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Efficiency, current throughput, and speed of electronic devices are to a great extent dictated by charge carrier mobility. The classic approach to impart high carrier mobility to polymeric semiconductors has often relied on the assumption that extensive order and crystallinity are needed. Recently, however, this assumption has been challenged, because high mobility has been reported for semiconducting polymers that exhibit a surprisingly low degree of order. Here, we show that semiconducting polymers can be confined into weakly ordered fibers within an inert polymer matrix without affecting their charge transport properties. In these conditions, the semiconducting polymer chains are inhibited from attaining long-range order in the p-stacking or alkyl-stacking directions, as demonstrated from the absence of significant X-ray diffraction intensity corresponding to these crystallographic directions, yet still remain extended along the backbone direction and aggregate on a local length scale. As a result, the polymer films maintain high mobility even at very low concentrations. Our findings provide a simple picture that clarifies the role of local order and connectivity of domains. [ABSTRACT FROM AUTHOR]

Regioregular poly(3-hexylthiophene) has been successfully incorporated into various poly( N, N-dimethylamino-2-ethyl methacrylate)-based block copolymers, i.e., P3HT- b-PDMAEMA, via Grignard metathesis (GRIM) method and atom transfer radical polymerization (ATRP) reactions. The structure of the diblock copolymers was fully confirmed by FT-IR, H NMR spectroscopy, gel permeation chromatography (GPC), and ultraviolet-visible spectroscopy (UV-vis). The recovered copolymers could be treated by protonation of the pending tertiary amine functions and depending on the relative content in PDMAEMA, the copolymers could be solubilized in more polar solvents where P3HT alone proved to be totally insoluble. [ABSTRACT FROM AUTHOR]

Abstract: Organic semiconductor blends are commonly used in organic based (opto-) electronic devices. They are composed of two types of (macro-) molecules, referred to as the guest and host. To achieve optimum device operation, the chemical nature, electronic structure, molecular order and the relative concentration of the guests and host are crucial. Here, we present simulation results of the current density versus the voltage (J–V) behavior of a two terminal device based on a variable-range hopping model in which the electronic states of the guest and host are represented by two Gaussian distributions. The J–V behavior is investigated for various energetic mismatches between guest and host states, widths of the distribution as well as the guest concentrations. Finally, a simple tool enabling easy prediction of the J–V behavior of organic host–guest diodes is derived. [Copyright &y& Elsevier]

The oxygen reduction reaction (ORR) is an essential process in electrocatalysis limiting the commercialization of sustainable energy conversion technologies, such as fuel cells. The use of conducting polymers as molecular porous and conducting catalysts obtained from the high abundance elements enables the route towards low cost and high-throughput fabrication of disposable plastic electrodes of fuel cells. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a 2-electron ORR electrocatalyst yielding specifically hydrogen peroxide that limits the full utilization of chemical energy of oxygen. Here, we demonstrated an innovative product-to-intermediate relay approach achieving complete oxygen reduction reaction (cORR) with Prussian blue (PB) integrated microporous PEDOT cathode in fuel cells. The microporous structured PEDOT electrode prepared via a simple cryosynthesis allows the bulk integration and stabilization of the poor conducting PB co-catalyst into the PEDOT ion-electron conductor, while the microporous PEDOT allows effective oxygen diffusion into the matrix. We evaluated systematically the effect of sequential PEDOT 2-electron ORR followed by PB co-catalysis launching hydrogen peroxide reduction reaction (HPRR) into H 2 O. This resulted in the establishment of electronic and ionic transport between PEDOT and PB catalyst enabling the combination of enhanced ORR electrocatalysis by means of the ORR course extension from 2- to 4-electron reduction to achieve cORR. The cORR performance delivered by the product-to-intermediate relay between microporous PEDOT and PB co-catalysis led to a four times increase in power density of model proton-exchange membrane fuel cell (PEMFC) assembled from the polymer-based air-breathing cathode. Image 1 • The inorganic redox material was integrated into the bulk of conducting polymer. • The conducting polymer enables both electronic and ionic transports to immobilized inorganic semiconductor. • The conducting polymer contributes with intrinsic 2-electron oxygen reduction reaction yielding convertible product. • We achieved the multistep electrochemical conversion of oxygen to water on conducting polymer. • We developed one of the first polymer-based air cathode for proton-exchange membrane fuel cell. [ABSTRACT FROM AUTHOR]

