Organic-inorganic Metal Halide Research Articles

Highly efficient self-trapped exciton luminescence of Sb3+-doped (CH6N3)3BiCl6 for ethanol detection

Zero-dimensional (0D) organic–inorganic metal halide hybrids (MHHs) are considered promising luminescent materials due to their unique “host–guest” structure and tunable emission spectrum.

Near-unity emission in zero-dimensional Sb(III)-based halides intervened by hydrogen bonds towards efficient solid-state lighting technology

Zero-dimensional (0D) metal halides have garnered considerable interest owing to their superb optical characteristics, and adaptable architectures. Two 0D organic-inorganic metal halides (OIMHs) (C20H20P)2SbCl5·(EA) ([C20H20P]+ = ethyltriphenylphosphine) and (C20H20P)2SbCl5·(IPA) were successfully synthesized and investigated using a simple solvent-evaporation approach. These OIMHs possess a similar structure, except for the solvent molecules in the lattice, however, their photoluminescence quantum yields (PLQYs) exhibit a considerable difference, with 99.82% in (C20H20P)2SbCl5·(EA) and 73.7% in (C20H20P)2SbCl5·(IPA). Bond-order and crystal orbital Hamilton population (COHP) calculations reveal that (C20H20P)2SbCl5·EA system exhibits stronger hydrogen bonds, leading to stronger supramolecular interactions, which suppress non-radiative transition. The experimental results and density functional theory (DFT) calculations suggest an increase in PLQY, which could be attributed to the stronger hydrogen bonding in (C20H20P)2SbCl5·(EA) resulting in strong interactions between the organic and inorganic components, good mobility, and improved exciton utilization. This study introduces a rational strategy for microstructure optimization, which builds upon solvent modulation to achieve stronger hydrogen bonding and thus improve the PLQY of 0D OIMHs.

Antisolvent‐Enhanced Crystallization of Luminescent All‐Green Organic–Inorganic Manganese‐Halide Films Deposited by Aerosol‐Assisted Chemical Vapor Deposition Technique on Either Glass or Elastomer Substrates

The in situ deposition of emerging organic–inorganic metal halides (OIMHs) films on glass or stretchable substrates has been challenging, and no methodology has been reported to achieve this goal. The aerosol‐assisted chemical vapor deposition technique using an antisolvent‐enhanced crystallization process (AEC–AACVD) is a simple, cost‐effective, scalable, and high‐throughput technique operated under ambient atmosphere and pressure. The AEC–AACVD technique (an all‐green chemistry methodology) is used in this work to deposit TPA2MnCl2Br2 luminescent films on glass and highly stretchable elastomer substrates. The effect of using different antisolvents on the structural, morphological, and photoluminescent (PL) characteristics of films deposited on glass is reported. It is found that the intensity of the characteristic green emission peaks at 511 nm for this OIMH, improving with the antisolvent application. The TPA2MnCl2Br2 films deposited using a mixture of antisolvents result in the maximum emission intensity when deposited on stretchable substrates, maintaining their overall PL characteristics. The processability, scalability, and performance reported here for these films prove their potential application in the next generation of OIMH‐based optoelectronic technologies.

Revealing Unusual Bandgap Shifts with Temperature and Bandgap Renormalization Effect in Phase‐Stabilized Metal Halide Perovskite Thin Films

AbstractHybrid organic–inorganic metal halide perovskites are emerging materials in photovoltaics, whose bandgap is one of the most crucial parameters governing their light‐harvesting performance. This work presents the temperature and photocarrier density dependence of the bandgap in two phase‐stabilized perovskite thin films (MA0.3FA0.7PbI3 and MA0.3FA0.7Pb0.5Sn0.5I3) using photoluminescence and absorption spectroscopy. Contrasting bandgap shifts with temperature are observed between the two perovskites. Using X‐ray diffraction and in situ high‐pressure photoluminescence spectroscopy, it is shown that thermal expansion plays only a minor role in the large bandgap blueshift, which is attributed to the enhanced structural stability of the samples. The first‐principles calculations further demonstrate the significant impact of thermally induced lattice distortions on the bandgap widening. It is proposed that the anomalous trends are caused by the competition between static and dynamic distortions. Additionally, both the bandgap renormalization and band‐filling effects are directly observed for the first time in fluence‐dependent photoluminescence measurements and are employed to estimate the exciton effective mass. The results provide new insights into the basic understanding of thermal and charge‐accumulation effects on the band structure of hybrid perovskite thin films.

