Showing papers in "Chemistry of Materials in 2023"

Monolithic Covalent Organic Frameworks with Hierarchical Architecture: Attractive Platform for Contaminant Remediation

Abstract: The insolubility in solvents and poor processability of powder covalent organic frameworks (COFs) considerably impede their practical application. To address these issues and bridge the gap between powder COFs and their practical application, the construction of monolithic COFs has emerged as a feasible and effective solution. Monolithic COFs (i.e., macroscopic three-dimensional architectures) with hierarchical structures have attracted tremendous interest for environmental remediation and exhibited good contaminant removal performances owing to their wide distribution of pore sizes ranging from micropores to macropores, large specific surface area, tailored chemical components, and excellent chemical stability. Monolithic COFs can be either pure COFs with self-supporting structures or composites of COFs with other materials. The resulting COF-based monoliths inherit the merits of the parent powder COFs (such as tunable pore size, tailored structure, and super chemical/thermal stability) and the intriguing features of monolithic materials, such as hierarchical structure, high porosity, and easy handling, endowing them with fast mass transfer and high adsorption capacity. This review provides a comprehensive summary of the recent advances in the synthesis of monolithic COF materials. Additionally, the recent progress of their application in environmental remediation is summarized, including metal-ion removal, organic-pollutant capture, and oil–water separation. Furthermore, this review discusses the current challenges and provides future perspectives. We sincerely hope that it will contribute to the further development of COF-based materials in other fields, especially environmental remediation.

The Future of Drug Delivery

Abstract: ADVERTISEMENT RETURN TO ISSUEEditorialNEXTThe Future of Drug DeliveryJingjing GaoJingjing GaoCenter for Nanomedicine, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Boston, Massachusetts 02115, United StatesHarvard Medical School, Boston, Massachusetts 02115, United States;More by Jingjing Gao, Jeffrey M Karp*Jeffrey M KarpCenter for Nanomedicine, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Boston, Massachusetts 02115, United StatesHarvard Medical School, Boston, Massachusetts 02115, United States;Harvard-MIT Program in Health Sciences and Technology, MIT, Cambridge, Massachusetts 02139, United StatesHarvard Stem Cell Institute, Cambridge, Massachusetts 02138, United StatesBroad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, United States*Email: [email protected]More by Jeffrey M Karp, Robert Langer*Robert LangerHarvard-MIT Program in Health Sciences and Technology, MIT, Cambridge, Massachusetts 02139, United StatesDepartment of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States;Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States*Email: [email protected]More by Robert Langerhttps://orcid.org/0000-0003-4255-0492, and Nitin Joshi*Nitin JoshiCenter for Nanomedicine, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women’s Hospital, Boston, Massachusetts 02115, United StatesHarvard Medical School, Boston, Massachusetts 02115, United States;*Email: [email protected]More by Nitin JoshiCite this: Chem. Mater. 2023, 35, 2, 359–363Publication Date (Web):January 24, 2023Publication History Received30 September 2022Published online24 January 2023Published inissue 24 January 2023https://doi.org/10.1021/acs.chemmater.2c03003Copyright © Published 2023 by American Chemical SocietyRIGHTS & PERMISSIONSArticle Views4706Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-AlertsSUBJECTS:Cancer therapy,Drug delivery,Drug release,Nanoparticles,Pharmaceuticals Get e-Alerts

ARC–MOF: A Diverse Database of Metal-Organic Frameworks with DFT-Derived Partial Atomic Charges and Descriptors for Machine Learning

Abstract: Metal–organic frameworks (MOFs) are a class of crystalline materials composed of metal nodes or clusters connected via semi-rigid organic linkers. Owing to their high-surface area, porosity, and tunability, MOFs have received significant attention for numerous applications such as gas separation and storage. Atomistic simulations and data-driven methods [e.g., machine learning (ML)] have been successfully employed to screen large databases and successfully develop new experimentally synthesized and validated MOFs for CO2 capture. To enable data-driven materials discovery for any application, the first (and arguably most crucial) step is database curation. This work introduces the ab initio REPEAT charge MOF (ARC–MOF) database. This is a database of ∼280,000 MOFs which have been either experimentally characterized or computationally generated, spanning all publicly available MOF databases. A key feature of ARC–MOF is that it contains density functional theory-derived electrostatic potential fitted partial atomic charges for each MOF. Additionally, ARC–MOF contains pre-computed descriptors for out-of-the-box ML applications. An in-depth analysis of the diversity of ARC–MOF with respect to the currently mapped design space of MOFs was performed─a critical, yet commonly overlooked aspect of previously reported MOF databases. Using this analysis, balanced subsets from ARC–MOF for various ML purposes have been identified, with a case study of the effect of training set on the ML performance. Other chemical and geometric diversity analyses are presented, with an analysis on the effect of the charge-assignment method on atomistic simulation of the gas uptake in MOFs.

