Materials Horizons最新文献

Correction for 'Highly-efficient and scalable TrioN (3N0C) synaptic cell for analog process-in-memory' by Junyoung Choi et al., Mater. Horiz., 2025, 12, 7509-7519, https://doi.org/10.1039/D5MH00324E.

Mechanical metamaterials with tunable bending stiffness are significant for realizing smart adaptable machines or structures composed of beams, shells and plates. However, different from tuning longitudinal stiffness, realizing broad-range, continuous, and in situ (without global shape morphing) tunability of bending properties remains a major challenge. Here, we report a deformation conversion principle for designing meta-beams/plates that offer such extraordinary tunability. The metamaterials incorporate planetary gear assemblies as tension-compression fibers within sandwich beams or plates, effectively transferring the localized tunable longitudinal stiffness of these geared units into the global tunable bending stiffness. This principle enables diverse tunable bending modes, including the static bending deformation, vibrational modal shapes and frequencies, and bending wave bandgaps. Their smoothly tunable properties and mechanisms are demonstrated based on analytical, numerical and experimental methods. This work offers a new pathway for developing structures with adaptively tunable bending properties that are free from the constraints of intrinsic material properties, elucidating innovations and applications of mechanical metamaterials and structures for intelligent systems.

Asymmetric structure design in non-fullerene acceptors (NFAs) has driven a significant breakthrough in the power conversion efficiency (PCE) of organic solar cells (OSCs). However, finding high-performing moieties out of the vast amount of candidates and their potential combinations is a significant challenge. In this work, we propose a machine learning (ML)-guided high-throughput screening approach to identify optimal acceptor moieties for both symmetric and asymmetric A-DA'D-A type NFAs. By standardizing and splitting the NFA structures and using one-hot encoding to construct feature vectors, a reliable XGBoost model is established to predict structure-activity relationships. Combined with interpretability analysis, core contributors to solar cell performance, such as end groups, conjugated scaffolds, and central cores, were identified. From over a million virtually generated molecules, we screened the molecules to find the best acceptor matches with a donor polymer (e.g., PM6) exhibiting predicted PCEs greater than 18%. The Sankey diagram visualizes the best combined paths for NFAs, highlighting the great potential of asymmetric design. Furthermore, quantum chemical calculations verified that the picked-out acceptor molecules (K01-K12) with asymmetric structures and predicted PCEs of over 19% are potentially promising in terms of energy levels, electrostatic potentials, and charge transfer characteristics. Moreover, assessment of synthesis accessibility indicated their good experimental feasibility, and applicability to multiple donor systems. This work not only facilitates a transition from empirical trial-and-error to a data-driven approach, but also advances molecular engineering from symmetric simplicity to asymmetric function-oriented design.

Direct conversion of body heat into electricity through thermoelectric (TE) devices is emerging as an attractive option to power wearable electronics. As semiconducting TE devices suffer from the trade-off between electronic and thermal conductivity and high operating temperature, ionic thermoelectric devices relying on atmospheric humidity perfectly fit this low-temperature operating condition. Here, atomically thin 2D channels of reconstructed clay membranes were applied to demonstrate the possibility of harvesting electricity from body heat through the ionic thermoelectric (i-TE) effect. Nanofluidic membranes prepared by reconstructing layers of montmorillonite clay (MMT) displayed outstanding i-TE characteristics. Thermal transport of intercalating cations through an interconnected network of 2D channels yielded a Seebeck coefficient (S_i) of up to 13.63 ± 1.13 mV K^-1. As the hydration of molecularly thin 2D channels relies on atmospheric water molecules, the ionic conductivity and S_i of MMT increase with increasing humidity levels in the atmosphere. In contrast to polymer-based i-TE devices, clay membranes sustain exposure to high temperatures (∼200 °C, 5 min) and self-repair physical damages with the help of water droplets. The MMT membrane deposited on a PET film generated voltages of up to 63 mV (ΔT = 1.8 K) at 85% RH upon being pasted on human skin.

Epitaxial BiVO₄ photoanodes with precisely controlled crystallographic orientations were fabricated to elucidate the intrinsic influence of facet anisotropy on photoelectrochemical (PEC) glycerol oxidation. The b-axis-oriented (0k0) BiVO₄ film exhibited a 2.4-fold higher photocurrent density and a 2.6-fold greater charge-separation efficiency than the c-axis-oriented (00l) film, achieving a production rate of 81.4 mmol m^-2 h^-1 under AM 1.5 G illumination. PEC and charge-transfer analyses reveal that the enhanced activity of the (0k0) facet originates primarily from improved bulk charge separation and transport rather than surface catalytic effects. This work establishes crystallographic orientation control as an effective design strategy for developing energy-efficient oxide photoanodes for solar-driven glycerol oxidation beyond conventional water splitting.

