Large-area Preparation Research Articles

Optimization of NC-LSPR coupled MoS2 phototransistors for high-performance broad-spectrum detection

Abstract In this work, negative-capacitance (NC) and local surface plasmon resonance (LSPR) coupled MoS2 phototransistors with a gate stack of HZO/AuNPs/Al2O3/MoS2 are fabricated, and the impacts of Al2O3 interlayer-thickness (T AlO) on the LSPR effect, the tensile strain on MoS2 from the Au nanoparticles (AuNPs), the capacitance matching of the NC effect from Hf0.5Zr0.5O2 (HZO) ferroelectric layer and the optoelectrical properties of the relevant devices are investigated. Through optimizing T AlO, excellent optoelectrical properties of phototransistors with a T AlO of 3 nm are achieved: a subthreshold swing (SS) of 25.76 mV/dec and ultrahigh detectivity of over 1014 Jones under 740 nm illumination. This is primarily because the NC-LSPR coupled structure can achieve an ultra-low SS through capacitance matching and a good interface passivation through optimizing Al2O3 interlayer to maintain effective LSPR and strain effects cross the MoS2 to enhance optical absorption and detection range. This work provides a comprehensive analysis on effective distance range of the non-direct-contacted LSPR effect and its combination with capacitance matching of NC effect, culminating in an optimized NC-LSPR coupled MoS2 phototransistor with a good consistency across an array of 30 devices, and offering a viable solution for the preparation of large-area, high-performance and broad-spectrum response 2D phototransistor array.

Ultra-high Prussian blue loading in SPEEK matrix fabricated by one-step electrostatic spraying as proton exchange membranes for fuel cell

Mixed matrix proton exchange membrane is promising for fuel cell application, but maximizing nanofiller loading to enhance performance is significant challenge. This study developed a one-step electrostatic spraying strategy to prepare ultra-high Prussian blue loading (up to 66.7 wt%) in sulfonated poly(ether ether ketone) matrix (PB@SPEEK). By coupling the electrostatic spraying and in situ solvent evaporation densification, SPEEK fills the voids between PB nanoparticles, forming a bicontinuous microstructure in the membrane. The ultra-high PB content of 66.7 wt% enable a fully utilization of its intrinsic properties, resulting in extremely low swelling ratio of 3.4% at 80°C, excellent flexibility of freely folding, and nearly 100% mass retention after 12-hour immersion in Fenton reagent at 60°C. In single-cell tests, the PB@SPEEK mixed matrix membrane shows stable internal resistance due to easily water hydration, therefore achieving excellent low-temperature peak power (1973.9 mW/cm2 at 40 °C and 2078.0 mW/cm2 at 60°C). The strategy developed in this study enables the one-step preparation of large-area, ultra-thin and ultra-high capacity of inorganic nanofiller mixed matrix proton exchange membranes for high-performance fuel cell.

Construction of Durable, Colored, Superhydrophobic Wood-Based Surface Coatings Using the Sand-In Method.

Highly durable color superhydrophobic coatings have attracted much attention in indoor and outdoor decorative applications. In this paper, colorful superhydrophobic coatings with excellent durability were prepared using silane coupling agent-modified iron oxide as the pigment and polydimethylsiloxane-compounded epoxy resin as the base material by the three-step method of "spraying-sanding-spraying". The method is low cost, has a simple preparation process, enables large-area preparation, and has a restorative function. The use of red, yellow, blue, and green four kinds of modified iron oxides through the single color or multicolor into the sand can be obtained by a variety of color coatings, and silica mixed with a variety of colors can be obtained from light to dark coatings. The coating has excellent superhydrophobicity and self-cleaning ability to withstand sandpaper abrasion, water impact, sand impact, UV exposure, and environmental testing. The coating is suitable for interior and exterior decoration and for protection of wooden buildings.

