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In this study, intermolecular interactions were investigated for increasing the charge carrier mobility of organic field-effect transistors (OFETs) based on a conjugated polymer. A diketopyrrolopyrrole (DPP)-based conjugated polymer widely used in OFETs, i.e., poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)] (PDPP-DTT), was assembled using 2-bromobenzaldehyde (2-BBA) and used as an active layer for OFETs. Morphological characterization and analysis for non-covalent intermolecular interactions suggested that the halogen bonding between the bromide of 2-BBA and electron-donor group of PDPP-DTT and the association between the electron-acceptor group in 2-BBA and sulfur of PDPP-DTT improved the hole transfer in the PDPP-DTT-based OFETs. The intermolecular interactions resulting from the addition of 2-BBA contributed to the two-fold enhancement of the hole mobility, two-order increase in magnitude of the current on/off ratio, and 50% decrease in the threshold voltage of the OFETs based on PDPP-DPP.

Colorimetric chemosensors are widely employed for in-field analysis to detect transition metal ions in real-time with the naked eye. Colorimetric chemosensors have attracted considerable attention because they can conveniently provide quantitative and qualitative information at a low cost. However, the development of colorimetric chemosensors for multiple-ion sensing where metal cations coexist has been limited. For this reason, we developed a new type of transition metal ion sensing material by selectively replacing functional groups on (diphosphine)Pt(dmit) molecules. The terminal groups of the diphosphine ligand were successfully substituted by the cyclohexyl groups, increasing the electron density of the thione moiety. Due to the electron donation ability of the cyclohexyl terminal groups, the proposed chemosensing material was able to selectively detect the mixture of Hg2+, Cu2+, and Ag+ in the presence of many types of interfering cations. To gain insight into the binding mechanisms between the metal ions and the developed (dchpe)Pt(dmit) molecule, density functional theory calculations were also performed.

The spread of wearable and flexible electronics devices has been accelerating in recent years for a wide range of applications. Development of an appropriate flexible power source to operate these flexible devices is a key challenge. Supercapacitors are attractive for powering portable lightweight consumer devices due to their long cycle stability, fast charge-discharge cycle, outstanding power density, wide operating temperatures and safety. Much effort has been devoted to ensure high mechanical and electrochemical stability upon bending, folding or stretching and to develop flexible electrodes, substrates and overall geometrically-flexible structures. Supercapacitors have attracted considerable attention and shown many applications on various scales. In this review, we focus on flexible structural design under six categories: paper-like, textile-like, wire-like, origami, biomimetics based design and micro-supercapacitors. Finally, we present our perspective of flexible supercapacitors and emphasize current technical difficulties to stimulate further research.

Metal-containing porous structures have been widely used in the fields of electrochemical and acid-base catalysis, bio-filtration, and heat-dissipation. Here, we propose a method for the fabrication of robust macroporous metallic sponges using agarose gel and HAuCl4 as soft-sacrificial templates and Au precursor, respectively. We demonstrate that the preparation of self-supporting macroporous Au sponges is practicable by heating the soft-agarose framework in the range of temperatures from 200 to 500°C. Before the calcination of agarose framework, Au precursor was reduced using NaBH4. A series of data obtained from X-ray photoelectron spectroscopy and X-ray diffraction indicates that the Au sponges were well synthesized with high crystallinity. The structural properties of porous Au were methodically investigated using Rietveld refinement and density-functional-theory calculations. The use of agarose gel as a soft template for the fabrication of metallic sponges has various advantages over conventional methods, as this approach is environmentally benign, shape-controllable, inexpensive, and scalable for mass production.