In recent years, there has been rapid development in the field of nanoscale light trapping for solar cells. This has been driven by the decrease in thickness of solar cells in order to reduce materials costs, as well as advances in fabrication technology and computer power for simulating nanoscale structures. Nanoscale light trapping offers the possibility of enhancing absorption beyond the limits achievable with geometrical optics for certain structures. It also allows the optical design to be separated from the electrical design, as for example in plasmonic solar cells. Most importantly, thin-film cell designs will need to incorporate nanophotonic light trapping in order to reach their ultimate efficiency limits. In this article, we review the major types of nanophotonic light trapping, including plasmonic, diffraction gratings, and random scattering surfaces and describe the major advantages and disadvantages of each. In addition, we describe the most important related fabrication and characterization technologies and provide an outlook on future directions in this field.

A number of applications such as displays, touch sensors, and ultrathin heating elements contain flexible and optically transparent plastic films covered with highly electrically conductive coatings. In most cases, indium tin oxide (ITO) is used as the conductive material for these coatings due to its additional property of being transparent to visible light. Once deposited onto the foil, ITO has to be patterned before use, which is generally a tricky, time-consuming, and costly process. A newly developed economical roll-to-roll printing process utilizing metallic grids now offers a direct print alternative with better functional characteristics.

We present a brief review of the phase diagrams of the transition metal, electron-doped BaFe2As2 systems and a comparison between them. This article also reviews the phase diagrams of hole- and isoelectronic-doped BaFe2As2, as well as BaFe2As2 under pressure. Empirical rules on the conditions necessary to induce superconductivity in this material are outlined. Evidence for multiple Lifshitz transitions in Co-doped BaFe2As2 and possible connections to superconductivity are also discussed.

This article summarizes current applications and the future potential of highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT). The main focus of the article is a water dispersed complex of PEDOT with poly(styrenesulfonic acid) (PSS) as the counter-ion. The availability of PEDOT:PSS as an ink allows many facile ways of solution processing. The basic chemical and physical properties of the PEDOT:PSS complex are discussed to show the fundamentals that allow for the use of PEDOT in transparent conductive applications. Due to the increase in conductivity and transparency of the PEDOT:PSS complex in recent years, this versatile material now has reached the requirements for current devices such as displays, touch screens, and solar cells, and offers an alternative to inorganic transparent conductive oxides. Further advantages of this polymer are the ductility, use in low-cost production processes such as printing, safe handling, and availability on a large scale.

This article gives a brief comparative overview of the upper critical fields Hc2(T)—the magnetic fields above which superconductivity disappears—of MgB2- and Fe-based superconductors. We discuss manifestations of multiband superconductivity, Pauli pair-breaking, and pairing symmetry in the shapes of Hc2(T) curves, and the ways of tuning Hc2(T) by doping and by impurity scattering. We show that the effective route to high Hc2 is by disordering in MgB2 and by doping-assisted tuning of the Fermi surface in Fe-based superconductors. These effects allow extremely high Hc2 values in both material classes that well exceed those found in Nb-based superconductors, opening up new opportunities for high-field applications.

Future energy production and storage in the chemical and refinery industries, stationary power generation, and transportation sectors will employ a diverse suite of technologies, including renewables, such as biomass, untapped energy resources, and processes with improved energy efficiency. Heterogeneous nanocatalysts will play an ever-increasing role in these technologies. Increased precision in molecular architecture over multiple length scales and/or tailored multi-functionality will often be needed in these materials. Advances in computational-based discovery of such nanomaterials are described through examples that predict the molecular architecture of emergent catalytic materials and reveal mechanisms of colloidal metal nanoparticle growth.

Bacterial biofilms are interface-associated colonies of bacteria embedded in an extracellular matrix that is composed primarily of polymers and proteins. They can be viewed in the context of soft matter physics: the rigid bacteria are analogous to colloids, and the extracellular matrix is a cross-linked polymer gel. This perspective is beneficial for understanding the structure, mechanics, and dynamics of the biofilm. Bacteria regulate the water content of the biofilm by controlling the composition of the extracellular matrix, and thereby controlling the mechanical properties. The mechanics of well-defined soft materials can provide insight into the mechanics of biofilms and, in particular, the viscoelasticity. Furthermore, spatial heterogeneities in gene expression create heterogeneities in polymer and surfactant production. The resulting concentration gradients generate forces within the biofilm that are relevant for biofilm spreading and survival.

In recent years, biomaterial investigators have increasingly focused their research on hydrogels and their capability to be fabricated into tissue engineering scaffolds. Although several fabrication methods have been used to produce hydrogel scaffolds, those methods are unable to routinely produce three-dimensional submicron and nanoscale scaffolds with precise control of the geometry, a crucial factor necessitated by the recent developments in the field of tissue engineering. Femtosecond laser-induced two-photon polymerization is a promising technique that fulfills these requirements. In our work, we used a femtosecond laser to fabricate three-dimensional submicron-scale scaffolds with poly(ethylene glycol) (PEG). The modulus, dimensions, and shape of the scaffold can be readily adjusted by changing both the laser parameters and the molecular weight of the PEG prepolymer. With the femtosecond laser, we also fabricated two-dimensional topographical patterns, which have important applications in basic biological research. To improve the throughput of femtosecond laser fabrication, we integrated the femtosecond direct-write process with a nano-imprint process by which the femtosecond laser is used to produce nano-patterned molds. We then carried out nanoimprinting to transfer the nanofeatures in the mold to the hydrogel in a massively parallel fashion.