Advanced Materials Interfaces

Publisher: Wiley

Journal description

Advanced Materials Interfaces provides a forum for interface-related research across different disciplines with a demonstrable potential for applications. We cover the physics and chemistry at surfaces and interfaces which relate to functional materials in the nano/micro field whose properties are driven by interface rather than by bulk properties. This comprises surfaces, solid/liquid interfaces, solid/solid interfaces, and liquid/liquid interfaces.

RG Journal Impact: 2.80 *

*This value is calculated using ResearchGate data and is based on average citation counts from work published in this journal. The data used in the calculation may not be exhaustive.

RG Journal impact history

2017 RG Journal impactAvailable summer 2018
2015 / 2016 RG Journal impact2.80

Additional details

Cited half-life0.60
Immediacy index0.86
Eigenfactor0.00
Article influencedata not available
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ISSN2196-7350

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Publications in this journal

    • [...]
    Highly anisotropic polyolefin elastomer (POE)/natural graphite (NG) composites with high through-plane thermal conductivity and excellent mechanical properties, in which NG sheet perfectly aligns along one direction, are prepared by two-roll milling, hot compression, and mechanical cutting. The through-plane thermal conductivity coefficient of POE/NG composites is markedly improved to be 13.27 W m⁻¹ K⁻¹ at an NG loading of 49.30 vol%. When the composite is used as a thermal management material, it shows excellent heat dissipating capability in the through-plane direction, which is very important for thermal management in electronic applications. This effective method is highly probable to be widely used for the facile fabrication of polymer-based thermal management materials.
    • [...]
    Herein, molybdenum disulfide (MoS2) and tungsten disulfide (WS2) quantum dots (QDs) are prepared by a facile and green technique, and characterized by microscopy and spectroscopy. The resulting products display exceptional stability in polyalkylene glycol (PAG) base oil, and are used for the first time as friction reducing and antiwear additives in PAG for steel/steel contact. Tribological measurements indicate that the stable dispersion consisting of PAG mixed with MoS2/WS2 QDs exhibits significant tribological properties compared with pure PAG and PAG containing MoS2/WS2 QDs nanosheets under different loads at elevated temperatures. The excellent tribological behaviors of MoS2/WS2 QDs are attributed to the formation of a boundary lubrication film, which can be generated not only by the physical entrapment of MoS2/WS2 QDs at the ball-disk contact surfaces, but also by tribochemical reaction between MoS2/WS2 and the iron atoms/iron oxide species.
    • [...]
    The use of dry transferred graphene as a templating layer to enhance face-to-face stacking in poly(3-hexylthiophene) (P3HT) systems which is widely used for organic optoelectronics is investigated. In contrast to conventional poly(methyl methacrylate) (PMMA) assisted wet transferred graphene, dry transferred graphene is found in the current work to be quite suitable for use in the roll-to-roll process due to its lack of PMMA residue, whose removal would require high-temperature annealing. Grazing-incidence wide-angle X-ray scattering (GIWAXS) is used to determine the percentages of P3HT molecules adopting a face-on orientation on the various substrates tested. When a P3HT film with a thickness of 30 nm is produced, the face-on populations of P3HT are prominent on both the dry and wet transferred graphene layers. As the film thickness is increased to 50 nm, the face-on population decreases on the wet transferred graphene surface, but retains high levels on the dry transferred graphene. GIWAXS, near-edge X-ray absorption fine structure, and atomic force microscopy data are combined to propose schematic models for the molecular stacking of P3HTs on the two differently transferred graphene surfaces.
  • The thermal transport properties of nanostructured composite colloidal assemblies are investigated. These are of importance for future phase change material applications, which increasingly address the micrometer and sub-micrometer ranges. Polystyrene silica core–shell colloidal particles sizes of 270–480 nm and shell thicknesses of 15–42 nm are used as a structurally well-defined model system. This allows deducing precise structure property relationships with the lowest thermal conductivity being observed for particles with a large diameter, a thin shell thickness, and the highest polymer content. Importantly, clear evidence is found for polymer leakage through 15 nm silica shells when exceeding the glass transition temperature of the core polymer. This leads to a steady increase in thermal conductivity but also presents a lower limit for the silica shell thickness to contain the second phase. For a complete understanding, the findings are discussed in the light of colloidal crystals consisting of pure silica and polystyrene particles. Solid silica sphere colloidal crystals possess the highest thermal conductivity, and pure polymer beads the lowest. This demonstrates to which extent the thermal transport properties can be solely adjusted by the particle composition and morphology.
  • Precise patterning of solution-processed oxide semiconductors is critical for cost-effective, large-scale, and high throughput fabrication of circuits and display application. In this paper, demonstration and comparison are made using the additive and subtractive patterning strategies to precisely fabricate wafer-scale thin film transistor arrays (1600 devices), which are based on high-quality solution-processed indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO). The IZO and IGZO TFTs exhibit field-effect mobility up to 8.0 and 5.2 cm² V⁻¹ s⁻¹ when using the additive method, whereas the highest mobility of 24.2 and 13.7 cm² V⁻¹ s⁻¹ for IZO and IGZO TFTs is achieved when using the subtractive method. The X-ray photoelectronic spectroscopy studies and quantitative 2D device simulations together reveal that good device performance is attributed to moderate shallow donor-like states (providing electrons) from oxygen vacancy and few accepter-like states (trapping electrons) resulted from the dense structural framework of MO bonds. After examining the uniformity and reliability of the devices, the solution-patterned inverters are demonstrated using negative-channel metal oxide semiconductors, which show full swing output transfer characteristics and thus provide a promising method for solution-based fabrications of circuits.