Investigation of the regulatory mechanism of monolayer colloidal crystals prepared by gas-liquid-solid three-phase interfacial self-assembly method

In recent years, the gas-liquid interface self-assembly method has emerged as a recognized and efficient technique for preparing two-dimensional monolayer colloidal crystals. However, challenges such as limited preparation area, dependence on complex equipment, and high costs persist in the conventional preparation process. This paper proposes a straightforward, rapid, and cost-effective method to implement a gas-liquid-solid three-phase interfacial self-assembly strategy. This approach enhances the gas-liquid interfacial self-assembly method, allowing for the preparation of large-area, high-quality single-layer colloidal crystals (>10 cm2) without using any surfactant. The gas-liquid-solid three-phase interfacial self-assembly process was analyzed in detail, and it was found that the main factors affecting the quality of the monolayer colloidal crystals were the volume ratio of PS colloidal solution to ethanol and the self-assembly temperature. It was shown that the optimal self-assembly conditions were achieved after dispersion by ultrasonic dispersion in a water bath at 32 °C–30 °C at a volume ratio of 1:2.5 of PS colloidal solution to ethanol. In addition, particles of various sizes can be prepared by this method to produce tightly arranged monolayer films that can be transferred to a variety of different substrates with great versatility. The demonstrated efficiency of this self-assembly method underscores its significant potential for application in large-scale manufacturing and practical industrialization.

Easy and fast preparation of superhydrophobic multi-level structures with high stability and oil-water separation efficiency

Superhydrophobic materials can solve the problem of oil pollution in water resources. In this paper, superhydrophobic PDMS-SiO2 with macro-micro-nano multi-level structures was prepared by impregnation method. The superhydrophobic PDMS-SiO2 material has good physical and chemical stability, and retains its superhydrophobicity after sandpaper abrasion, tape peeling, water immersion, acid or alkali immersion, and high temperature baking. The superhydrophobic PDMS-SiO2 material has a high oil-water separation efficiency, with the highest oil-water separation efficiency reaching more than 99%, and the oil-water separation efficiency of different oils all exceeding 96%. The preparation of superhydrophobic PDMS-SiO2 material is simple, inexpensive and environmentally friendly, which can achieve fast and large-area preparation, with good engineering application prospects.

Controlled epitaxial growth of strain-induced large-area bilayer MoS2 by chemical vapor deposition based on two-stage strategy

Two-dimensional (2D) bilayer transition metal dichalcogenides (TMDCs) have attracted considerable attention due to their promising applications in the fields of electronics, optoelectronics, valleytronics and nonlinear optics. However, the precise synthesis of large-area, high-yield and uniform bilayer MoS2 semiconductors remains a significant challenge. Herein, we have developed one two-stage chemical vapor deposition strategy based on strain engineering, enabling the controlled preparation of large-area (4 × 6 cm2) bilayer MoS2 nanostructures. Systematic characterizations indicate that compressive strain was introduced during the growth of first layer MoS2, which effectively induces the synthesis of the second layer MoS2. First-principles calculations based on density functional theory further reveal the mechanism of strain induced controllable growth of bilayer MoS2. Field-effect transistors based on AA and AB stacking bilayer MoS2 have been fabricated exhibiting excellent electronic properties. Our work provides a new pathway for the precise preparation of bilayer TMDCs nanostructures, offering experimental support for their application in the field of electronic and optoelectronic devices.

Dense Perovskite Thick Film Enabled by Saturated Solution Filling for Sensitive X-ray Detection and Imaging.

