Inorganic Framework Research Articles

Polyaniline@MoS2: An organic and inorganic hybrid framework for asymmetric supercapacitor applications

The polyaniline and MoS2-based organic and inorganic hybrid composite have been synthesized by varying MoS2 concentrations ranging from 1 to 10 wt% and their charge storage performances were analyzed in a three-electrode and in asymmetric cell configuration to understand their electrochemical characteristics. The electrochemical characteristics of the as-prepared electrodes such as cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy were studied in 1 M H2SO4 electrolyte. Among the prepared compositions PANI@MoS2 (5 wt%) electrode showed a high specific capacity of 148.6 F g−1 at 0.5 A g−1 among the prepared compositions. Further, the asymmetric hybrid pouch cell was fabricated where PANI@MoS2 and activated carbon were used as a positive and negative electrode, respectively. The 2 × 2 cm2 asymmetric cell (AC||PANI@MoS2(5 wt%) delivered a specific energy of 32 Wh kg−1 at a specific power of 3.2 kW kg−1 in the PVA-H2SO4 hydrogel electrolyte. This specific energy is two-fold higher than the AC||PANI asymmetric cell where the specific energy and specific power are about 18.66 Wh kg−1 and 3.2 kW kg−1, respectively. The cycle stability of the AC||PANI@MoS2 (5 wt%) was also performed at 2 A g−1 and the cell showed capacitance retention of about 99.27% after 13,000 cycles. The cell performances at different bending angles were analyzed to ensure the flexible nature of the pouch cell. Thus, the proposed organic and inorganic hybrid composite electrode is believed to be a potential electrode material for supercapacitor application in an acidic electrolyte medium.

Optimizing Molecular Passivation in MAPbI3 Perovskites: Impact of Dipole Moments and Structural Parameters.

In the realm of perovskite materials, organic molecules situated at the A site play a critical role in stabilizing the structure through specific orientations and weak interactions with the inorganic framework. These polar interactions significantly influence the optoelectronic properties of perovskites, and the introduction of polar molecules can disrupt the inherent polarization, thereby altering the material performance. The research primarily focuses on the relationship between the length and width of these organic cations and their polar inductive effects. Overall, the interplay between the chain length, molecular width, and dipole moments was shown to significantly affect the lifetime of MAPbI3 materials. Key findings indicate that non-radiative recombination, which is a major energy loss mechanism in solar cells, is intrinsically linked to the variations of hydrogen bonds and PbI6 octahedral distortion. The analysis revealed a strong negative correlation between octahedral angles, highlighting the complex relationship between these variables and their collective effects on charge carrier dynamics.

The Molecular Additive N-Acetyl-L-Phenylalanine Delays the Crystallization and Suppresses the Phase Impurity for Achieving Triple-Cation Perovskite Solar Cells with Efficiency Over 25.

The crystallization process plays an important role in the formation of high-quality perovskite film for achieving efficient perovskite solar cells (PSCs), especially in the formation of mixed-cation perovskite film, as there are normally more phase impurities than in pure CH(NH2)2PbI3 (FAPbI3) film. Herein, a molecular additive strategy, i.e., introducing non-planar molecule N-acetyl-L-phenylalanine (APO) into the lead iodide (PbI2) precursor solution, is proposed to modulate crystallization kinetics and inhibit the generation of phase impurities of metastable pretreated perovskite film. The delayed crystallization process promotes a sufficient reaction between organic salts solution and inorganic Pb-I framework, and perovskite phase decomposition is prevented by forming strong hydrogen bonds between ─NH and I, resulting in the formation of uniform film with large-size crystal grains and high-purity crystalline phase. Ultimately, the target PSC devices achieve an impressive power conversion efficiency (PCE) of 25.05%, which is among the highest values of triple-cation (FAMACs) PSCs. Meanwhile, PSC modules with 10.8 cm2 obtain a PCE of 20.35%. Furthermore, the unencapsulated PSCs retain 94% of the initial efficiency after 40 days of storage under ambient conditions with 20% RH and also yield superior operational stability under light soaking at maximum power point tracking (MPPT) in nitrogen (N2) atmosphere.

Precise Modification of Organic Cations to Enhance the Moisture Stability and Luminescence Efficiency of Mn-Based Halides.