  • The multifunctional nanocomposites with grafting polyamidoamine dendrimers up to third generation (G3) are grown onto the surface of mesoporous silica-coated gold nanorods (AuNRs@SiO2) via a divergent technique. The resultant AuNRs@SiO2-G3 nanocomposites with uniform size and excellent stability not only enable their utilization as targeted contrast agents for photothermal cancer therapy but also serve as scaffolds for the intracellular delivery of anticancer drug and small interfering RNA (siRNA) to enhance the efficiency of cancer therapy. The controlled doxorubicin (DOX) release from AuNRs@SiO2-G3 nanocomposites is significantly improved under lower pH condition and near-infrared laser irradiation. The Bcl-2-targeted siRNA is transfected into tumor cells and induces knockdown of the protein expression, which is confirmed by western blot assays. Furthermore, the complementary effect of chemo- and gene therapy to MCF-7 cells for improved photothermal therapy is demonstrated by MTT assay. The DOX and siRNA coloaded AuNRs@SiO2-G3 nanocomposites show much lower cytotoxicity compared to the DOX, resulting in low toxicity to normal tissues. The multifunctional nanocomposites have potential application as nanoplatforms to integrate the photothermal-chemo-gene tumor therapy with high efficiency.
  • Fabrication process that enables selective growth of vertically oriented zinc oxide (ZnO) nanowires (NWs) via chemical vapor deposition method and mask-free patterning approach is reported. It is shown that synthesis of high-quality ZnO nanowires in various architectures is achievable by optimizing the growth conditions and by precise patterning of catalytic ink precursors. Parallel direct-write patterning method is utilized to fabricate arrays of different architectures on Si/SiO2 substrates and directly on devices at preselected locations. The production of high-quality, crystalline ZnO NWs is demonstrated using aqueous iron catalytic inks. The composition of the ink and the lateral size of the patterns deposited on substrates are shown to affect the resulting nanowires and thus, allowing to control the geometry (length and diameter) of the individual ZnO NWs in the patterned assemblies. The results indicate that our protocols are tailored to the fabrication of ZnO NWs with specific surface geometries and interface functionalities for variety of targeted device applications.
  • The ability to control nanoflows is critical to design and fabricate ever more versatile nanosystems. Scientists are currently interested in finding ways to handle fluid dynamics inside nanoporous networks, not only to increase our knowledge of fluidic behavior but also to develop novel nanodevices that have potential utility in applications ranging from diagnostics to the production of high-value chemicals. Here, we demonstrate how fluid motion can be manipulated by controlling the coexisting infiltration and evaporation phenomena in mesoporous films. A versatile actuation approach through liquid–vapor dynamic modulation was developed by integrating mesoporous substrates with a thermoelectric cell. This actuation resulted in fast and reversible fluid displacements through the mesoporous matrix, which was achieved with relatively small temperature variations by controlled voltage inputs. The versatility of the strategy is demonstrated by tunable cycling of fluid imbibition and switched nanofluidic connection of liquids into the substrate. This novel nanoflow manipulator could be the basis for smart nanofluidic devices toward exciting applications in actuators, controlled pattern formations and release systems.
  • Polymer particles are promising particulate materials for renowned biomedical applications such as targeted drug delivery, tissue engineering, and biosensing. Surface properties of the polymer particles are of key importance for biomedical applications because they directly interact with biological systems. Particularly, wrinkled as well as porous surfaces possess an enhanced ability for cell attachment without any additional chemical modification. Therefore, a key objective is to fabricate the particles with desired degree of wrinkles and porosity. Many methods such as solvent evaporation, plasma treatment, emulsion instability, and electrospraying are being employed for the generation of porous, wrinkled and/or textured surfaces. Advantageously, an application of microfluidics can support the induction of surface instabilities on droplets in a case of droplet-based systems. Furthermore, microfluidics allows tuning of size and shape of the generated droplets as well as particles with desired surface textures. In this minireview article, surface characteristics (especially surface wrinkles and porosity) of the hydrophobic and hydrophilic polymer particles are presented for the potential applications toward biological as well as biomedical field. In addition, the impact of microfluidics is highlighted in order to produce the polymer particles of functional surface properties.
  • Inspired by the lotus leaf, nonwetting surfaces have drawn widespread attention in the field of surface engineering due to their remarkable water repelling characteristics. There are many applications for these surfaces, for instance, self-cleaning walls and windows, anti-icing surfaces, or low drag microfluidic channels. However, the adoption of nonwetting surfaces in large scale industrial applications has been hampered by synthesis techniques that are not easily scalable and the limited long term stability and wear robustness of these surfaces in service. This study demonstrates a simple, low cost, and scalable electrochemical technique to produce robust composite coatings with tunable nonwetting properties. The composite coatings are composed of an ultrafine grain nickel matrix with embedded hydrophobic cerium oxide ceramic particles. A comprehensive characterization is performed, including wetting property measurements, electron microscopy, focused ion beam analysis, hardness measurements, and abrasive wear testing to establish the structure–property relationships for these materials. The ultrafine grain structure of the nickel matrix contributes to the high hardness of the composites. As a result of the bimodal CeO2 particle size, hierarchical roughness is present on the surface of the composite, leading to remarkable nonwetting properties, even after 720 m of abrasive wear.
  • Jonathan D. Poplawsky and co-workers demonstrate a scanning transmission electron microscopy (STEM) verified method for atom probe tomography (APT) to accurately quantify Si/SiGe interfaces with 1Å precision in article number 1700622. The image depicts the atom probe field evaporation process with Si and Ge atoms field evaporating and being detected from a needle shaped SiGe specimen. The APT results are compared to STEM data after the post-reconstruction process, and the results are in good agreement.
