Molecular semiconductors synergize a variety of uniquely advantageous properties such as excellent absorption and emission properties, soft and deformable mechanical properties, and mixed ionic and electrical conduction. Over the past two decades, this outstanding set of features has put molecular semiconductors in the spotlight for a variety of optoelectronics and sensing applications. When it comes to mass-market adaptation, however, a challenge in these soft and van der Waals-bonded materials remains their electrical as well as environmental stability and degradation. This Prospective will summarize some of our current understanding of why organic semiconductors degrade with a strong emphasis put on the quintessential role played by water in this process. Furthermore, it will be revisited by which mechanisms water-related stability shortcomings might be addressed in the future and how these lessons can be translated to relevant hybrid systems such as perovskites and carbon nanotubes. Throughout this discussion, some parallels and key differences between organic and hybrid materials will be highlighted, and it will be elaborated on how this affects the associated device stability.

Several methods for determination of elastic–plastic parameters by instrumented spherical indentation tests have been presented in the past few years. Each method was established according to a specific constitutive model. Identification of the constitutive models of new materials has become an indispensable step in order to choose an appropriate indentation method to extract the elastic–plastic parameters. In the present work, the half depth energy accumulation rate and Meyer's index were related to the elastic–plastic constitutive models via qualitative and numerical analyses. A method for identification of the elastic–plastic constitutive models by instrumented spherical indentation test was proposed.

Thorium dioxide (thoria, ThO2) is used in refractory applications and as nuclear fuel. Its melting temperature, the highest of any binary oxide, makes it a difficult system to process. Here we report on the effects of flash sintering on the densification of thoria. We found 95% of theoretical density is obtained at ~950 °C (~30% of the melting temperature) with an electric field of 800 V/cm. Variation in power density had a minimal effect on the densification. Scanning electron microscopy images show the effects of flash sintering on grain size as a function of electric field.

We have used phase-separated poly(3-hexyltiophene) (P3HT)/poly(L-lactic acid) (PLLA) blends to fabricate low-voltage ion-modulated transistors on a rough paper substrate. The semiconductor and insulator are mixed together in a solution and spin casted onto the paper substrate. Owing to their different solubilities and surface energies the P3HT and PLLA will phase separate vertically during the spinning process creating a thin layer of semiconductor on top of the insulator. This thin semiconductor layer, difficult to achieve by other means on an absorbing paper substrate, creates faster ion-modulated transistors. Using this approach we have created ring-oscillators on paper oscillating at 5 Hz.

We report on the structural evolution of diamond-like carbon (DLC) films by the nanosecond pulsed laser annealing process. DLC film is coated on cemented carbide (WC-Co) by cathodic arc ion plating, which is then annealed by ArF laser (193 nm, 20 ns) at different laser fluences (0.9–1.7 J/cm2). Upon laser annealing, Raman spectra divulge higher sp3 fractions accompanied by a blue shift in the G-peak position, which indicates the changes of sp2 sites from rings to chains. At higher fluence (>1.2 J/cm2), the film converts into reduced graphene oxide confirmed by its Raman-active vibrational modes: D, G, and 2D.

To systematically investigate the influence of electrolyte substrates on Sr-segregation and SrSO4 formation in (LaSr)(CoFe)O3 (LSCF) cathodes in solid oxide fuel cells, model thin films were grown on Gd-doped ceria (GDC) and on Y-doped BaZrO3 (BZY) electrolytes by pulsed laser deposition and heat treated at 800–1000 °C in synthetic air with a trace amount of SO2. A severe SrSO4 formation was observed in LSCF on GDC as compared with the BZY, especially at low temperature. The difference in Sr-segregation and SrSO4 formation on the LSCF was discussed in relation to Sr diffusion and related elemental redistribution across the interfaces.