Facile High-Yield Synthesis of Ag–In–Ga–S Quaternary Quantum Dots and Coating with Gallium Sulfide Shells for Narrow Band-Edge Emission

Abstract: Among cadmium-free quantum dots (QDs), ternary or quaternary chalcogenide semiconductor QDs composed of groups 11, 13, and 16 elements have extensively been studied. Herein, monodispersed quaternary nanoparticles of silver indium gallium sulfide (AgInxGa1–xS2) are synthesized by a new route that specifically produces the target product without solid byproducts. The difference in the reactivity between groups 11 and 13 metals with chalcogen is a common issue in synthesizing the groups 11, 13, and 16 ternary or quaternary semiconductor QDs. Instead of a common approach to suppress the reactivity of group 11 metals, this study utilizes their high reactivity; rapid injection of a Ag source into the solution containing a thiocarboxylate produced small Ag2S nanoparticles. These Ag2S nanoparticles are then exposed to indium-, gallium-, and sulfur-containing species in situ and then converted into quaternary nanoparticles comprising AgInxGa1–xS2. Due to the well-controlled reaction steps, the product yield based on Ag was increased to 60%, which significantly exceeds that obtained using our previous approach of heating all-mixed raw materials (5–15%). After coating with gallium sulfide (GaSy) shells, the core/shell QDs exhibited an intense, green-colored band-edge emission with a tunable peak wavelength between 499 and 543 nm. The excellent uniformity of the core nanoparticles in terms of size and composition demonstrated a quite narrow band-edge emission with the full width at half maximum of 31 nm, which is equal to the record-narrow values of green-emitting cadmium-free QDs. Additionally, a near-unity photoluminescence quantum yield was achieved after postsynthetic surface treatment by alkylphosphines, indicating the defect-free nature of the prepared AgInxGa1–xS2/GaSy core/shell QD system.

Fine Tuning of Defects Enables High Carrier Mobility and Enhanced Thermoelectric Performance of n-Type PbTe

Abstract: High carrier mobility is critical to improving thermoelectric performance over a broad temperature range. However, traditional doping inevitably deteriorates carrier mobility. Herein, we develop a strategy for fine tuning of defects to improve carrier mobility. To begin, n-type PbTe is created by compensating for the intrinsic Pb vacancy in bare PbTe. Excess Pb2+ reduces vacancy scattering, resulting in a high carrier mobility of ∼3400 cm2 V–1 s–1. Then, excess Ag is introduced to compensate for the remaining intrinsic Pb vacancies. We find that excess Ag exhibits a dynamic doping process with increasing temperatures, increasing both the carrier concentration and carrier mobility throughout a wide temperature range; specifically, an ultrahigh carrier mobility ∼7300 cm2 V–1 s–1 is obtained for Pb1.01Te + 0.002Ag at 300 K. Moreover, the dynamic doping-induced high carrier concentration suppresses the bipolar thermal conductivity at high temperatures. The final step is using iodine to optimize the carrier concentration to ∼1019 cm–3. Ultimately, a maximum ZT value of ∼1.5 and a large average ZTave value of ∼1.0 at 300–773 K are obtained for Pb1.01Te0.998I0.002 + 0.002Ag. These findings demonstrate that fine tuning of defects with <0.5% impurities can remarkably enhance carrier mobility and improve thermoelectric performance.

Solvatochromic Near-Infrared Aggregation-Induced Emission-Active Acrylonitriles by Acceptor Modulation for Low-Power Stimulated Emission Depletion Nanoscopy

Abstract: Stimulated emission depletion (STED) nanoscopy has broadened our horizons to unravel mysterious functions of cellular structures on an unparalleled nanometer scale. Nevertheless, an intense depletion laser power is a general prerequisite for STED super-resolution imaging with a satisfactory resolution, inevitably leading to severe photobleaching of fluorophores, irreparable photodamage to biosamples, and impaired imaging quality. Herein, by modulating distinct acceptor units, a series of donor–acceptor–acceptor structured fluorescent acrylonitriles featured with aggregation-induced emission (AIE) for STED super-resolution imaging at a low depletion power were systematically developed. These AIE luminogens (AIEgens) exhibited tunable near-infrared emissions (650–733 nm) and high fluorescence quantum yields (QYs of up to 26.8%) in the solid state, significant Stokes shifts, and large two-photon absorption cross-sections. They also exhibited a typical solvatochromic effect and ultrahigh QYs of up to 98.4% in low-polarity solvents. Furthermore, these lipophilic solvatochromic acrylonitriles specifically lit up lipid droplets (LDs) with exceptionally high photostability in a wash-free manner. By taking TPA-BT-ANBI as an example, the STED super-resolution imaging of LDs with excellent resolution of 62 and 80 nm for cytosolic and nuclear LDs, respectively, at a low saturation depletion power of 0.83 MW/cm2 and extended time-lapse imaging of LD dynamics was achieved. Subsequent use of TPA-BT-ANBI for the optical discrimination of fatty liver tissues and two-photon deep-tissue imaging was also demonstrated. This study opens new avenues for versatile photostable materials at low depletion powers for target-specific STED super-resolution imaging.