  • Acoustic active surfaces are developed by Peer Fischer and co-workers based on two-dimensional arrays of acoustically resonant micro-bubbles, which provide highly directional propulsive forces in fluids through acoustic streaming in article number 1700933. The surfaces are remotely powered by an external acoustic field and are directly attached to miniaturized robots to propel them with multiple degrees of freedom. Image by Alejandro Posada/MPI-IS.
  • In article number 1700918, Jian Cao and co-workers introduce a new method to fabricate a superhydrophobic surface with a micro-stripe array structure. The cover illustrates this surface that can be used in a magnetic control micro-droplet release system. The fabrication process, based on diffusion bonding and selective corrosion, is shown at the bottom. The hierarchical structure of this surface is demonstrated in the background by a SEM image of CuO grown on the copper bulges.
  • Solid polymer electrolytes have shown to be a promising solution to suppressing dendrite growth for safer and higher performance lithium batteries. This article reports the fabrication and characterization of a series of nanostructured polymer electrolyte membranes (PEMs) comprised of poly(ethylene glycol)/bis(trifluoromethane)sulfonimide lithium electrolyte and acrylate–thiol-ene crosslinked resin using a holographic polymerization (HP). Nanoscale long-range order is observed and this unique structure imposes intriguing mechanical and ion-conducting properties of the PEMs. The modulus of the holographically polymerized PEMs can be tuned to vary from 150 to 1300 MPa while room temperature conductivities of ≈2 × 10−5 S cm−1 and 90 °C conductivity of ≈5 × 10−4 S cm−1 are achieved. The HP nanostructure is also capable of directing ion transport either parallel or perpendicular to the membrane surface; an unprecedented ionic conductivity anisotropy as high as 3 × 105 is achieved. It is anticipated that these PEMs may be excellent candidates for lithium battery applications.
  • Chang Hyun Sung, Ramireddy Boppella, and co-authors design a hollow nanostructured carbon-coated Ti³⁺ self-doped TiO2-reduced graphene oxide as Pt catalyst support with high electrochemical stability in article number 1700564. The developed electrode offers an excellent overall catalytic activity with an outstanding electrochemical stability under high potential cycling (1.2–1.7V) compared with conventional carbon black support materials that normally induce electrochemical corrosion during fuel cell operation, indicating a potential candidate of catalyst supports for polymer electrolyte membrane fuel cells in automotive applications (e.g. fuel cell electric vehicle).
  • High performance lightweight and flexible supercapacitors with superior electrochemical performance are in extremely high demand for wearable electronic device applications. Herein, a novel synthesis process is reported for developing highly flexible supercapacitor electrodes from carbon black doped carbon nanofiber/polyaniline core–shell nanofibers via electrospinning followed by carbonization and electrospray techniques. Resultant supercapacitor electrodes offer exceptional specific capacitance (SC) of 501.6 F g−1 at 0.5 A g−1, excellent capacitance retention of 91% even after 5000 cycles, demonstrating a long and stable life of the fabricated device. Moreover, solid state supercapacitor shows no obvious change in SC when subjected to various bending angles up to 180°. This simple three step (i.e., electrospinning, carbonization, and electrospray) fabrication technique paves new insights into the development of lightweight flexible supercapacitors.
  • Chemical modification of surfaces is recognized as efficient strategies to prevent bacterial contamination and the associated infection. Herein, a novel ionic liquid derivative 1-(((4-benzoylbenzoyl)oxy)methyl)-3-methyl-1H-imidazol-3-ium bromide (BMI) containing benzophenone moieties is developed to act as both a photoreactive cross-linker and an antibacterial agent. BMI can rapidly and efficiently form a “smart” antibacterial film on a variety of substrate surfaces in 2 min under mild UV irradiation. The modified surfaces show highly antibacterial activity, achieving more than 99% bacterial killing efficiency against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli using live/dead staining methods. In addition, the BMI-modified surfaces can release ≈97% of the killed bacteria via ion-exchange of hexametaphosphate (PP⁶⁻) anions and can regenerate bactericidal properties over three cycles. Moreover, in vitro cytocompatibility tests indicate that the BMI-modified surfaces have good biocompatibility. Thus, it can be concluded that cross-linked BMI layers provide a practical and convenient approach for the fabrication of “smart” antibacterial surfaces.
  • Adsorption of proteins associating with their conformational changes plays crucial roles in regulating biomaterial–cell interactions and consequent tissue responses to implanted biomaterials. This study reports direct visualization of typical serum protein, vitronectin, one of the key adhesive proteins that participate in mediating cell behaviors, upon adsorption on typically designed surfaces. Carbon films with their surfaces being plasma grafted functional groups COOH and NH2 are used as the model substrata for this study. Negative-staining electron microscopy technique is employed for visualizing the adsorbed protein and 2D image classification is made and interpreted. Results show that adsorbed vitronectin tends to form multimer aggregate on the COOH-grafted surfaces, exposing extensively its cell-binding RGD (arginine-glycine-aspartic acid) motif for enhanced cell adhesion. The adsorbed vitronectin on the NH2-grafted surface forms dimer aggregate with the binding sites being enwrapped. The COOH-grafting triggers enhanced expressions of ITGA5, ITGAV, ITGB1, and ITGB3 of the adhered cells and this is likely attributed to the special spatial alignment of vitronectin upon adsorption. The conformational information of adsorbed vitronectin gained from the single particle electron microscopy analyses would shed light on design and construction of appropriate biomaterials surfaces for desired cellular behaviors.
