Focused electron beam-induced deposition (FEBID) is capable of producing metal-containing nanostructures with lateral resolution on the sub-nanometer scale. Practical application of this nanofabrication technique has been hindered by ligand-derived contamination from precursors developed for thermal deposition methods. Mechanistic insight into FEBID through surface science studies and gas-phase electron–molecule interactions has begun to enable the design of custom FEBID precursors. These studies have shown that precursors designed to decompose under electron irradiation can produce high-purity FEBID deposits. Herein, we highlight the progress in FEBID precursor development with several examples that incorporate this mechanism-based design approach.

Oxoammonium cation of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) was used as an oxidizing dopant of triaryl amines to efficiently and almost quantitatively generate radical cations of the amines or a hole carrier. The doped-triaryl amines yielded an amorphous and homogeneous layer without any residual oxidant or neutral TEMPO molecule through its sublimination or warming the layer. The TEMPO cation-doped spiro-OMeTAD [tetrakis(dimethoxyphenylamine)spirobifluorene] produced a high hole mobility of 2 × 10−4 cm2/Vs. The perovskite solar cell fabricated with the TEMPO cation-doped or residual dopant-free spiro-OMeTAD as the hole-transporting layer displayed a photo-conversion efficiency of 20.1% with durability.

We review progress studying unique plasmonics in topological insulators (TIs). First, we describe exfoliation and deposition synthesis approaches. TI materials have substantially improved: it is now possible to grow samples with few trivial electrons and controllable doping. We then describe the theory behind the unique behavior of the coupled, 2D Dirac plasmons. While reviewing experimental efforts, we note that Dirac plasmons have been conclusively demonstrated in TIs and they show remarkable properties including long lifetimes, large mode indices, and huge modulation depths. Finally, we describe the opportunities that are present now that high-quality materials can be obtained, including spin and nanoparticle plasmons.

The ferroelectricity in fluorite-structure oxides such as hafnia and zirconia has attracted increasing interest since 2011. They have various advantages such as Si-based complementary metal oxide semiconductor-compatibility, matured deposition techniques, a low dielectric constant and the resulting decreased depolarization field, and stronger resistance to hydrogen annealing. However, the wake-up effect, imprint, and insufficient endurance are remaining reliability issues. Therefore, this paper reviews two major aspects: the advantages of fluorite-structure ferroelectrics for memory applications are reviewed from a material's point of view, and the critical issues of wake-up effect and insufficient endurance are examined, and potential solutions are subsequently discussed.

Multiscale modeling and simulation techniques are transforming the way we can address questions concerning design, characterization, and optimization of novel materials. This transformation is enabled by advanced computational models that incorporate realistic geometries of porous media and serve as tools to predict flow and transport phenomena. Recent developments in mesoscopic and pore-scale modeling include workflows that combine experimental information and direct modeling into an integrated multiscale approach. This review surveys the progress, challenges, and future directions in predictive modeling and simulation of multiphysics phenomena in porous media.

Using kerf-free wafering technologies material losses in semiconductor manufacturing processes can be reduced drastically. By the use of externally applied stress, crystalline materials can be separated along crystal planes with clearly defined thickness. Nevertheless, during this process striations caused by the crack propagation occur. These crack growth features are river and Wallner lines. In this work, we demonstrate a process for spalling that scales favorably for large-area semiconductor substrates with a diameter up to 300 mm. To get rid of the crack growth features, a laser-conditioning process with a high numerical aperture at photon energies below the material bandgap energy, using multi-photon effects is utilized. The process affords a surface roughness Ra after spalling of <1 µm.

Bismuth vanadate (BiVO4) is regarded as a viable material for water oxidation due to various benefits such as visible light absorption, low production cost, and resistance to photocorrosion. Recently, numerous attempts have been adopted to improve the performance of BiVO4. In this work, we highlight the important strategies that have been made for improving the performance of the photoanode material, such as fabricating nanostructured electrode, controlling reacting facet, stacking with other materials, utilizing plasmonics, loading co-catalyst, and controlling the interfacial band bending with ferroelectrics. Taking advantage of the strategies, highly efficient BiVO4 photoelectrodes could be demonstrated. Finally, we discuss the perspective of BiVO4-based photoanodes.

Metal–air batteries promise higher energy densities than state-of-the-art Li-ion batteries and have, therefore, received significant research attention lately. The most distinguishing feature of this technology is that it takes advantage of reversible conversion reactions of O2 or other air components (such as N2 or CO2) at the cathode. To promote these reactions, catalysts are often needed. A large number of materials have been studied for this purpose. In the present paper, we discuss the roles played by catalysts in metal–air battery systems. In particular, we choose to focus the discussions on the Li–O2 batteries as they are most intensely studied in the literature. Within this context, catalysts are often shown effective to facilitate the oxygen (O2) reduction reactions and/or O2 evolution reactions. The overall cell performance as measured by the round-trip efficiencies and charge/discharge rates can be significantly improved by the incorporation of catalysts. However, the presence of catalysts is also found to complicate the chemical reactions as they often exhibit activities toward parasitic chemical reactions such as electrolyte and electrode decompositions. The issue is especially acute in aprotic Li–O2 batteries, where organic electrolytes and reactive O2 species are mixed. In addition to heterogeneous catalysts, we also discuss the roles played by homogeneous catalysts as redox mediators, which are effective to promote redox reactions that are critical to energy storage applications.