Thick polycrystalline perovskite films synthesized by using solution processes show great potential in X-ray detection applications. However, due to the evaporation of the solvent, many pinholes and defects appear in the thick films, which deteriorate their optoelectronic properties and diminish their X-ray detection performance. Therefore, the preparation of large area and dense perovskite thick films is desired. Herein, we propose an effective strategy of filling the pores with a saturated precursor solution. By adding the saturated perovskite solution to the polycrystalline perovskite thick film, the original perovskite film will not be destroyed because of the solution-solute equilibrium relationship. Instead, it promotes in situ crystal growth within the thick film during the annealing process. The loosely packed grains in the original thick perovskite film are connected, and the pores and defects are partially filled and fixed. Finally, a much denser perovskite thick film with improved optoelectronic properties has been obtained. The optimized thick film exhibits an X-ray sensitivity of 1616.01 μC Gyair-1 cm-2 under an electric field of 44.44 V mm-1 and a low detection limit of 28.64 nGyair s-1 under an electric field of 22.22 V mm-1. These values exceed the 323.86 μC Gyair-1 cm-2 and 40.52 nGyair s-1 of the pristine perovskite thick film measured under the same conditions. The optimized thick film also shows promising working stability and X-ray imaging capability.

Responsive Liquid Crystal Network Microstructures with Customized Shapes and Predetermined Morphing for Adaptive Soft Micro-Optics.

Stimuli-responsive materials have garnered substantial interest in recent years, particularly liquid crystal networks (LCNs) with sophisticatedly designed structures and morphing capabilities. Extensive efforts have been devoted to LCN structural designs spanning from two-dimensional (2D) to three-dimensional (3D) configurations and their intricate morphing behaviors through designed alignment. However, achieving microscale structures and large-area preparation necessitates the development of novel techniques capable of facilely fabricating LCN microstructures with precise control over both overall shape and alignment, enabling a 3D-to-3D shape change. Herein, a simple and cost-effective in-cell soft lithography (ICSL) technique is proposed to create LCN microstructures with customized shapes and predesigned morphing. The ICSL technique involves two sequential steps: fabricating the desired microstructure as the template by using the photopolymerization-induced phase separation (PIPS) method and reproducing the LCN microstructures through templating. Meanwhile, surface anchoring is employed to design and achieve molecular alignment, accommodating different deformation modes. With the proposed ICSL technique, cylindrical and spherical microlens arrays (CMLAs and SMLAs) have been successfully fabricated with stimulus-driven polarization-dependent focusing effects. This technique offers distinct advantages including high customizability, large-area production, and cost-effectiveness, which pave a new avenue for extensive applications in different fields, exemplified by adaptive soft micro-optics and photonics.

Study on the High-Efficiency Preparation of Superhydrophobic Polymer Thin Films by Continuous Micro/Nano Imprinting.

In order to improve the preparation efficiency, quality stability, and large-area preparation of superhydrophobic thin films, a roll-to-roll continuous micro-nano imprinting method for the efficient preparation of superhydrophobic polymer films is proposed. A wear-resistant mold roller with hierarchical microstructure is prepared by wire electrical discharge machining (WEDM). The rheological filling model is constructed for revealing the forming mechanism of superhydrophobic polymer films during continuous micro/nano imprinting. The effects of imprinting temperature, rolling speed and the surface texture size of the template on the surface texture formation rate of polymer films are analyzed. The experimental results show that, compared with other process methods, the template processed by WEDM shows excellent wear resistance. Moreover, the optimal micro/nano imprinting parameters are the mold temperature of 190 °C (corresponding film temperature of 85 ± 5 °C), rolling speed of 3 rpm and roller gap of 0.1 mm. The maximum contact angle of the polymer film is 154°. In addition, the superhydrophobic polymer thin film has been proven to have good self-cleaning and anti-icing performance.

Competing formation of α and δ-FAPbI3 in perovskite ink using 2-methoxyethanol as the solvent

2-Methoxyethanol (2-Me) is a promising solvent for large-area perovskite film preparation. Understanding the competing processes of α and δ-FAPbI3 in 2-Me is crucial for advancing the application of 2-Me in FAPbI3 film coating. In this study, FAPbI3 microcrystals are fabricated by inverse temperature crystallization method at 100 °C, and are used as a platform to investigate the competing formation of α and δ-FAPbI3 in 2-Me. Perovskite inks are analyzed using Raman, FTIR and DLS, and it is found that cluster ratio is closely related to the kinetic formation of δ-FAPbI3. The formation of α-FAPbI3 can be significantly promoted when clusters are dissociated with additives (excess FAI or I2). These findings provide valuable insights into the influence of precursor inks on perovskite phases.

