Recent STM molecular break-junction experiments have revealed multiple series of peaks in the conductance histograms of alkanedithiols. To resolve a current controversy, we present here an in-depth study of charge transport properties of Au|alkanedithiol|Au junctions. Conductance histograms extracted from our STM measurements unambiguously confirm features showing more than one set of junction configurations. On the basis of quantum chemistry calculations, we propose that certain combinations of different sulfur-gold couplings and trans/gauche conformations act as the driving agents. The present study may have implications for experimental methodology: whenever conductances of different junction conformations are not statistically independent, the conductance histogram technique can exhibit a single series only, even though a much larger abundance of microscopic realizations exists.

Single-layer transition-metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, spintronics, catalysis, and so on. Here, we demonstrate the epitaxial growth of high-quality single-crystal, monolayer platinum diselenide (PtSe2), a new member of the layered TMDs family, by a single step of direct selenization of a Pt(111) substrate. A combination of atomic-resolution experimental characterizations and first-principle theoretic calculations reveals the atomic structure of the monolayer PtSe2/Pt(111). Angle-resolved photoemission spectroscopy measurements confirm for the first time the semiconducting electronic structure of monolayer PtSe2 (in contrast to its semimetallic bulk counterpart). The photocatalytic activity of monolayer PtSe2 film is evaluated by a methylene-blue photodegradation experiment, demonstrating its practical application as a promising photocatalyst. Moreover, circular polarization calculations predict that monolayer PtSe2 has also potential applications in valleytronics.

Perylene imides have been an object of research for 100 years and their derivatives are key n-type semiconductors in the field of organic electronics. While perylene diimides have been applied in many electronic and photonic devices, their use can be traced back to the first efficient organic solar cell. By functionalizing different positions of the in total 12 positions (four peri, four bay, and four ortho-positions) on the perylene core, perylene imides with significantly different optical, electronic and morphological properties may be prepared. Perylene imides and their derivatives have been used in several types of organic photovoltaics, including flat-, and bulk-heterojunction devices as well as dye-sensitized solar cells. Additionally perylene imides-based copolymers or oligomers play an important role in single junction devices. In this review, the relationship between the photovoltaic performance and the structure of perylene imides is discussed.

A novel approach to functionalize graphene with large aromatic donor and acceptor molecules consisting of nanographene units is presented, producing an unprecedented class of graphene and nanographene composites with tunable electronic properties. The stability of aqueous dispersion of graphene sheets is greatly enhanced, and a large number of monolayer and double‐layer graphene sheets could be facilely fabricated on the substrates

The desert-dwelling sandfish (Scincus scincus) moves within dry sand, a material that displays solid and fluidlike behavior. High-speed x-ray imaging shows that below the surface, the lizard no longer uses limbs for propulsion but generates thrust to overcome drag by propagating an undulatory traveling wave down the body. Although viscous hydrodynamics can predict swimming speed in fluids such as water, an equivalent theory for granular drag is not available. To predict sandfish swimming speed, we developed an empirical model by measuring granular drag force on a small cylinder oriented at different angles relative to the displacement direction and summing these forces over the animal movement profile. The agreement between model and experiment implies that the noninertial swimming occurs in a frictional fluid.