Physics

We investigate the temperature-dependent complex dielectric function of bulk single-crystal In2O3 over the spectral range of 1–6 eV and temperatures from room temperature to 600 °C under high-vacuum conditions using in situ spectroscopic ellipsometry. The dielectric function was modeled using wavelength-by-wavelength and critical-point model dielectric function analyses. The dielectric function exhibits pronounced alterations with increasing temperature, attributed to thermally induced changes in the band structure and carrier dynamics. We identify direct and indirect interband transitions and excitonic contributions associated with the direct bandgap near the onset of absorption. At elevated temperatures, features in the dielectric function due to indirect transitions emerge below the direct bandgap energy, which shift toward shorter photon energies with increasing temperature. Combining our results with low-temperature data from previous reports, both observed shifts of the direct and indirect transitions can be seamlessly explained with the Bose–Einstein model. The direct transition is coupled less strong to the phonon bath (average temperature θB=512 K), leading to a smaller high-temperature slope (γ=−0.2 meV/K) than for the indirect transition (θB=360 K, γ=−1.3 meV/K). The exciton contributions diminish toward higher temperatures reflected by the decrease in amplitude and increase in broadening model parameters. Our parameter set can be used to calculate the model dielectric function In2O3 at elevated temperatures.

Entangled materials offer attractive structural features including tensile strength and large deformations, combined with infinite assembly and disassembly capabilities. How the geometry of individual particles governs entanglement, and, in turn, translates into macroscopic structural properties, provides a rich landscape in terms of mechanics, and offers intriguing possibilities in terms of structural design. However, there are major knowledge gaps on the entanglement mechanisms and how they can generate strength. In this report, we present tensile tests and discrete element method simulations on bundles of entangled staple-like particles that capture the combined effects of particle geometry and vibrations on local entanglement, tensile force chains, and strength. Standard steel staples with θ = 90° crown-leg angle initially entangle better than θ = 20° modified staples because of their more “open” geometry. However, as vibrations are applied, entanglement increases faster in θ = 20° bundles so that they develop strong and stable tensile force chains, producing bundles which are almost ten times stronger than θ = 90° bundles. Both tensile strength and entanglement density increase with vibrations and with deformations, up to a steady state value where the rate of entanglement balances the rate of disentanglement. Finally, we show that vibration and mechanical confinement can be used as a strategy to manipulate entanglement and disentanglement for disassembly and recycling. This work provides a fundamental understanding of how particle geometry and vibrations govern the properties of entangled materials, which can lead to better design guidelines for lightweight, reversible materials and structures and aggregate architectures.

Replicating the synergy of high toughness and rapid stress relaxation found in native tissues remains a central challenge for synthetic hydrogels on account of their intrinsic mechanical-temporal trade-off. Here we introduce a supramolecular hydrogel platform that leverages kinetic programming to precisely regulate crosslink dynamics through molecular dissociation kinetics. This molecular design allows independent tuning of relaxation dynamics and fracture toughness, decoupling properties that are typically correlated. The resulting hydrogels exhibit stress relaxation ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:msub><mml:mi>t</mml:mi> <mml:mrow><mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mn>2</mml:mn></mml:mrow> </mml:msub> <mml:annotation>${t}_{1/2}$</mml:annotation></mml:semantics> </mml:math> = 0.1-100 s) two orders of magnitude faster than conventional networks while achieving exceptional fracture energy ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>G</mml:mi> <mml:mi>c</mml:mi></mml:msub> <mml:mo>=</mml:mo> <mml:mn>14</mml:mn> <mml:mo>,</mml:mo> <mml:mn>500</mml:mn> <mml:mspace></mml:mspace> <mml:mi>J</mml:mi> <mml:mspace></mml:mspace> <mml:msup><mml:mi>m</mml:mi> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>2</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$G_c = 14{,}500\,\mathrm{J\,m^{-2}}$</mml:annotation></mml:semantics> </mml:math> ), well above natural rubber. Slowing crosslink dissociation significantly enhances energy dissipation under load, revealing a kinetic principle for toughening viscoelastic networks. This work establishes a molecular blueprint for designing soft materials with programmable, time-dependent mechanics.