Eco-friendly organic-inorganic hybrid metal halides (OIMHs) are widely recognized as promising candidates for next-generation semiconductor materials. However, achieving inherent moisture stability in OIMHs remains a significant challenge due to the highly hygroscopic nature of the halide structures. In response, a strategy to precisely modify the organic cation (18-ACE: 4,13-diaza-18-crown 6-ether) was developed by introducing hydrophobic benzyl groups into 18-ACE, forming a protective layer that enhances the moisture stability of the OIMHs. Specifically, benzyl groups were incorporated into 18-ACE to create 18-ACE-Bn, which was then used as an organic component to construct zero-dimensional Mn-based (18-ACE)MnBr4 and (18-ACE-Bn)MnBr4·H2O, exhibiting photoluminescence quantum yields (PLQYs) of 68.18% and 97.17%, respectively. Notably, (18-ACE-Bn)MnBr4·H2O demonstrates exceptional moisture stability compared to (18-ACE)MnBr4, retaining 97% of its initial PLQY even after 180 days of exposure to 70% relative humidity. Molecular dynamics and density functional theory calculations indicate that this superior stability is attributed to the terminal benzyl groups embedded within the inorganic framework, forming a compact structure with abundant weak interactions. Leveraging the unique spectral characteristics of (18-ACE-Bn)MnBr4·H2O, a high-performance WLED with a wide color gamut of 125.2% NTSC (National Television Standard Committee) was developed, highlighting its potential for backlight display applications.

Kitaev interactions through extended superexchange pathways in the jeff=1/2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${j}_{{\\mathsf{eff}}}=1/2$$\\end{document} Ru3+ honeycomb magnet RuP3SiO11

Magnetic materials are composed of the simple building blocks of magnetic moments on a crystal lattice that interact via magnetic exchange. Yet from this simplicity emerges a remarkable diversity of magnetic states. Some reveal the deep quantum mechanical origins of magnetism, for example, quantum spin liquid (QSL) states in which magnetic moments remain disordered at low temperatures despite being strongly correlated through quantum entanglement. A promising theoretical model of a QSL is the Kitaev model, composed of unusual bond-dependent exchange interactions, but experimentally, this model is challenging to realise. Here we show that the material requirements for the Kitaev QSL survive an extended pseudo-edge-sharing superexchange pathway of Ru3+ octahedra within the honeycomb layers of the inorganic framework solid, RuP3SiO11. We confirm the requisite jeff=12\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${j}_{{\\mathsf{eff}}}=\\frac{1}{2}$$\\end{document} state of Ru3+ in RuP3SiO11 and resolve the hierarchy of exchange interactions that provide experimental access to an unexplored region of the Kitaev model.

Multifunctional Nanocomposite Polymer‐integrated Ca‐doped CeO2 Electrolyte for Robust and High‐rate All‐solid‐state Sodium‐ion Batteries

AbstractDue to the seamless interfaces between solid polymer electrolytes (SPEs) and electrode materials, SPEs‐based all‐solid‐state sodium‐ion batteries (ASSSIBs) are considered promising energy storage systems. However, the sluggish Na+ transport and uncontrollable Na dendrite propagation still hinder the practical application of SPEs‐based ASSSIBs. Herein, Ca‐doped CeO2 (Ca−CeO2) nanotube framework is synthesized and integrated with poly (ethylene oxide) methyl ether acrylate‐perfluoropolyether copolymer (PEOA‐PFPE), resulting in multifunctional solid nanocomposite electrolytes (namely SNEs, i.e., PEOA‐PFPE/Ca−CeO2). Our investigations demonstrate that the fluorous effect incurred by the fluorine‐containing PEOA‐PFPE and the oxygen vacancy effect induced by the Ca−CeO2 framework could synergistically promote the dissociation of sodium salt, ultimately enhancing the Na+ mobility in SNEs. Besides, the resultant SNEs construct rapid Na+ transport channels and homogenize the Na deposition in SNEs/Na interface, which effectively prevents the Na dendrite growth. Furthermore, the assembled carbon‐coated sodium vanadium phosphate (NVP@C)||PEOA‐PFPE/Ca−CeO2||Na coin cell delivers impressive rate capability of 97.9 mAh g−1 at 2 C and outstanding cycling stability with capacity retention of 84.3 % after 300 cycles at 1 C. This work illustrates that constructing multifunctional SNEs via incorporating functional inorganic frameworks into fluorine‐containing SPEs could be a promising strategy for the commercialization of robust and high‐performance ASSSIBs.

Multifunctional Nanocomposite Polymer-integrated Ca-doped CeO2 Electrolyte for Robust and High-rate All-solid-state Sodium-ion Batteries.