Organic–Inorganic Copper Halide Compound with a Near‐Unity Emission: Large‐Scale Synthesis and Diverse Light‐Emitting Applications

AbstractLow‐dimensional organic–inorganic metal halides (OIMHs) have emerged as promising light emitters due to their broadband emission originating from self‐trapped excitons (STE), especially for Cu‐based OIMHs. Herein, Cu(I)‐based OIMH with a structure of (TPP)2Cu4I6·2DMSO (TPP stays for tetraphenylphosphonium, and DMSO – for dimethyl sulfoxide) has been synthesized, both in form of single crystals and as a microcrystalline powder. This compound exhibits a broadband green emission with a peak at 515 nm and a full width at half‐maximum of 78 nm, and a near‐unity photoluminescence quantum yield of 99.5%. Experimental data supported by theoretical calculations indicate that the STE emission is responsible for the green emission with a long lifetime of 2.53 µs. Down‐conversion light‐emitting device with a high luminous efficiency of 50 lm W−1 based on this compound have been fabricated, and white light has also been achieved with a high color rendering index of 96.7. Moreover, green emissive (TPP)2Cu4I6·2DMSO is utilized in scintillators for X‐ray detection and imaging, and as a luminescent ink for encryption applications.

Syntheses, crystal structures, optical properties, antibacterial activity and DFT calculations of two tetrachlorocobaltate(II) salts with substituted methyl pyridinium

The syntheses, compositions, and structural analyses of two new organic-inorganic metal halides benzyl-2-methyl pyridinium tetrachlorocobaltate(II) [Bz-2-MePy]2[CoCl4](1) and benzyl-4-methyl pyridinium tetrachlorocobaltate(II) [Bz-4-MePy]2[CoCl4](2) were presented in this paper. Single-crystal X-ray diffraction analyses revealed that 1 and 2 crystallized in the monoclinic space group C2/c and the orthorhombic space group Pna21, respectively, composed of two [Bz-2-MePy]+/[Bz-4-MePy]+ cations and a [CoCl4]2− anion, in which the [CoCl4]2− anion displayed a tetrahedral geometry. Two crystals investigated by TG-DTA technique were stable up to 162.7 °C (1) and 226.3 °C (2), respectively. The HOMO–LUMO energy gaps and UV–vis diffuse reflectance spectra explained the charge transfer interactions between [CoCl4]2− cations and the [Bz-2-MePy]+/[Bz-4-MePy]+ cations. In addition, their low band gap values (1.88 eV in gas state and 1.65 eV in solid state for 1, 1.18 eV in gas state and 1.64 eV in solid state for 2) indicated the appropriateness of the crystals for optical applications. The first hyperpolarizabilities (βtot) of two salts were 459 and 70,000 times higher than the standard KDP crystal (βKDP = 6.85 × 10−31 esu), respectively. The antibacterial experiments demonstrated that both salts exhibited superior bactericidal activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).

The Scale Effects of Organometal Halide Perovskites.

Organometal halide perovskites have achieved great success in solution-processed photovoltaics. The explorations quickly expanded into other optoelectronic applications, including light-emitting diodes, lasers, and photodetectors. An in-depth analysis of the special scale effects is essential to understand the working mechanisms of devices and optimize the materials towards an enhanced performance. Generally speaking, organometal halide perovskites can be classified in two ways. By controlling the morphological dimensionality, 2D perovskite nanoplatelets, 1D perovskite nanowires, and 0D perovskite quantum dots have been studied. Using appropriate organic and inorganic components, low-dimensional organic-inorganic metal halide hybrids with 2D, quasi-2D, 1D, and 0D structures at the molecular level have been developed and studied. This provides opportunities to investigate the scale-dependent properties. Here, we present the progress on the characteristics of scale effects in organometal halide perovskites in these two classifications, with a focus on carrier diffusion, excitonic features, and defect properties.

