Polycrystalline organic semiconductor thin films have attracted increasing interest because of their high charge-carrier mobility and low-cost solution processability. However, their electrical performance is highly sensitive to ambient humidity, which severely limits long-term device stability. To address this challenge, this study systematically examines the influence of ambient moisture on the electrical characteristics of organic field-effect transistors (OFETs) based on small-molecule organic semiconductor/polystyrene-blended polycrystalline thin films. The results demonstrate that ambient moisture plays a dual role in device operation. On one hand, water molecules preferentially accumulate at grain boundaries and at the semiconductor/dielectric interface, where they act as defect sources that introduce additional trap states, leading to a gradual reduction in carrier mobility and a positive shift in threshold voltage. On the other hand, the polarization effect associated with the high dielectric constant of moisture enhances channel carrier modulation, resulting in a temporary increase in current response. Nevertheless, this polarization process is inherently dynamic, ultimately leading to pronounced fluctuations in device parameters and long-term electrical instability. To mitigate moisture-induced degradation, molecular dopants were introduced as a strategy for structural regulation and interface stabilization. Although the incorporation of 1% dopant reduces grain size and slightly compromises initial device performance, it effectively passivates grain-boundary defects and significantly suppresses the formation of moisture-related trap states. Consequently, device stability under ambient conditions is substantially enhanced, with both carrier mobility and threshold voltage remaining stable after prolonged air exposure. This study elucidates the fundamental role of ambient moisture as both a “trap-inducing source” and a “polarization medium” in polycrystalline OFETs, and proposes a simple yet effective molecular doping strategy for achieving high-performance, environmentally stable polycrystalline OFETs.

Surface-enhanced Raman spectroscopy (SERS) has emerged as a powerful analytical technique for trace analysis owing to its exceptional sensitivity and unique molecular “fingerprint” recognition capability. However, the widespread application of traditional SERS substrates remains limited by factors such as high cost, poor biocompatibility, and unsatisfactory signal reproducibility. π-conjugated organic small molecules (π-COSMs), with their tunable electronic structures, high crystallinity, and superior charge-transfer properties, provide a promising strategy for developing novel SERS substrates. This review systematically summarizes recent advances in applying π-COSMs to SERS technology. Molecular engineering strategies, including precise modulation of energy levels and substituents within the conjugated system, have been shown to significantly enhance the chemical enhancement (CE) mechanism. Furthermore, constructing organic/two-dimensional material heterostructures enables a synergistic effect between electromagnetic enhancement and CE, substantially improving signal stability and detection sensitivity. These π-COSM-based substrates have shown significant potential in environmental monitoring, offering highly sensitive, selective, and fluorescence-free detection of microplastics and nanoplastics, antibiotics, and their interactions with bacteria. In summary, π-conjugated molecules open a new avenue for developing low-cost and biocompatible SERS platforms. Future research focusing on an in-depth understanding of structure-activity relationships and optimized design is expected to further promote the practical application of SERS technology in single-molecule science and real-time monitoring within complex environments.

GeTe-based alloys have attracted considerable attention as promising mid-temperature thermoelectric materials owing to their excellent performance. In this study, a series of Ge_0.8-xMn_0.1Pb_0.1Bi_xTe alloys were synthesized by vacuum melting followed by hot-press sintering. The results demonstrate that Bi incorporation significantly enhances the Seebeck coefficient. With increasing Bi content, the crystal structure gradually evolves from a rhombohedral to a cubic phase. Simultaneously, Bi-induced lattice distortion intensifies phonon scattering, leading to a marked reduction in lattice thermal conductivity, while the electronic thermal conductivity also decreases as a result of reduced electrical conductivity. At 773 K, the total thermal conductivity of Ge_0.8-xMn_0.1Pb_0.1Bi_0.02Te reaches a low value of 1.34 W/(m·K). Consequently, the alloys exhibit enhanced thermoelectric figure of merit (Z_T) values in the low-to-mid temperature range while maintaining high Z_Tat elevated temperatures, yielding a high average thermoelectric figure of merit (Z_T,avg) of 0.80.

Potassium tantalate niobate (KTN)-based ferroelectric single crystals with a perovskite structure have been extensively studied over the past few decades due to their advantages such as high piezoelectric constants, high phase transition temperatures, and nontoxic chemical compositions. With a deeper understanding of crystal growth processes and post-growth treatments, researchers have improved crystal quality and continuously increased crystal sizes using the top-seeded solution growth method. Recent studies have reported a piezoelectric constant exceeding 505 pC/N and an electromechanical coupling factor of 0.75 for tetragonal KTN single crystals. A high unipolar strain of 0.32% was achieved under an electric field of 15 kV/cm. This paper systematically reviews the research progress of piezoelectric properties of KTN-based ferroelectric single crystals, encompassing their growth techniques and approaches for enhancing electromechanical properties, such as ion doping and domain structures. Key technical approaches such as domain engineering and those for reducing growth defects and enhancing electromechanical performance are discussed. In addition, the current research challenges are identified, and future development prospects are outlined.