  • In this work, a facile strategy is presented for the fabrication of precisely metallized patterns on polymer substrate based on the copper-free laser sensitizer through laser direct structuring (LDS) technology. A series of characterization methods are carried out to investigate the surface chemistry and morphology of polymer/antimony-doped tin oxide (ATO) composites after laser activation and selective metallization. X-ray photoelectron spectroscopy results show that a small part of Sn⁴⁺ and Sb⁵⁺ in ATO is reduced to Sn²⁺ and Sb³⁺, and it does not detect any Sn⁰ (elemental tin) after laser activation. This study confirms that ATO is a good copper-free laser sensitizer and an efficient catalyst for selective metallization. Furthermore, the obtained copper layer is anchoring into the substrate leading to a superior adhesion property (highest 5 B level after Scotch tape test) between the copper layer and polymer substrate. Meanwhile, the obtained copper circuit line exhibits high conductivity (1.26 × 10⁷ Ω⁻¹ m⁻¹) and excellent stability over time. This study also provides a guideline to develop copper-free laser sensitizer for LDS technology.
  • Silicon nanowires (SiNWs) are a promising anode material for Li-ion batteries due to their exceptionally high charge capacity. However, direct implementation is hindered by large volume expansion induced during lithiation, which results in mechanical failure during repeated charge cycling. Recent experimental works show thin metal oxide coatings can significantly increase the cycle stability of SiNWs. However, the deformation mechanisms underpinning this performance enhancement are not understood, presenting an opportunity for a fundamental investigation of core–shell mechanics. In this study, molecular dynamics simulations investigating the mechanical behavior of silica- and alumina-coated SiNWs under uniaxial tension are performed. Metal oxide coated nanowires possess significantly improved ductility, increasing the elongation to failure from 16% to greater than 47%. This occurs without significant reduction in tensile strength, resulting in apparent toughness 2–4 times that of uncoated nanowires. During loading, the oxide coating absorbs strain energy through breaking of bonds between highly coordinated atoms. At the same time, the coating maintains the structural integrity of the silicon core by increasing the defect nucleation rate from the core-coating interface, preventing localized deformation. Under both athermal (0 K) and room temperature conditions, the underlying deformation mechanism changes from amorphization within a localized shear band to dislocation twinning and large-scale amorphization.
  • To fabricate a flexible thermoelectric generator (f-TEG) that can be applied to curvilinear surfaces such as the human body, the screen-printing technique is a practical method for forming the thermoelectric (TE) elements. One of the main obstacles to fabricating high-performance screen-printed f-TEGs is the high contact resistance. In this work, the output power of a screen-printed f-TEG is increased by 80% through engineering of the contact and its formation process. Reduction ambient annealing is a process that removes the surface oxides while modulating the tellurium (Te) concentration on the surface, easily forming a favorable intermetallic compound at the contact interface. The wetting angle of the solder is also drastically reduced by applying an anti-diffusion bilayer. Using these methods, the specific contact resistivity (ρC) is reduced from 8.2 to 3.3 × 10⁻⁶ Ω cm⁻² and 75 to 4.7 × 10⁻⁶ Ω cm⁻² for p- and n-type TE material respectively. The device figure of merit measured for one leg is increased from 0.301 to 0.595 and 0.247 to 0.481 for p- and n-type respectively. The improved contact characteristics result in an increase in the output power of the complete module (a 72-couple f-TEG) from 0.25 to 0.4 W at a temperature difference of 40K.
  • Few-layered MoSe2 nanosheets have great promise as a low-cost alternative to noble Pt-based electrocatalysts for electrochemical hydrogen evolution reaction (HER). In this work, arrays of ZnSe/MoSe2 nanotubes on fluorine-doped tin oxide (FTO) glass substrates are synthesized and employed as an efficient binder-free HER electrocatalyst for the first time. The hybrid ZnSe/MoSe2 nanotubes have thicknesses of 3–20 nm. The growth of ZnSe layer is attributed to ion exchange with ZnO nanorods while the formation of MoSe2 layer is resulted from chemical bath deposition. Compared with the bare MoSe2 electrocatalyst, the hybrid ZnSe/MoSe2 nanotube electrocatalyst exhibits striking kinetic metrics with a small Tafel slope (73 mV per decade) and a low onset potential (68 mV). Beside benefits from the nanoarray structure as binder-free electrode as well as interlayer expansion of layered MoSe2, electron transfer from n-type ZnSe to MoSe2 induced by alignment of energy levels at heterointerface contributes to fast electron transport and active electrocatalytic behavior of MoSe2 at the electrocatalyst–electrolyte interface, which is responsible for the significant improvement in HER performance. This work opens up a new door for developing high-performance HER electrocatalysts by designing semiconductor heterojunction.
  • The increasing interest in Li–O2 battery arises from its unparalleled theoretical energy density. Nevertheless, the poor reversibility of cathode reaction and unstable characteristic of Li anode hinder its further application. To address these issues, a high-performance sandwich-structured quasisolid polymer electrolyte (QSPE) is designed to meet the requirement of both cathode and anode. For the first time, lithiated Nafion ionomer (Li-Nafion) is introduced into Li–O2 cell to separate “catholyte” and “anolyte.” Redox mediator (RM) is introduced into gel-like catholyte, based on polymethymethacrylate, to achieve high capacity and reversibility. Polypropylene carbonate is chosen as solid-state anolyte for enhancing interface stability of lithium anode. It is demonstrated that the QSPE exhibits excellent permselectivity to block RM shuttling, as well as good ionic conductivity and high electrochemical window. A solution mechanism formation of discharge product is demonstrated in the Li–O2 cell with QSPE and the RM works well for cycles at room temperature. This sandwich-structured design strategy will provide a new pathway to promote the properties of Li–O2 battery.