Terminal Groups of Nonfullerene Acceptors: Design and Application

Abstract: Materials design plays a critical role in improving the power conversion efficiency (PCEs) of organic solar cells (OSCs). Recent advances in nonfullerene acceptors (NFAs) have achieved great success and made a large contribution to the rapid increase in PCEs. The current state-of-the-art OSCs have PCEs of >19%, demonstrating their great potential for use in practical applications. All high-efficiency NFAs adopt an A–D–A or A–DA′D–A (A = acceptor and D = donor) structure. Modulating the electron push–pull effect using an alternating D–A structure has proven to be an effective molecular design method. Specially, for NFAs, the design and application of terminal groups are of great significance. In this Perspective, a brief introduction is given to the development of terminal groups and representative materials. We highlight the critical role of the molecular electrostatic potential in evaluating the electron-withdrawing strength. The applications of terminal groups in designing wide-, middle-, and low-bandgap NFAs are discussed. Then, an outline of the other functions of terminal groups in affecting the intermolecular packing, blend morphology, and energy loss is presented. Furthermore, insights into the key issues that should be considered when developing new terminal groups, including efficiency, cost, and stability, are discussed.

Nanointerface Engineering of Metal Hydrides for Advanced Hydrogen Storage

Abstract: With global efforts to relieve the formidable impact of climate change, hydrogen is considered a viable replacement for fossil fuels without intermittency concerns of other renewable sources. Hydrogen storage plays a pivotal role in the implementation of hydrogen economy, coupling hydrogen production with fuel cell technologies. Storing hydrogen in the form of solid-state hydride materials has been studied as a future hydrogen storage technology for enabling a safe, energy-efficient, and high-energy-density system. However, hostile thermodynamic and kinetic properties of each hydride material result in insufficient hydrogen storage performance for practical applications, such as sluggish hydrogen absorption or desorption, high dehydrogenation temperatures, and sometimes limited reversibility; thus, these kinetic and thermodynamic characteristics need to be thoroughly understood depending on each hydride material. Among various strategies, nanostructuring has been regarded as a general approach to tackling such limitations regarding thermodynamic and kinetic characteristics of hydride materials. In particular, the formation of nanosized hydrides within a nanostructured scaffold─also known as nanoconfinement─is of great potential for advanced hydrogen storage because it can additionally leverage host–guest interactions at the nanointerfaces of hydride materials and scaffolds. In this context, the active tuning of such nanointerfaces brings about additional thermodynamic or kinetic changes in hydrogen sorption reactions compared to the unmodified nanoconfined hydride composites, holding great promise for tailored strategies for each metal hydride. In this Perspective, we summarize the major thermodynamic and kinetic barriers of each metal hydride and highlight the recent progress in overcoming such limits, mainly focusing on nanointerface engineering in nanoconfined metal hydrides. Further, we provide our insight and current challenges in understanding the underlying mechanisms of the interaction at the nanointerface, whereby the noticeable technological leaps can be emulated in practical systems.

Bimolecular Reaction Mechanism in the Amido Complex-Based Atomic Layer Deposition of HfO2

Abstract: The surface chemistry of the initial growth during the first or first few precursor cycles in atomic layer deposition is decisive for how the growth proceeds later on and thus for the quality of the thin films grown. Yet, although general schemes of the surface chemistry of atomic layer deposition have been developed for many processes and precursors, in many cases, knowledge of this surface chemistry remains far from complete. For the particular case of HfO2 atomic layer deposition on a SiO2 surface from an alkylamido-hafnium precursor and water, we address this lack by carrying out an operando atomic layer deposition experiment during the first cycle of atomic layer deposition. Ambient-pressure X-ray photoelectron spectroscopy and density functional theory together show that the decomposition of the metal precursor on the stoichiometric SiO2 surface in the first half-cycle of atomic layer deposition proceeds via a bimolecular reaction mechanism. The reaction leads to the formation of Hf-bonded methyl methylene imine and free dimethylamine. In addition, ligand exchange takes place involving the surface hydroxyls adsorbed at defect sites of the SiO2 surface.

Synthesis, Surface Chemistry, and Fluorescent Properties of InP Quantum Dots

Abstract: InP quantum dots (QDs) have great potential as emitters for solid-state lighting, lasing, and bioimaging without the inherent toxicity concern of Cd and Pb-based emitters. Indium phosphide’s small bandgap and high covalency make it uniquely capable of color-pure fluorescence that can be tuned throughout the visible and lower IR spectrum. Until recently, InP-based QDs consistently underperformed when compared with CdSe-based counterparts. Recent efforts to understand indium phosphide’s nonclassical growth mechanisms, control the nanocrystal shape, control in situ formation of surface oxides, and grow thick, uniform shells have produced InP-based QDs comparable to their CdSe competitors with >95% quantum yields (QYs) in red, green, and blue emission wavelengths. This review covers the most common synthetic techniques, the most recent theories on InP formation mechanisms, the current understanding of InP surface chemistries, and the breadth of fluorescent properties of InP-based QDs.