Due to the seamless interfaces between solid polymer electrolytes (SPEs) and electrode materials, SPEs-based all-solid-state sodium-ion batteries (ASSSIBs) are considered promising energy storage systems. However, the sluggish Na+ transport and uncontrollable Na dendrite propagation still hinder the practical application of SPEs-based ASSSIBs. Herein, Ca-doped CeO2 (Ca-CeO2) nanotube framework is synthesized and integrated with poly (ethylene oxide) methyl ether acrylate-perfluoropolyether copolymer (PEOA-PFPE), resulting in multifunctional solid nanocomposite electrolytes (namely SNEs, i.e., PEOA-PFPE/Ca-CeO2). Our investigations demonstrate that the fluorous effect incurred by the fluorine-containing PEOA-PFPE and the oxygen vacancy effect induced by the Ca-CeO2 framework could synergistically promote the dissociation of sodium salt, ultimately enhancing the Na+ mobility in SNEs. Besides, the resultant SNEs construct rapid Na+ transport channels and homogenize the Na deposition in SNEs/Na interface, which effectively prevents the Na dendrite growth. Furthermore, the assembled carbon-coated sodium vanadium phosphate (NVP@C)||PEOA-PFPE/Ca-CeO2||Na coin cell delivers impressive rate capability of 97.9 mAh g-1 at 2 C and outstanding cycling stability with capacity retention of 84.3 % after 300 cycles at 1 C. This work illustrates that constructing multifunctional SNEs via incorporating functional inorganic frameworks into fluorine-containing SPEs could be a promising strategy for the commercialization of robust and high-performance ASSSIBs.

How the Spacer Influences the Stability of 2D Perovskites?

Two-dimensionallead halide perovskites (2D HPs) represent as an emerging class of materials given their tunable optoelectronic properties and long-term stability in perovskite solar cells. However, the ever-growing field of optoelectronic devices using 2D HPs requires fundamental understanding of the influence of the spacer on the physiochemical properties and stability of perovskites as well as establish which cation properties are closely related to suppress the halogen ion mobility. This study focuses on investigating the influence of organic spacers with intrinsic properties (e.g., rigidity and flexibility, special groups) and variations of material dimensions on the stability of halogen ions and inorganic frameworks in 2D HPs. It is found that the perovskite structure composed of rigidity molecules owns better stability of halogen ion and inorganic framework than that of flexible molecules. The stability of ions exhibits a negative correlation with the dimensions of perovskite. More importantly, a simple descriptor for measuring the stability of halogen ions in 2D HPs is constructed. By causal discovery algorithms with more physical and chemical significance, the Kappa shape index, number of rotatable bonds, and aromatic carbocycles in organic spacers are identified as causal and important features for the stability of halogen ions in 2D HPs.

Remote chirality transfer in low-dimensional hybrid metal halide semiconductors.

In hybrid metal halide perovskites, chiroptical properties typically arise from structural symmetry breaking by incorporating a chiral A-site organic cation within the structure, which may limit the compositional space. Here we demonstrate highly efficient remote chirality transfer where chirality is imposed on an otherwise achiral hybrid metal halide semiconductor by a proximal chiral molecule that is not interspersed as part of the structure yet leads to large circular dichroism dissymmetry factors (gCD) of up to 10-2. Density functional theory calculations reveal that the transfer of stereochemical information from the chiral proximal molecule to the inorganic framework is mediated by selective interaction with divalent metal cations. Anchoring of the chiral molecule induces a centro-asymmetric distortion, which is discernible up to four inorganic layers into the metal halide lattice. This concept is broadly applicable to low-dimensional hybrid metal halides with various dimensionalities (1D and 2D) allowing independent control of the composition and degree of chirality.

A-Site Cation Chemistry in Halide Perovskites.

Metal halide perovskites are an important class of semiconductors now being implemented as photovoltaic absorbers and explored for light emission, among other device applications. The semiconducting properties of halide perovskites are deeply intertwined with their composition and structure. Specifically the symmetry, tilting, and distortions of the metal halide octahedra impact the band structure and other optoelectronic properties. In this review, we examine the various compositions of monovalent A-site cations in three-dimensional (3D) halide perovskites AMX3 (M = divalent metal; X = halide). We focus on how the A-site cation templates the inorganic metal-halide perovskite framework, resulting in changes in the crystal structure symmetry, as well as M-X bonding parameters, summarized in a comprehensive table of AMX3 structures. The A-site cation motion, effects of alloying, and 2D Ruddlesden-Popper perovskite structures with unique A-site cations are further overviewed. Correlations are shown between these A-site cation dominated structural parameters and the resulting optoelectronic properties such as band gap. This review should serve as a reference for the A-site cation structural chemistry of metal halide perovskites and inspire continued research into less explored metal halide perovskite compositions and structures.

