Film Layer Research Articles

Optical properties of transparent TiO2 films by sintering anatase nanoparticles with a CO2 laser

A novel CO2 laser additive manufacturing technique is reported in this paper for depositing transparent TiO2 films on quartz substrates using anatase TiO2 nanoparticles (NPs). Single- and double-layers of TiO2 films were prepared in two stages: (i) wet deposition using the spin-coating technique, and (ii) laser-assisted both drying of the wet layer and then sintering of the dried NPs to form a film. A theoretical model is presented to select and optimize the laser processing parameters. Scanning electron microscopy (SEM) revealed that the laser heating induces necking and coalescence of TiO2 NPs without cracking the sintered films or damaging the quartz substrate. An anti-reflection coating (ARC) model is utilized to select the film material and film thickness, aiming to reduce the reflectance and enhance the transmittance at certain wavelengths. UV/Vis spectrophotometry showed transmittance above ∼90% in the visible (Vis) range. The effect of laser power on the enhancement of transmittance is presented in this paper. Different concentrations of TiO2 NPs were used to optimize the film thickness. Single layer (∼110nm thick) and double layer films of the same total thickness as the single layer were analyzed to infer the effects of interface on the transmittance of TiO2 films. The transmittance of the single layer is higher, same as that of the double layer. Therefore, the difference in the transmittance of the single- and double-layer may be due to the effect of interface. The optical properties of the anti-reflection TiO2 coating in the UV–Vis ranges were investigated. X-ray diffraction (XRD) analysis showed that the thickness affects the crystallinity of the sintered TiO2 films.

Effect of deposition rate and annealing on Nb thin film growth on Cu substrate: Molecular dynamics simulation

Molecular dynamics (MD) simulations are performed to study the growth mechanisms of Nb thin film on Cu substrate. In this investigation, we provide insights and information about the quality of the deposited Nb thin film by analyzing the growth mode, stress, and evolution of its microstructural and morphological properties by considering different deposition rates and thermal annealing processes. The results show that the growth of Nb atoms on the Cu substrate follows the island mode. The interface analysis reveals the presence of a nucleation phenomenon, moreover, the results indicate that the first layer of Nb film remains incomplete until approximately the amount of 4 monolayers of Nb is deposited. The analysis of interdiffusion indicates that Nb penetration is initially limited to the first Cu layer. However, after annealing, there is a significant increase in Nb atom penetration and a clear rearrangement of Nb within each layer of the film. The film adopts a BCC structure, with crystallinity rates varying based on the deposition rate. The highest crystallinity rate is observed at 5 atoms/ps, and annealing further increases these percentages. Deposition at different rates leads to different levels of compressive normal and biaxial stress.

Ladybug-inspired hierarchical composite adhesives for enhanced surface adaptability

Abstract Enhanced adhesion on rough surfaces is highly desired for a wide range of applications. On the other hand, surface roughness compatibility and structure stability are two critical but competing factors for biologically-inspired dry adhesives in the real world. Inspired by ladybug, a hierarchical structural composite dry adhesive (denoted as PP-M) with enhanced robustness on surface roughness is developed, which is composed of a thin compliant contact layer (a thin soft polydimethylsiloxane (PDMS) film supported discretely by PDMS micropillars) and a rigid bottom layer magnetorheological elastomers (MREs). The PP-M shows a high pull-off strength of 8.2 N cm−2 on a smooth surface and nano-scale rough surface at a mild preload (2 N cm−2). For micro-scale rough surfaces, the PP-M exhibits better surface adaptability compared to the double-layered adhesive (PDMS on MRE) without micropillar support. The increased compliance of the contact layer also leads to a 2.11 fold superior pull-off strength at a wider range of roughness (Sq > 2.23 μm). Element analysis confirms PP-M’s enhanced adaptability, attributed to deeper indentation and lower contact stress. This hierarchical composite structure in PP-M, characterized by a ‘soft on top and hard on bottom’ stiffness distribution, synergizes the flexible contact layer with the stiff MRE bottom layer, leading to superior adhesive properties. The results provide a new reference for achieving enhanced adhesion on rough surfaces.