One-step synthesis of functional slippery lubricated coating with substrate independence, anti-fouling property, fog collection, corrosion resistance, and icephobicity

Ranging from industrial facilities to residential infrastructure, functional surfaces encompassing functionalities such as anti-fouling, fog collection, anti-corrosion, and anti-icing play a critical role in the daily lives of humans, but creating these surfaces is elusive. Bionic dewetting and liquid-infused surfaces have inspired the exploitation of functional surfaces. However, practical applications of these existing surfaces remain challenging because of their inherent shortcomings. In this study, we propose a novel functional slippery lubricated coating (FSLC) based on a simple blend of polysilazane (PSZ), silicone oil, and nano silica. This simple, nonfluorine based, and low-cost protocol promotes not only hierarchical micro-nano structure but also favorable surface chemistry, which facilitates robust silicone oil adhesion and excellent slippery properties (sliding angle: ∼1.6°) on various solid materials without extra processing or redundant treatments. The highly integrated competence of FSLC, characterized by robustness, durability, strong adhesion to substrates, and the ability for large-area preparation, render them ideal for practical production and application. The proposed FSLC holds outstanding application potentials for anti-fouling, self-cleaning, fog collection, anti-corrosion, and anti-icing functionalities.

Development and Challenges of Large‐Area All‐Perovskite Tandem Solar Cells and Modules

The efficiency of all‐perovskite tandem solar cells has recently surpassed that of single‐junction perovskite solar cells, showing great potential as a future photovoltaic technology due to its low manufacturing cost and high power conversion efficiency potential, yet the size of these cells is still at the laboratory level. It is highly required to develop scalable preparation methods to fabricate large‐area all‐perovskite tandem solar modules for commercial applications. Herein, the key challenges encountered in the laboratory of all‐perovskite tandem solar cells and the existing solutions are summarized and some views on the preparation of large areas and modules are given.

Controlled Preparation of Highly Stretchable, Crack-Free Wrinkled Surfaces with Tunable Wetting and Optical Properties.

Constructing wrinkles by utilizing strain-driven surface instability in film-substrate systems is a general method to prepare micronano structures, which have a wide range of applications in smart surfaces and devices such as flexible electronics, reversible wetting, friction, and optics. However, cracks generated during the preparation and use process significantly affect the uniformity of wrinkled surfaces and degrade the functional properties of the film devices. The realization of crack-free wrinkles with high stretchability in hard film systems is still a great challenge. Here, we report on a facile technique for controllable preparation of large-area, highly stretchable, crack-free wrinkled surfaces by ultraviolet ozone (UVO) treatment of Ecoflex. The thickness dependence of the wrinkles and the in situ wrinkling process during mechanical loading are investigated. The wrinkles including striped, labyrinth-like, herringbone, and transitional structures are controllable by changing strain mode (uniaxial or biaxial), loading history (simultaneous or sequential), strain anisotropy, and gradient loading. The wrinkled surfaces obtained using UVO-treated Ecoflex have tunable wetting and optical properties and can maintain excellent mechanical stability under large strains. This study provides a facile method for the preparation of large-area, crack-free wrinkles, which is simple, fast, low-cost, and robust. The resulting wrinkled surfaces remain stable under high stretching, which is beneficial for many practical applications, especially in the cases of large strains.