Ferroelectric optoelectronic artificial synapses, as an emerging class of intelligent devices, are regarded as ideal candidates for constructing neuromorphic visual systems owing to their advantages, such as ultrafast read-write speed and ultra-low energy consumption. This Perspective systematically reviews recent research progress in ferroelectric optoelectronic artificial synaptic devices. First, the operating mechanisms of two types of devices—namely photoconductive and photovoltaic devices—and their simulation of basic synaptic functions are discussed. Subsequently, the applications of these devices in neuromorphic visual systems are reviewed, including the simulation of learning and memory functions in biological visual systems, image information preprocessing and recognition, the detection and processing of dynamic visual information, and applications in multimodal interaction systems. Finally, the main challenges in the development of this class of devices are summarized from the perspectives of material preparation, device fabrication processes, and system architecture, and future development prospects are also presented. This Perspective not only provides a structured knowledge framework for experts in the field but also offers valuable reference information and directional guidance for advancing the development of novel low-power intelligent visual hardware.

Ammonia is an essential chemical feedstock; however, its conventional synthesis via the Haber-Bosch process is associated with high energy consumption and substantial carbon emissions. Developing green and efficient electrocatalytic routes for ammonia synthesis is therefore of significant importance. To overcome sluggish reaction kinetics and limited electron transfer, 26-faceted Cu₂O polyhedra were synthesized using a template-free chemical precipitation method, followed by the deposition of Ag particles onto the Cu₂O surface via photoreduction. This catalyst design optimizes the electronic structure, facilitates interfacial charge transfer, and enhances the intrinsic activity for converting key reaction intermediates (such as *NO₂ and *NH₂OH) into NH₃. As a result, the hydrogen evolution reaction and by-product formation are suppressed, leading to improved electrocatalytic performance for nitrate reduction to ammonia. Electrochemical evaluations demonstrate that Ag-Cu₂O exhibits excellent catalytic activity for the nitrate reduction reaction, achieving a Faradaic efficiency of up to 88%, which outperforms Au-Cu₂O and pristine Cu₂O, while generating lower amounts of the nitrite by-product and the competing hydrogen product. The catalyst maintains effective performance across a wide range of nitrate concentrations, supporting its potential applicability in nitrate wastewater treatment with varying pollutant levels. This study provides new insights into the rational design of high-performance and durable electrocatalysts for nitrate reduction and offers a valuable reference for advancing electrocatalytic technologies in wastewater treatment and green ammonia synthesis.

To achieve efficient utilization of the full solar spectrum and enhance the photocatalytic performance of cobalt tungstate (CoWO₄), one-dimensional CoWO₄ nanomaterials doped with rare-earth (RE) elements (Ce³⁺, Eu³⁺, Yb³⁺, and La³⁺) were synthesized using electrospinning technology. The structural, morphological, photocatalytic, and photothermal sterilization properties of the synthesized nanomaterials were systematically investigated. X-ray diffraction analysis revealed that all samples retained the monazite monoclinic structure of wolframite, with RE doping inducing lattice distortion. Scanning electron microscopy and transmission electron microscopy results demonstrated that doping increased the surface roughness of the nanotubes and generated a porous structure, thereby providing more active sites for reactions. Photocatalytic performance tests showed that 7% Ce-CoWO₄ achieved a degradation rate of 90.54% for ciprofloxacin under visible light within 140 min and 81.84% under near-infrared (NIR) light within 7 h. Electrochemical tests indicated that RE doping effectively reduced charge-transfer resistance and enhanced the photocurrent response. In terms of photothermal performance, 5% Yb-CoWO₄ increased the temperature of the liquid system to 65℃ within 360 s under NIR irradiation, demonstrating excellent photothermal conversion capability. Antimicrobial experiments confirmed that the re-doped samples exhibited significant photothermal sterilization effects against Escherichia coli under NIR irradiation. This study provides new insights into the development of efficient, multifunctional photocatalytic materials with full-spectrum response capabilities.