Highly Efficient Layer-by-Layer Organic Photovoltaics Enabled by Additive Strategy

In this work, layer-by-layer organic photovoltaics (LbL OPVs) were prepared by sequentially spin-coating PM1 and L8-BO solutions. The solvent additive 1,8-diiodooctane (DIO), which has a high boiling point, and solid additive l,3,5-trichlorobenzene (TCB), which has a high volatile, were deliberately selected to incorporate with the L8-BO solutions. The power conversion efficiency (PCE) of LbL OPVs was considerably enhanced from 17.43% to 18.50% by employing TCB as the additive, profiting by the concurrently increased short-circuit current density (JSC) of 26.74 mA cm−2 and a fill factor (FF) of 76.88%. The increased JSCs of LbL OPVs with TCB as additive were ascribed to the tilted-up absorption edge in the long wavelength range and the external quantum-efficiency spectral difference between LbL OPVs with and without TCB as an additive. The molecular arrangement of L8-BO and the PM1 domain was enhanced with TCB as an additive, which was most likely responsible for the increased charge mobilities in the layered films processed with additives. It was indicated that the dynamic film-forming process of the acceptor layers plays a vital role in achieving efficient LbL OPVs by employing additive strategy. Over 6% PCE improvement of the LbL OPVs with PM1/L8-BO as the active layers can be achieved by employing TCB as additive.

Surface plasmon resonance microscopy for optical EHL measurement systems

This study investigates the suitability and limitations of surface plasmon resonance (SPR) microscopy for optical elastohydrodynamic lubrication (EHL) measurement systems. SPR microscopy developed in this study can quantify the lubricant density distribution in contact region with high spatial-temporal resolution using simple total reflection optical systems. It means that, if either the temperature or pressure distribution can be estimated, the other can be calculated. To examine the practicalities, we determined specific optical setting conditions such as the incident angle and thickness of each film layer for surface plasmon excitations under EHL conditions based on numerical calculations and demonstration experiments.

Триплетные сверхпроводящие корреляции гибридной меза-структуры с двухслойной ферромагнитной прослойкой

We present results on electron transport in hybrid Josephson mesa-structure Sd/F1F2/S, consisting of epitaxial films of cuprate superconductor YBa2Cu3O7-δ (Sd), bi-layer ferromagnetic interlayer (F1F2), thin film of metallic Nb was deposited on the top of a thin protective Au film layer used as the upper superconducting electrode (S). The long-range triplet component of superconducting correlations arises when strontium ruthenate SrRuO3 F1 and manganiteLa0.7Sr0.3MnO3 with non-collinear magnetizations are used as ferromagnetic material F2. Superconducting current took place up to the thickness d = 52 nm of the F1F2 interlayer. Superconducting current disappeared in the case of a single ferromagnetic interlayer of manganite (La0.7Sr0.3MnO3 or La0.7Ca0.3MnO3) and SrRuO3 with minimized thicknesses, limited by the occurrence of pinholes. The magnetic field properties of mesa-structure are discussed as well, along with the impact of the second harmonic in the superconducting current-phase relation.

Mono-axial stretching-induced growth of crystalline phase of melt-processed perfluoroalkoxy alkane (PFA) films for protecting inner layer of battery pouch films

Cast polypropylene (CPP) is employed as an inner layer of pouch films; however, CPP shows poor electrolyte, mechanical, and electrical stability, which can lead to instability during cell operation. In this study, we pioneered the use of perfluoroalkoxy alkanes (PFA) in the melt extrusion process to fabricate films based on their high melting flow index, establishing optimal conditions for producing uniform films. We further enhanced the functionality of these films by controlling the crystalline phase orientation through high-temperature uniaxial stretching, which is aimed at applications in battery pouch films. The stretched PFA films exhibited dramatically improved mechanical and insulation properties compared to traditional CPP films, 307.4% increase in tensile strength and 1,748.8% increase in breakdown strength, respectively. Based on these findings, we proposed that stretched PFA films, with their superior performance, are viable substitutes for CPP as the inner layer in battery pouch films. This research not only advances the material science of polymer films but also contributes to the development of safer and more efficient battery technologies.

New Hybrid Materials Based on N-Doping Copolymers of Thiophene Derivatives for Electrochemical Energy Storage

