Materials Horizons最新文献

Next-generation ultrahigh-definition (UHD) displays demand blue organic light-emitting diodes (OLEDs) that can achieve high efficiency, long operational stability, and the stringent color purity required by the BT.2020 standard. Although thermally activated delayed fluorescence (TADF) and phosphorescent emitters enable full exciton utilization, conventional donor-acceptor TADF systems typically exhibit broad emission spectra arising from long-range charge-transfer character, ultimately limiting their color purity. Multiple-resonance (MR) TADF materials deliver intrinsically narrowband emission through short-range charge-transfer transitions induced by orthogonally arranged resonance atoms. In this comprehensive material review, we describe molecular design strategies for high-performance blue MR-TADF emitters, emphasizing boron-nitrogen-, carbonyl-nitrogen-, and indolocarbazole-based molecular frameworks. We discuss how structural engineering such as π-extension, peripheral shielding, spiro-locking, carbonyl incorporation, and heteroatom modulation assists in precisely controlling HOMO-LUMO distributions, suppressing vibronic coupling, and enhancing reverse intersystem crossing to achieve narrow emission bandwidths (<20 nm) with high photoluminescence quantum yields. In addition, key device-engineering approaches, including phosphorescence-sensitized fluorescence and TADF-sensitized fluorescence, further mitigate exciton loss, efficiency roll-off, and aggregation-induced quenching in practical devices. By integrating molecular and device design perspectives, this review highlights the current progress, remaining challenges, and future opportunities in realizing efficient, stable, and spectrally pure blue MR-TADF OLEDs suitable for next-generation display applications.

Fabricating robust superamphiphobic coatings on the inner surfaces of narrow tubes remains a long-standing challenge due to restricted mass transport, geometric confinement, and limited interfacial reaction efficiency. Despite extensive progress in planar superamphiphobic surfaces, achieving durable liquid repellency in confined tubular systems-particularly on chemically inert substrates-has remained essentially unsolved. Herein, we report a versatile dynamic circulation coating (DCC) strategy for constructing robust superamphiphobic coatings on both planar substrates and, more importantly, the inner walls of narrow and chemically inert tubes. In the DCC process, a peristaltic pump precisely controls precursor delivery, enabling uniform coating under confined geometry. The coatings are fabricated through co-deposition of tannic acid and dopamine with silica microparticles as a primer layer with abundant hydroxyl groups on chemically inert substrates, followed by confined self-assembly of silicone nanofilaments with vinyl groups and subsequent covalent fluorination via thiol-ene click chemistry, forming a hierarchical micro-/nanostructure with ultralow surface energy. The resulting coatings exhibit exceptional superamphiphobicity, an outstanding static/dynamic pressure resistance of up to 2.0 MPa, and excellent chemical/mechanical durability. This work overcomes the critical barrier of applying high-performance superamphiphobic coatings to confined geometries, paving the way for their use in microfluidics, medical devices, industrial tubing, etc.

Imaging of invisible mechanical stresses is a significant challenge in a variety of fields. 2D distribution imaging of compression stresses applied by irregularly shaped 3D objects is not achieved using conventional sensing materials and devices. In the present work, such a compression-stress distribution in the range of 0.1 kPa-5 MPa is imaged using 3D transparent silicone rubber containing stimuli-responsive color-changing conjugated polymer, layered polydiacetylene (PDA). Compression-responsive capsules, liquid droplets surrounded by solid particles, collapse with compression on the rubber. The outflowed interior liquid containing polyethyleneimine (PEI) oligomer is diffused into the bulk rubber through the free volume space of the rubber matrix. PEI serves as a guest for intercalation into the interlayer space of the layered PDA, i.e. chemical stress, directing the blue-to-red color change. As the red-color intensity increases with increasing applied compression stress, the strength is colorimetrically quantified. The transparent 3D device enables 2D distribution imaging of the compression stresses applied by irregularly shaped 3D objects in the millimeter to the centimeter scales. The device design can be applied to achieve 2D stress-distribution imaging in various length scales and strength ranges.