  • Janus nanoparticles (JNPs) can offer significant potential for synthesis of multifunctional materials, due to their inherent property contrast between the lobes. Asymmetric surface chemical modifications on JNPs can be performed such that each lobe can carry different surface and/or bulk-like properties, which could be combined in surprising ways. In this work, it is shown that snowman-type polymeric JNPs can be used to make conductive materials with tunable resistance and surface polarity. By changing the relative size between a conductive and an electrically insulating lobe, the bulk powder conductivity within a series of JNPs by a factor of 10 without changing the intrinsic conductivity of the polymer can be tuned. In the same time, the surface polarity of the powder material decreased by a factor of 5. The possibility to synthesize multifunctional materials from JNPs building blocks that enable the coupling of a bulk-like property with a surface functionality is therefore demonstrated.
  • Graphene oxide (GO) can be enriched at the air–water interface by the adsorption of surfactant molecules to the surfaces of the GO sheets. The synergism between the surfactant and GO is shown to be responsible for the improved interfacial performance of the composite through a subtle balance of surface charge and surface activity. The use of a photoaddressable surfactant provides a unique probe for investigating the fundamental mechanisms that control adsorption, by inducing spatiotemporal modulation of the surfactant properties by irradiation with light of certain wavelengths. Tensiometry measurements uncover the interfacial activity of the materials, whereas X-ray reflectivity serves to independently determine the interfacial structure and composition. The ratio between the surfactant and GO appears to be the key factor controlling adsorption, with pH and salt offering additional finer control of interfacial properties. This synergism between GO sheets and a surface active small molecule surfactant is utilized to stabilize oil-in-water emulsions with unprecedented effectiveness.
  • The unique combination of layered structure and chemical moieties grant very interesting physio-chemical properties to graphene oxide (GO). Functional groups such as epoxide, hydroxyl and carboxyl are abundantly distributed along the hexagonal lattice of carbon atoms. The superior properties of GO and increased interfacial interaction with other compounds make them excellent filler materials in polymers such as epoxies for creating multifunctional composites. Alternatively, the presence of epoxide group on GO opens up the possibility of using it as the major epoxy matrix constituent rather than just as a filler material. In this work, we report the formation of GO-xy (cross-linked GO via the epoxide functionality) resin by reaction of GO with polymercaptan based hardener by completely eliminating the need for conventional epoxy component. Substituting epoxy with GO marks notable advance in preparing adhesive materials with high temperature stability.
  • The hierarchical chiral self-assembly of peptides in evaporating liquid film is reported by Wei Qi and co-workers in article number 1700514. By changing the fluid mechanical effects under two distinct regimes: the “coffee ring” effect caused by outward capillary flow and the Rayleigh convection by buoyancy force, the peptides could self-assemble into well-aligned nanohelixes with their axis parallel or perpendicular to the substrate.
  • Although methods for perovskite morphology and thickness control have significantly improved the power conversion efficiency (PCE) of planar solar cell, they are rarely investigated in the field of fiber solar cell. Electrical heating-assisted multiple coating, as a solution-based film process, is proposed for the first time to control perovskite coverage and thickness on metal fiber. It solves the challenges by continuous deposition and hot coating technique. Study of film formation mechanism indicates that adding a drying procedure ensures steady deposition during continuous coating. Continuous deposition feature allows improving film coverage and controlling thickness by simply changing the number of coating times, which differentiate this method from other techniques. In addition, electrical heating is applied to accelerate film formation and perovskite transformation. Thus, a fully covered thin film of perovskite is obtained due to the improved perovskite loading and homogeneity. Corresponding devices achieve a high average PCE of 6.58% with a narrow standard deviation of 0.558. Above that, characterizations demonstrate difficulties in balancing high coverage and appropriate thickness accounts for the wide distribution of PCE and poor reproducibility. It is anticipated this method can move the field toward high efficiency and reproducibility goals.
  • The performance of organic light-emitting diodes (OLEDs) can change when they are subjected to thermal stress after manufacture. The effect of heat on OLED film stacks is studied, in which the emissive layer (EML) comprises either a phosphorescent iridium(III) dopant blended in a host at different concentrations or materials with alkyl substituents to increase the steric bulk of the host and/or dopant. Neutron reflectometry with in situ photoluminescence measurements shows that interdiffusion between the emissive and hole transport layers within the films occurs on thermal annealing. Interdiffusion occurs independent of dopant concentration or steric bulk of the EML components. Importantly, when held at relatively low temperatures, the EML materials are found to only partially diffuse into an adjacent charge transport layer. The movement of materials is found to correlate with the change in luminescence from the hole transport material and an initial enhancement of the emission from the iridium(III) dopant. The results provide an explanation for the burn-in often observed for OLEDs as well as the need to change the driving characteristics over time to ensure that pixels can be held at the requisite brightness.
  • Similarly to transition metal dichalcogenides akin to MoS2, transition metal polysulfides like tri- and tetrachalcogenide materials are nowadays incorporated into catalysts and composites used for energy conversion and storage, etc. However, polysulfide structures feature SS units, which make them strikingly different from the widely known MoS2 and other dichalcogenides. At the same time, their surface chemistry and its relation to properties are very little studied. Reported here is one of the first observations on the oxidizing properties of disulfide bridges (SS)2− forming surfaces in polysulfide crystals. Upon interaction with silver salts or silver nanoparticles, MoS2 acts as most supports, that is, it stabilizes metallic Ag at its surface; in contrast, curiously, patronite VS4 and NbS3 stabilize Ag2S nanoparticles under identical reducing conditions. The Ag/MoS2, Ag2S/NbS3, and Ag2S/VS4 samples are characterized with X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Apparently, the unexpected formation of Ag2S is due to complex redox processes involving disulfide fragments –S–S– of nanorods VS4 or nanoribbons NbS3, which are absent in MoS2 nanosheets. This result is important for fundamental understanding of the properties of sulfur-rich surfaces and also for contributing to the number of available synthetic paths toward Ag2S nanoparticles.