Perovskite materials are known for their unique crystal structure, which allows for easy anion exchange. Notably, the characteristics of the resulting materials can differ substantially depending on the precursors used for the exchange. In this study, we aimed to synthesize red-emitting perovskite nanocrystals by mixing trimethylsilyl iodide (TMSI) with tri-n-octylphosphine (TOP), and through detailed analysis, we found that the mixture led to the formation of phosphonium salt ([TOPH]⁺I^-) and trimethylsilanol (TMSOH). Through various analyses, we demonstrated that phosphonium salts act as iodine precursors, effectively enabling the composition exchange from CsPbBr₃ to CsPb(Br/I)₃ nanocrystals. In particular, X-ray photoelectron spectroscopy revealed the presence of TMSOH on the surface of the perovskite nanocrystals. Furthermore, the ability of TMSOH to function as a surface-passivating ligand was verified through comparative analysis with other commonly used precursors. We propose a detailed mechanism for the formation of TMSOH and [TOPH]⁺I^- based on ³¹P NMR and ¹H-³¹P NMR spectroscopy. Additionally, the LED devices exhibited excellent performance, with a maximum EQE of 21.69% at 669 nm.

Visual memristors, which integrate resistive switching with optical feedback, are attracting growing interest for neuromorphic computing, nonvolatile storage, and human-machine interfaces. By directly coupling electrical states with optical outputs, such devices enable both data processing and intuitive visualization, providing new opportunities for interactive and multifunctional systems. Here, we innovatively demonstrate a carbon dot (CD)-based visual memristor that combines reliable resistive switching with tunable electroluminescence. The device exhibits stable storage, reproducible hysteresis loops, and multilevel conductance control, while its emission spectra systematically evolve with resistive states, enabling "visible" memory and computation. This dual-mode behavior bridges the electrical and optical domains, closely resembling synaptic plasticity and supporting artificial neuromorphic functions. Benefiting from the unique properties of CDs, including strong luminescence, abundant surface functionalities, and facile solution processing, the proposed device represents a new platform for multifunctional optoelectronic systems. These results open pathways toward next-generation neuromorphic optoelectronics that unify perception, memory, and processing.

Developing materials that combine both softness and stiffness is crucial for meeting the demands of complex and versatile applications. The realization of multistability through elaborate units has been demonstrated, but the trade-off between performance and light weight across different states remains underdeveloped. In this work, we pioneer the application of the soft-stiff responsive strategy to lightweight cellular materials through architecturally nesting two materials with contrasting properties. The proposed cellular materials can be reconfigured and switched between soft and stiff states, as demonstrated experimentally, theoretically and numerically. The soft state represents high perturbation sensitivity and prominent vibration isolation properties. The stiff state exhibits a strong load-carrying capability due to multi-synergistic mechanisms, with a crushing modulus and strength 668.78 and 1037.55 times as high, respectively, as the soft state in the cases of soft materials embedded in metal materials. The manipulable mechanical properties can be tuned across a broad design space while maintaining robust switchability. These advantages of the proposed bistate cellular materials offer promising application prospects from adaptive protection to shock absorption and beyond.

High-power outdoor electronics, such as 5G base stations, need energy-efficient thermal management. Passive daytime radiative cooling (PDRC) represents a promising solution, but faces practical limitations due to low thermal conductivity and performance degradation associated with coloration. Herein, we demonstrate a hierarchically structured asymmetric bilayer composite, fabricated through a scalable and feasible self-stratification process, which integrates a cholesteric photonic lattice of cellulose nanocrystals (CNCs) with a highly thermally conductive framework of boron nitride (BN) nanosheets. The top photonic CNC layer provides vivid structural color and high mid-infrared emissivity (εMIR = 91.5%), while the bottom BN-rich layer delivers high solar reflectance (96.9%) and enhanced through-plane thermal conductivity (8.9 W m^-1 K^-1). The material achieves a temperature drop of up to 17.8 °C under realistic solar and thermal loads, while its asymmetric heat transfer property suppresses parasitic heat gain from the environment. Furthermore, the composite enables scalable structural color patterning via screen printing without compromising the cooling performance, offering both aesthetic customization and environmental durability. This work presents a scalable self-assembly strategy for high-performance, aesthetically versatile radiative cooling materials that address key challenges in next-generation electronic thermal management.

Detectable adhesives that provide real-time feedback on the curing status and bonding strength via colorimetric or electrical signals hold great promise for industrial quality control and intelligent manufacturing. However, systems that simultaneously offer non-destructive, instrument-free detection remain scarce, posing a critical challenge for their broader practical deployment. In this study, a design strategy for visually trackable adhesives that exhibit real-time, non-destructive curing-state indication is proposed, enabled by the incorporation of photochromic spiropyran molecules. The adhesive features a linseed oil core and a calcium alginate shell, allowing air-curable adhesion and mechanically triggered release. The system achieves a high transparency of over 95% and a maximum bonding strength of 15 MPa after full curing, demonstrating both optical and mechanical superiority. Compared to existing intelligent adhesives, this MLOA system integrates adhesion, visualization, and sustainability, while maintaining excellent performance under liquid nitrogen and solvent exposure and exhibiting strong compatibility with a wide range of substrates. This dual-feedback system bridges sensing and adhesion in a single platform, opening new avenues for real-time monitoring and adaptive control in next-generation smart manufacturing.