Heat sensors form an important class of devices that are used across multiple fields and sectors. For applications such as electronic skin and health monitoring, it is particularly advantageous if the output electronic signals are not only high, stable, and reproducible, but also self-generated to minimize power consumption. Here, we present an ultrasensitive heat sensing concept that fulfills these criteria while also being compatible with scalable low-cost manufacturing on flexible substrates. The concept resembles a traditional thermocouple, but with separated electrodes bridged by a gel-like electrolyte and with orders of magnitudes higher signals (around 11 mV K−1). The sensor pixels provide stable and reproducible signals upon heating, which, for example, could be used for heat mapping. Further modification to plasmonic nanohole metasurface electrodes made the sensors capable of also detecting light-induced heating. Finally, we present devices on flexible substrates and show that they can be used to detect human touch. [ABSTRACT FROM AUTHOR]

A conjugated polymer with a low band gap of 1.21 eV, i.e., absorbing infrared light, is demonstrated as active material in field-effect transistors (FETs). The material consists of alternating fluorene units and low band gap segments with electron donor-acceptor-donor units composed of two electron-donating thiophene rings attached on both sides of a thiadiazolo-quinoxaline electron-acceptor group. The polymer is solution-processable and air-stable; the resulting FETs exhibit typical p-channel characteristics and field-effect mobility of 0.03 cm2 V-1 s-1. [ABSTRACT FROM AUTHOR]

Energy harvesting from photosynthetic membranes, proteins, or bacteria through bio‐photovoltaic or bio‐electrochemical approaches has been proposed as a new route to clean energy. A major shortcoming of these and solar cell technologies is the underutilization of solar irradiation wavelengths in the IR region, especially those in the far IR region. Here, a biohybrid energy‐harvesting device is demonstrated that exploits IR radiation, via convection and thermoelectric effects, to improve the resulting energy conversion performance. A composite of nanocellulose and the conducting polymer system poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is used as the anode in biohybrid cells that includes thylakoid membranes (TMs) and redox mediators (RMs) in solution. By irradiating the conducting polymer electrode by an IR light‐emitting diode, a sixfold enhancement in the harvested bio‐photovoltaic power is achieved, without compromising stability of operation. Investigation of the output currents reveals that IR irradiation generates convective heat transfer in the electrolyte bulk, which enhances the redox reactions of RMs at the anode by suppressing diffusion limitations. In addition, a fast‐transient thermoelectric component, originating from the PEDOT:PSS‐nanocellulose‐electrolyte interphase, further increases the bio‐photocurrent. These results pave the way for the development of energy‐harvesting biohybrids that make use of heat, via IR absorption, to enhance energy conversion efficiency. [ABSTRACT FROM AUTHOR]

The mass implementation of renewable energy sources is limited by the lack of energy storage solutions operating on various timescales. Electrochemical technologies such as supercapacitors and batteries cannot handle long storage time because of self‐discharge issues. The combination of fuel storage technology and fuel cells is an attractive solution for long storage times. In that context, large‐scale fuel cell solutions are required for massive energy storage in cities, which leads to possible concepts such as low‐cost disposable fully organic membrane assemblies in fuel cells to avoid regeneration of expensive poisoned electrodes. Here, the formation of an organic gas diffusion electrode (GDE) fabricated by paper‐making production, combined with in situ polymerization is demonstrated for the first time. Cellulose is used as a 3D scaffold functionalized with poly(3,4‐ethylenedioxythiophene) (PEDOT) serving as both an electrical conductor and an electrocatalyst of high efficiency for the oxygen reduction reaction. The PEDOT‐cellulose porous GDE is implemented in a membrane assembly and demonstrated in a H2‐O2 fuel cell. The demonstration of low‐cost material/manufacturing that is environmentally friendly is a paradigm shift in the development of fuel cells for a sustainable society. [ABSTRACT FROM AUTHOR]

Since their discovery in the seventies, conducting polymers have been chemically designed to acquire specific optical and electrical properties for various applications. Poly(3,4‐ethylenedioxythiophene) (PEDOT) is among the most successful polymers as indicated by ≈12 000 articles mentioning it to date. PEDOT is found as transparent polymer electrodes in solar cells and light‐emitting diodes, as printed electrodes in transistors, and as the main component of electrochromic displays, supercapacitors, and electrochemical transistors. For around seven years, PEDOT has been classified as the first thermoelectric polymer that converts heat flow into electricity. This has triggered a renewed interest in the scientific community, with about 400 publications including the keyword "PEDOT" and "thermoelectric." Among the topics covered by those scientific works are: i) the optimization of the thermoelectric properties, ii) understanding of the interplay between electrical properties and morphology, iii) the origin of the Seebeck coefficient, iv) the characterization of its thermal conductivity; and v) the design of thermoelectric devices. This work aims to be a pedagogical introduction to PEDOT but also to review the state‐of‐the art of its thermoelectric properties and thermoelectric devices. Hopefully, this work will inspire scientists to find chemical design rules to bring organic thermoelectrics beyond PEDOT. [ABSTRACT FROM AUTHOR]