Preparation of wide-bandgap perovskite thin films by propylamine hydrochloride assisted gas quenching method

Perovskite is a material with excellent photovoltaic properties, and the efficiency of perovskite solar cells has increased rapidly in recent years. By utilizing the adjustable bandgap characteristics of perovskite materials, wide-bandgap perovskite solar cells can be combined with narrow-bandgap solar cells to make tandem solar cells. Tandem devices can improve the utilization of the solar spectra and achieve higher power conversion efficiency. An important prerequisite for preparing efficient photovoltaic devices is to fabricate high-quality perovskite active layers. Antisolvent-assisted spin-coating is currently a commonly used method for preparing high-quality perovskite films in the laboratory. However, the low solubility of inorganic cesium and bromine salts in the preparation of wide-bandgap perovskite thin films leads to a fast crystallization rate, poor crystallization quality and a large number of defects, seriously reducing the photovoltaic performance of the devices. In addition, the antisolvent has a narrow working window, which is not conducive to the preparation of large-area perovskite films. In this work, a mild gas quenching process is used to assist the spin-coating method in preparing wide-bandgap perovskite films, and propylamine hydrochloride is introduced as an additive to improve the crystallization quality and uniformity of large-area preparation of perovskite film. The interaction between the propylamine cation and the perovskite component produces a two-dimensional perovskite phase. Two-dimensional phase is used as the growth template for perovskite composition in order to reduce the formation energy of <i>α</i>-phase perovskite, which is beneficial to uniform nucleation and preferential orientation growth of perovskite, the increase of grain size and the decrease of grain boundaries within the film. The improvement of the crystalline quality of the perovskite film can reduce the defect density inside the film and suppress the non-radiative recombination of the photogenerated carriers. The perovskite solar cell with a bandgap of 1.68 eV, prepared by using this strategy, achieves a power conversion efficiency of 21.48%. In addition, the 8 cm×8 cm wide-bandgap perovskite films prepared by this method exhibit good uniformity. This work provides a strategy for developing the process of efficient and large-area perovskite photovoltaic devices.

Low temperature UV cross-linked fluorinated polyurethane for organic thin film transistors

A FPU dielectric can be cured quickly at low temperature by UV cross-linking, for use in flexible devices; it is suitable for large-area preparation by a solution method and has good solvent resistance. OTFTs with FPU perform better than those with a PU dielectric.

An alternative mechanism of dry reforming enhanced growth of high-quality graphene: CO2-assisted CVD

The Cu-CH4-CVD system is a common method for the preparation of large-area and high-quality graphene, but high preparation temperature is usually essential to provide the high energy required to obtain active carbon species, causing inevitable intrinsic pollution. Here, we demonstrated a new technique for the high-quality preparation of graphene and proposed a new nucleation growth mechanism of graphene on the experimental basis in combination with computational materials science. By introducing CO2 into the traditional CVD system, the problem of intrinsic pollution was solved while the graphene-shaping nuclear energy was reduced, and Gr films with few layers, large domain size and small defect density were prepared. Ultimately, the Schottky PD composed of the prepared Gr film and Ge film achieved 1550 nm photoelectric detection and showed good performance.

Enhanced second harmonic generation from a quasi-periodic silver dendritic metasurface

The preparation of the vast majority of nonlinear optical metal metasurfaces currently relies on complex top-down methods such as electron beam or ion beam etching, which are expensive and difficult to meet the requirement of large area preparation. In this paper, an easily prepared quasi-periodic silver dendritic metasurface model with high Q factor is established in the near-infrared band based on a simple and easy-to-operate electrochemical deposition method. The simulations prove that the silver dendritic metasurface has a high Q factor (exceeds 104) because of its strong electric field localization ability, which is analogous to the superposition of multiple split-ring resonators. It is demonstrated that the second harmonic generation (SHG) intensity of the dendritic metasurface at a large incident angle (such as 85°) is about 30 times that of the metasurface at a small incident angle when the x-polarized pump light is incident obliquely to break the centrosymmetry of the metasurface. The influences of the incident angle or dendritic structure’s dimensions on the Q factor and SHG efficiency have also been researched through a lot of simulation. This easily prepared quasi-periodic silver dendritic metasurface SHG device may provide a new avenue for the development and application of miniature, integratable nonlinear optical devices.

Step-Nucleation In Situ Self-Repair to Prepare Rollable Large-Area Ultrathin MOF Membranes.

