Abstract Ultra‐lightweight solar cells have attracted enormous attention due to their ultra‐conformability, flexibility, and compatibility with applications including electronic skin or miniaturized electronics for biological applications. With the latest advancements in printing technologies, printing ultrathin electronics is becoming now a reality. This work offers an easy path to fabricate indium tin oxide (ITO)‐free ultra‐lightweight organic solar cells through inkjet‐printing while preserving high efficiencies. A method consisting of the modification of a poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) ink with a methoxysilane‐based cross‐linker (3‐glycidyloxypropyl)trimethoxysilane (GOPS)) is presented to chemically modify the structure of the electrode layer. Combined with plasma and solvent post‐treatments, this approach prevents shunts and ensures precise patterning of solar cells. By using poly(3‐hexylthiophene) along rhodanine‐benzothiadiazole‐coupled indacenodithiophene (P3HT:O‐IDTBR), the power conversion efficiency (PCE) of the fully printed solar cells is boosted up to 4.73% and fill factors approaching 65%. All inkjet‐printed ultrathin solar cells on a 1.7 µm thick biocompatible parylene substrate are fabricated with PCE reaching up to 3.6% and high power‐per‐weight values of 6.3 W g −1 . After encapsulation, the cells retain their performance after being exposed for 6 h to aqueous environments such as water, seawater, or phosphate buffered saline, paving the way for their integration in more complex circuits for biological systems.
A new generation of polythiophene-based polyelectrolytes is reported to address fundamental issues in organic electrochemical transistors (OECTs). In such devices, the semiconductor must be able to transport and store ions and possess simultaneously a very high electronic mobility. For this, the ion-conducting 6-(thiophen-3-yl) hexane-1-sulfonate tetramethylammonium monomer (THS–TMA+) is copolymerized with the hole-conducting 3-hexylthiophene (3HT) to obtain copolymers, PTHS–TMA+-co-P3HT 1–3 with a gradient architecture. The copolymers having up to 50 mol % 3HT content are easily oxidizable and are crystalline. Consequently, for the copolymers, a higher stability in water is achieved, thus reducing the amount of cross-linker needed to stabilize the film. Furthermore, OECTs using copolymers with 75 and 50 mol % of PTHS–TMA+ content exhibit 2–3 orders of magnitude higher ON/OFF ratio and an extremely lower threshold voltage (−0.15 V) compared to PTHS–TMA+. Additionally, high volumetric capacitance (C* > 100 F/cm3) is achieved, indicating that the ion transport is not hampered by the hydrophobic 3HT up to 50 mol %, for which a very high OECT hole mobility of 0.017 cm2/(V s) is also achieved. Thus, the concept of copolymerization to combine both ionic and electronic charge transport in an organic mixed conductor offers an elegant approach to obtain high-performance OECT materials.
Abstract Poly(3,4‐ethylenedioxythiophene) (PEDOT) is a prime example of conducting polymer materials for supercapacitor electrodes that offer ease of processability and sophisticated chemical stability during operation and storage in aqueous environments. Yet, continuous improvement of its electrochemical capacitance and stability upon long cycles remains a major interest in the field, such as developing PEDOT‐based composites. This work evaluates the electrochemical performances of hydroxymethyl PEDOT (PEDOTOH) coupled with hydrogel additives, namely poly(ethylene oxide) (PEO), poly(acrylic acid) (PAA), and polyethyleneimine (PEI), fabricated via a single‐step electrochemical polymerization method in an aqueous solution. The PEDOTOH/PEO composite exhibits the highest capacitance (195.2 F g −1 ) compared to pristine PEDOTOH (153.9 F g −1 ), PEDOTOH/PAA (129.9 F g −1 ), and PEDOTOH/PEI (142.3 F g −1 ) at a scan rate of 10 mV s −1 . The PEDOTOH/PEO electrodes were then assembled into a symmetrical supercapacitor in an agarose gel. The type of supporting electrolytes and salt concentrations were further examined to identify the optimal agarose‐based gel electrolyte. The supercapacitors comprising 2 M agarose‐LiClO 4 achieved a specific capacitance of 27.6 F g −1 at a current density of 2 A g −1 , a capacitance retention of ∼94% after 10,000 charge/discharge cycles at 10.6 A g −1 , delivering a maximum energy and power densities of 11.2 Wh kg −1 and 17.28 kW kg −1 , respectively. The performance of the proposed supercapacitor outperformed several reported PEDOT‐based supercapacitors, including PEDOT/carbon fiber, PEDOT/CNT, and PEDOT/graphene composites. This study provides insights into the effect of incorporated hydrogel in the PEDOTOH network and the optimal conditions of agarose‐based gel electrolytes for high‐performance PEDOT‐based supercapacitor devices.