Polybenzodiazine Aerogels: All-Nitrogen Analogues of Polybenzoxazines─Synthesis, Characterization, and High-Yield Conversion to Nanoporous Carbons

Abstract: Tetrahydroquinazoline (THQ) was designed as an all-nitrogen analogue of main-stream benzoxazine monomers. THQ solutions in DMF gelled at 100 °C via HCl-catalyzed ring-opening polymerization to polybenzodiazine (PBDAZ) wet gels, which were dried in an autoclave with supercritical fluid CO2 to aerogels. These as-prepared PBDAZ-100 aerogels undergo ring-fusion aromatization at 240 °C under O2. This oxidized form is referred to as PBDAZ-240. Chemical identification of PBDAZ-100 and PBDAZ-240 relied on consideration of all nine possible polymerization pathways, in combination with elemental analysis, infrared and solid-state 13C NMR spectroscopy, and 15N NMR spectroscopy of aerogels from the selectively 15N-enriched THQ monomer. Fully oxidized PBDAZ-240 aerogels were carbonized at 800 °C under Ar to carbon aerogels with 61% w/w yield and with retention of the nanomorphology of the parent PBDAZ-100 aerogels. Direct pyrolysis of PBDAZ-100 at 800 °C, i.e., without prior oxidation, resulted in only 40% w/w yield and complete loss of the fine nanostructure. The evolution of PBDAZ-240 aerogels along pyrolysis toward carbonization was monitored using progressively higher pyrolysis temperatures from 300 to 800 °C under Ar. Aerogels received at 600 and 800 °C (referred to as PBDAZ-600 and PBDAZ-800, respectively) had relatively high surface areas (432 and 346 m2 g–1, respectively), a significant portion of which (79% in both materials) was assigned to micropores. The new polymer aerogels, together with polybenzoxazine aerogels, comprise a suitable basis set for comparing N-rich versus O-rich porous carbons as adsorbers.

CsPbBr₃ in the Activation of the C–Br Bond of CBrX₃ (X = Cl, Br) under Sunlight

Abstract: A newly synthesized green-fluorescent, orthorhombic, bromide-rich, perovskite nanocrystal (Φ ∼ 0.93, τ ∼ 12.5 ns, Eox = +1.6 V) obtained from an unprecedented bromide precursor dibromoisocyanuric acid was found to be an excellent visible-light (sunlight or blue-light-emitting diode (LED)) photocatalyst toward the synthesis of gem-dihaloenones for the first time. The photoactivated CsPbBr3 catalyzed the homolytic cleavage of CBrX3 (X = Cl, Br) to generate the •CX3 radical, which underwent cascaded C–C cross-coupling with terminal alkynes into the corresponding gem-dihaloenones. Radical-trapping experiments and luminescence-quenching studies helped establish a single-electron-transfer (SET) mechanism. Interestingly, other highly stable CsPbBr3 NCs, obtained from N-bromosuccinimide (NBS) and dibromohydantoin (DBHT) precursors, are unable to carry out these transformations. These results not only enrich the CsPbBr3 synthetic methodology but also encourage the research community to develop efficient and cost-effective photocatalytic materials.

Surface Chemistry of InP Quantum Dots, Amine–Halide Co-Passivation, and Binding of Z-Type Ligands

Abstract: Understanding and controlling the surface chemistry of colloidal quantum dots (QDs) are essential steps toward improving their opto-electronic properties and tailoring the material for specific applications. For oleylamine–chloride co-passivated InP QDs synthesized using di-ethylaminophosphine (DEAP), knowledge of possible exchange reactions and their effect on the QD properties is still very limited. In this work, we address this issue by a combination of experimental and computational studies. First, we prove that InP QDs are passivated by a combination of oleylamine (OlNH2) and chloride, bound as L-type and X-type ligands, respectively. By exposure to organic acids such as carboxylic acids or thiols, this L–X combination can be replaced with oleylammonium chloride in an acid–base-mediated ligand exchange reaction that results in the binding of carboxylates or thiolates as X-type ligands. The latter tend to quench the band-edge emission by forming strongly localized mid-gap states on the sulfur atoms of the thiolates. Furthermore, we observe that the binding of ZnCl2 to the InP QD surface, a process enabled by the prior complexation of this Z-type ligand with OlNH2, considerably increases the band-edge emission. However, as the resulting photoluminescence efficiency remains modest, we conclude that InP QDs synthesized using DEAP feature a diverse set of surface states, for which passivation depends at least on the elimination of undercoordinated surface phosphorous and the choice of the X-type ligand.

