This work established the feasibility of flexible solution-processed radiation sensors prepared from an organic scintillator (1-phenyl-3-mesityl-2-pyrazoline) and a biocompatible semiconducting polymer (violanthrone-79). Absorbance, steady-state, and time-resolved photoluminescence measurements demonstrated a high efficiency for the transfer of absorbed energy from the scintillator to the semiconductor. Blended nanoparticles containing both materials were fabricated in order to reduce the intermolecular distance between molecules, creating a highly efficient energy transfer pathway. Radiation-sensing devices were then constructed from the materials. These exhibited successful sensitivity for gamma radiation from a 137Cs source that was not present for the control semiconducting polymer alone.

Many materials systems comprise complex structures where multiple materials are integrated to achieve a desired performance. Often in these systems, it is a combination of both the materials and their structure that dictate performance. Here the authors layout an integrated computational–statistical–experimental methodology for hierarchical materials systems that takes a holistic design approach to both the material and structure. The authors used computational modeling of the physical system combined with statistical design of experiments to explore an activated carbon adsorption bed. The large parameter space makes experimental optimization impractical. Instead, a computational–statistical approach is coupled with physical experiments to validate the optimization results.

In this work, RF-sputtered metallic tin (Sn) film was sulfurized through di-tert-butyl-disulfide vapor at 350 °C for 150, 180, 210, and 240 min. According to the Raman spectra analysis, 210 min was sufficient to form dominantly SnS film. X-ray diffraction and X-ray photoelectron spectroscopy (XPS) studies of SnS film were evaluated. The n-type window layers CdS and high transmittance Cd(S,O) were deposited by chemical bath deposition through two different baths without and with TX-100 surfactant, respectively. XPS analysis of CdS and Cd(S,O) films was carried out. SnS solar cells formed in the superstrate solar cell device configuration. The photovoltaic performances were evaluated.

We report on a new type of polymer electrolyte fuel cell based on a hydroxide ion conductive polymer combined with a non-noble chromium–nickel (Cr–Ni) catalyst for the oxygen reduction reaction (ORR). We study variable fractions of Cr in Ni by density functional theory simulating the thermodynamic potentials characterizing the ORR. We found increased ORR catalytic activity employing the rotating disk electrode technique. The polarization curve and power densities measured for the constructed fuel cell indicate considerable performance improvement with the Cr–Ni catalyst. Thus we expect that this kind of fuel cell may open up alternative routes in fuel cell research using non-noble catalysts.

We report on the intermediate-temperature synthesis (973 K) and operation (<750 K) of Ce4.67(SiO4)3O-based thin-film oxy-apatites. The apatite thin films show the high conductivity of ~0.05–0.5 S/cm and excellent stability in reducing atmosphere (<10−17 atm), which makes promising these materials as anodes for intermediate-temperature solid oxide fuel cell (SOFC) application. The proto-type SOFCs implementing single-layer apatite and apatite/Pt bilayer anodes were fabricated and the resulting performance (e.g., peak power density of ~5 mW/cm2 at 748 K) presents notable feasibility of ZCS-based oxy-apatite anodes for thin-film SOFC devices.

Clathrates based on Si and Ge have very low lattice thermal conductivity (~1 W/m-K). This value can potentially be further reduced by alloying and nano-structuring. In this work, the thermal conductivity of Si and Ge clathrates alloy have been investigated using model based on the relaxation time approximation. By including alloy scattering, we find that the lattice thermal conductivity of Ba8Cu6Si40 is reduced by 50% from 1.64 to 0.80 W/m-K in Ba8Cu6Si40(1−x)Ge40x alloy. Further ~90% reduction of the thermal conductivity is possible for nanowire clathrate alloys. The ultra-low thermal conductivity in the nanowire will be very suitable for the thermoelectric application.

The narrow bandgap of Ag2S quantum dots was used to decorate TiO2 nanotube arrays (TiO2 NTAs) by the successive ionic layer adsorption and reaction (SILAR) method to enhance its photoelectrochemical performance. The micromorphology of the photoanode films prepared by the SILAR under different parameters (including different cycle times, capillary spot sample, and ultrasound-assisted) was systematically analyzed. The photoanode film Ag2S/TiO2 prepared by the SILAR under the ultrasound-assisted method shows Ag2S evenly distributed in TiO2 NTAs. At the same time, the corresponding photoabsorption range has been extended to the visible area, while the photocurrent density and photoconversion efficiency have been increased to ~1.8 mA/cm2 and 0.6%, respectively.

We study strain fields and deformation patterns produced by wedge indentation of metals using high-resolution imaging, image correlation and simulation. A long-standing problem associated with simulation of narrow angle wedge indentation is overcome by introducing a weak form of the symmetry boundary conditions. The simulated deformation fields show good agreement with experiment. Based on strain localization, three distinct modes of deformation largely cover the range of wedge angles. Importantly, narrow angle wedge indentation is characterized by intense strain localization at points close to the free surface and thus offers a possible new tool to probe strain gradient effects.

Polymer electrolyte membrane fuel cells (PEMFCs) provide a renewable source of energy through the redox reaction of hydrogen and oxygen gas; however, operation relies on a costly platinum catalyst layer. This study investigates how electrospun catalyst layers may be employed to increase the surface area:volume ratio for catalysis to optimize PEMFC performance. When preparing electrospinning solutions, several base polymers were evaluated in varying concentrations to optimize fiber formation, with poly(acrylic acid) found to be preferable at a 12 wt% concentration. Ultimately, PEMFCs with electrospun catalyst layers achieved a 108% increase in power output compared to those air-sprayed.

