Electroactive ionic gel/metal nanocomposites are produced by implanting supersonically accelerated neutral gold nanoparticles into a novel chemically crosslinked ion conductive soft polymer. The ionic gel consists of chemically crosslinked poly(acrylic acid) and polyacrylonitrile networks, blended with halloysite nanoclays and imidazolium-based ionic liquid. The material exhibits mechanical properties similar to that of elastomers (Young's modulus ≈ 0.35 MPa) together with high ionic conductivity. The fabrication of thin (≈100 nm thick) nanostructured compliant electrodes by means of supersonic cluster beam implantation (SCBI) does not significantly alter the mechanical properties of the soft polymer and provides controlled electrical properties and large surface area for ions storage. SCBI is cost effective and suitable for the scaleup manufacturing of electroactive soft actuators. This study reports the high-strain electromechanical actuation performance of the novel ionic gel/metal nanocomposites in a low-voltage regime (from 0.1 to 5 V), with long-term stability up to 76 000 cycles with no electrode delamination or deterioration. The observed behavior is due to both the intrinsic features of the ionic gel (elasticity and ionic transport capability) and the electrical and morphological features of the electrodes, providing low specific resistance (<100 Ω cm ), high electrochemical capacitance (≈mF g ), and minimal mechanical stress at the polymer/metal composite interface upon deformation.

consumption and sensing as well as high-energy-density batteries for energy storage. Recently, interest in developing systems that interface seamlessly with the human body (e.g., wearables, braincomputer interfaces, and soft robots) has driven the development of soft, organic, and biomimetic materials that emulate the functions of their inorganic counterparts. Beyond emulation, these materials are unique because they provide an opportunity to embody such multifunctional properties within the material itself, rather than relying on device design. These multifunctional properties are intrinsic to organic mixed ionic electronic conductors (OMIECs), that is, once synthesized and processed, OMIECs can serve as the active component of multiple devices (be it transistors, sensors, energy-storage devices, etc.), where essentially the material is the device.OMIECs generally consist of a conjugated backbone for electronic conduction as well as sidechains to facilitate ionic intercalation from the operational electrolyte and to aid in solvation in processing solvents. [1] Organic chemistry provides a large toolbox in the molecular design of the backbone, side chains, and other additives, resulting in an almost infinite design space for the corresponding materials properties: energy levels, electronic and ionic conductivity, optical, volume, and moduli. Additionally, one or more of these properties can be modified during device operation, thereby transducing an input (e.g., ionic) into an output (e.g., electronic), allowing OMIECs to be used for a variety of applications including sensors, transistors, optoelectronic devices, energy-storage electrodes, and actuators. The multifunctionality of OMIECs is illustrated in Figure 1 to highlight their versatility in design and their ability to respond to a variety of stimuli.The underlying and unifying phenomena behind these property changes arise from the large modulation in electronic and ionic charge density in the bulk of the OMIEC. This modulation in turn results in second-order effects such as modulations in electrochemical potential (electron energy levels), electronic and ionic transport, capacitance, free volume, optical bandgap, and modulus. Tuning these properties throughout the bulk of the material enables new design parameters that were previously untapped in traditional electronic devices where Organic mixed ionic-electronic conductors (OMIECs) have gained recent interest and rapid development due to their versatility in diverse applications ranging from sensing, actuation and computation to energy harvesting/ storage, and information transfer. Their multifunctional properties arise from their ability to simultaneously participate in redox reactions as well as modulation of ionic and electronic charge density throughout the bulk of the material. Most importantly, the ability to access charge states with deep modulation through a large extent of its density of states and physical volume of the material enables OMIEC-based devices to display exciting new characteristics...

Through specific marker bands, IR and Raman spectra of chemically doped polyconjugated polymers allow investigation of doping and monitoring of its effectiveness. The vibrational modes associated with the doping-induced features provide information about the polymer units affected by the transferred charge and the structure relaxation associated with the formation of the polaron. Here, we doped the P(NDI2OD-T2) copolymer with three differently substituted 1H-benzimidazoles, which allow for doping in solution, leading to an increase of conductivity values up to four orders of magnitude. Careful inspection of the IR and Raman spectra of P(NDI2OD-T2) while varying the dopant concentration and the kind of dopant proves that the polaron markers are almost independent from the dopant species. The IR intensity of the polaron markers is a very sensitive probe of charge delocalization upon doping: for n-doped P(NDI2OD-T2), these bands show absorption intensities of the same strength as those of the pristine species. In other words, they are very weak in comparison to the so-called IRAV bands of doped polyacetylene, polythiophenes, and related materials. This experimental observation provides evidence of the strong confinement of the polaron on the NDI2OD unit. Multiwavelength Raman spectra of n-doped P(NDIOD-T2) further corroborate this point, showing that the T2 moiety is almost unaffected by doping. The analysis of the experimental data is complemented by DFT calculations which fully support the diagnosis of the formation of localized polarons. Hence, vibrational spectroscopy is an effective tool to characterize charge carriers induced by doping P(NDIOD-T2): it indicates that the observed conductivity enhancement is ascribed to an efficient interchain hopping involving charged NDI2OD units, whereas polaron diffusion along the chain is unlikely.

Molecular doping of conjugated polymers causes bleaching of the neutral absorbance and results in new polaron absorbance transitions in the mid and near infrared. Here, the concentration dependent changes in the spectra for a series of molecularly doped diketopyrrolopyrrole (DPP) co‐polymers with a series of ultra‐high electron affinity cyanotrimethylenecyclopropane‐based dopants is analyzed. With these strong dopants the polaron mole fraction (Θ) reaches saturation. Analysis of the full spectrum enables separation of neutral and polaron signals and quantification of the polaron mole fraction using a simple noninteracting site model. The peak ratios for both neutral and polaron peaks change systematically with increasing polaron mole fraction for all measured polymers. Analysis of the spectral changes indicates that the polaron mole fraction can be quantified to within 5%. While the total change in the absorbance spectrum with increasing polaron mole fraction is linear, the lowest energy polaron peak (P1) grows nonlinearly, which indicates increased polarization/delocalization. Molecular doping of polymers that form either H‐ or J‐aggregates shows systematically different spectral changes in the vibronic peak ratios of the neutral spectra and provides insights into the polymer configuration at undoped sites in the film.

Organic electrochemical transistors (OECTs) have shown promise as transducers and amplifiers of minute electronic potentials due to their large transconductances. Tuning the OECT threshold voltage is important to achieve low‐powered devices with amplification properties within the desired operational voltage range. However, traditional design approaches have struggled to decouple channel and materials properties from threshold voltage, thereby compromising on several other OECT performance metrics, such as electrochemical stability, transconductance, and dynamic range. In this work, simple solution‐processing methods are utilized to chemically dope polymer gate electrodes, thereby controlling their work function, which in turn tunes the operation voltage range of the OECTs without perturbing their channel properties. Chemical doping of initially air‐sensitive polymer electrodes further improves their electrochemical stability in ambient conditions. Thus, OECTs that are simultaneously low‐powered and electrochemically resistant to oxidative side reactions under ambient conditions are demonstrated. This approach shows that threshold voltage, which is once interwoven with other OECT properties, can in fact be an independent design parameter, expanding the design space of OECTs.