  • In the field of photovoltaic industry, organolead halide perovskite solar cells (PSCs) as cleaner and cheaper photo-voltaic devices have shown a bright prospect with power conversion efficiency (PCE) rapidly climbing from 3.8% to certified 22.1% in a few years. Interface engineering has been proven to be highly effective to solve the instability-to-moisture issue and enhance the performance of PSCs. Here, this work develops a simple and easy-proceeding strategy that depositing both aminocaproic acid [H2NCH2(CH2)4COOH, abbreviated as AmCA] and caproic acid [CH3(CH2)4COOH, CA] at the mesoporous TiO2/perovskite interface leads to significant enhancement in both the efficiency and stability of PSCs. These two organic modifiers work synergistically to enhance the overall performance of PSCs by promoting electron transfer through the interaction between amino groups on AmCA and perovskite layer, and resisting moisture with alkyl chains from CA. The champion efficiency of modified cells reaches 18.2%, with an average PCE of 17.5% in reliable reproducibility, with significant improvement in stability under 50 ± 5% relative humidity in air. The developed simple interfacial modification approach should be effective to enhance both efficiency and stability of PSCs with other architectures as well. More importantly, this scenario may provide insight into the commercialization of perovskite solar cells in the not-too-distant future.
  • In article number 1700740, Huiliang Wang, Xiaojing Yang, and co-workers propose a strategy to isolate and stabilize ZnAl-layered double hydroxide 2D crystals via polymer gel formation. The polymer gels are prepared by copolymerizing of acrylic acid anion and acrylamide in situ in the colloidal solution of the 2D crystals (pink hexagonal disks). The 2D crystals with ultrahigh surface exposure exhibit high adsorptivity toward phosphate (gray balls).
  • In this work, a novel lamination method employing hydrogen-bond interaction to assemble a highly conductive free standing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film as a common electrode is demonstrated in a solution processed metal-free foldable integrated photocapacitor (IPC) composed of a monolithic organic solar cell (OSC) and a capacitor. The highlights of the work are: (1) micrometer free standing PEDOT:PSS electrode is successfully laminated onto a relatively large area (1 cm2) OSCs; (2) a free standing capacitor based on the PEDOT:PSS electrode is achieved; (3) the IPC demonstrates an overall efficiency of 2% and an energy storage efficiency of 58%, which is comparable with those of IPCs based on metallic common electrodes; (4) the novel lamination method for PEDOT:PSS electrode enables free standing PEDOT:PSS broad applications in solution processed flexible organic electronics, especially tandem or/and integrated organic electronic devices. Furthermore, the IPC is foldable with excellent cycling stability (no decay after 100 recycles at 1 mA cm−2). These results indicate that free standing PEDOT:PSS film is a promising candidate as common electrodes for IPCs to break the restrictions of metal electrodes. The demonstrated lamination method will greatly extend the applications of PEDOT:PSS electrodes to large area flexible organic electronic devices.
  • Slippery liquid infused porous surface (SLIPS) is fabricated based on the femtosecond laser induced 3D porous network microstructures by Feng Chen, Qing Yang, and co-workers in article number 1700552. The preparation process of SLIPS mainly includes three steps: femtosecond laser ablation, fluoroalkyl layer modification, and infusion of lubricating liquid. A broad range of liquids could easily slide down the 10° tilted SLIPS, revealing that the resultant SLIPS had excellent liquid-repellent ability.
  • Wenyu Yuan and co-workers design a novel 2D-layered carbon/TiO2 (C/TiO2) architecture via one–step CO2 oxidation of 2D Ti3C2 in article number 1700577. The 2D carbon layers play a key role in enhancing separation efficiency of carriers, enhance the light utilization and facilitate the diffusion of H2. This research broadens the applications of C/TiO2 hybrids and provides a new approach to synthesize novel 2D layered materials for photocatalytic applications.
  • The understanding on the friction properties of black phosphorus (BP) is very crucial for such applications as strain-engineered devices and micro/nanoelectromechanical systems. Herein, the relationship between the layer number of few-layer BP flakes and its nanoscale friction, as well as the atomic-scale friction anisotropy, is studied. BP flakes thicker than about five layers show almost the same friction as that of the bulk value, and the friction increases with the layer number decreasing from five, due to the strengthening mechanism. Obvious friction anisotropy of BP flakes are observed in that the friction for the armchair direction is the highest, that for the zigzag direction the lowest, and that for the lattice orientation between the two directions the intermediate. Supported by the theoretical prediction with 2D Tomlinson model, the observed phenomena are explained by the anisotropies in the amplitudes of the tip-induced flexural deformations of BP flakes.
  • The overall electrocatalytic activity toward hydrogen evolution reaction for layered transition metal dichalcogenides is governed by their intrinsic activity, the corresponding density of active sites, and the electron transfer resistance. Here, nanoengineering strategies to scale down both the lateral size and thickness of layered 1T-TiS2 powder to quantum dots (QDs) by bath sonication and probing sonication incision are employed. Uniform lateral size of 3–6 nm in the resulting QDs enhances the density of edge sites while the atomic layer thickness (1–2 nm) facilitates the electron transfer from the substrate to the edge sites. The obtained TiS2 QDs exhibit superior hydrogen evolution reaction activity over TiS2 nanosheets and MoS2 QDs prepared by the same method. The turnover frequency of TiS2 QDs with a small loading of 0.7 ng cm−2 in an optimal deposition on electrode reached ≈2.0 s−1 at an overpotential of −0.2 V versus RHE, several orders of magnitude higher than TiS2 nanosheets (0.01 s−1) and MoS2 QDs (0.07 s−1).
