Scalable Integration of Single-Crystalline Ag Nanosheets for Threshold Voltage Engineering in Oxide Thin-Film Transistors

ACS Nano

Amorphous oxide semiconductor-based thin-film transistors (TFTs), particularly those utilizing indium gallium zinc oxide (IGZO), have garnered significant attention for next-generation display backplanes and flexible electronics. However, the precise and reliable modulation of threshold voltage (Vth) remains a persistent challenge, often requiring doping or vacancy engineering approaches that compromise process uniformity and device reliability. In this study, we introduce a scalable and low-temperature strategy for Vth tuning via the incorporation of two-dimensional (2D), single-crystalline silver nanosheets (Ag NSs) within the IGZO channel. These quasi-two-dimensional nanostructures have nanometer-scale thickness and lateral single crystallinity and are assembled using an ultrasonic-driven solution process that allows tunable coverage over large-area substrates. By varying Ag NS coverage up to 6.8%, we achieve a systematic and reproducible positive shift in Vth, with minimal degradation in mobility, on/off ratio, and subthreshold swing. Mechanistic studies using X-ray photoelectron spectroscopy and electrical bias stress testing reveal that the modulation arises from Schottky barrier formation and electrostatic screening at the Ag–IGZO interface rather than from modulation of oxygen vacancy concentrations. Devices incorporating Ag NSs exhibit excellent stability, with minimal hysteresis (ΔVth ≈ 1 V), negligible parameter drift under a ±20 V gate bias stress for 60 min, and long-term retention after 390 days of ambient storage. To validate the circuit-level applicability of this method, we fabricated depletion-load NMOS inverters combining pristine and Ag NS-modified IGZO TFTs, wherein the switching threshold could be finely tuned via the Ag NS coverage. This work demonstrates a wafer-compatible and solution-processable route to deterministic Vth engineering in oxide TFTs, offering a promising platform for future high-performance, flexible, and large-area electronic systems.

Low-temperature solution-processed flexible NH3 gas sensors based on porous CuBr films derived from 2D Cu nanosheets

Sensors and Actuators B: Chemical

The sensitive and selective detection of ammonia (NH3) gas at sub-ppm level and room temperature has attracted significant attention due to its promising applications in environment monitoring and medical diagnosis. Furthermore, these applications require flexible and wearable functionalities for both potential and practical use. Here, we report an NH3 gas sensor based on a porous copper bromide (CuBr) film, converted from the two-dimensional (2D) copper nanosheets (Cu NSs). The porous CuBr film as a sensing material is prepared by an all-solution and vacuum-free process at low temperature, enabling device fabrication on a plastic substrate. The optimized gas sensor, achieved by controlling the morphology and surface coverage of the porous CuBr film, exhibits a sensitive and selective NH3 gas response at sub-ppm levels and room temperature. The mechanical bending test over 1000 bending cycles at a bending radius (r) of 2 mm reveals the feasibility of flexible and wearable applications.

Omni-Directional Assembly of 2D Single-Crystalline Metal Nanosheets

Advanced Materials

Scalable and cost-effective fabrication of conductive films on substrates with complex geometries is crucial for industrial applications in electronics. Herein, an ultrasonic-driven omni-directional and selective assembly technique is introduced for the uniform deposition of 2D single-crystalline copper nanosheets (Cu NS) onto various substrates. This method leverages cavitation-induced forces to propel Cu NS onto hydrophilic surfaces, enabling the formation of monolayer films with largely monolayer films with some degree of nanosheet overlap. The assembly process is influenced by solvent polarity, nanosheet concentration, and ultrasonic parameters, with non-polar solvents significantly enhancing Cu NS adsorption onto hydrophilic substrates. Furthermore, selective assembly is achieved by patterning hydrophobic and hydrophilic regions on the substrate, ensuring precise localization of Cu NS films. The practical potential of this approach is demonstrated by fabricating a Cu NS-coated capillary tube heater, which exhibits excellent heating performance at low operating voltages. This ultrasonic-driven and selective assembly method offers a scalable and versatile solution for producing conductive films with tailored geometries, unlocking new possibilities for applications in flexible electronics, energy storage, and wearable devices with complex structural requirements.

