Advanced Materials Interfaces最新文献

Ultrafast charge-carrier and phonon dynamics at the buried heterointerface of GaP/Si(001) are investigated by means of two-color pump-probe reflectivity measurements. The carrier-induced reflectivity signal exhibits a resonant enhancement at a pump-photon energy of 1.4 eV, which is assigned to an optical transition at the interface. In addition, the transient reflectivity is modulated by a coherent oscillation at 2 THz, whose amplitude also becomes maximum at 1.4 eV. The observed resonant behavior of the oscillation, in combination with the characteristic wavelength-dependencies of its frequency and its initial phase, strongly indicates that the 2-THz mode is a difference-combination mode between a GaP-like and a Si-like phonon at the heterointerface and that the corresponding second-order Raman scattering process can be enhanced by a double resonance involving the interfacial electronic states.

The meniscus-guided coating (MGC) of a binary fluid mixture containing a solute and a volatile solvent that undergoes spinodal decomposition is investigated numerically. Motivation is the evaporation-driven deposition of material during the fabrication of organic thin film electronics. A transition in the phase-separation morphology from an array of droplet-shaped domains deposited periodically parallel to the slot opening to isotropically dispersed solute-rich droplets with increasing coating velocity is found. This transition originates from the competition between the injection of the solution into the film and diffusive transport that cannot keep up with replenishing the depletion of solute near the domains. The critical velocity of the transition is determined by the ratio of two length scales: i) the spinodal length, which implicitly depends on the evaporation rate and the properties of the solution, and ii) a depletion length proportional to the ratio of the diffusivity of the solute and the coating velocity. For coating below the critical velocity, the domain size and deposition wavelength are proportional to a solute depletion length. This competition in the mass transport is inherent in any kind of unidirectional deposition of demixing solutions and the findings should therefore apply to many coating techniques and forced demixing processes.

Compound Eye Lens

Dragonflies use their 360-degree wide-angle view to catch small prey and escape from natural enemies approaching from behind. This functionality is made possible by a three-dimensional compound eye, which consists of more than 30000 individual eyes. In article 2400480, Kenshin Takemura and co-workers develop a mold that could perfectly reproduce the compound eyes of dragonflies using a wide variety of materials.

Supercooled liquid water drops, with temperatures below freezing point, are common in high-altitude clouds. These drops, despite being in a metastable state, can remain liquid for extended periods if temperatures are above the homogeneous nucleation point. Impact of such liquid drops with a cold solid surface is one of the reasons for ice accretion, which in many cases can represent a safety hazard. The study of supercooled drop impact dynamics is key to developing materials that provide resistance against the formation and accumulation of ice. In this work, the impact of supercooled water drops on dry icephobic coatings based on gradient polymers deposited via initiated chemical vapor deposition (iCVD) under several conditions is analyzed. Experimental results show that coated surfaces potentially decrease the freezing probability upon impact. The gradient polymer surfaces with higher roughness and lower wettability do not increase the freezing probability upon impact but result in rebound and eventual roll off the surface, indicating that surface hydrophobic properties prevailed over the impact. The findings demonstrate the remarkable efficacy of gradient polymer coatings in inhibiting drop freezing, even under high wind velocities, and provide insights for the design of durable and effective anti-icing coatings across diverse applications.

The intractable prevalence of contact-mediated infections warrants the development of next-generation antimicrobial materials. Since bare metals like aluminum (Al) are prone to limitations such as microbial contamination and corrosion, it is imperative to develop a sustainable substrate using infinitely recyclable aluminum, with robust antimicrobial activity. This study reports broad-spectrum antibiofilm and antimicrobial activity of electro-chemically deposited reduced graphene oxide on aluminum (rGO-Al) substrates toward clinically important pathogens, Gram-negative E. coli, Gram-positive S. aureus, and fungus C. albicans. This further evaluates the knowledge gap by correlating the observed antimicrobial properties of rGO-Al materials to the possible mechanism(s). Next, measurements of water contact angle and 4-probe conductivity tests confirm the hydrophobic and conducting nature of the synthesized substrates respectively. In vitro, experimental results show that rGO-Al substrates can significantly inhibit the growth and viability of test organisms. While scanning electron microscopy (SEM) analyses confirm contact-mediated cell membrane damage, fluorescence microscopy reveals potent antibiofilm activity of test substrates. Alterations in membrane potential and reactive oxygen species (ROS) production provide further evidence for the antimicrobial activity via microbial membrane disruption. Thus, a perspective mechanism is proposed, where the surface hydrophobicity of rGO-Al promotes a stable interaction with the microbes. Further, conductivity-driven-electron transfer induces ROS production leading to membrane damage. Current research will facilitate the development of high-performance aluminum-based nanomaterials that can replace bare Al in the industrial and biomedical sectors. The sustainable nature of rGO-Al substrates will enhance the longevity and functionality of underneath Al surface by inhibiting microbial colonization and concurrent outcomes.