Over the past decade, electroactive conducting polymers (ECPs) are among the most potential pseudocapacitive materials for the electrodes of microsupercapacitors. ECPs exhibit several advantages, such as good conductivity (up to 103 S cm-1), flexibility, high specific capacitance (values ranging from 300 to 800 F.g-1 depending on synthesis and electrochemical performance conditions), relatively cheap and ease of synthesis [4]. Therefore, the electrochemical deposition of ECPs revealed a new strategy to design a great variety of various polymer morphologies as an innovative pseudocapacitive materials. Based on the different storage mechanism, electrochemical supercapacitors can be divided into three types, namely electrochemical double layer capacitors (EDLCs), pseudosupercapacitors and hybrid supercapacitors in which ECPs and other pseudocapacitive materials such as carbon materials, transition metal oxides, nitride complexes allow to store higher amount of capacitance per gram (faradic reactions) than EDLCs (pure capacitive energy storage reaction).In this work, we have elaborated new n-doped conducting polymers Poly[3,6-bis(2-thienyl)pyridazine] and Poly[3,6-bis(2-(3-n-hexylthienyl))pyridazine] by making electropolymerization on Pt disk electrode and 3 nm alumina coated silicon nanowires in acetonitrile organic electrolyte. The comonomers 3,6-bis(thienyl)pyridazine and (3,6-bis(2-(3-nhexylthienyl))pyridazine) have been successively synthesized. The produced polymeric materials Poly[3,6-bis(2-thienyl)pyridazine] and Poly[3,6-bis(2-(3-n-hexylthienyl))pyridazine] during n-doping process on Pt working electrode in acetonitrile solution of TBAPF6 (0.1 M) expose very low potential value of -2.23 V and -2.19 V at current density of -0.25 mA.cm-2 and -0.06 mA.cm-2, respectively. The elctropolymerization of synthesized comonomer 3,6-bis(thienyl)pyridazine has been done on Al2O3@SiNWs and resulted in thin layer of polymer film with micropores. The experimental results are compared to electropolymerization study of thiophene monomer on Pt disk and Al2O3@SiNWs electrodes to highlight the similarities and electrochemical advancements.

Evaluating the quantum confinement effects modulating exciton and electronic band structures of two-dimensional layered MoSSe films and their photodetection potentials

Evaluating the quantum confinement effects modulating exciton and electronic band structures of two-dimensional layered MoSSe films and their photodetection potentials

Resource utilization of emulsion evaporation modified aluminum industrial refractory waste in the preparation of composite modified asphalt

AbstractAluminum industrial refractory waste pose a huge risk to the environment, and hence a safe resource utilization is mandatory to build a green industrial construction industry. Herein, a thermoplastic polyester elastomers‐spent refractory material (TPEE‐SRM) modifier having a two‐layer structure of “protective layer‐functional layer” was developed. Scanning electron microscopy and surface area analysis revealed that Eps used in the protective layer formed a dense film layer (50% decrease in specific surface) with a 97.7% sequestration of fluoride. As the reaction occurred in an organic solution, fluoride posed no risk to the environment. TPEE functional layer itself melted and dissolved with asphalt under high‐temperature conditions, and hence it established a strong interfacial interaction with asphalt. This led to an increase of 99.73% in the complex modulus (G*) and 41.75% in the rutting‐resistance performance (Jnr) of the TPEE‐SRM composite modified asphalt than that of the pristine styrene‐butadiene‐styrene (SBS) modified asphalt. The performance of the TPEE‐SRM/SBS composite modified asphalt after 10 years of use was also evaluated by conducting high pressure aging simulation tests. The linear amplitude scanning test results showed a 27.1‐fold increase in Nf 5.0%. Owing to the efficient and green modification method, the newly designed TPEE‐SRM modifier poses great application prospects and feasibility for designing advanced functional modified asphalt for construction and highway industries alongside a suitable disposal aspect for SRM.

Dimensional Engineering in Efficient and Stable Inverted Perovskite Solar Cells

Perovskite solar cells (PSCs) have attracted much attention in the field of photovoltaics, due to their high power conversion efficiency (PCE) and low cost. In recent years, inverted PSCs have achieved significant advancements in PCE and operational stability. Among the strategies for optimizing PCE and lifespan of inverted PSCs, dimensional engineering plays a critical role and garners increasing attention due to its versatile functions of passivating defects, releasing residual tensile stress, strengthening structural stability, ameliorating carrier transport and extraction, and so on. Considering the importance of dimensional engineering, a comprehensive and deep understanding of 2D perovskites and 2D/3D heterojunction is definitely necessary. In this review, first, the progress of low‐dimensional perovskite light‐harvesting materials in inverted PSCs is summarized. Subsequently, the advances in constructing 2D/3D perovskite heterojunctions, including 2D/3D bulk heterojunction within perovskite materials, 2D/3D interfacial heterojunction at the interface between perovskite film and carrier transport layer, and bottom‐up 2D/3D perovskite heterojunction are discussed. The simultaneous construction of 2D/3D heterojunction at dual interfaces is highlighted. Finally, the legitimate outlook on the further development of dimensional engineering is proposed to advance the commercialization of inverted photovoltaic technology.