The rapid expansion of green hydrogen production is vital for decarbonizing hard-to-abate sectors. Photocatalytic water splitting, which generates hydrogen directly from sunlight and water, has therefore attracted major research attention. Yet translating this promise into scalable reality requires re-examining how photocatalysts are studied and benchmarked. A long-standing laboratory practice involves the use of sacrificial agents (SAs), such as alcohols, sulfides, or amines, that act as hole scavengers to facilitate the hydrogen evolution reaction (HER). While this approach has accelerated catalyst discovery and mechanistic understanding, it differs fundamentally from true overall water splitting (OWS), where the HER and the oxygen evolution reaction (OER) occur simultaneously. In SA-assisted systems, the oxidation half-reaction is replaced by sacrificial oxidation chemistry, making their performance metrics unsuitable for direct extrapolation to practical solar-fuel generation. Nevertheless, publications on SA-driven HER continue to outpace those on genuine OWS. Here, we argue that sustained reliance on SAs risks diverting resources, delaying innovation, and weakening confidence in photocatalytic hydrogen as a scalable climate solution. We advocate for greater recognition, support and increased focus on emerging alternatives that bridge laboratory discovery with sustainable OWS, fostering a constructive methodological shift toward practical solar-hydrogen technologies.

All-organic circularly polarized luminescence (CPL) emitters acting as intrinsic liquid polarizers provide a promising route to reduce optical crosstalk and enhance spatial resolution in displays by directly emitting circularly polarized light, thereby eliminating external polarizers and minimizing energy loss. Herein, we report a highly efficient, all-organic CPL-active liquid polarizer based on chiral organic binary composites (COBCs), in which camphorquinone-derived chiral inducers are integrated with polymeric carbon quantum dots (PCQDs), opening a previously unexplored pathway toward chiral organic-quantum dot composites. The composites exhibit intense blue emission with a photoluminescence quantum yield (PL QY) of 64%, and strong enantioselective CPL with luminescence dissymmetry factors (g_lum ≈ ±10^-2). Circular dichroism spectroscopy reveals multiple Cotton effects with high absorption anisotropy (g_abs = 1.2 × 10^-2), while time-resolved photoluminescence and electrochemical analyses indicate that hydrogen-bonded chiral networks promote charge transfer and generate intrinsic chiral fields enabling selective CPL emission. A prototype device based on COBCs achieves a spatial resolution of 4 lp mm^-1, nearly double that of achiral analogues, while effectively suppressing glare and enhancing image contrast. Our findings establish a design strategy for transforming achiral CQDs into CPL-active materials, opening pathways toward next-generation, energy-efficient photonic and display technologies.

Molybdenum carbide (Mo₂C) has emerged as an earth-abundant catalyst for the hydrogen-evolution reaction (HER), yet the impact of surface-oxidized species on its performance remains unknown. Here, we compare the activity of pristine Mo₂C with a Mo/Mo₂C heterostructure synthesised by carbothermal reduction and evaluate their structural evolution under working conditions using in situ Mo K-edge X-ray absorption spectroscopy and Raman spectroscopy complemented by density functional theory (DFT). Despite its metallic component, Mo/Mo₂C delivers a lower HER activity (204 mV at 10 mA cm^-2) than Mo₂C (117 mV at 10 mA cm^-2). Spectro-electrochemical studies reveal that both catalysts oxidise to tetra-oxo (MoO₄)^2- motifs during operation, but the transformation is faster and more extensive in the case of Mo/Mo₂C. EXAFS analysis reveals that Mo₂C stabilises a defect-rich MoO_x layer resembling MoO₂, contributing to the enhanced HER activity, while Mo/Mo₂C undergoes pronounced oxidative transformation that depletes the active sites. The in situ-formed and regenerable active species from surface-reconstructed Mo₂C@MoO_2-x bestow the catalyst with high activity. DFT calculations indicate that the reconstructed Mo₂C@MoO_2-x optimises the Gibbs free energy of hydrogen adsorption by preserving moderate Mo-H binding, while excessive oxidation attenuates binding and retards the Volmer-Heyrovsky step. Thus, we identify a controllable, self-limited surface reconstruction step, rather than the metallic Mo constituent, as the key performance descriptor, guiding the design of stable carbide-based catalysts for alkaline water electrolyser technologies.