Developing highly sensitive and selective biosensors remains a critical challenge in molecular diagnostics. A novel peptide nucleic acid (PNA)-based biosensor platform is designed by integrating anatase-phase titanium dioxide nanotubes (TiO₂-NTs) with gold nanoparticles (AuNPs), deposited through sputtering and calcination to enhance signal intensity and suppress non-specific binding. The synergistic effect arises from the high electrical conductivity of AuNPs, which reduces interfacial resistance and promotes rapid electron transfer. The anatase phase of TiO₂-NTs further enhances charge separation, improving overall device performance. Under 50 °C hybridization conditions, the 300-s AuNPs sputtered TiO₂-NT electrodes demonstrate up to a 15-fold higher complementary deoxyribonucleic acid (coDNA) signal intensity (354.75 µA cm⁻²) than bare TiO₂ electrodes, confirming robustness and improved electron transfer efficiency. Furthermore, the signal intensity of single-stranded DNA (scDNA) decreases from 202.60 µA cm⁻² on the 60-s AuNPs sputtered sample to 65.70 µA cm⁻² on the 300-s sputtered sample, highlighting enhanced selectivity. This improvement is attributed to the denser AuNP distribution and enhanced electrostatic barrier formed by the electric double layer, which effectively suppresses non-specific interactions by repelling negatively charged DNA molecules. This integration establishes a highly sensitive and selective biosensing platform with promising applications in target nucleotide diagnostics.

Production scalability, efficiency, and stability challenges continue to impede the commercial viability of perovskite solar cells (PSCs). In this study, a multifunctional passivation technique is introduced, designed to enhance the efficiency and stability of printable, air-processed PSCs with laminated carbon electrodes. This findings indicate that tin(II) phthalocyanine (SnPC) molecules act as an interfacial layer between the absorber and the hole-transporting layer (HTL), effectively passivating surface trap states and facilitating hole extraction. Optimal SnPC surface treatment reduces the trap density in the perovskite layer from 2.1 × 10¹⁵ to 1.5 × 10¹⁵ cm⁻³, increases carrier mobility (from 2.7 × 10⁻³ to 2.8 × 10⁻³ cm² Vs⁻¹), and extends carrier lifetime. SEM, AFM, EDS, and XPS analyses confirm the presence of SnPC on the perovskite layer surface and its influence on surface morphology. Devices treated with an optimal SnPC concentration exhibit significant efficiency improvements, from 6.4% to 8.5%, along with a threefold increase in photo-stability. Thus, SnPC may serve as a passivating buffer layer for the perovskite surface, offering protection against photo-degradation.

Aluminum (Al) corrosion starts off at the micron or even submicron scale and if it is coating protected, it occurs at the metal-coating interface. These corrosion events are by and large studied using bulk corrosion measurements making the understanding incomplete due to its micrometric scale occurrence. This gap is therefore targeted in current study by using a combination of SECM mapping modes together with a new strategy of employing redox-mediator mixtures. These combinations allow the exploration of both Al surface topographic features as well as corrosion hotspots. Nine differently finished AAxxxx surfaces (namely, AA5083-rolled-Zr, AA6061-rolled-Zr, AA6061-grinded-Zr, AA6111-rolled-Zr, AA6111-grinded-Zr, AA7075-grinded-Zr, AA7075-rolled-Zr, AA7075-rolled-ZnPh with sealer and AA7075-rolled-ZnPh without sealer) are investigated by SECM in their as-received state for corrosion and mapped on a 1 mm² scale with high precision. The most interesting outcome is that typically grinded samples show more cathodic current and a higher number of hotspots. The resultant SECM maps are then quantified to extract corrosion hotspots and correlate them with both bulk corrosion outcomes and the real-life corrosion road tests performed for 2 years. These investigations present a strong corrosion predictive strategy, which makes this study comprehensive and highly applicable to sectors like automobiles and aerospace) employing Al surfaces.

Moldable polymers, such as polydimethylsiloxane (PDMS), are widely used for microstructures. Various PDMS microstructures have been developed by molding and applied to microfluidic devices. In addition to the moldability of PDMS, its elasticity, optical transparency, gas permeability, and biocompatibility facilitate its utilization in diverse applications. However, the permeability of PDMS makes it unsuitable in cases that require sealing. For instance, inflatable soft devices, including pneumatic balloon actuators, require their constituent material to exhibit both elastic and impermeable features to utilize driving pressure effectively. In this context, this paper presents the poly-para-xylylene (parylene)-caulking of PDMS without losing elasticity of PDMS. Parylene-caulked PDMS is obtained by etching coated parylene on PDMS. In the context of the previous study on parylene-caulked PDMS and similar works published recently, updated surface analysis results, and prepolymer ratio dependences are reported in this paper. Surface analysis is performed based on Fourier transform infrared spectrometry and time-of-flight secondary ion mass spectrometry is used to examine the presence of parylene on and inside the PDMS superficial layer. Parylene-caulked PDMS is attractive for inflatable soft actuators. This study believes that these results will potentially contribute to a wide range of applications that require gas impermeability.

Czochralski Method

High-angle annular dark-field scanning transmission electron microscopy image of a β-(Al_0.2Ga_0.8)₂O₃ crystal along the [010] projection grown by the Czochralski method. More details can be found in article 2400122 by Zbigniew Galazka and co-workers.