Compression loading on CrN/Cu/Si(100) micropillars containing 45°-inclined interfaces yielded unequivocal evidence of shear plastic flow within Cu thin films confined between non-deforming Si and CrN. Confined shear plastic flow occurred over Cu thicknesses between ~100 and 1200 nm, with a monotonically increasing flow stress as the thickness decreases. The demonstration of a significant dependence of the shear flow stress on the confined Cu film thickness offers a new example of scale-dependent plasticity, and a new experimental test case for non-local plasticity theories.

Rare earth Pr-doped cadmium oxide (CdO) powders with various Pr contents (0–2.0 at.%) were synthesized by a coprecipitation process and characterized by x-ray diffraction, field emission scanning electron microscopy, and UV-vis spectrophotometry. The experimental results indicate that Pr doping led to a decrease of average particle size and change of optical property. The CdO powder with Pr content 0.5 at.% show a maximum Eg decrease of about 3.6% and an absorbance increase of about 8.26%. This variation is explained by the available band gap narrowing models and variations in lattice parameter and density with Pr content.

The novel Three-dimensional rambutan-like NiCo2O4 microspheres have been successfully coated onto surface of carbon nanofibers (CNFs) to form NiCo2O4–CNFs hybrids. The composition and microstructure of NiCo2O4–CNFs were characterized by the field-emission scanning electronmicroscopy, x-ray photoelectron spectroscopy, transmission electron microscopy, and x-ray diffractometer. The obtained NiCo2O4–CNFs exhibited a specific capacity of 160 mAh/g at 1 mA/cm2 in 2 M potassium hydroxide aqueous solution. The specific capacity gradually increases with the increasing of cycles; and after 3000 cycles, the specific capacity still can be remained over 90%.

We analyzed the contact mechanisms of bioinspired microfibrillar adhesives using in situ scanning electron microscopy. During adhesion tests we observed that (i) the superior adhesion of mushroom-shaped fibrils is assisted by the stochastic nature of detachment, (ii) the aspect ratio of microfibrils influences the bending/buckling behavior and the contact reformation, and (iii) the backing layer deformation causes the microfibrils to elastically interact with each other. These studies give new insights into the mechanisms responsible for adhesion of bioinspired fibrillar adhesives.

In this topical review of two-photon stereolithography (TPS), we discuss novel materials and demonstrate applications of this technology. Two-photon-initiated chemical processes are used to fabricate arbitrary three-dimensional structures in TPS. In the first part of this article, the development of novel photoactive materials to fabricate pure inorganic or organic–inorganic hybrid microstructures is discussed. The second part discusses the fabrication of functional microstructures for highly specific applications to demonstrate the importance of TPS in different fields of science.

Biofilms can damage implants and are difficult to treat. Here, we assessed the performance of a tripeptide that self-assembles into an antifouling coating over a broad range of shear conditions that are relevant to biomedical applications. Adhesion assays were performed using a parallel plate flow chamber. The results show that the coating can reduce Escherichia coli adhesion up to 70% when compared with glass. At a shear rate of 15/s, typical for urinary catheters, the coating reduced the adhesion by more than 50%. These findings suggest critical features that should be considered when developing surfaces for biomedical purposes.

High-performance electrochemical hydrogen peroxide (H2O2) sensors based on PdAg nanoparticle-decorated reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNT) hybrids were developed. The nanostructures were characterized using transmission electron microscopy, scanning electron microscopy, energy-dispersive spectroscopy, thermogravimetric analysis, Fourier transform spectroscopy, and x-ray diffraction techniques. It was found that introduction of MWCNT in the catalyst layer improved the sensitivity and widened the linear range. Sensitivities of 393.2, 437.1, and 576.6 µA/mM/cm2 were obtained for PdAg/rGO–MWCNT (2:1), PdAg/rGO–MWCNT (1:1), and PdAg/rGO–MWCNT (1:2), respectively. Furthermore, hierarchical structure of rGO–MWCNT nanohybrids enabled the detection of H2O2 up to 80 mM.