Regions of deformation resulting from nanoindentation testing of nanoporous gold (np-Au) are characterized by cross-sectional imaging of the ligament structure directly beneath the surface, after lift-out using focused ion beam techniques. Permanent deformation of the porous structure was not exclusively confined to the region directly in contact with the indenter but extended much deeper into the sample. Implications of these observations with respect to previous measurements of the mechanical properties of np-Au are discussed. The conclusions provide initial insight into the deformation behavior of np structures during nanoindentation, as well as a basis for extending this technique to other np metals.

Different sized graphene quantum dots (GQDs) have been synthesized by an inexpensive wet chemical method using bird charcoal as a precursor. Obtained GQDs found to have luminescence and visible light absorption. These GQDs are further coupled with titanium dioxide (TiO2) to form TiO2–GQDs nanocomposites. GQD nanostructures exhibit band gap tunability and have the potential to enhance the photoabsorption in TiO2. The hybrid combination of the nanomaterials decrease the recombination of charge carriers, increase charge carrier mobility, and improve the overall photoconversion efficiency. The composites exhibit higher photocatalytic activity and rate constants value than pure TiO2.

Rational design of bio-hybrid photovoltaic and/or optoelectronic devices requires systematic electrochemical characterizations of photosystem I (PSI), the photosynthetic membrane protein, assembled onto tailored biotic–abiotic interfaces. This work communicates our research findings on the role of PSI microenvironment alterations at organic/inorganic interfaces, via biomimetic lipid membrane confinements and plasmonic coupling with Ag nano-pyramid structures, in tuning the photoactivated charge separation and photocurrent generations from surface-assembled PSI. The observed photocurrent enhancements and the associated mechanistic insights from this study will facilitate the future design of tailored interfaces that can optimally tune the photoactivity and photostability of PSI in solid-state bioelectronics.

The goal of this study is to examine whether participation in high school research apprenticeships increases pursuit of degrees and careers in science, and to explore other apprenticeship benefits. Students who participated in a research apprenticeship were surveyed about its influence on their undergraduate, graduate, and professional decisions. A control group who attended the same high schools, had similar grade point averages, and graduated with the apprenticeship participants was also surveyed. It was found that a significantly higher fraction of the apprenticeship group majored in Science, Math, Engineering, and Technology (STEM) fields, pursued careers in STEM disciplines, and found the experience to strategically influence their job performance.

Metal–insulator–metal (MIM) resonant absorbers comprise a conducting ground plane, a thin dielectric, and thin separated metal top-surface structures. The dielectric SiO2 strongly absorbs near 9 µm wavelength and has correspondingly strong long-wave-infrared (LWIR) dispersion for the refractive index. This dispersion results in multiple absorption resonances spanning the LWIR, which can enhance broad-band sensitivity for LWIR bolometers. Similar considerations apply to silicon nitride Si3N4. TiO2 and AlN have comparatively low dispersion and give simple single LWIR resonances. These dispersion-dependent features for infrared MIM devices are demonstrated by experiment, electrodynamic simulation, and an analytic model based on standing waves.

Ternary sulfides and selenides in the distorted-perovskite structure (“chalcogenide perovskites”) are predicted by theory to be semiconductors with a band gap in the visible-to-infrared and may be useful for optical, electronic, and energy conversion technologies. Here we use computational thermodynamics to predict the pressure–temperature phase diagrams for select chalcogenide perovskites. Our calculations incorporate formation energies calculated by density functional theory, and empirical estimates of heat capacities. We highlight the windows of thermodynamic equilibrium between solid chalcogenide perovskites and the vapor phase at high temperature and very low pressure. These results can guide the adsorption-limited growth of ternary chalcogenides by molecular beam epitaxy.

Porphyrins are photosensitisers used in photodynamic therapy (PDT) due to their tumor localization and in situ singlet oxygen generation. However, their limited absorption, insolubility, and aggregation in an aqueous medium limited their effective application in PDT. To overcome these limitations, we herein, report a large-scale aqueous synthesis of CuInS2/ZnS ternary quantum dots, and its conjugation to 5, 10, 15, 20-meso(4-hydroxyphenyl) porphyrin. The singlet oxygen generation of this highly aqueous soluble novel conjugate shows its potential for PDT applications.

This study presents in situ detection of Zn2+ using a novel two-step square-wave anodic stripping voltammetry (SWASV)-based needle-type microsensor for citrus plant applications. A double-barrel bismuth/platinum (Bi/Pt) microelectrode was fabricated with a solid metal tip (~110 µm), which was durable enough to penetrate the thick skin of the citrus leaves and sensitive enough to detect ppb changes in Zn2+ concentration using SWASV. The microelectrode tip size was also determined to reduce mass transport limitation and improve limit of detection. Overall, the developed Bi/Pt microelectrode successfully measured Zn2+ concentrations within the vascular bundle of citrus plants.

A great challenge in the field of neurocomputing is to mimic the brain behavior by implementing artificial synapses and neurons directly in hardware. This work shows that a Leaky Integrate and Fire (LIF) artificial neuron can be realized with a two-terminal device made of Mott insulator thin films. Polycrystalline thin films of the well-known Mott insulator oxide (V0.95Cr0.05)2O3 were deposited by magnetron sputtering and patterned with micron-scale TiN electrodes. These devices exhibit a volatile resistive switching and a remarkable LIF behavior under a train of pulses suggesting that LIF artificial neurons may be realized from (V0.95Cr0.05)2O3 thin films.