Design and fabrication of metal spherical conformal thin film multisensor for high-temperature environment

Conformal thin-film sensors enable precise monitoring of the operating conditions of components in extreme environments. However, the development of these sensors encounters major challenges, especially in uniformly applying multiple film layers on complex metallic surfaces and accurately capturing diverse operational parameters. This work reports a multi-sensor design and multi-layer additive manufacturing process targeting spherical metallic substrates. The proposed high-temperature dip-coating and self-leveling fabrication process achieves high-temperature thin-film coatings with excellent uniformity, high-temperature electrical insulation, and adhesion properties. The fabricated Ag/Pt thin film thermocouple arrays and a heat flux sensor exhibit a maximum temperature resistance of up to 960 °C, with thermoelectric potential outputs and high-temperature resistance closely mirroring those of wire-based Ag/Pt thermocouples. Harsh environmental testing was conducted using high-power lasers and a flame gun. The results show that the array of thin-film conformal thermocouples more accurately reflected temperature changes at different points on a spherical surface. The heat flux sensors achieve responses within 95 ms and withstand environments with heat fluxes over 1.2 MW/m2. The proposed multi-sensor design and fabrication method offers promising monitoring applications in harsh environments, including aerospace and nuclear power.

Spaceflight associated dry eye syndrome (SADES): Radiation, stressors, and ocular surface health

Crewed spaceflight missions require careful scrutinization of the health risks including alterations to the tear film lipid layer in astronauts. We review the current literature and prior published work on tear film lipid layer biophysics and secondary spaceflight-associated dry eye syndrome (SADES). We define the term spaceflight-associated dry eye syndrome to describe the collection of ocular surface signs and symptoms experienced by astronauts during spaceflight. Our review covers the ocular surface and lipidomics in the spaceflight environment. From our literature review, we extrapolate biophysical principles governing the tear film layer to determine the changes that may arise from the harsh conditions of spaceflight and microgravity. Our findings provide vital information for future long-duration spaceflight, including a return to the Moon and potential missions to Mars.

Influence of borax on the structure and tribological properties of aluminum alloy plasma electrolytic fluorination film layer

In recent years plasma electrolytic fluorination (PEF), as an emerging surface treatment technology, has been widely used to prepare fluorinated layers on metal surfaces. In this paper, different concentrations of borax are used as additives for plasma electrolytic fluorination of 6061 aluminum alloy. The effect of borax on the discharge characteristics of ion plasma electrolytic fluorination, as well as the coating growth process and the evolution of the tissue structure are systematically investigated. The results show that the surface of the coating prepared by adding a quantitative amount of borax is smoother and flatter, and at the same time has better abrasion and corrosion resistance, so it has a wide range of application prospects in the engineering field.

Advances in optical coating uniformity of interference filters

We propose a method to obtain uniform multilayer coatings using vacuum assemblies with a linear ion source to manufacture narrow-band interference filters essential in astrophysical research for space object imaging in important spectral lines, and to provide multi-channel fiber-optic transmission of information. Interference filters and other optical systems, for example, high-reflective mirrors, steep-front beam splitters contain up to hundreds of film layers deposited onto a substrate. During the coating deposition, film thickness on the substrate must be strictly withstood and be uniform throughout the entire surface. This can be achieved by placing the linear source and target on the same platform and by conducting a test target sputtering on a fixed substrate. There is an inflection line on the coating thickness distribution on the substrate. By moving the platform, the inflection line midpoint is aligned with the center of the rotating working substrate, and in this position, the substrate is coated to a specified thickness, which is monitored during the deposition process.

On modeling tear breakup dynamics with a nematic lipid layer

One of the main roles of the lipid layer (LL) of the tear film (TF) is to help prevent evaporation of the aqueous layer (AL). The LL thickness, composition, and structure all contribute to its barrier function. It is believed that the lipid layer is primarily nonpolar with a layer of polar lipids at the LL/AL interface. There is evidence that the nonpolar region of the LL may have liquid crystalline characteristics. We investigate the structure and function of the LL via a model of the tear film with two layers, using extensional flow of a nematic liquid crystal for the LL and shear-dominated flow of a Newtonian AL. Evaporation is taken into account and is affected by the LL thickness, internal arrangement of its rod-like molecules, and external conditions. We conduct a detailed parameter study with a focus on the evaporative resistance parameter, the Marangoni number, and primary liquid crystal parameters including the Leslie viscosities and director angle. This new model responds similarly to previous Newtonian models in some respects; however, incorporating internal structure via the orientation of the liquid crystal molecules affects both evaporation and flow. As a result, we see new effects on TF dynamics and breakup.

