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As conducting polymers become increasingly important in electronic devices, understanding their charge transport is essential for material and device development. Various semi-empirical approaches have been used to describe temporal charge carrier dynamics in these materials, but there have yet to be any theoretical approaches utilizing ab initio molecular dynamics. In this work, we develop a computational technique based on ab initio Car–Parrinello molecular dynamics to trace charge carrier temporal motion in archetypical conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Particularly, we analyze charge dynamics in a single PEDOT chain and in two coupled chains with different degrees of coupling and study the effect of temperature. In our model we first initiate a positively charged polaron (compensated by a negative counterion) at one end of the chain, and subsequently displace the counterion to the other end of the chain and trace polaron dynamics in the system by monitoring bond length alternation in the PEDOT backbone and charge density distribution. We find that at low temperature (T = 1 K) the polaron distortion gradually disappears from its initial location and reappears near the new position of the counterion. At the room temperature (T = 300 K), we find that the distortions induced by polaron, and atomic vibrations are of the same magnitude, which makes tracking the polaron distortion challenging because it is hidden behind the temperature-induced vibrations. The novel approach developed in this work can be used to study polaron mobility along and between the chains, investigate charge transport in highly doped polymers, and explore other flexible polymers, including n-doped ones. [ABSTRACT FROM AUTHOR]

The surge in the number of distributed microelectronics and sensors requires versatile, scalable, and affordable power sources. Heat‐harvesting organic thermoelectric generators (TEGs) are regarded as potential key components of the future energy landscape. Recent advances in the performance of organic thermoelectric materials have made practical applications of organic TEGs more feasible than ever before, yet the challenges of designing and fabricating organic TEGs suitable for real scenarios are scarcely addressed. Specifically, small sensors and wearables demand for micro‐thermoelectric generators (µTEGs) with high power density architectures and small form factors, while typical demonstrations of organic TEGs are characterized by < 10 thermocouples (TCs) per cm2. This work presents a rolled, organic µTEG architecture combining large‐area, solution‐based deposition techniques, such as inkjet and spray‐coating, and an ultrathin parylene substrate to achieve a thermocouple density of 1842 TCs cm−2. Such demonstrative µTEG reaches a thermoelectric conversion performance of 0.15 µW cm−2 at ΔT = 50 K. Such power output is well in line with finite element method simulations, which highlight the benefit of the architecture and show that remarkable power densities, in the mW cm−2 range at ΔT = 10 K, are realistically achievable with geometrical improvements and already ongoing advancements in organic thermoelectric inks. [ABSTRACT FROM AUTHOR]

Mechanically deformable polymeric semiconductors are a key material for fabricating flexible organic thin‐film transistors (FOTFTs)—the building block of electronic circuits and wearable electronic devices. However, for many π‐conjugated polymers achieving mechanical deformability and efficient charge transport remains challenging. Here the effects of polymer backbone bending stiffness and film microstructure on mechanical flexibility and charge transport are investigated via experimental and computational methods for a series of electron‐transporting naphthalene diimide (NDI) polymers having differing extents of π‐conjugation. The results show that replacing increasing amounts of the π‐conjugated comonomer dithienylvinylene (TVT) with the π‐nonconjugated comonomer dithienylethane (TET) in the backbone of the fully π‐conjugated polymeric semiconductor, PNDI‐TVT100 (yielding polymeric series PNDI‐TVTx, 100 ≥ x ≥ 0), lowers backbone rigidity, degree of texturing, and π–π stacking interactions between NDI moieties. Importantly, this comonomer substitution increases the mechanical robustness of PNDI‐TVTx while retaining efficient charge transport. Thus, reducing the TVT content of PNDI‐TVTx suppresses film crack formation and dramatically stabilizes the field‐effect electron mobility upon bending (e.g., 2 mm over 2000 bending cycles). This work provides a route to tune π–π stacking in π‐conjugated polymers while simultaneously promoting mechanical flexibility and retaining good carrier mobility in FOTFTs. [ABSTRACT FROM AUTHOR]

Practical interest in oxygen reduction reaction (ORR) has traditionally been due to its application at fuel cells' cathode following its complete 4e route to the water. In search of new electrode materials, it was discovered that conducting polymers (CPs) also are capable of driving ORR, though predominantly halting the process at 2e reduction leading to hydrogen peroxide generation. As alternative ways to produce this "green oxidant" are attracting increasing attention, a detailed study of the ORR mechanism at CP electrodes gains importance. Here, we summarize our recent theoretical work on the topic, which underscores the fundamental difference between CP and electrocatalytic metal ORR electrodes. Our insights also bring to us the attention of outer‐sphere electron transfer, not unknown but somewhat ignored in the field. We also put the action of CP electrodes in a more general context of chemical ORR and redox mediation responsible for the electrocatalytic ORR mechanism. [ABSTRACT FROM AUTHOR]

The first example of inkjet‐printed, electrolyte‐gated organic field‐effect transistors, fabricated on flexible polyimide substrates is presented. The interdigitated source and drain electrodes, and the coplanar gate electrodes, are inkjet‐printed using a homemade gold nanoparticle ink. A semiconducting ink based on the p‐type, organic semiconductor poly[2,5‐(2‐octyldodecyl)‐3,6‐diketopyrrolopyrrole‐alt‐5,5‐(2,5‐di(thien‐2‐yl)thieno [3,2‐b] thiophene)] (DPP‐DTT) is formulated and inkjet‐printed onto the channel. The performances of inkjet‐printed, coplanar devices are compared to those of transistors whose gate electrode consists in a metallic wire inserted in the electrolyte. Printed transistors show excellent electrical properties with field‐effect mobility as high as 0.04 cm2 V−1 s−1. The electrical behavior of inkjet‐printed, coplanar devices is also modeled using the Nernst–Planck–Poisson (NPP) equations, where the output and transfer curves are calculated based on the charge and potential distribution inside the device. Good quantitative agreement between the simulation and experiments is achieved, outlining the attainable use of NPP simulations as predictive tools for device design and optimization. To demonstrate an example of application, printed transistors are functionalized for the detection of complementary DNA strands. This study opens an avenue for the next generation of low‐cost, flexible sensors and circuits, both through experimental studies and device modeling. [ABSTRACT FROM AUTHOR]