Structural design considerations of solution-processable graphenes as interfacial materials via a controllable synthesis method for the achievement of highly efficient, stable, and printable planar perovskite solar cells

Development and characterization of a superabsorbing hydrogel film containing Ulmus davidiana var. Japonica root bark and pullulan for skin wound healing

Ulmus davidiana var. japonica (UD) has widely been used in Korean traditional medicine for the treatment of various types of diseases including inflammation and skin wounds. The UD root bark powders possess gelling activity with an excellent capacity for absorbing water. This distinct property could make the UD root bark powders to be a great material for manufacturing a gel film specifically for the healing of large and highly exudating wounds (e.g., pressure sores and diabetic ulcers). In this research, we separated the UD root bark powder into 4 different samples based on their sizes and then tested their water absorption capacity and flowability. Based on these results, 75-150 μm sized and below 75 μm sized samples of UD root bark powders were chosen, and UD gel films were prepared. The UD gel films showed good thermal stability and mechanically improved properties compared with pullulan only gel film with excellent swelling capacity and favorable skin adhesiveness. Further, in the animal studies with the skin wound mice model, the UD gel films exhibited significant therapeutic effects on accelerating wound closure and dermal regeneration. Overall, this study demonstrated the applicability of UD root bark powders for hydrogel wound dressing materials, and the potential of UD gel films to be superior wound dressings to currently available ones.

Solvent-free electrically conductive Ag/ethylene vinyl acetate (EVA) composites for paper-based printable electronics

Solvent-free electrically conductive composites have been applied to flexible electronics to obtain high electrical conductivity. However, some of the proposed composites have low electrical conductivities and are unable to meet the requirements of commercial printable electronics. In this study, solvent-free electrically conductive Ag/EVA (ethylene vinyl acetate) composites for paper-based printable electronics were prepared by a thermal melting method. The properties of these electrically conductive Ag/EVA composites, including particle sizes, morphologies and phase purities of the flake silver flake powders, were investigated using a particle size analyzer, scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results showed that nanometer-thick flake silver flake powders with smooth and flat surfaces were made by the nanofilm transition technique. These obtained powders were able to form smooth face-to-face contacts, which facilitated the formation of an excellent conductive network in the conductive system. Dynamic mechanical analysis (DMA) was conducted to investigate the mechanical properties of EVA and Ag/EVA composites. A Fourier transformation infra-red (FTIR) spectrometer, laser micro-Raman spectrometer and thermogravimetric analyzer were used to analyze the organic functional groups, glass transition temperatures and thermal weight losses of the EVA resin and solvent-free electrically conductive composites. The solvent-free electrically conductive Ag/EVA composite, which contained 55 wt% of the as-prepared flake silver flake powders, was found to have an extremely low volume resistivity of 1.23 × 10^-4 Ω cm as well as excellent bending performance and adhesion. These features indicate the great potential of these composites for application in printed electronics.

Acetonitrile based single step slot-die compatible perovskite ink for flexible photovoltaics

Low viscosity rapid drying perovskite formulations designed to give high quality solar films when slot-die coated on flexible roll-to-roll compatible substrates are developed .