Monolithic cementitious materials lack fracture resistance and are brittle. Advancements in additive manufacturing techniques with cement-based materials and architected designs have remained limited to the use of a single (cement-based) constituent. This work charts a new pathway for manufacturing and designing tough, ductile, and strong architected cement-based composites by proposing a novel multi-material additive manufacturing (MMAM) technique for the first time, integrated with a coupled experimental-numerical design approach. The new class of architected cementitious composites (ACC) of mortars and elastomeric constituents (silicone and polyurethane) are exemplified, through a layered hard-soft architected design, inspired by the microstructure of a sea sponge (glass sponge Euplectella aspergillum). The MMAM technique alternates extrusion of hard-soft composites, enabling systematic control over the geometry and constituents of resulting architected structures. The results demonstrate layered mortar-silicone composites achieved up to 3.9- and 8.8-fold enhancements in fracture toughness and up to 11.7- and 12.4-fold enhancements in ductility relative to monolithic 3D-printed (3DP) and cast mortars, respectively. A coupled large-deformation phase-field-cohesive-zone (PF-CZM) framework was used to systematically probe soft-layer thickness and bulk soft-material properties. Simulations revealed that combining higher-stiffness soft layers with reduced thickness can yield up to a 24-fold increase in work-of-fracture while recovering the load-bearing capacity of monolithic mortar. Guided by numerical predictions, experiments on thin, stiffer polyurethane interlayers validated the numerical predictions and provided additional experimental evidence that the proposed (mortar-polyurethane) composites achieve 82- and 187-fold higher fracture toughness, and 22.6-fold higher ductility, relative to 3DP and cast monolithic references while recovering the flexural strength to levels statistically comparable to monolithic mortar. These large gains arise from three synergistic mechanisms: crack arrest/deflection, crack bridging, and discontinuous layerwise crack re-nucleation, activated by the layered hard-soft architecture and supported by DIC/AE fracture analyses). The proposed MMAM-enabled fabrication-design-mechanics approach in ACC can unleash entirely new pathways for engineering next-generation damage-resilient and multi-functional concrete structures.

All-inorganic CsPbI₃ inverted perovskite solar cells (PSCs) suffer from severe nonradiative recombination and interfacial defects, which limit their efficiency and stability. To address this, we developed an interface engineering strategy based on CsPbBr₃ quantum dots anchored in pore-size-tuned mesoporous silica nanoparticles (CPBQDs@MSNs), constructing a CsPbI₃/CPBQDs@MSNs heterojunction. Notably, CPBQDs@M-MSNs (∼8 nm) match the exciton Bohr radius of CsPbBr₃ (∼7 nm), enabling optimal exciton-photon critical coupling. This coupling strongly suppresses nonradiative recombination and thermal activation of defects, leading to superior fluorescence stability over a broad temperature range. The CPBQDs@MSNs treatment further enhances crystallinity, reduces grain boundary defects, and optimizes interfacial energy level alignment, thereby facilitating efficient charge-transport. Consequently, the inverted CsPbI₃ PSCs achieve a remarkable power conversion efficiency (PCE) of 22.15%, the highest value for such devices, along with a record open-circuit voltage (V_OC) of 1.28 V. The devices exhibit excellent stability, retaining 93.16% of their initial PCE after 1300 h in ambient air and 98.14% after 1000 h of continuous illumination. This work highlights the crucial role of size-controlled QDs in interfacial engineering and offers a promising strategy for developing high-performance and stable perovskite optoelectronic devices.

Implantable bioelectronics offer precise control of neural activity and hold great therapeutic potential for neurological diseases and refractory autoimmune disorders. However, conventional implants suffer from non-adaptive nerve interfaces, including geometric mismatch, suture-related trauma, and absence of neuron-like bioelectrical signals, which significantly undermine their long-term biosafety and efficacy. Here we present a multifunctional ferroelectric bioelectronic interface (FBI) that integrates a bilayer natural polymer-based hydrogel, ferroelectric poly(vinylidene fluoride-co-trifluoro ethylene) (P(VDF-TrFE)) polymer, and photothermal carbon nanotubes (CNT), imparting unprecedented synergistic functions, including self-rolling geometric matching, strong interfacial adhesion that eliminates the need for suturing, and neuron-mimetic polarization-change-induced bioelectrical signaling. When applied to the vagus nerves, this adaptive FBI enables near-infrared-mediated neuromodulation that effectively reduces pro-inflammatory cytokine levels. Compared with conventional vagus nerve modulators, such innovative FBI avoids nerve compression, minimizes focal inflammation, and maintains persistent neuromodulation efficacy during long-term implantation. By integrating precise geometric adaptability, seamless bioadhesive fixation, bioelectrical biomimicry, and robust biosafety, the FBI platform offers a new paradigm for next‑generation implantable bioelectronics for durable nerve modulation and treatment of neurological and autoimmune conditions.