Binding Affinity of Monoalkyl Phosphinic Acid Ligands toward Nanocrystal Surfaces

Abstract: We recently introduced monoalkyl phosphinic acids as a ligand class for nanocrystal (NC) synthesis. Their metal salts have interesting reactivity differences compared to metal carboxylates and phosphonates and provide a cleaner work-up compared to phosphonates. However, little is known about the surface chemistry of NCs with monoalkyl phosphinate ligands. Here, we probe the relative binding affinity of monoalkyl phosphinate ligands with respect to other X-type ligands. We perform competitive ligand exchange reactions with carboxylate and phosphonate ligands at the surface of hafnia, cadmium selenide, and zinc sulfide NCs. We monitor the ligand shell composition by solution 1H and 31P NMR spectroscopy. Using a monoalkyl phosphinic acid with an ether functionality, we gain an additional NMR signature, apart from the typical alkene resonance in oleic acid and oleylphosphonic acid. We find that carboxylate ligands are easily exchanged upon exposure to monoalkyl phosphinic acids, whereas an equilibrium is reached between monoalkyl phosphinates and phosphonates, slightly in the favor of phosphonate (K = 2). Phosphinic acids have thus an intermediate binding affinity between carboxylic acids and phosphonic acids for all the NCs studied. These results enable the sophisticated use of monoalkyl phosphinic acids for NC synthesis and for post-synthetic surface engineering.

Defect-Stabilized Tin-Based Perovskite Solar Cells Enabled by Multifunctional Molecular Additives

Abstract: Sn-based perovskite solar cells (Sn-PSCs) are the most viable replacements for Pb-based PSCs. However, the facile oxidation of Sn2+ and a high defect density on the surfaces and grain boundaries in Sn-PSCs complicate the task of attaining highly stable Sn-PSCs. Here, both surfaces and grain boundaries are passivated using a fulleropyrrolidine with a triethylene glycol monoethyl ether side chain (PTEG-1) as a multifunctional molecular additive for the first time. The ether group and fullerene group in PTEG-1 interact with Sn2+ and I–, respectively, thereby inhibiting the formation of Sn4+ and I3–. This multifunctional passivation suppresses nonradiative recombination and improves the stability of Sn-PSCs. As a result, Sn-PSCs with encapsulation retain 65% of their initial power conversion efficiency after 1000 h of light illumination under ambient conditions. Our results provide a guideline for the future design of multifunctional molecules with functional groups that enable the fabrication of stable Sn-PSCs.

Coordination Sphere Flexibility Leads to Elastic Deformation in a One-Dimensional Coordination Polymer Crystal

Abstract: Coordination polymers exhibiting mechanical flexibility including elastic or plastic bending are rare. Here, we report an example of a mechanically flexible one-dimensional coordination polymer that shows elastic bending. Quantitative insights on the inter and intra-chain bonding as well as structural flexibility from a combination of techniques including variable temperature single crystal X-ray diffraction (XRD), high-pressure crystallography (ambient─15 GPa), synchrotron micro-XRD mapping of the bent crystal, and high-resolution synchrotron X-ray charge density analysis show that the helical coordination polymer behaves like a spring when subjected to external stimuli. Changes that occur with the variation of temperature, pressure, or bending, however, result in very different mechanistic changes. The exceptional coordination sphere flexibility rendered by the presence of Jahn–Teller distorted coordination bonds leads to the flexibility of the polymer.

The Autonomous Formulation Laboratory: An Open Liquid Handling Platform for Formulation Discovery Using X-ray and Neutron Scattering

Abstract: The application of machine learning techniques to X-ray scattering experiments has been of significant recent interest, offering advances in areas such as the study of complex oxides. Despite these success stories, few applications of these techniques into soft materials have been reported, likely due in part to the highly nonequilibrium nature of soft materials phase spaces and the complexities associated with autonomous formulation preparation. Here, we report the design of the Autonomous Formulation Laboratory, a robust platform for the automated synthesis and measurement of complex liquid mixtures using X-ray and neutron scattering, readily extensible to system-specific complementary techniques such as spectroscopy and rheometry. We describe the application of the platform to generate dense, highly reproducible data sets on material systems ranging from silica nanoparticles to block copolymer micelles. We expect the platform to prove revolutionary to the understanding of the stability of complex liquid formulations and the resulting data sets to provide fertile ground for the development of machine learning techniques for complex soft materials phase spaces.

Regulating Eu2+ Multisite Occupation through Structural Disorder toward Broadband Near-Infrared Emission

Abstract: To promote the development of near-infrared (NIR) light sources in optoelectronic and biomedical applications, the discovery of NIR-emitting phosphor materials and their design principles are essential. Herein, we report a novel Eu2+-activated broadband NIR-emitting phosphor, BaSrGa4O8:Eu2+, which features multisite occupation due to Ba/Sr and oxygen site occupancy disorder. With an increase in the Ba/Sr atomic ratio from 1:1 to 1.7:0.3, the Eu2+ emission band maximum red-shifts from 670 to 775 nm, along with an enlargement of the full width at half-maximum (FWHM) from 140 to 230 nm. The underlying mechanism for the structure–property relationship is elucidated using density functional theory calculations. The application of the NIR phosphor-converted light-emitting diodes (pc-LEDs) is demonstrated, showing their potential in night-vision technology. Our results can initiate further exploitation of the host structural disorder toward Eu2+ broadband NIR luminescence for applications in pc-LEDs.