Full‐Color Tunability Room Temperature Phosphorescence from Inorganic Crystal Frameworks

AbstractRoom temperature afterglow (RTA) materials have aroused prodigious research interests owing to their unique long‐life luminescent properties. However, it is rare for RTA materials to be reported with full‐color afterglow emission. Herein, a universal strategy is designed to activate full‐color tunability RTA based on phenylboronic acid derivatives (BOH) and boric acid (BA) via an ingenious solvent‐free solid‐phase heating. As the conjugation degrees of aromatic groups of the guest molecule expanded, the BOH/BA composites showed tunable afterglow colors ranging from blue to red after ultraviolet (UV) irradiation. This strategy is to firmly anchor the guest molecule in a rigid framework of the inorganic metaboric acid matrix by abundant hydrogen‐bonding interactions between the host and guest, suppressing molecular motion and promoting the intersystem crossing (ISC) rate between the singlet and triplet excited states for enhanced afterglow emission. In addition, through mixing in multiple guest molecules into BA simultaneously, the obtained composite can be modulated in a wide excitation range from blue to red. This fascinating study provides a simple and universal method to fabricate full‐color tunability RTA composites, making them a promising candidate for applications in advanced information security and multi‐level encryption.

A Low‐Dimensional Donor‐Acceptor Perovskite for High‐Performance X‐Ray Detection

AbstractPerovskite materials hold significant promise for X‐ray detection due to their high X‐ray attenuation coefficient, efficient charge mobility, and tunable compositions and optoelectronic properties. Nonetheless, extracting the charges deep inside the thick semiconductors remains a challenge. Here, the 1D cytidine lead bromide perovskite (CytPbBr3) with a regularly arranged Donor (D)–Acceptor (A) heterojunction structure is reported. The organic interlayer contributes to the conduction band, while the inorganic framework constructs the valance band. Such a D–A heterojunction structure offers two separate channels for electrons and holes transport, suppressing the charge recombination rates with improved charge collection efficiency, and thus yields a high device sensitivity of 1.2 × 106 µC Gyair−1 cm−2 with a low noise equivalent dose (NED) of 44.6 pGyair.

Tuning the atomic ordering of AFI framework with templates charge

In this work, AlPO4-5 (AFI) zeotype materials were synthesized using the microwave approach in the presence of two organic templates i.e. tripropylamine (R) and tetrapropylammonium (R+). The long- and short-range crystalline order of the samples were investigated by considering the effect of the template's charge on the atomic-level ordering of the AFI framework. Using advanced NMR spectroscopy, we shed the light on the importance of templates' role on the organization of the inorganic framework of aluminophosphates. The spectroscopic data clearly show a wider distribution of Al and P environments in the materials synthesized with the charged template (R+) due to the need of hydroxyl groups charge compensators that induce some bridges distortions. When a charged molecule (R+) was used, aluminum appears to be responsible for the charge compensation mechanism via the association of OH groups, impacting the environment of phosphorus as well. The hydroxyl groups needed for charge compensation in samples synthesized with R+ persist after calcination. Consequently, the hydrophilicity of the sample synthesized with R+ features approximatively two times higher values compared to the one synthesized with R.

The role of metal-halide bond in the distortions and asymmetric non-covalent interactions in chiral hybrid perovskites

Abstract Hybrid organic–inorganic perovskites have become interesting materials with a set of applications spanning from optoelectronics to energy conversion technologies. Recently, chiral hybrid perovskites encapsulating chiral organic ligands into the inorganic framework, have garnered significant attention for their promising potential in chiroptoelectronics. The generation of chirality and the corresponding chiroptical response are attributed to a chiral bias that arises from the chiral organic ligands extending into the inorganic framework. This was proposed to affect the inorganic geometry, propagating within the whole hybrid perovskite scaffold. Herein, we aim at clarifying the connection between coordination geometries and their distortions in chiral perovskites, by comparing tin and lead 2D perovskites encapsulating chiral methyl benzyl ammonium, S-(MBA+)2PbI4 and S-(MBA+)2SnI4. Ab-initio molecular dynamics simulations based on density functional theory methods were used and disclosed higher degrees of distortion for the tin-based chiral HOIP model, with prominent alteration of the equatorial coordination and evident bending of the equatorial angle. Such geometrical distortions stabilize non-covalent CH-π interaction observed in the tin-based chiral perovskite in which reduced ligand–ligand distances have been found during the dynamics. The substitution of lead with tin ions within the crystallographic coordinates of S-(MBA+)2PbI4 maintains the same degree of distortion observed in S-(MBA+)2SnI4. This result indicates that the central metal strongly influences the overall packing encapsulating the chiral ligands stabilized by non-covalent interactions. The more the central metal is a hard acid, the more the bond with the soft iodide base is weak or viceversa the more the central metal is a soft acid, the more the bond with a hard base is weak. The weakeness of the metal-halide bond increases the distortion and asymmetric non-covalent interactions within the chiral perovskite scaffold.

