Metal-free halide perovskites have recently emerged as promising candidates for optoelectronic applications. However, their synthesis has largely depended on water-based single-crystal growth that limits material diversity, scalability, and practical implementation. Here, we present a mechanochemical route to synthesize N,N-diazabicyclo[2.2.2]octonium (H-DABCO)-based halide perovskites from the (DABCO)(NH4)X3 (X = I, Br) compositions. The structural properties were confirmed by X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy. Thin films were prepared from mechanosynthetic powders by spin-coating and characterized by in-situ grazing incidence wide-angle scattering measurements, as well as by UV-vis absorption and steady-state photoluminescence spectroscopy. This mechanosynthetic strategy provides a scalable, environmentally friendly pathway to broaden the scope of metal-free perovskites and advance their potential in sustainable optoelectronic technologies.

Modifying glass compositions is key to creating silicate-based glasses for technologies including optical fibres, catalytic supports, protective coatings and separation membranes. Here we extend this concept to metal-organic framework (MOF) glasses by modifying the MOF glass former ZIF-62 with Li(bim) and Na(bim) as compatible glass modifiers (benzimidazolate, bim-). Melt-quenching of physical mixtures with increasing Na(bim) content yields modified MOF glasses that exhibit a systematic decrease in the glass transition temperature (Tg), accompanied by increased liquid fragility, configurational heat capacity at Tg and density: paralleling silicate glass chemistry through partial network depolymerization. Structural and spectroscopic analysis, coupled with density-functional theory calculations, confirm that Na(bim) is incorporated homogeneously into the MOF glass framework rather than the pores and reveal the presence of undercoordinated sodium ion environments. Finally, extraction of the modifier by water treatment increases glass porosity, akin to established borosilicate glass processes. This work introduces a transferable approach for tailoring the structure and properties of MOF glasses.

Localized delivery of antibiotics is a promising strategy that leads to transformative treatment pathways of bacterial biofilms and increases the effectiveness of their administration in contrast to traditional delivery methods requiring high antibiotic doses. Hydrophobic antibiotics have poor activity against bacterial biofilms due to their limited penetration and are particularly challenging to deliver. Nanoparticles are ideal drug delivery agents to achieve spatially controlled delivery, but commonly their designs are either soft or porous, which limits temporally triggered release, with the result that most of the antibiotic does not reach deeply into the biofilm. In this study, we present designs of nonporous silica nanoparticles that encapsulate a lipophilic antibiotic, rifampicin, with noncovalent interactions and enable controlled release triggered by Low-Frequency Ultrasound (LFUS). Staphylococcus aureus biofilms treated with the nonporous, core@shell, rifampicin-encapsulated nanoparticles, RIF⊂PhSiO 2 @SiO 2 , combined with LFUS, achieved 90% biofilm eradication, compared to 20% without ultrasound; treatment with free rifampicin and LFUS resulted only in a 10% reduction. Nanoparticle penetration into biofilm layers was visualized using fluorescent nanoparticles prepared with coencapsulation of the Nile red fluorophore, RIF+NR⊂PhSiO 2 @SiO 2 . Confocal fluorescence imaging of the biofilms demonstrated penetration of the nanoparticles throughout all the layers of the biofilm upon LFUS application, in sharp contrast to their presence in only the top few biofilm layers without LFUS. Scanning Electron Microscopy of the biofilms confirmed the presence of nanoparticles and the dual role of LFUS in promoting penetration and facilitating drug release by disrupting molecular interactions within the nanoparticle. This work introduces a design paradigm for nonporous nanoparticle agents combined with ultrasound, enabling both temporal and spatial control of drug release in bacterial biofilms. This will open transformative therapeutic approaches for effective localized delivery of drugs that have previously been challenging to deliver.