Structural diversity and photoluminescence enhancement of indium-based hybrid metal halides

Low-dimensional organic-inorganic metal halides have attracted increasing attention for their diverse structure and excellent photoelectric properties. Here, we report two zero-dimensional indium-based halides, (C3H12N2)3In2Cl12·2 H2O ([C3H12N2]2+ is N-methylethylenediamine cation) with space group of P-1 and (C3H12N2)2InCl7 with space group of P21/c. Upon UV excitation, 1 %Sb doped (C3H12N2)3In2Cl12·2 H2O exhibits luminescence centering at 588 nm with a full width at half-maximum of 149 nm (0.527 eV), as well as a large Stokes shift of 262 nm (1.69 eV) with photoluminescence quantum yields as high as 56 %. The broad emission originates from the electron transitions of the Sb3+ 5s2 lone pair. 1 %Sb doped (C3H12N2)3In2Cl12·2 H2O exhibits more intense, broader emission and larger Stokes shift than that of 1 %Sb doped (C3H12N2)2InCl7 which is due to that the crystalline water increases the hydrogen bonding and leading to more distorted [SbCl6]3- octahedra. This work unveiled the relationship between structure and photoluminescence properties, and provide new types of organic-inorganic metal halides for potential application in light-emitting diodes.

Highly efficiency blue emissive from Bi3+ ions in zero-dimensional organic bismuth halide for white LED applications

Zero-dimensional organic-inorganic metal halides (OMHs) attract increasing interest in the fabrication of light-emitting diodes because of their broad emission band and high photoluminescence quantum yield. Thus, almost all OMHs showed green and yellow emissions, while blue was rarely reported. The luminescence mechanism of OMHs was attributed to the self-trapped excitons (STEs), no matter the similar performances between STEs and translations from energy levels of ns2 ions (Sb3+, Bi3+, and Te4+ ions). In this work, zero-dimensional organic tetraphenylphosphonium bismuth chloride TPP2BiCl5 (C48H40P2BiCl5, abbreviated as TBC, TPP=tetraphenylphosphonium.) was synthesized via the antisolvent method The obtained TBC showed the highest efficiency (58%) in blue light emission at 480 nm. While most of the OMHs function according to the STE mechanism, the emission of TBC was confirmed to originate from the 3P1-1S0 transition of Bi3+ ions. The white light-emitting diodes (WLEDs) with a color rendering index of 81 were fabricated by using a near-ultraviolet (NUV) chip, blue emitting single crystal TBC, green-emitting single crystal TPP2MnCl4 (C48H40P2MnCl4, abbreviated as TMC), and red-emitting single crystal TPP2SbCl5 (C48H40P2SbCl5, abbreviated as TSC). Moreover, the single-component white emission was achieved by doping Mn2+ and Sb3+ ions into the lattice of TBC. This work demonstrates the different emission mechanism of ns2 ions based OMHs, and the great potential of bismuth-based OMHs in the applications of WLEDs.

Investigating the Performance of Efficient and Stable Planer Perovskite Solar Cell with an Effective Inorganic Carrier Transport Layer Using SCAPS-1D Simulation

Organic–inorganic metal halide perovskite (OIMHP) has emerged as a promising material for solar cell application due to their outstanding optoelectronics properties. The perovskite-based solar cell (PSC) demonstrates a significant enhancement in efficiency of more than 20%, with a certified efficiency rating of 23.13%. Considering both the Shockley limit and bandgap, there exists a substantial potential for further efficiency improvement. However, stability remains a significant obstacle in the commercialization of these devices. Compared to organic carrier transport layers (CTLs), inorganic material such as ZnO, TiO2, SnO2, and NiOX offer the advantage of being deposited using atomic layer deposition (ALD), which in turn improves the efficiency and stability of the device. In this study, methylammonium lead iodide (MAPbI3)-based cells with inorganic CTL layers of SnO2 and NiOX are simulated using SCAPS-1D software. The cell structure configuration comprises ITO/SnO2/CH3NH3PbI3/NiOX/Back contact where SnO2 and NiOX act as ETL and HTL, respectively, while ITO is a transparent front-end electrode. Detailed investigation is carried out into the influence of various factors, including MAPbI3 layer size, the thickness of CTLs, operating temperature parasitic resistance, light intensity, bulk defects, and interfacial defects on the performance parameters. We found that the defects in layers and interface junctions greatly influence the performance parameter of the cell, which is eliminated through an ALD deposition approach. The optimum size of the MAPbI3 layer and CTL was found to be 400 nm and 50 nm, respectively. At the optimized configuration, the PSC demonstrates an efficiency of 22.13%, short circuit current (JSC) of 20.93 mA/m2, open circuit voltage (VOC) of 1.32 V, and fill factor (FF) of 70.86%.