Self-Healing Multimodal Flexible Optoelectronic Fiber Sensors

Abstract: Fiber-optic sensors are attracting attention because of their high sensitivity, fast response, large capacity-transmission, and anti-electromagnetic interference advantages. Nevertheless, rigid optical fibers are inevitably damaged or even fractured in applications involving large tensile or bending strains (e.g., human body monitoring, soft robotics, and biomedical devices) and the position of the fracture is difficult to locate and repair. Therefore, optically self-healing fiber-optic sensors are highly desirable. Here, we report a design strategy for increasing the polymer segmental mobility and reversible non-covalent bond density of poly(polymerizable deep eutectic solvent) (PDES) to continuously fabricate a core–cladding poly(PDES) optical fiber (CPOF) with significant optical, electrical, and mechanical self-healing abilities. It also possesses low optical propagation attenuation (0.31 dB cm–1), wide temperature tolerance (−77–168 °C), and excellent biocompatibility. Moreover, CPOFs have been validated for gesture recognition, subcutaneous self-healing, and pressure–temperature detection, owing to their ability to transmit dual optical-electrical signals in real time, and are promising for various applications in industrial and technological fields.

Graphene/Polyolefin Elastomer Films as Thermal Interface Materials with High Thermal Conductivity, Flexibility, and Good Adhesion

Abstract: Heat dissipation has become a central issue for the development of the microelectronic industry. Thermal interface materials (TIMs) have been widely applied to electron component cooling, which is used to bond the heat spreader and the chip together. Most research on TIMs has only dealt with thermal conductivity enhancement. However, the mechanical properties and adhesion of TIMs are indispensable for practical applications, as well as postcleaning to remove TIMs. A graphene nanosheet/polyolefin elastomer (GNP/POE) film was designed and prepared by a facile method, in which the heat conduction paths were efficiently constructed, and the good mechanical properties of POE were reserved. The thermal conductivity of as-prepared GNP/POE film can reach 1.07 W m–1 K–1 at an extremely low filler loading of 0.62 wt %. Furthermore, the tensile strength, elongation at break, and adhesion of the prepared GNP/POE film are as good as those of commercial TIM productions. The prepared GNP/POE film can be used as TIMs for chip cooling and exhibits a good heat dissipation effect. Additionally, the prepared GNP/POE film can be peeled off from the chip without residue, after the chip has finished running, which is significant for practical production. This work provides valuable information and insight into the design and fabrication of TIMs in the future.

Bilayered Dion–Jacobson Hybrid Perovskite Bulk Single Crystals Constructed with Aromatic Diammonium for Ultraviolet–Visible–Near-Infrared Photodetection

Abstract: Two-dimensional (2D) Dion–Jacobson (DJ) hybrid perovskites (HPs) are widely used in the photodetection field due to their high stability and excellent carrier transport performance. However, current photodetectors based on DJ HPs can work only in the ultraviolet and visible wavebands, which limits their application in near-infrared (NIR) photodetection. Herein, for the first time, ultraviolet–visible–NIR photodetection is realized in the bulk single crystal of 2D bilayered DJ HP (3AMPY)(EA)Pb2Br7 (3AMPY = 3-(aminomethyl)pyridinium, EA = ethylamine). Structurally, the introduction of aromatic diammonium makes (3AMPY)(EA)Pb2Br7 have a shorter layer spacing (3.561 Å) and a more rigid structure. In addition, benefiting from the strong quantum and dielectric confinements of 2D HPs, (3AMPY)(EA)Pb2Br7 shows an excellent two-photon absorption (TPA) coefficient of up to 61.1 cm/MW under the excitation of an 800 nm femtosecond laser. Notably, (3AMPY)(EA)Pb2Br7 exhibits efficient photodetection from ultraviolet (377 nm) and visible (405 nm) to NIR (800 nm) wavebands, with on/off ratios of current higher than 103.

Anthracene-Bridged Photosensitizers for Effective and Safe Photodynamic Therapy

Abstract: Photodynamic therapy (PDT) is a minimally invasive therapeutic modality. However, the residual photosensitizers (PSs) after PDT can still produce toxic singlet oxygen (1O2) under sunlight to damage normal tissues. The PS that can be switched off after PDT is desirable but rare. Herein, we propose a general strategy to design effective and self-degradable PSs by embedding an anthracene bridge into donor–acceptor (D–A) structures. First, the steric anthracene can regulate the orbital distribution for enhancing the 1O2 production capacity. More importantly, the anthracene is responsive to the self-produced 1O2 for self-degradation. Besides, the degradation rate can be fine-tuned by the hydrophilicity of PSs. In this way, the PSs can realize a balance between treatment and suicide to ensure PDT and post-treatment safety. This work provides new insights into the design of degradable PSs with a clear mechanism, aiming to improve the post-safety of PDT.