Interfacial oxide layers on gallium-based liquid metal (LM) have traditionally been regarded as obstacles to stable electrohydrodynamic actuation. Here, we demonstrate that such oxides can be leveraged to achieve programmable flow field control. By introducing a Faradaic depolarization model that accounts for interfacial redox reactions, we resolve the long-standing discrepancy between theoretical predictions and experimental observations in continuous electrowetting (CEW). We reveal that oxide coverage dictates flow direction and pattern under identical electrical inputs, enabling full reversal of jet flows without changing the driving signals. Experimentally, four distinct flow regimes are identified under impulsed and unbiased AC excitations, showing excellent agreement with our model. Moreover, we demonstrate oxide-mediated flow operations such as bubble-free pumping, reconfigurable fluidic logic, and sustained performance exceeding 19 h. This work establishes an encoding framework for small-scale pumps capable of multi-mode and long-term operation, enabling on-demand flow field programming and paving the way for intelligent milli-microfluidic systems in adaptive thermal management and autonomous lab-on-a-chip devices.

Controlling the polymorphic phases within the thermal budget of atomic layer deposition (ALD) is essential for integrating high-k dielectrics into dynamic random-access memory (DRAM) capacitors. Rutile TiO₂ offers a dielectric constant significantly higher than that of tetragonal ZrO₂ and anatase TiO₂. However, its application on industry-standard TiN electrodes is impeded by the lack of rutile-compatible lattice matching. A top-interface-driven stabilization strategy is demonstrated, where a structurally compatible RuO₂ upper layer stabilizes rutile TiO₂ at 400°C regardless of the crystallinity of the underlying ZrO₂/TiN stack. Thickness-dependent phase maps reveal an interfacial-energy-driven anatase-to-rutile transition for thin amorphous TiO₂ layers, enabling rutile formation even on amorphous ZrO₂. The resulting TiO₂/ZrO₂/TiN capacitors exhibit a dielectric constant of approximately 80 and a reduced equivalent oxide thickness, comparable to that of ZrO₂-based stacks. A methanol-assisted reduction-etching process allows selective removal of RuO₂ by O₃ with minimal TiN oxidation. This top-interface engineering concept offers a substrate-agnostic approach to rutile TiO₂ that is compatible with DRAM process windows and can be extended to other polymorphic oxides.

Ternary random copolymerization, which enables precise control over optoelectronic characteristics and processing compatibility by incorporating a third functional unit, serves as an effective method for tailoring polymer acceptor properties. However, competing reactivity ratios of monomers during random copolymerization induce sequence inhomogeneity, disrupting the periodic arrangement of monomers and the structure of polymer acceptor molecules. The intricate intermolecular interactions and aggregation behaviors in random copolymers pose significant challenges for achieving optimal morphology. Herein, we propose the concept of ternary regular copolymerization, which precisely controls copolymer microstructure, aligns the monomer arrangement, and enhances crystallization. Regular copolymers (named RC10) and random copolymers (named UC10) were synthesized by using monomers containing benzothiadiazole and benzoquinoxaline units. The intramolecular alternating arrangement of monomers endows the polymer acceptor with a well-defined molecular conformation and enhanced molecular stacking. Consequently, the binary device based on PM6:RC10 achieves an impressive efficiency of 20.03%. Furthermore, another two regular copolymers were synthesized and characterized, both of which exhibit better photovoltaic performance as compared to that of their random counterparts, demonstrating the broad applicability of this strategy. Our study reveals that regular copolymerization holds significant potential for regulating molecular aggregation and alignment in polymer acceptors, providing valuable insights for designing high-performance acceptor materials.

The field of polymer thermoelectrics has undergone transformative development in recent years, marked not only by addressing the conventional performance disparity between p-type and n-type polymers, but also by innovations in doping methodologies, new strategies for suppressing dopant-induced disorder, approaches for overcoming the inherent thermoelectric trade-off, and advancements in achieving better ambient and thermal stability, as well as their variety of new applications. Collectively, these pivotal advances have brought the field into a new era. This review focuses on the recent development of high-performance polymers that bridge the long-standing performance gap, introduces doping frontiers for more highly optimized thermoelectric properties, and discusses sophisticated strategies for decoupling electronic and thermal transport. Moreover, this work unlocks the emerging understanding of the degradation mechanisms of doped polymers that enables the design of materials with superior ambient and thermal robustness, and showcases the burgeoning applications of thermoelectric polymers in unconventional domains.

