Although stretchable polymer-based devices with promising electrical performance have been produced through the polymer blend strategy, the interplay between the blend film microstructure and macroscopic device performance under deformation has yet to be unambiguously articulated. Here, we discuss the formation of robust semiconducting networks in blended films through a thermodynamic perspective. Thermodynamic behavior along with the linear absorption and photoluminescence measurements predict the competition between polymer phase separation and semiconductor crystallization processes during film formation. Semiconducting films comprised of different pi-conjugated semiconductors were prepared and shown to have mechanical and electronic properties similar to those of films comprised of a model P3HT and PDMS blend. These results suggest that a film’s microstructure and therefore robustness can be refined by controlling the phase separation and crystallization behavior during film solidification. Fine-tuning a film’s electrical, mechanical, and optical properties during fabrication will allow for advanced next-generation of optoelectronic devices.

The development of semiconducting conjugated polymers for organic field effect transistors (OFETs) has been the focus of intense research efforts for their key role in plastic electronics as well as a vision of solution processability leading to reduced costs in device fabrication relative to those of their inorganic counterparts. The pursuit of high-performance n-channel (electron-transporting) polymer semiconductors vital to the development of robust and low-cost organic integrated circuits has faced significant challenges, mainly for poor ambient operational stability and OFET device performance lagging far behind that of pchannel organic semiconductors. As an alternative to the ubiquitous donor−acceptor molecular design strategy, an all-acceptor (A−A) unipolar approach was implemented in the design of poly(2-(2decyltetradecyl)-6-(5-(5′-methyl[2,2′-bithiaol]-5-yl)-3-(5-methylpyridin-2-yl)-5-(tricosan-11-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (PDBPyBTz). The n-channel copolymer allowed investigation of the impact of electron-withdrawing moieties on conjugated polymer device performance and the utility of the A−A molecular design strategy. As an analogue to benzene, the pyridines flanking the diketopyrrolopyrrole moiety in PDBPyBTz were strategically chosen to lower the energy levels and impart planarity to the monomer, both of which aid in achieving stable n-channel performance. Incorporation of PDBPyBTz into a bottom-gate/bottom-contact OFET afforded a device that exhibited unipolar electron transport. In addition to developing a high-performance n-channel polymer, this study allowed for an investigation of structure−property relationships crucial to the design of such materials in high demand for sustainable technologies, including organic photovoltaics and other solution-processed organic electronic devices.

Conjugated monomers and polymers containing 2,2′-bithiazole (BTz) and naphthalene diimide (NDI) units in the main chain were prepared. Polymer PNDI2Tz was obtained via palladium-catalyzed Stille polycondensation of a dibromo-substituted NDI derivative with distannyl-2,2′-bithiazole. The optical and electronic properties were investigated using UV–vis absorption spectroscopy and ultraviolet photoelectron spectroscopy. It was found that the polymers show very broad absorption bands in the 540 nm region, and PNDI2Tz has an optical bandgap of 1.87 eV. Computational analysis demonstrates that holes and electrons are mainly localized on the 2,2′-bithiazole and NDI units, respectively. Organic field-effect transistors (OFETs) fabricated with PNDI2Tz exhibit unipolar n-channel characteristics with mobility as high as 0.05 cm2 V–1 s–1.

Battery electrodes are complex mesoscale systems comprising an active material, conductive agent, current collector, and polymeric binder. Although significant research on composite electrode materials for Li-ion batteries focuses on the design, synthesis, and characterization of the active particles, the binder component has been shown to critically impact stability and ensure electrode integrity during volume changes induced upon cycling. Herein, we explore the ability of water-soluble, carboxylated conjugated polymer binders to aid in electron and ion transport in magnetite-based anodes. Specifically, poly[3-(potassium-4-butanoate)thiophene] (PPBT) and a potassium carboxylate functionalized 3,4-propylenedioxythiophene (Pro-DOT)-based copolymer (WS-PE 2 ) were investigated and evaluated against the control, potassium salt form of poly(acrylic acid) (PAA-K). When used in conjunction with a polyethylene glycol (PEG) surface coating for the magnetite active material, PPBT provided for overall improved electrode performance as a result of more favorable intermolecular interactions between the composite constituents. The ProDOT-based copolymer WS-PE 2 exhibited comparable cycling performance to PPBT, whereas PAA-K and PPBT were similar with respect to rate capability. This investigation compares and contrasts a series of carboxylated polymers to elucidate the roles of different functional groups and identify materials chemistry-based structural parameters that can be manipulated to assist overall electrochemical performance of composite Li-ion battery anodes.

Melting and resolidification of a mixture of two metal powders with significantly different melting points under irradiation of a stationary or a moving Gaussian laser beam were investigated numerically and experimentally. The liquid motion driven by capillary and gravity forces as well as the shrinkage of the powder bed caused by the overall density change were taken into account in the physical model. The liquid flow was formulated by using Darcy’s law, and the energy equation was given using a temperature transforming model. Prediction were compared with experimental results obtained with nickel braze and AISI 1018 steel powder. The effects of laser properties and the scanning velocity on the laser sintering process were also investigated. An empirical correlation that can be used to predict the cross-sectional area of the heat affected zone is proposed. [S0022-1481(00)70201-5]