Lignosulfonate (LS) is a large‐scale surplus product of the forest and paper industries, and has primarily been utilized as a low‐cost plasticizer in making concrete for the construction industry. LS is an anionic redox‐active polyelectrolyte and is a promising candidate to boost the charge capacity of the positive electrode (positrode) in redox‐supercapacitors. Here, the physical‐chemical investigation of how this biopolymer incorporates into the conducting polymer PEDOT matrix, of the positrode, by means of counter‐ion exchange is reported. Upon successful incorporation, an optimal access to redox moieties is achieved, which provides a 63% increase of the resulting stored electrical charge by reversible redox interconversion. The effects of pH, ionic strength, and concentrations, of included components, on the polymer–polymer interactions are optimized to exploit the biopolymer‐associated redox currents. Further, the explored LS‐conducting polymer incorporation strategy, via aqueous synthesis, is evaluated in an up‐scaling effort toward large‐scale electrical energy storage technology. By using an up‐scaled production protocol, integration of the biopolymer within the conducting polymer matrix by counter‐ion exchange is confirmed and the PEDOT‐LS synthesized through optimized strategy reaches an improved charge capacity of 44.6 mAh g−1. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: heat sensing; ionic thermodiffusion; plasmonic heating; pyroelectric copolymer In article number 1900572, Dan Zhao, Magnus P. Jonsson, and co-workers present a new sensor capable of detecting heat, light, and warm touch. Heat sensing, ionic thermodiffusion, plasmonic heating, pyroelectric copolymer.

Sensors for monitoring temperature, heat flux, and thermal radiation are essential for applications such as electronic skin. While pyroelectric and thermoelectric effects are suitable candidates as functional elements in such devices, both concepts show individual drawbacks in terms of zero equilibrium signals for pyroelectric materials and small or slow response of thermoelectric materials. Here, these drawbacks are overcome by introducing the concept of thermodiffusion‐assisted pyroelectrics, which combines and enhances the performance of pyroelectric and ionic thermoelectric materials. The presented integrated concept provides both rapid initial response upon heating and stable synergistically enhanced signals upon prolonged exposure to heat stimuli. Likewise, incorporation of plasmonic metasurfaces enables the concept to provide both rapid and stable signals for radiation‐induced heating. The performance of the concept and its working mechanism can be explained by ion–electron interactions at the interface between the pyroelectric and ionic thermoelectric materials. [ABSTRACT FROM AUTHOR]

Corn starch and citric acid, two low-cost and abundant materials, were used for establishing a novel screen printable hydrogel for printed electronics applications. Corn starch was modified with citric acid by melt-blending; the so obtained thermoplastic starch was ground to powder and added to a water–starch suspension. Ultrasonication was used to prepare hydrogels of different citric acid concentrations. The most promising hydrogel contained 10% citric acid by weight, provided an ionic conductivity of (2.30 ± 0.07) mS cm−1 and appropriate rheological properties for screen and stencil printing. The hydrogel shows superb printability and prolonged stability against degradation. The corn starch hydrogel was used as printable gel polymer electrolyte in fully printed supercapacitors. The specific capacitance of the printed supercapacitor reached 54 F g−1. The printable hydrogel-polymer electrolyte is easy to produce without in-depth chemical knowledge, is based on widely used and non-toxic materials, and may be used as a functional layer in other printed electronics applications such as printed batteries. [ABSTRACT FROM AUTHOR]

Semiconducting polymers are promising materials for manufacturing optoelectronic devices, such as large‐area solar cells or small light‐emitting diodes, through the use of printing technologies. In their oxidized form, π‐conjugated polymers become good electrical conductors and their optical absorption shifts to the infrared region. It is demonstrated that conducting polymers can be integrated in bolometers for IR detection. A bolometer is a thermally isolated thin device that absorbs IR radiation and translates a temperature change into a change in electrical resistance. While commercial bolometers are usually made of complex architectures comprising several materials (that is, an IR absorbing layer, a conducting layer, and a thermally insulating layer), the first polymer bolometer is demonstrated with a freestanding layer of poly(3,4‐ethylene‐dioxythiophene) having high IR absorption, low thermal conductivity, and good thermistor action in one single layer. The solution processability of conducting polymers, their compatibility with high‐resolution printing technologies, and their unique combination of optoelectronic properties can lead to a breakthrough for low‐cost uncooled IR cameras, which are in high demand for security and safety applications. [ABSTRACT FROM AUTHOR]