As a promising candidate for flexible and portable photovoltaic devices, all-polymer solar cells (all-PSCs) have recently garnered significant attention in the field of organic photovoltaics. However, due to the unfavorable morphology and weak crystallinity caused by complex chain entanglement within all-polymer systems, the power conversion efficiencies (PCEs) of all-PSCs still lag behind those of small-molecule-acceptor-based organic solar cells. Given that conventional thermal annealing (TA) lacks sufficient control over the crystallization and vertical distribution of polymer acceptors, we developed an innovative wet-assisted annealing (WAA) strategy. By leveraging the selective dissolution and volatilization effects of assist solvents during the thermal annealing process, the vertical distribution of donors and acceptors in bulk heterojunction (BHJ) structures were finely optimized. More importantly, this strategy enhances the molecular stacking of polymer acceptor, and achieves well-defined fibrillar network morphology. Benefiting from this approach, the PM6:PY-DT-based binary all-PSCs achieved a record PCE of 20.04% with enhanced stability, significantly exceeding the performance of conventional TA-processed devices. Meanwhile, the WAA strategy demonstrated consistent effectiveness across different batches of the polymer acceptor, underscoring its robustness and practical value for fabricating high-efficiency and stable all-PSCs.

Electrical stimulation effectively promotes nerve regeneration and functional recovery, but its clinical application faces challenges such as energy supply limitations, long-term stability issues, and implantation safety concerns. Inspired by the bioelectrogenic mechanism of electric eels, this study developed an electric-eel-inspired ionogel battery (EE-iHB) using chitosan (CS), chondroitin sulfate (CSA), and hydroxyethyl cellulose (HEC). The battery exhibits not only excellent biocompatibility but also outstanding ionic conductivity. By mimicking the intricate multilayer structure of electric eel electrocytes and employing a layer-by-layer self-assembly technique, synergistic optimization of mechanical properties and electrical conductivity was achieved in the nerve conduit. In vitro experiments confirmed the stable and continuous generation of bioelectrical signals. In vivo studies using a rat sciatic nerve injury model demonstrated that the experimental group implanted with this novel conduit showed superior nerve regeneration speed and functional recovery compared to conventional nerve conduits. Histological and electrophysiological analyses further verified that the weak current generated by the battery effectively activation of Schwann cells, guides orderly axonal growth, and promotes myelination. The use of flexible gel materials ensures seamless integration with neural tissues, guaranteeing both safety and long-term reliability in neural repair applications.

The persistent coupling between lattice thermal conductivity (κ_L) and carrier mobility (µ) remains the central bottleneck in thermoelectric optimization: randomly distributed defects that scatter phonons inevitably degrade electron transport. This review establishes the disorder-to-order transition of crystallographic defects as a unifying design principle to overcome this trade-off. We systematically examine three defect families, including substitutional atoms, vacancies, interstitials and antisite defects demonstrate how their spatial reconfiguration from random distributions into ordered architectures fundamentally decouples phonon and electron transport. Representative examples include iso-size alloying and symmetry enhancement in substitutional systems, vacancy-derived dislocation networks and ordered vacancy layers, lattice planarization via targeted vacancy filling, and self-assembled interstitial clusters and climb dislocations. We further extend this paradigm into the mechanical domain, showing that ordered interstitials at twin boundaries simultaneously enhance mechanical strength and thermoelectric performance. A consistent conclusion emerges across all systems: performance gains arise from controlling defect spatial arrangement rather than introducing additional disorder, offering a coherent framework for the next generation of high-performance, mechanically robust thermoelectric materials.

The slow reaction kinetics, particularly at high rates, hinder the practical use of lithium-sulfur batteries (LSBs). To overcome the inadequate ion transport in conventional electrodes, a two-dimensional layered bimetallic sulfide (FeMo₂S₄) as a sulfur host, creating fast ion-conduction pathways is developed. Using a free-standing FeMo₂S₄/carbon cloth cathode with a Li₂S₆ catholyte, high-rate performance is achieved. Crucially, in situ high-resolution TEM directly visualized rapid inter-particle lithium ion transport between the layered FeMo₂S₄ flakes, offering direct evidence of enhanced kinetics. This phenomenon, combined with strong polysulfide adsorption and high catalytic activity, boosts reaction rates. The Li₂S₆-based battery delivered a high initial capacity of 1516 mAh g^- ¹ and outstanding stability with only 0.028% decay per cycle at 3C. This work highlights the effectiveness of layered hosts with fast ion channels and bimetallic catalysis for durable, high-rate LSBs.

Abstract We present a comprehensive modeling framework to analyze the magnetic response of type-II superconductors in both the Meissner and mixed states, in the limit of thin-film geometries. Starting from the fluxoid quantization condition, we compute the magnetic susceptibility and its dependence on the penetration depth λ, highlighting the experimental resolution needed to detect small variations in λ. To describe the penetration of vortices in the mixed state, we implement a critical state model that imposes local current constraints, enabling simulation of magnetization curves in samples with and without weak links, such as grain boundaries. The flux penetration of the virgin magnetization curves exhibit quadratic dependency on the applied field, contrary to Brandt et. al.'s cubic prediction owing to his simplification of the problem by assuming an infinitely long strip. Two complementary approaches—numerical minimization and flux front tracking yield consistent predictions for magnetization and allow extraction of both intra- and intergranular critical current densities. The simulated magnetic response, including subtle features in the derivative of magnetization with respect to the applied field, is in excellent agreement with experimental AC susceptibility measurements on single- and bicrystalline thin films.