Abstract Molecular single-source precursors are a promising way of obtaining multi-element extended solids directly. We show that thermal decomposition of well-defined mono-, bi- and trimetallic polyoxovanadates (POVs) proceeds through a series of intermediate amorphous and crystalline species which we characterise using solid-state NMR spectroscopy, pair-distribution function (PDF) analysis and in-situ X-ray diffraction, before forming crystalline V2O5 and BiVO4 products. This synthetic strategy enables the formation of phases inaccessible using other routes, including a previously unknown polymorph of BiVO4 which we name β-BiVO4 due to its similarity to β-SnWO4. Local structure information also reveals the temperature dependent incorporation of Zn do pants into BiVO4. The study also explores the electrochemical properties of amorphous mixed-valence vanadium oxides as Li-ion battery electrodes. We suggest that careful analysis of the thermal decomposition of molecular species may be a way of obtaining hitherto unknown kinetically stabilised polymorphs and amorphous variants of extended solids.

Foldamers have been widely used as responsive motifs within discrete supramolecular systems on account of their programmable stimuli-sensitivity. However, translation of this functionality into bulk matter and toward the creation of smart materials, such as switchable metallogels, remains largely unexplored. Further, characterization of local structure in metallogel networks is inherently challenging because of their semisolid nature, precluding the use of solution phase NMR spectroscopy. We report a dual light- and pH-responsive foldamer metallogel, comprised of aromatic oligoamide foldamers coordinated to palladium(II) centers. We show reversible gel-sol-gel behavior using UV illumination and subsequent heat treatment. Exposure to aqueous acid also induces a gel-sol transition. We determine the local structure of the gel using magic angle spinning (MAS) dynamic nuclear polarization (DNP) NMR spectroscopy. We thus identify square planar 4-fold coordination of Pd (II) by terminal pyridines in the foldamer as the primary structural motif comprising the gel backbone. Finally, successful exchange of the organic solvent with water, without compromising the gel structure, leads to the first example of a metallo-foldamer hydrogel.

We present a novel approach to enhance the efficiency and stability of inorganic CsPbI2Br based perovskite solar cells (PSCs) through the incorporation of a solvated palladium (Pd) complex, PdBr2(PhCN)2, into perovskite precursor inks (PhCN = benzonitrile). This modification not only stabilizes the α-phase of CsPbI2Br perovskite owing to Pd2+ ions, which were found to be incorporated into the perovskite structure at the B-site, but also effectively improves the perovskite film morphology through the removal of benzonitrile molecules during annealing. Further systematic study reveals that the addition of PdBr2(PhCN)2 results in a better matched energy-level alignment and reduced charge carrier recombination compared to the unmodified material. As a result, the optimized device enables an efficiency of 16.4% with an open-circuit voltage (VOC) of 1.27 V, which outperforms the control device (14.1%, 1.19 V). The device with PdBr2(PhCN)2 shows substantially enhanced environmental and operational stabilities, retaining ≈75% and 90% of their initial PCEs after 500 h aging, respectively. This study demonstrates the potential of B-site engineering via solvated precursors as an effective route toward stable and efficient inorganic perovskite photovoltaics.

Molecular piezoelectrics are a potentially disruptive technology, enabling a new generation of self-powered electronics that are flexible, high performing, and inherently low in toxicity. Although significant efforts have been made toward understanding their structural design by targeted manipulation of phase transition behavior, the resulting achievable piezoresponse has remained limited. In this work, we use a low-symmetry, zero-dimensional (0D) inorganic framework alongside a carefully selected 'quasi-spherical' organic cation to manipulate organic-inorganic interactions and thus form the hybrid, piezoelectric material [(CH3)3NCH2I]3Bi2I9. Using variable-temperature single crystal X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy, we demonstrate that this material simultaneously exhibits an order-disorder and displacive symmetry-breaking phase transition. This phase transition is mediated by halogen bonding between the organic and inorganic frameworks and results in a large piezoelectric response, d33 = 161.5 pm/V. This value represents a 4-fold improvement on previously reported halobismuthate piezoelectrics and is comparable to those of commercial inorganic piezoelectrics, thus offering a new pathway toward low-cost, low-toxicity mechanical energy harvesting and actuating devices.