Ultrathin membranes with ultrahigh permeance and good gas selectivity have the potential to greatly decrease separation process costs, but it requires the practical preparation of large area membranes for implementation. Metal-organic frameworks (MOFs) are very attractive for membrane gas separation applications. However, to date, the largest MOF membrane area reported in the literature is only about 100 cm2 . In the present study, a new step-nucleation in situ self-repair strategy is proposed that enables the preparation of large-area (2400 cm2 ) ultrathin and rollable MOF membranes deposited on an inexpensive flexible polymer membrane support layer for the first time, combining a polyvinyl alcohol (PVA)-metal-ion layer and a pure metal-ion layer. The main role of the pure metal-ion layer is to act as the main nucleation sites for MOF membrane growth, while the PVA-metal-ion layer acts as a slow-release metal-ion source, which supplements MOF crystal nucleation to repair any defects occurring. Membrane modules are necessary components for membrane applications, and spiral-wound modules are among the most common module formats that are widely applied in gas separation. A 4800 cm2 spiral-wound membrane modulewas successfully prepared, demonstrating the practical implementation of large-area MOF membranes.

Generic technology R&D strategies in dual competing photovoltaic supply chains: A social welfare maximization perspective

In the context of global warming, photovoltaic (PV) industry is growing rapidly to advance carbon neutrality. A new generation PV technology based on perovskite solar cells has attracted high attention from the industry due to its advantage of low cost and high photoelectric conversion efficiency, and has gradually carried out relevant technology research and development (R&D), as well as small and medium-sized product trials. However, there are still some generic technical issues with perovskite solar cells, such as the stability of large area preparation, efficiency over large areas, and long service life under high efficiency. Collaborative R&D around generic technologies among module suppliers across PV supply chains will help create complementary synergies and accelerate breakthroughs in generic technologies. To explore R&D strategies and subsidy policies for the generic technology in competing PV supply chains, twelve game-theoretical decision models considering cooperative/non-cooperative R&D with/without government subsidy under four scenarios are developed, analyzed and compared respectively. The research results indicate that: (i) in all four scenarios, the adoption of a centralized operational strategy is more effective in terms of government subsidies and the operational performance of the PV supply chains than a hybrid or decentralized operational strategy. (ii) the government should adopt an appropriate subsidy intensity for the dual-competing PV supply chains and set a “threshold” subsidy policy. (iii) the positive externality of R&D effort has a positive spillover effect on profits, social welfare and other indicators. The positive externality of R&D effort for the generic technology can be better exploited by the two PV supply chains jointly deciding on the level of R&D expenditure and by the government providing financial subsidy support. This study is a pioneering study of dual competing PV supply chains in terms of cooperative R&D of generic technology, which is very limited in the PV supply chain management and subsidy policy research literature. The findings and some unnoticed issues in this paper provide a basis for future PV supply chain research.

Large-area, stretchable, ordered silver nanowires electrode by superwetting-induced transfer of ionic liquid@silver nanowires complex

Stretchable transparent electrodes (STEs) are widely used in electronic skin, implantable biomedical devices and wearable devices, which need to meet metal-like conductivity and high transparency while being prepared in a large area. Silver nanowires are the most widely used material to construct conductive networks because of their excellent optoelectrical properties. However, the silver nanowires-based networks prepared by conventional large-area preparation processes are generally composed of disordered silver nanowires, which suffer both high junction resistance and high diffuse reflection. Herein, a large-area, stretchable, ordered silver nanowires electrode is prepared by superwetting-induced transfer of a self-assembled complex composed of ionic liquid (1-ethyl-3-methylimidazolium (bis-trifluoromethane sulfonyl) imide) and silver nanowires onto stretchable substrates. Then, electroless-welding is used to further reduce the junction resistance between silver nanowires. The generated STE shows a low sheet resistance of 26–46 Ω sq−1 and a high transmittance of 84 %–88 % at 550 nm. The STE is successfully applied for transparent heating devices, exhibiting high heating performance and tensile stability. This study provides a new method for the preparation of large-area high-performance STE for the next generation of stretchable devices.