2D Silver Nanosheet Assembly for an Isotropic, Stretchable, and Highly Conductive Nanomembrane

Advanced Materials

Achieving isotropic electrical and mechanical properties is essential for skin-integrated electronics to operate reliably under complex, multidirectional skin deformations. However, nanomaterial-based composites in skin electronics often rely on anisotropic filler configurations to meet demanding requirements for high-quality bio-interfacing materials, such as ultrathin thickness, high conductivity, and stretchability. While directional alignment of high-aspect-ratio nanofillers facilitates dense percolation, it compromises isotropic material uniformity. To overcome the trade-off between high performance and omnidirectional material properties in the nanocomposites, a controlled assembly strategy is proposed for silver nanosheets (AgNSs) that forms face-to-face contacts with partial overlaps, enhancing inter-sheet contact area and reducing contact resistance. Implementing this assembly configuration in an ultrathin elastomeric membrane yields a silver nanosheet nanomembrane (AgNS NM) with both isotropic material properties and high performance, featuring a high conductivity of ≈115 000 S cm−1, a stretchability of ≈50%, and a total thickness of ≈235 nm. Coarse-grained molecular dynamics simulations (CGMD) reveal that the degree of overlap correlates with nanosheet geometry, providing design insights for controlling interfacial contact configurations in nanomaterials. Finally, the potential of the AgNS NM for bio-interfacing applications is demonstrated through an electrical impedance tomography-based tactile electronic skin, enabling reliable multi-point pressure mapping and real-time tracking.

Conceptual design and 4E analysis of an ammonia synthesis process integrating methane thermal decomposition and dual chemical looping

Energy Conversion and Management

Ammonia has emerged as a promising hydrogen carrier and potential carbon-free fuel, increasing the demand for sustainable and energy-efficient production technologies. Conventional ammonia synthesis accounts for ∼1 %–2% of global energy use and 1 %–1.3 % of total greenhouse gas emissions, necessitating alternative approaches with lower environmental impacts. This study proposes an ammonia-production pathway that integrates methane thermal decomposition with a dual-chemical-looping system based on iron oxide (Fe2O3) and aluminum oxide (Al2O3). A comprehensive evaluation was conducted using energy, exergy, environmental, and economic (4E) analysis, benchmarked against conventional and single-looping processes. The results demonstrate that the proposed configuration improves the energy and exergy efficiencies by 8.4 % and 19.0 %, respectively, compared with conventional routes. Global warming potential was reduced by 15.85 kg CO2-eq/kg NH3. Furthermore, the levelized cost of ammonia decreased to 336.97 USD/t NH3, representing a 60.9 % reduction. These enhancements are primarily attributed to the synergistic integration of thermal and material flows, along with valorization of the process byproducts. Sensitivity analyses verified the stability of the system performance under a range of technoeconomic conditions, including variations in carbon pricing, electricity costs, and hydrogen market dynamics. Overall, this study highlights the technical and economic viability of the dual chemical looping approach for low-emission ammonia production, offering a strategic alternative for transitioning toward sustainable energy systems.

Reconfiguring Hierarchical Porous Architecture of 2D Metal Nanosheets for Multifunctional Triboelectric Nanogenerators

Advanced Materials

2D single-crystalline metal nanosheets are a promising platform for self-powered electronics, yet their potential for triboelectric nanogenerators (TENGs) remains unexplored. A key challenge in TENGs is overcoming low current output and limited durability. A hierarchical porous copper nanosheet-based TENG (HPC-TENG) is reported to substantially enhance triboelectric performance through a unique structural design. The method uses a simple spray-coating process to create a hierarchical porous conductive film from 2D copper nanosheets (Cu NSs). By infiltrating this film with polydimethylsiloxane (PDMS), interfacial contact is maximized, significantly boosting charge generation during mechanical cycling. The HPC-TENG achieves a remarkable 590% enhancement in electrical output compared to conventional Cu thin-film TENGs, while maintaining stable operation over 100 000 cycles. Beyond energy harvesting, this architecture provides integrated multifunctionality, including stable electromagnetic interference (EMI) shielding effectiveness exceeding 30 dB and efficient Joule heating. These findings highlight the strong potential of hierarchical porous metal nanosheet electrodes as a versatile platform for advanced energy harvesting, EMI shielding, and flexible heating, opening new avenues for next-generation wearable electronics.