Low-Temperature Ion Exchange Synthesis of Layered LiNiO2 Single Crystals with High Ordering

Abstract: Layered Ni-rich oxide cathode materials are being explored in an effort to boost the energy density of lithium-ion batteries, especially for automotive applications. Among them, the ternary-phase LiNiO2 (LNO) is a promising candidate but brings along various issues, such as poor structural stability. The material is prone to disordering (Li off-stoichiometry) when prepared by conventional solid-state synthesis, leading to the presence of Ni2+ in the Li layer. These point defects negatively affect the utilization of the Li inventory, thereby limiting the practical specific capacity. In this work, we report on a two-step synthesis approach that avoids the formation of nickel substitutional defects. First, NaNiO2 (NNO) is prepared, showing no such defects due to larger differences in ionic radii between Ni2+/Ni3+ and Na+. NNO is then subjected to Na+/Li+ exchange under mild conditions. In so doing, monolithic LNO particles free of NiLi• defects can be produced at relatively low temperatures. Notably, this route allows for tailoring of the grain size, a strategy that may be used to gain insights into the structure–size–property relations in single-crystalline LNO.

Spectroelectrochemical Network Measurements for Redox Bioelectronics

Abstract: Redox bioelectronics enlists electrochemical methods to connect to biology through biology’s native redox modality. The activities of this redox modality involve the exchange of electrons through redox reactions, and often, individual redox reactions are embedded within larger redox-reaction networks. Here, we examined electrodes coated with redox-active but non-conducting catechol-containing hydrogels that are emerging as important materials in redox-based bioelectronics. Previous studies have shown that electron “flow” through these catechol hydrogels involves redox reactions, and in some cases, catechol’s redox-state switching can be observed by orthogonal electrical and optical measurements. Here, we extend analysis by increasing the dimensionality of dynamic optical measurements from a single wavelength to a broader spectrum and adapt a minimal deterministic network model to reveal the intrinsic structure of this additional data. This increased dimensionality enhances our capabilities for detecting and interpreting discriminating signals, and we demonstrate these capabilities by comparing the response characteristics of conducting versus redox-active hydrogels and redox networks with different topologies. We discuss the importance of increasing measurement dimensionality to enhance both data-driven and theory-guided approaches for information processing in redox-based bioelectronics.

Differential Analysis of Galvanostatic Cycle Data from Li-Ion Batteries: Interpretative Insights and Graphical Heuristics

Abstract: Differentiation of a Li-ion battery cycling profile (galvanostatic voltage vs charge) yields a pair of complementary measures: differential capacity (dQ/dV vs voltage, also called incremental capacity) and differential voltage (dV/dQ vs charge). These metrics, especially when obtained under experimental conditions approximating cell equilibrium, are widely used to diagnose cell state and mechanisms related to cell aging. Central to the resulting diagnosis is the understanding of how the chemistry of individual electrode materials manifests in the full-cell differential plots. In this article, a fundamental theory of differential analysis is advanced from the starting point of idealized single electrode (half-cell) measurements, building up to the nontrivial translation to full cell data, with consideration of cell balancing and degradation. Various complementary approaches from the existing literature are harmonized with the aid of a novel graphical heuristic in which cell voltage and differential capacity data are superimposed on a 2D representation (“square plot”) of the cell thermodynamic state. Interpretative analysis based on the new approach is demonstrated using data from a commercial pouch cell with the well-characterized LiCoO2|graphite chemistry. A brief review of current literature on practical uses of differential analysis is also provided.

Surfactant-Free Colloidal Syntheses of Gold-Based Nanomaterials in Alkaline Water and Mono-alcohol Mixtures

Abstract: Gold nanoparticles (Au NPs) and gold-based nanomaterials combine unique properties relevant for medicine, imaging, optics, sensing, catalysis, and energy conversion. While the Turkevich–Frens and Brust–Schiffrin methods remain the state-of-the-art colloidal syntheses of Au NPs, there is a need for more sustainable and tractable synthetic strategies leading to new model systems. In particular, stabilizers are almost systematically used in colloidal syntheses, but they can be detrimental for fundamental and applied studies. Here, a surfactant-free synthesis of size-controlled colloidal Au NPs stable for months is achieved by the simple reduction of HAuCl4 at room temperature in alkaline solutions of low-viscosity mono-alcohols such as ethanol or methanol and water, without the need for any other additives. Palladium (Pd) and bimetallic AuxPdy NPs, nanocomposites and multimetallic samples, are also obtained and are readily active (electro)catalysts. The multiple benefits over the state-of-the-art syntheses that this simple synthesis bears for fundamental and applied research are highlighted.