Abstract Conjugated polyelectrolytes (CPEs) are a focus of research because combine their inherent electrical conductivity and the ability to interact with ions in aqueous solutions or biological systems. However, it is still not understood to what degree the counter ion in CPEs influences the properties of the CPE itself and the performance of electronic transducers. In order to investigate this, three different conjugated polyelectrolytes, poly(6‐(thiophen‐3‐yl)hexane‐1‐sulfonate)s (PTHS − X + ), are synthesized, which have the same polythiophene backbone but different X + counter ions: the bulky tetrabutylammonium (TBA + ), tetraethylammonium (TEA + ), and the smallest tetramethylammonium (TMA + ). At the interface with biological systems, thin CPE films have to be stable in an aqueous environment and should allow the inward and outward flow of ions from the electrolyte. Since the studied PTHS − X + have different solubilities in water, the optical properties of pristine PTHS − X + as well as of crosslinked PTHS − X + via UV–vis absorption spectroscopy are investigated additionally. PTHS − TMA + exhibits better aggregation, fast interdiffusion of ions, and fast recovery from the oxidized state. Additionally, spectroelectrochemical and cyclic voltammetric as well as electrochemical capacitance investigations show that PTHS − TMA + can be oxidized to a higher degree. This leads to a better performance of PTHS − TMA + ‐based organic electrochemical transistors.
Organic mixed (ionic and electronic) charge conductors and devices offer a new toolbox for interfacing with biological systems. One application for which they have compelling advantages is medical diagnostics. In this work, I will show how the mixed conductivity of these materials and the transistor type that leverages this type of transport is used to detect pathogens and proteins with performance that exceeds the state-of-the-art.
Organic mixed ionic-electronic conductors (OMIECs) have emerged as promising materials for biological sensing, owing to their electrochemical activity, stability in an aqueous environment, and biocompatibility. Yet, OMIEC-based sensors rely predominantly on the use of composite matrices to enable stimuli-responsive functionality, which can exhibit issues with intercomponent interfacing. In this study, an approach is presented for non-enzymatic glucose detection by harnessing a newly synthesized functionalized monomer, EDOT-PBA. This monomer integrates electrically conducting and receptor moieties within a single organic component, obviating the need for complex composite preparation. By engineering the conditions for electrodeposition, two distinct polymer film architectures are developed: pristine PEDOT-PBA and molecularly imprinted PEDOT-PBA. Both architectures demonstrated proficient glucose binding and signal transduction capabilities. Notably, the molecularly imprinted polymer (MIP) architecture demonstrated faster stabilization upon glucose uptake while it also enabled a lower limit of detection, lower standard deviation, and a broader linear range in the sensor output signal compared to its non-imprinted counterpart. This material design not only provides a robust and efficient platform for glucose detection but also offers a blueprint for developing selective sensors for a diverse array of target molecules, by tuning the receptor units correspondingly.
Propylene and butylene glycol oligoether chains have been employed as alternatives to ethylene glycol in thiophene based semiconductors for OECTs. Their impact on electrochemical, microstructure, and swelling properties are discussed.
Poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) is the conducting polymer with the biggest prospects in the field of organic (bio)electronics. However, new PEDOT (co)polymers are necessary with additional properties such...
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