Chiral Ruthenium Halide Semiconductor with Strong Antiferromagnetic Coupling

AbstractChiral hybrid organic–inorganic metal halides have attracted wide attention owing to their superior chiroptoelectronic and chirospintronic properties. Here, a new class of chiral lead‐free metal halides, (R/S‐MBA)3Ru2Br9 (MBA = methylbenzylammonium), with unique magnetic properties is reported. (R/S‐MBA)3Ru2Br9 is composed of a surface‐shared octahedron dimer separated by chiral cations and crystallizes into the Sohncke space group of P212121. The crystal structures, chiroptical, magnetic properties, and magnetic circular dichroism of (R/S‐MBA)3Ru2Br9 are systematically investigated. Owing to the strong antiferromagnetic coupling between the Ru atom through bromine bridge in the [Ru2Br9]3− dimer and the weak ferromagnetic coupling between the neighboring [Ru2Br9]3− dimer, (R/S‐MBA)3Ru2Br9 exhibits antiferromagnetic property with Néel temperature at 7 K. Considering the unique magnetic property of ruthenium, together with the rapid progress of antiferromagnetic spintronics and optospintronics recently, this work provides a novel multifunctional lead‐free chiral magnetic candidate toward chiral optoelectronics and antiferromagnetic spintronics.

Photoexcitation-induced passivation of SnO2 thin film for efficient perovskite solar cells.

A high-quality tin oxide electron transport layer (ETL) is a key common factor to achieve high-performance perovskite solar cells (PSCs). However, the conventional annealing technique to prepare high-quality ETLs by continuous heating under near-equilibrium conditions requires high temperatures and a long fabrication time. Alternatively, we present a non-equilibrium, photoexcitation-induced passivation technique that uses multiple ultrashort laser pulses. The ultrafast photoexcitation and following electron-electron and electron-phonon scattering processes induce ultrafast annealing to efficiently passivate surface and bulk defects, and improve the crystallinity of SnO2, resulting in suppressing the carrier recombination and facilitating the charge transport between the ETL and perovskite interface. By rapidly scanning the laser beam, the annealing time is reduced to several minutes, which is much more efficient compared with conventional thermal annealing. To demonstrate the university and scalability of this technique, typical antisolvent and antisolvent-free processed hybrid organic-inorganic metal halide PSCs have been fabricated and achieved the power conversion efficiency (PCE) of 24.14% and 22.75% respectively, and a 12-square-centimeter module antisolvent-free processed perovskite solar module achieves a PCE of 20.26%, with significantly enhanced performance both in PCE and stability. This study establishes a new approach towards the commercialization of efficient low-temperature manufacturing of PSCs.

Dimension-Controlled Synthesis of Hybrid-Mixed Halide Perovskites for Solar Cell Application.

Despite the rapid improvement of photovoltaic (PV) efficiency in hybrid organic-inorganic metal halide perovskites (HOIPs), the fabrication procedure of a compact thin film in a large-area application is still a tedious work. Apart from the quality of the thin film, the stability of the perovskite materials and the expensive organic hole transport layer (HTL) within the HOIP-based PV device are the major issues that need to be addressed prior to their commercialization. Herein, a unique glass rod-based facile fabrication technique for producing a compact and stable thin film utilizing a mixed-halide-based perovskite precursor solution is demonstrated. The fabricated devices deliver high photoconversion efficiency (PCE) without the use of any HTL and show an excellent stability under ambient conditions. By varying the organic CH3NH3I (MAI) and inorganic PbBr2 content, perovskite materials with different dimensions, i.e., 3D, 2D, and 1D, are synthesized to produce an active layer for PV devices. Although a 2D single-halide perovskite is reported earlier, herein two different mixed-halide 2D perovskites, i.e., MA2PbI2Br2 and MAPb2IBr4, are synthesized successfully, and their performance is compared in detail along with that of 1D and 3D mixed-halide perovskites. The facile synthesized mixed-halide 2D-based MA2PbI2Br2 perovskite shows a PCE of 10.14% with a high stability of 92% after 100 days without encapsulation, which is much superior as compared to that of the mixed-halide 3D MAPbIBr2. The semiconducting behavior as well as the nature of the bandgap of the synthesized compounds is examined by pursuing density functional theory calculations. Specifically, the role of iodine doping to modify the electronic band structure is investigated, and introduction of iodine is found to reduce the effective masses of both electrons and holes in the perovskite material.