Ag deposition-based multicolor electrochromic (EC) device we reported can switch various optical states among transparent, black, silver, cyan, magenta, and yellow by only using electrochemical deposition of Ag. However, the EC device had poor color retention property under open-circuit state because of dissolution of deposited Ag metal by Cu2+ ions, which is essential because it acts as redox material at counter electrode. Here, we introduced an anion exchange membrane to separate Cu2+ from the Ag deposit. The improved device achieved longer retention time of colored state. It is effective to maintain the coloring state without electric power for practical application.

In this study, we have developed a facile and simple route for preparation of ultrafine CoO/reduced graphene oxide (rGO) nanohybrids with tunable particle size and crystallinity for lithium-ion battery (LIB) application. At the optimized calcination time of 60 min, the homogeneous and ultrafine CoO nanoparticles with mean size of 4.5 nm can be intimately attached onto rGO surface to rapidly transport Li ions and electrons. The CoO/rGO exhibits excellent rate capability and high specific capacity of 520 mAh/g at 2400 mA/g. In addition, the capacity can be recovered to 900 mAh/g at 150 mA/g after 60 cycles, indicating the superior electrochemical performance of CoO/rGO for LIB applications.

Synthetic biology combines engineering and biology to produce artificial systems with programmable features. Specifically, engineered microenvironments have advanced immensely over the past few decades, owing in part to the merging of materials with biologic mimetic structures. In this review, the authors adapt a traditional definition of community ecology to describe “cellular ecology,” or the study of the distribution of cell populations and interactions within their microenvironment. The authors discuss two exemplar hydrogel platforms: (1) self-assembling peptide hydrogels and (2) poly(ethylene) glycol hydrogels and describe future opportunities for merging smart material design and synthetic biology within the scope of multicellular platforms.

We report a new pulsed chemical vapor deposition (PCVD) process to deposit nickel (Ni) and nickel carbide (Ni3C x ) thin films, using bis(1,4-di-tert-butyl-1,3-diazabutadienyl)nickel(II) precursor and either H2 gas or H2 plasma as the coreactant, at a temperature from 140 to 250 °C. All the PCVD films are fairly pure with low levels of N and O impurities. The films deposited with H2 gas at ≤200 °C are faced centered cubic-phase Ni metal films with low C content; but at ≥220 °C, another phase of rhombohedral Ni3C is formed and the C content increases. However, when H2 plasma is used, the films are always in rhombohedral Ni3C phase for the entire temperature range.

Gold nanoparticles (GNPs) of ~8 nm in diameter were used for the detection of organochlorine endosulfan pesticide (ESP) as colorimetric sensor and the design of GNP-based chemical sensor for its quantitative estimation has also been proposed. The original wine red color of GNPs changes into various shades of blue after the addition of different concentrations of ESP solutions. A GNP-based sensing electrode has been used for designing of ESP detection chemical sensor at ambient temperature. The response and sensitivity of ESP sensor parameters are obtained from their recovery curves of the change in resistance versus time.

We present for the first time the feasibility to recover the stiffness (here shear modulus) distribution of a three-dimensional heterogeneous sample using measured surface displacements and inverse algorithms without making any assumptions about local homogeneities and the stiffness distribution. We simulate experiments to create measured displacements and augment them with noise, significantly higher than anticipated measurement noise. We also test two-dimensional problems in plane strain with multiple stiff inclusions. Our inverse strategy recovers the shear modulus values in the inclusions and background well, and reveals the shape of the inclusion clearly.

When the Cassie–Baxter and Wenzel states coexist for a liquid droplet on a micropatterned surface, the Cassie-to-Wenzel transition takes place if the energy barrier is overcome. Although multiple metastable states coexist due to the micropattern, this paper presents a simple Cassie-to-Wenzel transition of a 2 µL water droplet on a particular micropillared surface: When the droplet is gently deposited above the surface, it equalizes to the Cassie state at zero gravity; however, it transitions to the Wenzel state at the terrestrial gravity, in which the gravitational potential energy overcomes the energy barrier between the Cassie and Wenzel states.