Modifying glass compositions is key to creating silicate-based glasses for technologies like optical fibres, catalytic supports, protective coatings, and separation membranes. Here, we extend this concept to metal-organic framework (MOF) glasses by modifying the MOF glass former ZIF-62 (Zn(im)1.8(bim)0.2, im– = imidazolate, bim– = benzimidazolate) with Na(bim) as a compatible glass modifier. Melt-quenching of physical mixtures with varying Na(bim) content (x Na(bim) · Zn(im)1.8(bim)0.2, 0 < x < 1.5) produces modified MOF glasses with a systematic decrease in the glass transition temperature (Tg), and increased liquid fragility, configurational heat capacity (∆C_V) at Tg, and density as x increases – paralleling the chemistry in silicate glasses due to partial network depolymerisation. Structural and spectroscopic analysis, coupled with density-functional theory calculations, confirm that Na(bim) is incorporated homogeneously into the MOF glass network rather than in the MOF pores and reveal the presence of undercoordinated sodium ion environments. Finally, extraction of the modifier by water treatment increases glass porosity, akin to established borosilicate glass processes. Thereby we introduce a transferable approach for tailoring the structure and properties of MOF glasses, expanding possibilities for these functional glass materials.

Formamidinium lead iodide (FAPbI3) is a material of interest for its potential in solar cell applications, driven by its remarkable optoelectronic properties. However, the low-temperature phase of FAPbI3 remains poorly understood, with open questions surrounding its crystal structure, octahedral tilting, and arrangement of formamidinium (FA) cations. Using our trained machine-learned potential in combination with large-scale molecular dynamics (MD) simulations, we provide a detailed investigation of this phase, uncovering its structural characteristics and dynamical behavior. Our analysis reveals the octahedral tilt pattern and sheds light on the rotational dynamics of FA cations in the low-temperature phase. Strikingly, we find that the FA cations become frozen in a metastable configuration, unable to reach the thermodynamic ground state. By comparing our simulated results with experimental nuclear magnetic resonance (NMR) and inelastic neutron scattering (INS) spectra, we demonstrate good agreement, further validating our findings. This phenomenon mirrors experimental observations and offers a compelling explanation for the experimental challenges in accessing the true ground state. These findings provide critical insights into the fundamental physics of FAPbI3 and its low-temperature behavior, advancing our understanding of this important material.

Metal halide perovskites have shown exceptional potential in converting solar energy to electric power in photovoltaics, yet their application is hampered by limited operational stability. This stimulated the development of hybrid layered (two-dimensional, 2D) halide perovskites based on hydrophobic organic spacers, templating perovskite slabs, as a more stable alternative. However, conventional organic spacer cations are electronically insulating, resulting in charge confinement within the inorganic slabs, thus limiting their functionality. This can be ameliorated by extending the π-conjugation of the spacer cations. We demonstrate the capacity to access Ruddlesden-Popper and Dion-Jacobson 2D perovskites incorporating for the first time aryl-acetylene-based (4-ethynylphenyl)methylammonium (BMAA) and buta-1,3-diyne-1,4-diylbis(4,1-phenylene)dimethylammonium (BDAA) spacers, respectively. We assess their unique opto(electro)ionic characteristics by a combination of techniques and apply them in mixed-dimensional perovskite solar cells that show superior device performances with a power conversion efficiency of up to 23 % and higher operational stability, opening the way for multifunctionality in layered hybrid materials and their application.

Polytetrafluoroethylene (PTFE) is a highly versatile material that has found widespread application owing to its exceptionally high chemical resistance and thermal stability. However, these properties mean that PTFE disposal is an energy intensive process, producing fluorinated materials which pose serious concerns regarding toxicity and environmental persistence. Herein we report a straightforward mechanochemical approach for the reductive defluorination of PTFE generating an environmentally benign mixture of elemental carbon and sodium fluoride. The process employs cheap and readily available chunks of sodium metal, proceeding rapidly at room temperature, in the absence of any organic solvent to form sodium fluoride (NaF) in 98% yield. The fluoride generated in the process can be directly upcycled into fine chemicals through in situ mechanochemical fluorination reactions, delivering valuable sulfonyl fluoride and acyl fluoride products in excellent yields.