Accurate Crystal Structure Prediction of New 2D Hybrid Organic-Inorganic Perovskites.

Low-dimensional hybrid organic-inorganic perovskites (HOIPs) are promising electronically active materials for light absorption and emission. The design space of HOIPs is extremely large, as a variety of organic cations can be combined with different inorganic frameworks. This not only allows for tunable electronic and mechanical properties but also necessitates the development of new tools for in silico high throughput analysis of candidate materials. In this work, we present an accurate, efficient, and widely applicable machine learning interatomic potential (MLIP) trained on 86 diverse experimentally reported HOIP materials. This MLIP was tested on 73 experimentally reported perovskite compositions and achieves a high accuracy, relative to density functional theory (DFT). We also introduce a novel random structure search algorithm designed for the crystal structure prediction of 2D HOIPs. The combination of MLIP and the structure search algorithm reliably recovers the crystal structure of 14 known 2D perovskites by specifying only the organic molecule and inorganic cation/halide. Performing this crystal structure search with ab initio methods would be computationally prohibitive but is relatively inexpensive with the MLIP. Finally, the developed procedure is used to predict the structure of a totally new HOIP with cation (cis-1,3-cyclohexanediamine). Subsequently, the new compound was synthesized and characterized, which matches the predicted structure, confirming the accuracy of our method. This capability will enable the efficient and accurate screening of thousands of combinations of organic cations and inorganic layers for further investigation.

Chirality-Mediated 1D-to-2D Phase Transition in Hybrid Lead Halide Perovskites.

Dimensionality engineering plays a pivotal role in optimizing the performance, ensuring long-term stability, and expanding the versatile applications of lead halide perovskites (LHPs). Currently, the manipulation of LHP dimensions primarily occurs during the synthesis stage, a procedure hampered by constraints, including synthetic complexity and irreversibility. This investigation successfully achieved a transition from one-dimensional (1D) to two-dimensional (2D) structures in chiral LHPs by applying hydrostatic pressure. Remarkably, this pressure-induced transition in dimensionality is absent in the racemic analogue due to the staggered arrangement of inorganic chains and the elevated steric hindrance posed by the organic cations. Notably, the hydrogen bonding between organic cations and the inorganic framework adopts a symmetrical arrangement in the racemic system but a helical configuration along the 1D chain direction in the chiral counterparts. This distinct helical arrangement induces a consequential distortion in the inorganic moiety, resulting in the emergence of a spin-polarized Rashba-Dresselhaus texture that explains the chirality's electronic spin origin. Furthermore, both experimental and density functional theory calculation results demonstrate that the 1D-to-2D phase transition in chiral halide perovskites can induce significant modifications in the electronic structures and associated optical emissions. In summary, the findings unveil novel avenues for manipulating optoelectronic properties in chiral perovskites through dimensionality engineering.

A FAIR comparison of activated carbon, biochar, cyclodextrins, polymers, resins, and metal organic frameworks for the adsorption of per- and polyfluorinated substances