Efficient charge separation remains a critical challenge in semiconductor photocatalysis. This study addresses this by designing a MoO2/Cu2O heterojunction through a valence-modulation strategy, where Mo4+ in MoO2 acts as an in situ reductant for Cu2O formation. The concomitantly generated Mo6+ species further enhance the interfacial charge dynamics. The synergistic interplay between the constructed heterojunction interface and the built-in electric field thus significantly promotes charge transfer and separation. As a result, the composite exhibits markedly improved optoelectronic properties: an electrochemical impedance as low as 1140 Ω, a photocurrent density of 0.19 μA·cm–2, and an open-circuit voltage of 1.23 mV, alongside an extended charge carrier lifetime. The photocatalyst demonstrates high performance in tetracycline degradation, achieving 96.3% removal within 60 min under visible light. The reaction mechanism, investigated via density functional theory calculations, HPLC–MS/MS, and toxicity assessment, aligns with a type-II heterojunction model. Intermediates analysis reveals effective detoxification pathways. This work provides a rational design strategy for high-performance transition metal oxide photocatalysts by harnessing valence-state chemistry.

Efficient removal of acidic impurities such as hydrogen chloride (HCl) is essential for hydrogen purification, yet most conventional adsorbents are nonregenerable and require frequent replacement, underscoring the need for scalable, regenerable alternatives. This study evaluates the aluminum-based metal–organic framework (MOF) Al-CAU-60 as a regenerable HCl adsorbent. A reproducible, scalable reflux synthesis was developed for phosphonate-based Al-CAU-60·6HCl, enabling 10 L scale production with high yield (151 g, >96%) and preserved crystallinity. Following neutralization, the MOF was shaped into mechanically robust pellets (Al-CAU-60/PVF) using 10 wt % polyvinyl formal (PVF) as a binder. Structural and chemical integrity were confirmed through scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX), powder X-ray diffraction (PXRD), attenuated total reflectance–Fourier transform infrared (ATR-FTIR), and thermogravimetric (TGA) analyses. Under dynamic breakthrough tests (10 bar, 25 °C, 100 ppm of HCl), Al-CAU-60/PVF showed an average HCl uptake of 1.38 mmol/g at the 1 ppm breakthrough and 1.73 mmol/g at saturation. The material retained its performance over seven adsorption–regeneration cycles using only water-triggered desorption, demonstrating an exceptional example of fully regenerable, phosphonate-based MOF sorbents. In contrast, zeolite 13X, while initially more active, lost ∼90% capacity after the first cycle, confirming the superior cyclic stability of Al-CAU-60/PVF. Mechanistic analysis revealed that HCl adsorption proceeds via reversible protonation–deprotonation of phosphonate groups during water-based regeneration.

A visible-light-driven C–S cross-coupling reaction using covalent organic frameworks (COFs) as heterogeneous photocatalysts is reported. Three β-keto-enamine-linked COFs, TpAzo, TpDPP, and TpBDMe2, were synthesized and systematically evaluated. Among them, TpAzo exhibited superior photocatalytic activity due to its high surface area (1725 m2 g–1), low band gap (1.78 eV), and efficient charge separation. To enhance the reusability and accessibility, a thin-film morphology of TpAzo COF was developed, which facilitated catalyst recovery and sustained performance over multiple cycles. The optimized protocol enabled the arylation of thiols with a wide range of aryl halides, including iodides, bromides, chlorides, tosylates, and mesylates, delivering the corresponding thioethers in good to excellent yields (55–94%) under ambient conditions. This study highlights the potential of COF-based photocatalysts for sustainable C–S bond formation and broadens their application in organic synthesis

Vertical scaling of 3D NAND devices calls for higher SiO2 and SiN etching rates and meaningful reduction of aspect ratio dependent etching. Recently, evolutionary improvements of the fluorocarbon gas process have been replaced by novel so-called cryo etching processes using HF as the main etch gas. In this paper, we report computational results for the activation Gibbs free energies ΔG‡ for the reaction of HF and various additive gases with SiO2 and SiN. The results are compared with available experimental trends. We find that the dipole moment of the additive gas is an indicator of its catalytic effect.