Transparent 0D Antimony Halides Glassy Wafer with Near‐Unity Photoluminescence Quantum Yield for High Spatial Resolution X‐Ray Imaging

AbstractLarge‐sized transparent scintillators with a high photoluminescent quantum yield (PLQY) and self‐absorption‐free properties are highly desired to achieve high spatial resolution X‐ray imaging. In this research, a transparent 0D organic–inorganic (ETP)2SbCl5 (ETP = Ethyl triphenylphosphine) amorphous wafer is developed by melting the ETPCl and SbCl3 mixture and then undergoing a quenching process. The obtained amorphous wafer exhibits a high light transmittance of 86% in the range of 450–800 nm. It also shows a light emission peak at 624 nm, a Stokes shift of 259 nm, and PLQY approaching unity (99.3%). These properties enable it to produce X‐ray images with a high spatial resolution of 19.0 lp mm−1 at a modulation transfer function (MTF) value of 0.2, among the best values reported. Additionally, it also shows remarkable stability under continuous X‐ray illumination. Its unique optical properties and ability to be processed in large sizes make the organic–inorganic metal halide transparent wafer a promising scintillator. This also demonstrates the potential application of the melt‐quenching method in fabricating highly luminescent, low‐electronic‐dimensional metal halide wafers.

Chiral Hybrid Germanium(II) Halide with Strong Nonlinear Chiroptical Properties

AbstractDue to the pronounced anisotropic response to circularly polarized light, chiral hybrid organic–inorganic metal halides have been regarded as promising candidates for the application in nonlinear chiroptics, especially for the second‐harmonic generation circular dichroism (SHG‐CD) effect. However, designing novel lead‐free chiral hybrid metal halides with large anisotropy factors and high laser‐induced damage thresholds (LDT) of SHG‐CD remains challenging. Herein, we develop the first chiral hybrid germanium halide, (R/S‐NEA)3Ge2I7⋅H2O (R/S‐NGI), and systematically investigated its linear and nonlinear chiroptical properties. S‐NGI and R‐NGI exhibit large anisotropy factors (gSHG‐CD) of 0.45 and 0.48, respectively, along with a high LDT of 38.46 GW/cm2; these anisotropy factors were the highest values among the reported lead‐free chiral hybrid metal halides. Moreover, the effective second‐order nonlinear optical coefficient of S‐NGI could reach up to 0.86 pm/V, which was 2.9 times higher than that of commercial Y‐cut quartz. Our findings facilitate a new avenue toward lead‐free chiral hybrid metal halides, and their implementation in nonlinear chiroptical applications.

Chiral Hybrid Germanium(II) Halide with Strong Nonlinear Chiroptical Properties.

Due to the pronounced anisotropic response to circularly polarized light, chiral hybrid organic-inorganic metal halides have been regarded as promising candidates for the application in nonlinear chiroptics, especially for the second-harmonic generation circular dichroism (SHG-CD) effect. However, designing novel lead-free chiral hybrid metal halides with large anisotropy factors and high laser-induced damage thresholds (LDT) of SHG-CD remains challenging. Herein, we develop the first chiral hybrid germanium halide, (R/S-NEA)3 Ge2 I7 ⋅H2 O (R/S-NGI), and systematically investigated its linear and nonlinear chiroptical properties. S-NGI and R-NGI exhibit large anisotropy factors (gSHG-CD ) of 0.45 and 0.48, respectively, along with a high LDT of 38.46 GW/cm2 ; these anisotropy factors were the highest values among the reported lead-free chiral hybrid metal halides. Moreover, the effective second-order nonlinear optical coefficient of S-NGI could reach up to 0.86 pm/V, which was 2.9 times higher than that of commercial Y-cut quartz. Our findings facilitate a new avenue toward lead-free chiral hybrid metal halides, and their implementation in nonlinear chiroptical applications.