  • In article number 1700540, Peng Wang and co-workers report that bismuth vanadate (BiVO4), when assisted by nickel cobalt oxides (NiCoO2), shows vastly improved photo(electro)catalysis (PEC) oxygen evolution reaction (OER) performance. The role of NiCoO2 is two folds: OER cocatalyst and band structure adjustment. The dual-role on single-component NiCoO2 improves surface reaction kinetics for PEC OER and enhances charge separation on the surface BiVO4 simultaneously, which is the determining factor for the unprecedented performance.
  • Charge conduction and redox events in films of doped conjugated polymers are necessarily accompanied by counterion transport. However, insights into how deposition conditions affect ion transport in a structurally diverse set of doped conjugated polymer films and across a polymer/electrolyte interface have not been gathered. Here, cyclic voltammetry and electrogravimetry measurements are used to probe solvent and ion transport across a doped conjugated polymer/electrolyte interface. A representative polymer, p-doped poly(3,4-ethlyenedioxythiophene) (PEDOT), obtained using two different deposition methods, vapor phase polymerization (VPP) and oxidative chemical vapor deposition (oCVD), is studied. PEDOT films obtained via VPP and oCVD display dissimilar morphologies at the micro- and nanometer length scales, resulting in significantly differing swelling behavior, mass trapping, and ion transport upon exposure to a periodic applied potential. PEDOT films obtained using oCVD display notable permselectivity and near-ideal mass transport during repeated doping/dedoping cycles in various electrolytes, indicating that these films are robust electroactive materials. This study underlines the extent to which film deposition conditions affect ion transport across polymer/electrolyte interfaces and provides insights into optimal film forming conditions for high-performance supercapacitors and electrochemical transistors.
  • Rubrene (RUB) is a benchmark organic semiconductor since the record exciton diffusion length and high charge carrier mobility are demonstrated in its orthorhombic single-crystal phase. In this respect, great research efforts on the growth and study of crystalline RUB thin films, the most suitable choice for device applications, are made, even though its oxidation remains a still open problem. Here, the oxidation of crystalline RUB thin films is focused, by studying and modeling the so-formed interface between RUB and its oxide. Optical spectroscopy carried out on freshly grown and aged crystalline RUB films gives evidence that oxidation occurs without altering the original crystal structure of the RUB films. To deeply analyze the process, a direct characterization of rubrene endoperoxide (RUBox) is proposed: after synthesizing a microcrystalline powder, its crystal structure and Raman response are determined. The joint results achieved on the RUBox powder and on aged RUB films demonstrate that RUBox forms as a crystalline native oxide layer with a well-defined epitaxial interface with the underlying RUB. Finally, structural constraints at the RUBox/RUB interface are shown to limit surface oxidation, with the oxide acting as a passivation layer against further oxidation.
  • Pulsed laser atom probe tomography (APT) has enabled the investigation of semiconducting materials at sub-nm length scales and 10 ppm chemical sensitivity. This has enabled APT to be the best technique for nanoscale detection of dopant distributions and low levels of chemical segregation at interfaces, which are both important for semiconductor processing; however, the accuracy of measured interfacial profiles is typically compromised by aberrations. Interfacial profiles in APT data will vary with respect to different interfacial combinations, especially when the evaporation field between two materials is drastically different. Here, the ability of APT to measure SiGe/Si/SiGe interfacial profiles is tested with an 8 nm Si well embedded in SiGe. The APT measurements are compared to those measured using scanning transmission electron microscopy (STEM) to evaluate reconstruction and post-reconstruction processing methods to appropriately measure interfacial profiles using APT. Without post-APT reconstruction processing, the measured Si/SiGe interfacial widths between APT and STEM match poorly, but after applying the z-redistribution algorithm, the interfacial profiles are in good agreement. These results indicate that APT can be used to accurately identify SiGe/Si/SiGe interfacial profiles after application of the z-redistribution algorithm, which will greatly impact the synergy between growth and characterization of semiconductor devices using Si/SiGe interfaces.
  • A major challenge that prevents the miniaturization of mechanically actuated systems is the lack of suitable methods that permit the efficient transfer of power to small scales. Acoustic energy holds great potential, as it is wireless, penetrates deep into biological tissues, and the mechanical vibrations can be directly converted into directional forces. Recently, active acoustic surfaces are developed that consist of 2D arrays of microcavities holding microbubbles that can be excited with an external acoustic field. At resonance, the surfaces give rise to acoustic streaming and thus provide a highly directional propulsive force. Here, this study advances these wireless surface actuators by studying their force output as the size of the bubble-array is increased. In particular, a general method is reported to dramatically improve the propulsive force, demonstrating that the surface actuators are actually able to propel centimeter-scale devices. To prove the flexibility of the functional surfaces as wireless ready-to-attach actuator, a mobile mini-robot capable of propulsion in water along multiple directions is presented. This work paves the way toward effectively exploiting acoustic surfaces as a novel wireless actuation scheme at small scales.
  • Control of defect densities at insulator/GaxIn1−xAs interfaces is essential for optimal operation of various devices like transistors and infrared detectors to suppress, for example, nonradiative recombination, Fermi-level pinning, and leakage currents. It is reported that a thin InOx interface layer is useful to limit the formation of these defects by showing effect of InOx on quantum efficiency of Ga0.45In0.55As detector and on photoluminescence of GaAs. A study of the Al2O3/GaAs interface via hard X-ray synchrotron photoelectron spectroscopy reveals chemical structure changes at the interface induced by this beneficial InOx incorporation: the InOx sheet acts as an O diffusion barrier that prevents oxidation of GaAs and concomitant As bond rupture.