This work is based on a recent theoretical study of how the hydrostatic pressure and core/shell sizes affect the optical properties associated with the transition from the ground state to first excited state (1s–1p), of an exciton confined in spherical core/shell quantum dots (SCSQDs). We have computed under an effective mass framework, linear, third-order nonlinear, and total absorption coefficients (AC) and refractive index (RI) as functions of photon energy for different sizes of SCSQDs with varying hydrostatic pressure. Our results show that the optical absorption is deeply dependent on the incident light intensity. Both AC and RI significantly influenced by the confinement and pressure effects.

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.

We report the use of electrospray to continuously deposit thin films, including patterned films, of a block copolymer (BCP). High substrate temperatures led to vertically oriented cylindrical microdomains at the film surface independent of the solvent composition and deposition rates utilized. Conversely, low substrate temperatures resulted in morphologies that were more sensitive to these parameters, with poorly ordered films of globular structures observed at the lowest temperatures considered. The deposition pattern is defined by spatially varying the electric field at the substrate using an underlying charged grid. These results open up new possibilities for patterned deposition of BCP films with morphological control.

In this work, we present a solvothermal method to prepare bismuth (Bi)-doped CuGaS2 chalcopyrite nanocrystals ink and apply it to an all-solution-processed approach for the preparation of films with a thickness of approximately 730 nm and with enhanced optical properties and lower band gap energy than the undoped semiconductor films. The low-cost deposition method is comprised by spray deposition of the chalcogenide nanocrystals ink onto the molybdenum substrates, producing microcrystalline films with grains larger than 400 nm originated from coalescence of Bi-doped nanocrystals. Bi-doped CuGaS2 microcrystalline films are a good candidate to be applied as an absorber layer in thin-film solar cells.

In the past decades, efforts have been made to couple nanoindentation with resistive measurements in order to monitor the real-time contact area, as an alternative to the use of traditional analytical models. In this work, a novel and efficient stand-alone method is proposed to compute the contact area using resistive-nanoindentation of noble metals (bulk or thin films). This method relies on three steps: tip shape measurement, set-up calibration, application to the sample to be characterized. The procedure is applied to nanoindentation tests on a sample with film-on-elastic-substrate rheology and is successfully validated against experimental measurements of the contact area.

Supercapacitor has received intense interest due to its high-charge/discharge rate and high-power density. C/Fe2O3 layer with different C/Fe ratios were synthesized by a solution-based approach for supercapacitor application. The influence of synthesis conditions on their electrochemical performances was investigated. Cobalt was added into C/Fe2O3 and significant improved its performance. The optimal C/Fe2O3 sample gives a high specific capacitance of 85.3 F/g and the addition of Co3O4 further increase the capacitance of obtained C/Fe2O3/Co3O4 to 144.4 F/g at 5 A/g. This work demonstrates an efficient supercapacitor application of low-cost metal oxides and facile solution-based synthesis approach.

Pseudo-line tensions are used in a continuum approach to simulate contact angle hysteresis. A pair of pseudo-line tensions in the receding and advancing states, respectively, are utilized to represent contact line interactions with a substrate because of the nanoscale topological and/or chemical heterogeneity on the substrate. A water droplet sitting on a horizontal or inclined substrate, whose volume is 4–30 µL, has been studied experimentally and numerically. Our simulation model predicts consistent hysteresis at four different droplet sizes compared with experiments. Meanwhile, the critical roll-off angles captured in simulations match well with experiments.

A piezoelectric biomedical microelectromechanical system (bioMEMS) cantilever device was designed and fabricated to act as either a sensing element for muscle tissue contraction or as an actuator to apply mechanical force to cells. The sensing ability of the piezoelectric cantilevers was shown by monitoring the electrical signal generated from the piezoelectric aluminum nitride in response to the contraction of iPSC-derived cardiomyocytes cultured on the piezoelectric cantilevers. Actuation was demonstrated by applying electrical pulses to the piezoelectric cantilever and observing bending via an optical detection method. This piezoelectric cantilever device was designed to be incorporated into body-on-a-chip systems.

This paper reports the molecular organization and mechanical properties of electrospun, post-drawn polyacrylonitrile (PAN) nanofibers. Without post-drawing, the polymer chain was kinked and oriented in hexagonal crystalline structures. Immediate post-drawing in the semi-solid state disrupted the crystal structures and chain kink at maximum draw ratio. Structural re-orientation at maximum draw resulted in a 500% increase in Young's modulus and a 100% increase in ultimate tensile strength. By applying post-drawing to electrospinning it may be possible to obtain PAN fibers and PAN-derived carbon fibers with enhanced mechanical properties compared to available fabrication technologies.

Direct arylation polycondensation (DArP) is an emerging synthetic method of producing conjugated polymers in an environmentally benign and cost-effective manner. We now report the synthesis of hole-transporting conjugated polymers, namely, DPP-OMe (Mn = 7.9 kg/mol) and DPP-F (Mn = 12.6 kg/mol), under microwave-assisted DArP conditions. These two polymers and the previously synthesized 3,6-Cbz-EDOT were evaluated as hole-transporting materials in mesoscopic perovskite solar cells. 3,6-Cbz-EDOT synthesized by DArP exhibited higher hole mobility and better photovoltaic properties than that synthesized by the Stille polycondensation. Moreover, chemical dopants improved the short-circuit current density (Jsc) and fill factor.

A thermoresponsive large-area plasmonic architecture, made from randomly distributed gold nanoparticles (GNPs) located at the substrate interface of a cholesteric liquid crystal (CLC) cell, is fabricated and thoroughly characterized. A photo-thermal heating effect due to the localized plasmonic resonance (LPR) mechanism is generated by pumping the GNP array with a resonant light beam. The photo-induced heat, propagating through the CLC layer, induces a gradual phase transition from the cholesteric to isotropic phase. Both the plasmonic and photonic properties of the system as both the selective reflection properties and frequency of the LPR are modulated.