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Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side-products. This is particularly important for bioelectronic devices, which are designed to operate in biological systems. While redox-active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side-reactions with molecular oxygen during device operation. Here, electrochemical side reactions with molecular oxygen are shown to occur during organic electrochemical transistor (OECT) operation using high-performance, state-of-the-art OECT materials. Depending on the choice of the active material, such reactions yield hydrogen peroxide (H 2 O 2 ), a reactive side-product, which may be harmful to the local biological environment and may also accelerate device degradation. A design strategy is reported for the development of redox-active organic semiconductors based on donor-acceptor copolymers that prevents the formation of H 2 O 2 during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte-gated devices in application-relevant environments., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Naphthalenediimide-based random copolymers (PNDI-TVTx) with different π-conjugated dithienylvinylene (TVT) versus π-nonconjugated dithienylethane (TET) unit ratios (x = 100→0%) are investigated. The PNDI-TVTx-transistor electron/hole mobilities are affected differently, a result rationalized by molecular orbital topologies and energies, with hole mobility vanishing but electron mobility decreasing only by ≈2.5 times when going from x = 100% to 40%., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Energetic disorder, an important parameter affecting the performance of organic photovoltaics, is significantly decreased upon the addition of processing additives in a highly efficient benzodithiophene-based copolymer blend (PBDTTT-C-T:PC71 BM). Wide-angle and small-angle X-ray scattering measurements suggest that the origin of this reduced energetic disorder is due to increased aggregation and a larger average fullerene domain size together with purer phases., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The distribution of dopant sites in doped poly(3-hexylthiophene) (P3HT) thin films is characterized using optical absorption, grazing-incidence X-ray diffraction, and conducting atomic force microscopy (c-AFM). It is shown that dopant sites can be directly observed using c-AFM and that the solution temperature dramatically impacts phase separation and conductivity in spin-cast films., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel approach to enhancing the performance of solution-processed n-type organic field-effect transistors by using trace amounts of molecular "aligners" to manipulate the assembly of "matrix" molecules in thin films is demonstrated. The device performance is one order of magnitude higher in 1wt% blended thin films than that in neat films, which correlates to an induced change of preferred orientation of the in-plane π-stacking molecules upon blending., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Encaged! Three-terminal interlocked molecular species were obtained by dynamic (2+3) assembly of a cagelike macro-bicycle around a trifurcated trispyridinium π guest. The complex is stabilized by π-π interactions and multiple [C-H⋅⋅⋅O] and [C-H⋅⋅⋅N] interactions. Uncomplexed guest molecules cocrystallize alongside the threaded complexes in the solid state, thus giving extended π-stacked columns., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ladder-type oligophenylenes (LOPP) with bridging heteroatoms are interesting systems as they offer novel electronic and photophysical properties on account of the rigid structural features, more efficient electron delocalization on the coplanar aromatic framework, and strong intermolecular interactions. LOPPs incorporating multiple phosphorous centers combine the excellent electronic properties of phospholes and rigidified conjugated framework of LOPPs, thus positioning themselves as an attractive class of organic semiconductors. To date, there still lacks an effective synthetic methodology towards LOPPs with multiple phosphorous bridges. Herein, we describe the synthesis and properties of a new class of bisphosphole-bridged ladder oligo(p-phenylene)s and the related phosphoxides. The synthesis of phospholes was achieved by a four-fold free-radical phosphanylation reaction of a tetrabromo p-terphenylene or biphenyl-thiophene. Sequential trapping of four highly reactive aryl radicals occurred effectively to give the desired phosphorous-containing ladder compound. The oxides of the phospholes are shown to be strong fluorophores that can be used as potential n-type building blocks for organic semiconducting materials., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)