Perovskite solar cells (PSCs) offer an efficient, inexpensive alternative to current photovoltaic technologies, with the potential for manufacture via high-throughput coating methods. However, challenges for commercial-scale solution-processing of metal-halide perovskites include the use of harmful solvents, the expense of maintaining controlled atmospheric conditions, and the inherent instabilities of PSCs under operation. Here, we address these challenges by introducing a high volatility, low toxicity, biorenewable solvent system to fabricate a range of 2D perovskites, which highly effective precursor phases for subsequent transformation to alpha-formamidinium lead triiodide (FAPbI3), fully processed under ambient conditions. PSCs utilising our FAPbI3 reproducibly show remarkable stability under illumination and elevated temperature (ISOS-L-2) and "damp heat" (ISOS-D-3) stressing, surpassing other state-of-the-art perovskite compositions. We determine that this enhancement is a consequence of the 2D precursor phase crystallisation route, which simultaneously avoids retention of residual low-volatility solvents (such as DMF and DMSO) and reduces the rate of degradation of FA+ in the material. Our findings highlight both the critical role of the initial crystallisation process in determining the operational stability of perovskite materials, and that neat FA+-based perovskites can be competitively stable despite the inherent metastability of the alpha-phase.

Engineering coordinated rotational motion in porous architectures enables the fabrication of molecular machines in solids. A flexible two-fold interpenetrated pillared Metal-Organic Framework precisely organizes fast mobile elements such as bicyclopentane (BCP) (107  Hz regime at 85 K), two distinct pyridyl rotors and E-azo group involved in pedal-like motion. Reciprocal sliding of the two sub-networks, switched by chemical stimuli, modulated the sizes of the channels and finally the overall dynamical machinery. Actually, iodine-vapor adsorption drives a dramatic structural rearrangement, displacing the two distinct subnets in a concerted piston-like motion. Unconventionally, BCP mobility increases, exploring ultra-fast dynamics (107  Hz) at temperatures as low as 44 K, while the pyridyl rotors diverge into a faster and slower dynamical regime by symmetry lowering. Indeed, one pillar ring gained greater rotary freedom as carried by the azo-group in a crank-like motion. A peculiar behavior was stimulated by pressurized CO2, which regulates BCP dynamics upon incremental site occupation. The rotary dynamics is intrinsically coupled to the framework flexibility as demonstrated by complementary experimental evidence (multinuclear solid-state NMR down to very low temperatures, synchrotron radiation XRD, gas sorption) and computational modelling, which helps elucidate the highly sophisticated rotor-structure interplay.

Titanium-oxo clusters can undergo photochemical reactions under UV light, resulting in the reduction of the titanium-oxo core and oxidation of surface ligands. This is an important step in photocatalytic processes in light-absorbing Ti/O-based clusters, metal-organic frameworks, and (nano)material surfaces; however, studying the direct outcome of this photochemical process is challenging due to the fragility of the immediate photoproducts. In this report, titanium-oxo clusters [TiO((OPr)-Pr-i)(L)](n) (n = 4, L = O2PPh2, or n = 6, L = (O2CCH2Bu)-Bu-t) undergo a two-electron photoredox reaction in the single-crystal state via an irreversible single-crystal to single-crystal (SC-SC) transformation initiated by a UV laser. The process is monitored by single crystal X-ray diffraction revealing the photoreduction of the cluster with coproduction of an (oxidized) acetone ligand, which is retained in the structure as a ligand to Ti(3+). The results demonstrate that photochemistry of inorganic molecules can be studied in the single crystal phase, allowing characterization of photoproducts which are unstable in the solution phase.

AbstractThe stability of hybrid organic–inorganic halide perovskite semiconductors remains a significant obstacle to their application in photovoltaics. To this end, the use of low‐dimensional (LD) perovskites, which incorporate hydrophobic organic moieties, provides an effective strategy to improve their stability, yet often at the expense of their performance. To address this limitation, supramolecular engineering of noncovalent interactions between organic and inorganic components has shown potential by relying on hydrogen bonding and conventional van der Waals interactions. Here, the capacity to access novel LD perovskite structures that uniquely assemble through unorthodox S‐mediated interactions is explored by incorporating benzothiadiazole‐based moieties. The formation of S‐mediated LD structures is demonstrated, including one‐dimensional (1D) and layered two‐dimensional (2D) perovskite phases assembled via chalcogen bonding and S–π interactions. This involved a combination of techniques, such as single crystal and thin film X‐ray diffraction, as well as solid‐state NMR spectroscopy, complemented by molecular dynamics simulations, density functional theory calculations, and optoelectronic characterization, revealing superior conductivities of S‐mediated LD perovskites. The resulting materials are applied in n‐i‐p and p‐i‐n perovskite solar cells, demonstrating enhancements in performance and operational stability that reveal a versatile supramolecular strategy in photovoltaics.