Solution Aggregate Structures of Donor Polymers Determine the Morphology and Processing Resiliency of Non-Fullerene Organic Solar Cells

Abstract: The solution-state aggregation of conjugated polymers is critical to the morphology and device performance of bulk heterojunction (BHJ) organic solar cells (OSCs). However, the detailed structures of polymer solution-state aggregates and their impact on the morphology and device performance of OSCs remain largely unexplored. Herein, we utilize a benzodithiophene-based donor polymer (PM7) and its ester-functionalized derivatives (PM7 D1 and D2) with reduced backbone rigidity as our model systems to demonstrate how a polymer solution-state aggregate structure impacts the morphology and processing resiliency of OSCs. Using X-ray scattering and microscopic imaging techniques, we ascertain that PM7 solution forms a combination of semi-crystalline fiber aggregates and amorphous polymer chain network aggregates, whereas PM7 D1 and D2 solutions primarily form amorphous network aggregates through sidechain associations. Interestingly, when the solution temperature is increased, the fiber aggregates of PM7 break down while the polymer network aggregates remain stable. Due to this temperature-dependent behavior of the fiber aggregates, blade-coated devices fabricated from the PM7 donor polymer and non-fullerene acceptor, ITIC-4F, lead to highly processing temperature-sensitive performance, whereas PM7 D1 and D2 polymers exhibit improved processing temperature resiliency. More importantly, we report that amorphous, network-like aggregates are conducive to superior device performance in blade-coated OSCs owing to the formation of blend films with short π–π stacking distance, small domain spacing, and face-on preferred molecular orientation. In contrast, we find that fiber-like aggregates lead to large π–π stacking distance, large domain spacing, and isotropic molecular orientation in the blend film, which deteriorate the device performance.

Recyclable, Fire-Resistant, Superstrong, and Reversible Ionic Polyurea-Based Adhesives

Abstract: Carbon dioxide (CO2) as a sustainable comonomer for the synthesis of polycarbonates, polyurea, and polyurethane is attracting continuous interest, whereas the development of multifunctional polymers directly from CO2 remains challenging for its inherent inertness. Herein, we report the synthesis and characterization of a recyclable, nonflammable, superstrong, and reversible adhesive via the polycondensation of CO2 and an amino-functionalized ionic liquid. The resulting CO2-sourced ionic polyurea (CIPUa) with commutative urea groups and ionic species in the skeleton shows much higher shear strength on various substrates even below −80 °C than commercial hot-melt adhesives and excellent nonflammability and antibacterial ability than isocyanate-derived nonionic polyurea. CIPUa also demonstrates facile degradation in ZnSO4 aqueous solution and can be recycled into fresh CIPUa. These properties are mainly endowed by the enhanced electrostatic interaction and attenuated hydrogen bonds between the CIPUa chains. This study provides an effective strategy for designing a sustainable CO2-sourced ionic polymer with multiple functions for broad applications.

Bringing Quantum Mechanics to Coarse-Grained Soft Materials Modeling

Abstract: Fundamental knowledge gaps are endemic in our understanding of how emergent properties of soft materials are linked to the quantum mechanical (QM) world. The limitations of current QM modeling paradigms inhibit the understanding and design of classes of soft materials for which QM phenomenology is critical. At its root, these limitations derive from the seemingly innocuous premise of requiring all atomic positions to solve the molecular Schrödinger equation, which necessitates supercomputing resources to incorporate even simple QM phenomenology into small (∼nm) systems of soft materials. Here, we review emerging efforts to overcome these challenges through the development of electronic prediction models that operate at the coarse-grained resolution. We motivate the origins of this new computational paradigm, denoted electronic coarse-graining (ECG), discuss its relationship to existing molecular modeling frameworks, and describe recent successes of ECG and related models for soft materials. Importantly, we highlight the classes of soft materials where ECG models can be potentially transformative.

Screening of Broadband Near-Infrared Cr3+-Activated Phosphors Using Ce3+ as a Probe

Abstract: Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are ideal miniaturized NIR light sources, but it is still difficult to find broadband-emitting NIR phosphors due to the lack of appropriate material design principles. In this work, we propose a method to find hosts yielding broadband NIR Cr3+ emission by screening Ce3+-doped phosphor hosts for which both Ce3+ and Cr3+ can occupy the same crystallographic site. A NIR phosphor Ba3Sc4O9:Cr3+ (BSO:Cr3+) with an emission peak at 835 nm and a full width at half-maximum (FWHM) of 188 nm is obtained, where Ce3+ or Cr3+ is accommodated at the same Sc3+ site. The BSO:Cr3+ ceramic is demonstrated to produce a NIR emitter with an output power of 14.56 mW when driven by a blue laser diode at 5.0 V/100 mA. By following the proposed method, two broadband NIR phosphors composed of Li3Sc2(PO4)3:Cr3+ (λem = 1000 nm, FWHM = 223 nm) and Na3Sc2(PO4)3:Cr3+ (λem = 895 nm, FWHM = 184 nm) are further discovered.