and luminescence experiments together with ab initio simulations based on the density functional theory has been performed for two isomorphous copper(I) halide compounds with the empirical formula [C8H6Cu2X2N2] (X = Br, I) up to 4.62(4) and 7.00(4) GPa for X-ray diffraction and 6.3(4) and 11.6(4) GPa for luminescence, respectively. An exhaustive study of compressibility has been completed by means of determination of the isothermal equations of state and structural changes with pressure at room temperature, giving bulk moduli of K0 = 14.4(5) GPa and K′0 = 7.7(6) for the bromide compound and K0 = 13.0(2) GPa and K′0 = 7.4(2) for the iodide compound. Both cases exhibited a phase transition of second order around 3.3 GPa that was also detected in luminescence experiments under the same high-pressure conditions, wherein redshifts of the emission bands with increasing pressure were observed due to shortening of the Cu–Cu distances. Additionally, ab initio studies were carried out which confirmed the results obtained experimentally, although unfortunately, the phase transition was not predicted.

Cu(I) Metal-Organic Framework Composites with AgCl/Ag Nanoparticles for Irradiation-Enhanced Antibacterial Activity against E. coli.

Metal-organic frameworks (MOFs) have emerged as prospective antibacterial agents or synergistic agents for their versatile chemical building components and structures. In this work, copper(I) halide MOFs of Cu(I)bpyCl (bpy = 4,4'-bipyridine) composited with AgCl/Ag nanoparticles were synthesized, and their antibacterial activities were measured against Escherichia coli and Staphylococcus aureus. The attached chlorine in Cu(I)2Cl2 nodes of the MOFs served as loading sites for silver ions, in which AgCl and concomitant metallic Ag nanoparticles were in situ generated. Exceptional antibacterial activity against E. coli was realized with a minimum inhibitory concentration (MIC) of ∼7.8 μg mL-1, while the MIC value was ∼16 μg mL-1 against S. aureus. Enhanced antibacterial activity against E. coli with light irradiation was measured by the disk diffusion method compared with that under dark conditions.

Исследование галогенидов натрия и меди методом мессбауэровской спектроскопии на изотопе -=SUP=-67-=/SUP=-Zn

The central shifts of the emission Mössbauer spectra on 67Cu(67Zn) impurity atoms in the crystal lattices of sodium and copper halides are determined, the relativistic Doppler shifts of the spectra are calculated, and, as a result, isomeric shifts are obtained, which are compared with the nature of the chemical bonding of zinc atoms with halogen atoms in the studied crystals. The values of the quadrupole interaction constants for impurity zinc centers in sodium halides are consistent with the results of calculating these values within the framework of the ionic model.

Mononuclear copper(I) complexes bearing a 3-phenyl-5-(pyridin-4-yl)-1,2,4-triazole ligand: synthesis, crystal structure, TADF-luminescence, and mechanochromic effects.

Three new mononuclear heteroleptic copper(I) halide complexes, [CuL(PPh3)2X] (X = Cl, Br, I), based on 3-phenyl-5-(pyridin-4-yl)-1,2,4-triazole (L) and triphenylphosphine (PPh3) ligands, have been prepared by reaction of CuX (X = Cl, Br, I), L and PPh3 in a molar ratio of 1 : 1 : 2 in MeCN solutions. The synthesized complexes exhibit blue light emission in solutions and bright green emission in the crystal state with quantum yields of up to 100%. The luminescence decay analysis and density functional theory calculations revealed that the emission of solid samples at room temperature corresponds to the thermally activated delayed fluorescence, while that at 77 K is assigned to phosphorescence. Utilizing the studied complexes in OLED heterostructures resulted in high-performing green-emitting devices with an external quantum efficiency of up to 13.4%.

Robust and highly emissive copper(I) halide 1D-coordination polymers with triphenylarsine and a series of bridging N-heteroaromatic co-ligands.