Despite significant progress in tin-based perovskites, the development of stable and high-performance tin-based perovskite solar cells (TPSCs) remains a challenge. In this pursuit, a multitude of strategies have been explored, encompassing the use of reducing agents, antioxidants, bulky cations, and customized solvent systems. We propose an improved approach for synthesizing SnI2 from elemental tin and iodine. Here, we generate tin nanoparticles grafted with a carboxylic acid in situ from tin powder-carboxylic acid-assisted synthesis (CAAS). This methodology not only improves the synthesis process of SnI2 but also enhances precursor stability against oxidation. We use Sn-119 MAS NMR to study the atomic-level structure of the resulting FASnI(3) thin films and find that the CAAS approach leads to highly pure and unoxidized material. We report remarkable reproducibility in fabricating large-area (1 cm(2)) flexible TPSCs with significant improvement in open-circuit voltage leading to the champion device showing a power conversion efficiency of 8.35%.

The stabilization of grain boundaries and surfaces of the perovskite layer is critical to extend the durability of perovskite solar cells. Here we introduced a sulfonium-based molecule, dimethylphenethylsulfonium iodide (DMPESI), for the post-deposition treatment of formamidinium lead iodide perovskite films. The treated films show improved stability upon light soaking and remains in the black α phase after two years ageing under ambient condition without encapsulation. The DMPESI-treated perovskite solar cells show less than 1% performance loss after more than 4,500 h at maximum power point tracking, yielding a theoretical T 80 of over nine years under continuous 1-sun illumination. The solar cells also display less than 5% power conversion efficiency drops under various ageing conditions, including 100 thermal cycles between 25 °C and 85 °C and an 1,050-h damp heat test.

AbstractPerovskite solar cells (PSCs) offer an efficient, inexpensive alternative to current photovoltaic technologies, with the potential for manufacture via high-throughput coating methods. However, challenges for commercial-scale solution-processing of metal-halide perovskites include the use of harmful solvents, the expense of maintaining controlled atmospheric conditions, and the inherent instabilities of PSCs under operation. Here, we address these challenges by introducing a high volatility, low toxicity, biorenewable solvent system to fabricate a range of 2D perovskites, which we use as highly effective precursor phases for subsequent transformation to α-formamidinium lead triiodide (α-FAPbI3), fully processed under ambient conditions. PSCs utilising our α-FAPbI3 reproducibly show remarkable stability under illumination and elevated temperature (ISOS-L-2) and “damp heat” (ISOS-D-3) stressing, surpassing other state-of-the-art perovskite compositions. We determine that this enhancement is a consequence of the 2D precursor phase crystallisation route, which simultaneously avoids retention of residual low-volatility solvents (such as DMF and DMSO) and reduces the rate of degradation of FA+ in the material. Our findings highlight both the critical role of the initial crystallisation process in determining the operational stability of perovskite materials, and that neat FA+-based perovskites can be competitively stable despite the inherent metastability of the α-phase.

Wide‐bandgap hybrid halide perovskites are increasingly relevant in the fabrication of tandem solar cells. However, their efficiency and stability during operation are still limited by several factors, among which ion migration at the interface with charge‐selective extraction layers is one of the most detrimental ones. Herein, a host–guest complexation strategy is employed to control interfacial ion migration by using dibenzo‐21‐crown‐7 in wide‐bandgap hybrid halide perovskites based on methylammonium lead bromide. The capacity of the crown ether is demonstrated that affect the performances and stabilities of MAPbBr3 solar cells. As a result, power conversion efficiencies of up to 5.9% are achieved with an open circuit voltage as high as 1.5 V, which is accompanied by stability over 300 h at 85 °C under nitrogen atmosphere, as well as more than 300 h at ambient temperature, maintaining ∼80% of initial performance. This provides a versatile strategy for wide‐bandgap photovoltaic devices.