Ultra-long room temperature phosphorescence of indium-based organic inorganic metal halides for naked-eye-visible afterglow

Ultra-long room temperature phosphorescence of indium-based organic inorganic metal halides for naked-eye-visible afterglow

Lead-free CsCu2Br3 perovskite for multilevel resistive switching memory

Organic–inorganic metal halide perovskites have recently attracted enormous interest in the field of resistive switching memories owing to their unique electrical properties. Unfortunately, two challenges, the inadequate long-term stability and the toxicity of lead, largely hinder their further practical application. Herein, a 1D all-inorganic lead-free CsCu2Br3 perovskite is proposed for resistive switching devices to resolve these issues. The CsCu2Br3-based resistive switching devices exhibit typical bipolar resistive switching behavior with low set voltage, high on/off ratio (103), stable retention properties (>2 × 104 s), and endurance (200 cycles) in air. The unencapsulated CsCu2Br3-based device still maintains resistive switching characteristics while stored in ambient environment for over 2 months. Moreover, four on-state multilevel information storage behavior has been observed by regulating the value of compliance current during set process. The resistive switching behavior is dominated by the formation and fracture of conductive filaments, which are induced by the movement of Br− ions under electrical bias. This work offers the opportunity and strategy for the design of air-stable and environment-friendly metal halide perovskite-based memory devices.

Anomalous Charge Transfer from Organic Ligands to Metal Halides in Zero-Dimensional [(C6H5)4P]2SbCl5 Enabled by Pressure-Induced Lone Pair-πInteraction.

Low-dimensional (low-D) organic metal halide hybrids (OMHHs) have emerged as fascinating candidates for optoelectronics due to their integrated properties from both organic and inorganic components. However, for most of low-D OMHHs, especially the zero-D (0D) compounds, the inferior electronic coupling between organic ligands and inorganic metal halides prevents efficient charge transfer at the hybrid interfaces and thus limits their further tunability of optical and electronic properties. Here, using pressure to regulate the interfacial interactions, efficient charge transfer from organic ligands to metal halides is achieved, which leads to a near-unity photoluminescence quantum yield (PLQY) at around 6.0 GPa in a 0D OMHH, [(C6H5)4P]2SbCl5. In situ experimental characterizations and theoretical simulations reveal that the pressure-induced electronic coupling between the lone-pair electrons of Sb3+ and the π electrons of benzene ring (lp-π interaction) serves as an unexpected "bridge" for the charge transfer. Our work opens a versatile strategy for the new materials design by manipulating the lp-π interactions in organic-inorganic hybrid systems.

Anomalous Charge Transfer from Organic Ligands to Metal Halides in Zero‐Dimensional [(C6H5)4P]2SbCl5 Enabled by Pressure‐Induced Lone Pair‐π Interaction

AbstractLow‐dimensional (low‐D) organic metal halide hybrids (OMHHs) have emerged as fascinating candidates for optoelectronics due to their integrated properties from both organic and inorganic components. However, for most of low‐D OMHHs, especially the zero‐D (0D) compounds, the inferior electronic coupling between organic ligands and inorganic metal halides prevents efficient charge transfer at the hybrid interfaces and thus limits their further tunability of optical and electronic properties. Here, using pressure to regulate the interfacial interactions, efficient charge transfer from organic ligands to metal halides is achieved, which leads to a near‐unity photoluminescence quantum yield (PLQY) at around 6.0 GPa in a 0D OMHH, [(C6H5)4P]2SbCl5. In situ experimental characterizations and theoretical simulations reveal that the pressure‐induced electronic coupling between the lone‐pair electrons of Sb3+ and the π electrons of benzene ring (lp‐π interaction) serves as an unexpected “bridge” for the charge transfer. Our work opens a versatile strategy for the new materials design by manipulating the lp‐π interactions in organic–inorganic hybrid systems.