Various 1D-coordination polymers with dinuclear rhombic {Cu2X2} cores (X = Br, I) were synthesized using a spontaneous evaporation method employing triphenylarsine (AsPh3) and six types of bidentate N-heteroaromatic co-ligands. The coordination polymers exhibited intense emission even at 298 K (quantum yield: up to 0.60), and their emission color was dependent on the N-heteroaromatic co-ligand. The emission efficiencies of these coordination polymers were higher than those of the discrete complexes with AsPh3 and monodentate N-heteroaromatic co-ligands reported in our previous work. In addition, the luminescence of these coordination polymers was more resistant to mechanical stimuli than that of the discrete ones.

Recent progress of copper halide perovskites: properties, synthesis and applications

Improvement in the synthesis of copper halide perovskites is fundamental in applications of different areas including LEDs, energy harvesting, detection,etc., and further highlights the direction for future research.

Quasi-linear CuX2(X = Cl, Br) motif-built hybrid copper halides realizing encouraging nonlinear optical activities

Two polar organic–inorganic metal halides (C20H20P)CuX2(X = Cl, Br) feature rare quasi-linear [CuX2]−units and exhibit phase-matchable SHG effects, and the structure–NLO properties relationship is investigated systematically.

Highly soluble copper(i) iodide-based hybrid luminescent semiconductors containing molecular and one-dimensional coordinated anionic inorganic motifs

A series of all-in-one (AIO) type copper halide based luminescent inorganic-organic hybrid semiconductors have been synthesized and characterized. The study offers insights into the structure-property relationships in this material family.

Stable and luminescent cesium copper halide nanocrystals embedded in flexible polymer fibers for fabrication of down-converting WLEDs.

Recently, CsPbX3 (X = I, Br, Cl) perovskite nanocrystals (NCs) have drawn wide attention owing to their outstanding photophysical and optoelectronic properties. However, the toxicity of such NCs remained a big challenge for further commercialization. Herein, we adopt facile methods for synthesizing green-emissive Cs3Cu2Cl5 and blue-emissive Cs3Cu2Br2.5I2.5 perovskite NCs that exhibit broad emission spectra with large Stokes shifts. These NCs showed photoluminescence quantum yields (PLQY) up to 65% (Cs3Cu2Cl5 NCs) and 32% (Cs3Cu2Br2.5I2.5 NCs) with limited stabilities. To further improve the stability, the NCs were blended with a hydrophobic polymer poly-methylmethacrylate (PMMA) and embedded inside the polymer fiber by an electrospinning process to form composite fibers. The as-prepared Cs3Cu2Cl5@PMMA and Cs3Cu2Br2.5I2.5@PMMA fiber films demonstrated good surface coverage and better thermal stability, and even retained their emission properties when dispersed in water. The emissive fibers were also deposited on flexible polyethylene terephthalate (PET) substrates that displayed high resistance towards bending and twisting with no signs of breakage, damage, or loss of optical properties. Finally, UV-pumped phosphor-converted WLEDs fabricated by using these blue and green-emitting fibers revealed CIE chromaticity coordinates at (0.27, 0.33) with a maximum luminous efficiency of 69 Lm W-1 and correlated color temperature (CCT) value of 8703 K. These outcomes can be beneficial for the development of futuristic flexible display technologies.

Highly Efficient White Emission from Semiconductor Ink Based on Copper Iodide Nanoclusters

Recent developments in the perovskite field have aimed at exploring cluster-based organic-inorganic copper(I) halides as novel luminescent materials because of their low toxicity and structural diversity. However, the poor framework stability and low dispersion in solvent constitute the key challenges to their practical applications such as luminescent inks. Herein, we report the preparation of highly luminescent inks via one-pot solution synthesis, which consisted of ionic CumIn clusters (tetrabutylammonium copper iodide) coupled with polymer polyvinylpyrrolidone (PVP). Benefiting from the high-affinity PVP to stabilize and disperse the Cu-I inorganic units, the obtained hybrid nanocrystals exhibit high structural stabilitiy/photostability and good dispersion in ethanol. The characteristics of bright white light emission from inks were explored by temperature-dependent photoluminescence experiments and theoretical calculations. Attractively, the stable, highly luminescent inks show great potential for practical applications, such as anticounterfeiting and imaging identification. Our study offers a new material designing strategy that may be generalized to many other material classes.