  • Cobalt (II) acetate is mixed with zinc methacrylate (ZnMAA) to form a photopatternable Co-doped zinc oxide precursor. By using deep-UV (DUV) interference lithography, Co-doped ZnMAA precursor can be patterned as negative tone resist and transformed into ferromagnetic Co:ZnO films after thermal treatment. Moreover, Co:ZnO patterns as small as 300 nm line-width can be easily obtained. To have an in-depth understanding to the effect of DUV-patterning process as well as thermal annealing on Co:ZnO films derived from Co-doped ZnMAA precursor, optical, magnetic, and electrical characterizations are performed on Co:ZnO films prepared in different conditions. For the Co:ZnO film prepared without DUV-patterning, large zero-field-cooling (ZFC)–field-cooling (FC) irreversibility appears in superconducting quantum interference device measurements after vacuum annealing, indicating that Co clusters have formed inside the film. On the other hand, no ZFC–FC bifurcation can be observed for the DUV-patterned Co:ZnO film after the vacuum annealing, suggesting that the uniformity of Co ion distribution inside ZnO lattice is improved by DUV-patterning.
  • Increasing the capacity of Li-rich layered oxide (LMNC) cathode material for high-energy density lithium-ion batteries relies on the increase of charge cut-off voltage toward 5 V, under the utilization of anodically stable electrolyte component. The utilization of di-(2,2,2 trifluoroethyl)carbonate (DFDEC)-containing electrolyte permits significant improvement of anodic stability, cathode–electrolyte interface, and cycling stability of LMNC cathode, with respect to conventional electrolyte. In the present study, the limit of anodic stability of DFDEC under charging to 5.5 V versus Li is explored, and the interfacial processes of DFDEC-derived surface protection mechanism are investigated, utilizing charge cut-off voltage-dependent surface and structural analyses. The oxidative decomposition of DFDEC is found to begin at 4.7 V, producing metal fluorides and CF-containing organic compounds as the earliest surface species, passivating the cathode surface and reducing metal dissolution, structural transformation, and cathode degradation. The tolerable limit of charge cut-off voltage of a model electrolyte of 0.1 m LiPF6/DFDEC is determined to be 5.0 V, to which the cathode outperforms conventional electrolyte, delivering discharge capacities of 261–225 mAhg⁻¹ with the capacity retention of 86% at the 50th cycle. The data give an insight into the principles of electrolyte design and high-voltage cathode–electrolyte interfacial stabilization toward advanced 5 V lithium-ion batteries.
  • To improve the figure of merit (ZT) of thermoelectric (TE) materials, the decoupling of the power factor and thermal conductivity, which are mutually dependent on each other in the traditional TE materials, is desired. The chalcogenides are one of the typical TE materials. When the chalcogenide TE materials are made from nanostructures, large interface density would apparently result in a low thermal conductivity. Additionally, the power factor of the chalcogenide TE materials can also be improved by some modification of their electronic structures. The bottom-up solution-processed synthesis to prepare the nanostructured chalcogenide TE materials is versatile, simple, low-cost, and compatible with the scale-up manufacture and printed flexible electronics. In this progress report, first, the techniques used to improve the ZT of chalcogenides with nanostructures are summarized. Subsequently, the chemical strategies to enhance the ZT are summarized. Finally, the interface and microstructure engineering concepts are concluded, which are crucial to improvement of the ZT of the chalcogenide TE materials from the solution-processed nanostructures.
  • Slippery liquid infused porous surface (SLIPS) is fabricated based on the femtosecond laser induced 3D porous network microstructures by Feng Chen, Qing Yang, and co-workers in article number 1700552. The preparation process of SLIPS mainly includes three steps: femtosecond laser ablation, fluoroalkyl layer modification, and infusion of lubricating liquid. A broad range of liquids could easily slide down the 10° tilted SLIPS, revealing that the resultant SLIPS had excellent liquid-repellent ability.
  • In the field of photovoltaic industry, organolead halide perovskite solar cells (PSCs) as cleaner and cheaper photo-voltaic devices have shown a bright prospect with power conversion efficiency (PCE) rapidly climbing from 3.8% to certified 22.1% in a few years. Interface engineering has been proven to be highly effective to solve the instability-to-moisture issue and enhance the performance of PSCs. Here, this work develops a simple and easy-proceeding strategy that depositing both aminocaproic acid [H2NCH2(CH2)4COOH, abbreviated as AmCA] and caproic acid [CH3(CH2)4COOH, CA] at the mesoporous TiO2/perovskite interface leads to significant enhancement in both the efficiency and stability of PSCs. These two organic modifiers work synergistically to enhance the overall performance of PSCs by promoting electron transfer through the interaction between amino groups on AmCA and perovskite layer, and resisting moisture with alkyl chains from CA. The champion efficiency of modified cells reaches 18.2%, with an average PCE of 17.5% in reliable reproducibility, with significant improvement in stability under 50 ± 5% relative humidity in air. The developed simple interfacial modification approach should be effective to enhance both efficiency and stability of PSCs with other architectures as well. More importantly, this scenario may provide insight into the commercialization of perovskite solar cells in the not-too-distant future.
  • In article number 1700540, Peng Wang and co-workers report that bismuth vanadate (BiVO4), when assisted by nickel cobalt oxides (NiCoO2), shows vastly improved photo(electro)catalysis (PEC) oxygen evolution reaction (OER) performance. The role of NiCoO2 is two folds: OER cocatalyst and band structure adjustment. The dual-role on single-component NiCoO2 improves surface reaction kinetics for PEC OER and enhances charge separation on the surface BiVO4 simultaneously, which is the determining factor for the unprecedented performance.

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