Study on protein-polysaccharide environmental foam dust suppressant based on Maillard reaction

Given the problems of traditional dust suppressants, such as high cost, poor environmental protection and degradation, this study developed a GEL-GG/OB-2 foam dust suppressant with high polymerized reticulation structure using polymer bio-based materials gelatin (GEL) and guar gum (GG) as the main materials for the Maillard reaction. The results of the orthogonal experiment showed that 0.1 % gelatin and 0.2 % guar gum reacted best at a temperature of 95 °C for 45 min, with a viscosity of 12.3 mPa·s. After drying, SEM observed that the surface formed a layer of compact film, and the hardness of the cemented coal layer could reach 79 HA. The contact angle with the coal sample after spraying for 3 s was 1.6°. It was found that the gelatin reacted with the polysaccharide hydrolysate by microscopic experiments. The affiliation of sugar molecules with gelatin molecules led to a change in the spatial conformation of the proteins, which led to the generation of the highly cross-linked polymer GEL-GG. The inhibition rates of PM2.5 and PM10 tested by the simulation test platform could reach 97.3 % and 98.2 %, respectively. In addition, GEL-GG/OB-2 is degradable and non-polluting, providing a feasible solution for the efficient suppression of coal mine dust.

Passivation Behavior of Chromium Alloyed High-Strength Rebar in Simulated Concrete Pore Solution

In this study, SEM, AFM, TEM, XPS, and electrochemical tests are used to study the passivation behavior of chromium alloyed high-strength rebar in simulated concrete pore (SCP) solutions with different pH values. The results show that after passivation in SCP solution with different pH values, the passivating film on the surface of the chromium alloyed rebar primarily consists of a layer of nanoscale oxide particles, which makes the passive film exhibit a p-n type semi-conductor, and the passive film presents a rhombohedral crystal structure. As the pH value of the SCP solution decreases, the nanoscale oxide particles on the surface of the rebar become denser, which leads to a reduction in the carrier density (Nq and Na) of the passive film and an increase in film resistance (R2) and charge transfer resistance (R3), thus increasing the corrosion resistance of the passive film. The passive film on the surface of the chromium alloyed high-strength rebar predominantly exhibits a three-layer structure, the outer passive film layer is composed of Fe oxides, the stable layer of the passive film is composed of Fe oxides and Cr oxides, and the growth layer of inner passive film is composed of Cr oxides. Compared with passivation 10 d in SCP solutions with pH 13.5 and pH 12.5, the passive film on the surface of the rebar has good stability at pH 10.5, which indicates that the addition of Cr is beneficial to promote the corrosion resistance of the rebar.

Interface reconstruction of NiCoP@NiMoP self-supported electrodes for highly efficient alkaline water/seawater electrolysis

Electrocatalytic water splitting is considered a feasible hydrogen generation technique. However, their sluggish kinetics and poor stability remains a huge challenge for alkaline water electrolysis. Herein, we report a corrosion-resistant NiCoP@NiMoP micro-pillar arrays for catalysts. It indicates that a layer of amorphous film on the surface of catalysts exposes many active sites and accelerates the species reconstruction. The prepared hybrid catalysts present an overpotential of 76 mV at −10 mA cm−2 for hydrogen evolution reaction (HER) and 268 mV@100 mA cm−2 for oxygen evolution reaction (OER). Furthermore, the assembled cell realizes a stable and high-efficiency water splitting with cycling life of 100 h in seawater media. This work provides a universal approach toward highly active and durable electrocatalysts.

Improvement of the Ferroelectric Response of La-Doped Hafnium Zirconium Oxide Employing Tungsten Oxide Interfacial Layer with Back-End-of-Line Compatibility.

In this work, the impact of a tungsten oxide (WO3) seed and capping layer for ferroelectric La-doped (Hf, Zr)O2 (La:HZO) based capacitors, designed with back-end-of-line (BEOL) compatibility, is systematically investigated. The WO3 capping layer supplies oxygen to the La:HZO layer throughout the fabrication process and during device cycling. This facilitates the annihilation of oxygen vacancies (Vo) within the La:HZO layer, thereby stabilizing its ferroelectric orthorhombic phase and resulting in an increase of the remanent polarization (Pr) value in the capacitor. Moreover, the effectiveness of the WO3 capping layer depends on the seed layer of the HZO film, suggesting that proper combination of the seed and capping layers should be employed to maximize the ferroelectric response. Finally, a TiN/TiO2 seed layer/La:HZO/WO3 capping layer/TiN capacitor is successfully fabricated and optimized by a complete set of atomic layer deposition (ALD) processes, achieving a superior 2Pr value and endurance value of more than 109 cycles at an electric field of 2.5 MV/cm. The WO3 capping layer is anticipated to offer a viable solution for doped HZO capacitors with reduced thickness, addressing the challenge of elevated Vo levels that favor the tetragonal phase and result in low 2Pr values.