Pulsed laser deposition of lead-free Cs3Cu2Br5 thin films on GaN substrate for ultraviolet photodetector applications

Recently, intensive attention has been paid to the development of copper halide perovskites (CsCuX, X = I, Br, and Cl) due to their suitable band gaps, large light absorption, environmental stability, eco-friendliness, and low cost. Although CsCuBr possesses a much larger band gap than CsCuI perovskites, there have been few reports about CsCuBr due to its poor stability in the ambient environment. In this study, high-quality Cs3Cu2Br5 thin films with good stability were prepared on GaN substrates by pulse laser deposition (PLD) for the first time. The morphology, crystal structure, and photoelectric properties of the Cs3Cu2Br5 thin films were systematically studied. Moreover, a self-powered UV photodetector based on Cs3Cu2Br5/n-GaN heterojunction was fabricated. The heterojunction device exhibits two clear dominant responses in the UV region located at 270 nm and 360 nm, with the corresponding detectivities of 5.29 × 1011 cm·Hz1/2W−1 and 3.35 × 1011 cm·Hz1/2W−1. Besides, the photoresponse mechanism of the Cs3Cu2Br5/GaN photodetector has been studied by Anderson model. Our results suggest that lead-free Cs3Cu2Br5 thin films prepared by PLD could be a potential candidate for stable and environment-friendly optoelectronic devices, such as UV detectors and light emitting devices.

Thermally Activated Delayed Fluorescent Scintillators Based on Mononuclear Copper(I) Halide Complexes for High‐Resolution X‐Ray Imaging

AbstractScintillators have attracted tremendous attention due to their great potential in radiation detection, industrial non‐destructive testing, and medical theranostic applications. Thermally activated delayed fluorescence (TADF) based scintillators can simultaneously harvest radiation‐induced singlet and triplet excitons for high‐efficient X‐ray excited luminescence. However, pure organic TADF materials composed of light elements exhibit low X‐ray absorption coefficients, resulting in relatively weak X‐ray excited luminescence. Herein, a series of novel high‐performance X‐ray scintillators based on TADF mononuclear Cu(I)‐halide complexes are successfully developed. Together with high X‐ray absorption coefficient of heavy halogen elements and halide‐to‐ligand charge transfer characteristics, these TADF scintillators display excellent performance with high X‐ray relative light yields (as high as 28385 ± 1335 photons MeV−1), good linear response to X‐ray dose rate and high resistance to humidity and radiation. X‐ray imaging tests show that a relatively high spatial resolution of 9.8 lp/mm is realized based on their flexible scintillator films. These features suggest that it is a promising strategy to realize strong X‐ray excited luminescence by incorporating heavy halogen elements in TADF materials, providing more possibilities for exploring new low‐cost and high‐performance scintillators.

Hybrid copper halide material with perovskite like structure with tetrahedral units; synthesis, characterization and optical properties

Many attempts have been made to substitute lead as the metal cation in perovskite materials but, at the same time, retain its favorable optical and electrical properties. Copper is a naturally abundant metal as well as more environmentally friendly than Pb, thus, can be used as the metal cation in regards to possible substitution candidate perovskites. Herein we report the synthesis and optoelectronic properties of two novel compounds with perovskite-like structure and Cu as the central cation. The analysis includes Powder XRD data and a Density Functional Theory (DFT) study for a thorough understanding of their structure. By Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Vibronic studies (FTIR, Raman), Nuclear Magnetic Resonance (NMR) and Mass spectra we fully explain the chemical analysis of the final material. Complete analysis of their optoelectronic properties is explained and presented with UV–vis measurements. Furthermore, we correlate their properties with their structure with Raman spectroscopy but also via computational theoretical DFT studies.