Per- and polyfluorinated substances (PFAS) have complex sorption behaviors, complicating removal from water and selection of suitable adsorbents. We evaluated adsorption of 44 PFAS across four adsorbent groups: activated carbon and biochar (AC and BC), cyclodextrin-based adsorbents (cyclodextrins), polymer-based adsorbents and resins, and inorganic adsorbents and metal organic frameworks (MOFs). We analyzed over 500 adsorption coefficients (Kd) from literature, calculated at aqueous equilibrium concentration of 1 ± 0.3 µg/L under comparable experimental conditions. On average, Kd of AC and BC exceeded 107 L/kg for PFAS with C-F bonds > 7, unlike other adsorbents with Kd < 107. This trend holds for C-F bonds ≥ 4. Cyclodextrins, polymer-based adsorbents and resins outperform AC and BC for C-F bonds < 4. For AC and BC, Kd follows the order PFOS>PFOA>PFBS>PFBA, with adsorption increasing with increasing point of zero charge of the adsorbent. For AC and BC, as well as cyclodextrins, Kd values were related to PFAS hydrophobicity and steric properties. Additionally, adsorption was influenced by head group type, non-fluorinated carbon atoms, and the presence of oxygen and/or chlorine in the PFAS. No clear relationship was found for the other adsorbents. Adsorption prediction using a Random Forest Regressor and literature data was feasible for AC and BC, but not for other adsorbents. Cyclodextrins outperform AC and BC for removing PFAS across varying mobilities from water, whereas AC and BC are superior for low mobility PFAS. To support further data use all data and code used are freely available, following FAIR data principles.

Unveiling the impact of organic cation passivation on structural and optoelectronic properties of two-dimensional perovskites thin films

Several organic cations have been used to passivate perovskite films; however, selecting the optimal cation remains challenging. In this work, we carried out density functional theory calculations to understand the effects induced by 17 different organic cations on the passivation (P-cations) of thin two-dimensional P2 (MAn−1)PbnI3n+1 perovskites films, where n=1 and 2. We found that the interactions between different types of P-cations and the inorganic slab affect the length and angles of the bonds within the inorganic framework (PbI6-octahedra). In general, the binding mechanism includes the interactions of organic cations with the inorganic framework, which leads to the accumulation of electron density within the halides, indicative of Brønsted–Lowry acid–base interactions. Oxygenated groups facilitate additional H-bond formation through -OH and -COOH groups, promoting the localization of the electron density between layers and improving the energetic stability of the system. Based on the results and analysis, we found that three P-cations might have higher potential for real-life applications, namely 4-fluorophenylethylammonium (FPEA), phenylethylammonium (PEA) and butylammonium (BtA).

Structural Changes and Differences in Intrinsic Photoluminescence of Four Cationic Two-Dimensional Lead Halide Frameworks Modulated by Synthesis Temperature.

Luminescent hybrid organolead halide materials with cationic inorganic frameworks and high chemical inertness have demonstrated broad application prospects in the visible light region. However, the corresponding relationship between structural changes and luminescence properties in such materials needs further clarification. Here, for the first time, we have successfully synthesized [Pb2X3](PDAH)(H2O) (X = Cl or Br, PDAH = C7H4NO4) single crystals via a facile hydrothermal method and then obtained [Pb11X14](PDA)4 (X = Cl or Br, PDA = C7H3NO4) at higher temperatures. The different synthesis temperatures resulted in significant differences in the luminescence properties of the two groups of structures. X-ray crystallography revealed the different degrees of distortion of the PbII centers' coordination environment between the two structures, which would significantly affect the electron-phonon coupling process under excited states and ultimately affect the emission properties originating from self-trapped excitons (STEs) of the two materials. In addition, density functional theory (DFT) calculations indicate that the two structures have different band gap characteristics due to the different proportions of inorganic and organic components, which also affect the optoelectronic properties of the two groups of materials. It is also worth mentioning that the broadband orange-light emission of [Pb11Br14](PDA)4 with a high photoluminescence quantum efficiency (PLQE) of 86% endows it with potential applications in WLEDs.

Low-Frequency Vibrational Spectra of 4-Fluorophenol Studied by THz Spectroscopy and Solid-State Density Functional Theory.

Hydrogen bonds serve as important intermolecular interactions organizing the spatial arrangement of molecular crystals. Determining the hydrogen-bond orientations remains a challenging task. In the previous XRD study, the authors assumed a single crystal structure of 4-fluorophenol in which molecules form hexamer-ring clusters via anticlockwise hydrogen bonding. However, the existence of the other structure, which adopts clockwise hydrogen bonding, remains uncertain and warrants further exploration. We unveil distinctive fingerprint information associated with both structures by using high-resolution terahertz spectroscopy. The distinct structures result in different intramolecular geometries of 4-fluorophenol regarding the O-H bond configurations, which are manifested by a noticeable peak splitting in the 20-200 cm-1 frequency range. This result illustrates the sensitivity of THz spectroscopy to hydrogen-bond conformational polymorphism. Our findings represent a significant advancement in utilizing high-resolution THz spectroscopy to resolve hydrogen-bond orientations in molecular crystals with possible broad applicability across diverse hydrogen-bonded organic and inorganic framework materials.