The development of neuromorphic visual systems aims to address the constraints in energy efficiency and stability within machine vision. However, neuromorphic photonic devices mostly encode hybrid optical-electrical signals or adjust the optical response through electrical bias, resulting in limited biological fidelity. Herein, a retina-inspired all-optical PDVT-10/IGZO heterojunction synapse with superior photoresponse tunability is proposed. Leveraging wavelength-dependent programming with 340 nm light for potentiation and 530 nm light for depression, the device functionally emulates bidirectional synaptic plasticity and multiple optical logic operations (i.e., "OR", "AND", "NOR", and "NAND"). This configuration yields an optical conductance tuning ratio of 8.2 and retains stable performance even after 9 months in the atmospheric environment. The light-induced mechanism can be attributed to the ionization and neutralization of oxygen vacancies within the IGZO layer. Such an all-optical synapse is further validated by integration with artificial neural networks, achieving a recognition accuracy of 97.4% in handwritten digit classification and demonstrating effective feature enhancement in image-denoising tasks. This bio-inspired design will endow machine vision systems with high biological fidelity, high energy-efficiency, and fully photonic operation.

Carbon nitride (CN) has been recognized as a promising photocatalyst for sustainable energy conversion and environmental remediation due to its moderate band gap (2.7-2.8 eV), facile synthesis, favorable band-edge positions, and high physicochemical stability. Despite numerous efforts in defect engineering, the development of CN-based photocatalysts still lacks unified design principles that correlate defect types and configurations with photocatalytic performance across different reactions. In addition to summarizing recent progress, this review emphasizes emerging design paradigms that elevate defect engineering from trial-and-error optimization to descriptor-driven and predictive strategies for next-generation CN-based photocatalysts. A comprehensive overview of defect-engineering strategies is put forward, including vacancy formation, cyano and amino modifications, as well as interstitial, substitutional, and anti-site defects, and how these structural modifications regulate the electronic structure and local coordination environment of CN is discussed. The influence of defects on key photocatalytic processes, light absorption, charge separation and transport, and surface redox reactions, is systematically analyzed, revealing how defect-induced electronic descriptors govern catalytic activity. Representative applications, such as hydrogen evolution, CO₂ reduction, and organic pollutant degradation, are discussed to illustrate the structure-activity relationships. Insights into the advances and challenges of this promising metal-free photocatalyst are provided, along with approaches for further exploring the immense potential to develop efficient CN-based photocatalysts.

Based on three-dimensional (3-D) printed acrylonitrile butadiene styrene (ABS) shells and carbonyl iron powder/polyimide (CIP/PI) composite patches, a low-profile and low-radar cross section (RCS) coding metasurface is proposed through the utilization of the hybrid mechanisms of energy absorption and scattering control. By adjusting the geometric parameters of the ABS shells and CIP/PI composite patches, diverse absorptive coding unit cells are designed. The arrangement of these absorptive unit cells is optimized through a genetic algorithm (GA), and the optimal backscattering reduction of the low-RCS metasurface is attained. The ratio of energy dissipation of the proposed metasurfaces clearly explains the effect of absorption and scattering on the RCS reduction. The results from theoretical calculations, full-wave simulations, and experimental measurements are in good agreement. The final experimental results demonstrate that the optimal coding metasurface achieves an RCS reduction exceeding the 10- dB level in the frequency range of 2.22 to 18 GHz, with a thickness of only 7 mm. Therefore, our proposal demonstrates considerable potential for engineering applications in platforms characterized by low-RCS properties.

We present a spatiotemporal gain-loss framework for eigenmode steering in coupled acoustic resonators. A cross-coupled gain-loss coefficient links the gain of one resonator to the intensity of its partner, creating nonlinear feedback that conserves total energy while driving the system toward the eigenmode associated with the eigenvalue having the largest imaginary part-a deterministic eigenmode steering. Spatial gain-loss profiles shape the eigenvalue spectrum and attractor landscape, while temporal modulation governs the transition dynamics. When symmetry prevents direct access to a target eigenmode, controlled spatiotemporal perturbations enable otherwise symmetry-forbidden transitions and accelerate convergence. Within this framework, parity-time () symmetry appears as a special case, allowing tunable switching between steering and Rabi-like oscillations near the exceptional point. Full-wave simulations of coupled Helmholtz resonators confirm precise and programmable acoustic energy routing, establishing spatiotemporal gain-loss engineering as a route to reconfigurable wave control and analog information processing.