Melilite-structured compounds with the general formula ABC₃O₇—where A is an alkaline earth metal (e.g., Ca²⁺, Sr²⁺, or Ba²⁺), B is a trivalent rare-earth ion, and C is a trivalent main-group element (e.g., Ga³⁺ or Al³⁺)—represent an important class of inorganic functional materials. Owing to their stable crystal structure, tunable chemical composition, excellent physical and chemical stability, and multiple lattice sites available for activator ions, these materials have shown considerable potential in luminescence applications. This article provides a systematic review of recent advances in ion-doped ABC₃O₇-based luminescent materials. It highlights the characteristic features of the melilite-type crystal structure and presents a comprehensive summary of the luminescent properties, site occupancy behaviors, and concentration quenching effects of representative activator ions, including Eu³⁺, Tb³⁺, Dy³⁺, Mn²⁺, and Cr³⁺, within this host lattice. Additionally, the energy transfer mechanisms between sensitizers (e.g., Bi³⁺) and activator ions are thoroughly examined, and strategies for color tuning and performance enhancement via ion co-doping are discussed. Finally, current challenges and future research directions are outlined, providing theoretical insights and practical guidance for the rational design of high-performance melilite-structured luminescent materials.

Lead-based halide perovskite nanocrystals have attracted extensive attention due to their outstanding optoelectronic properties. However, their small Stokes shifts often lead to severe self-absorption, which greatly limit their luminescence efficiency and practical applications. Moreover, the inherent biological toxicity of lead poses irreversible risks to human health and the environment. To address these issues, this study synthesized lead-free Cs₃Cu₂X₅(X=Cl, Br, I) perovskite nanocrystals using a hot-injection method and systematically characterized their phase purity, compositions, and microstructures. Optical measurements, including fluorescence spectroscopy and temperature-dependent fluorescence lifetimes, revealed that the high photoluminescence quantum yield and large Stokes shifts of Cs₃Cu₂X₅ nanocrystals originate from their self-trapped exciton emission mechanism. To enhance their applicability, we further coated the nanocrystals with a SiO₂ shell, which significantly improved their dispersibility in aqueous media and their biocompatibility. Finally, using Escherichia coli as a model bacterium, the photo-induced antibacterial performance of the Cs₃Cu₂X₅@SiO₂ core-shell nanocrystals was evaluated through turbidity analysis and colony counting assays. This study revealed the physical origin of the outstanding luminescent properties of Cs₃Cu₂X₅ nanocrystals and demonstrated their potential as efficient and safe optical materials in biomedical applications.

To address the compatibility issue between microstructure stability and mechanical property matching during the welding of high-nitrogen austenitic stainless steel, autogenous TIG butt welding was employed. With welding speed and shielding gas conditions kept constant, the welding current was used as the primary variable to systematically investigate its effects on the microstructural zoning characteristics, Cr₂N nitride precipitation behavior, and the evolution of mechanical properties of the welded joints. The results reveal that the welded joints exhibit typical microstructural zones, including the weld zone, coarse-grained heat-affected zone, and fine-grained heat-affected zone. Welding current significantly affects the grain characteristics and microstructural uniformity in each zone. XRD analysis indicates that Cr₂N is detectable in the weld metal at currents from 160 to 200 A, whereas when the welding current is increased to 220 A and above, the diffraction peaks of Cr₂N are significantly weakened and eventually disappear. Based on the analysis of welding thermal cycles, this suggests that higher welding currents kinetically suppress the precipitation process of Cr₂N by reducing the effective residence time of the weld zone within the critical temperature range sensitive to Cr₂N precipitation. Mechanical property tests show that the tensile strength and impact toughness of the welded joints exhibit a nonmonotonic trend with increasing welding current—initially decreasing, then increasing, and finally decreasing again. Optimal strength-toughness matching was achieved at 220 A. Overall, welding current plays a critical role in regulating Cr₂N precipitation behavior and microstructural gradient characteristics, thereby substantially affecting the microstructure stability and mechanical properties of high-nitrogen austenitic stainless steel welded joints.

Indium tin oxide (ITO) targets are crucial for depositing transparent conductive films, yet their fabrication often faces challenges such as cracking and density inhomogeneity, especially in large-sized green bodies. Gel-casting technology, with its advantages of in-situ solidification of high-solid-content slurries, high green body strength, and uniform structure, is suitable for the preparation of high-performance ITO targets. However, cracking during drying remains a critical issue in the methacrylamide (MAM) system. The effects of monomer/crosslinker ratio, slurry solid loading, and gelation temperature on the cracking behavior of ITO green bodies are systematically investigated. The results indicate that crack-free ITO green bodies with uniform microstructure can be achieved under the optimized conditions: monomer content of 1%, monomer/crosslinker ratio of 20, solid loading of 80%, and gelation temperature between 55 ℃ and 65 °C. This work provides a reliable gel-casting strategy for fabricating high-quality ITO targets.