Conductive PEDOT Research Articles

The Effects of Acidic Secondary Dopants to the Electrical Conductivity of PEDOT: PSS Fabrics

Conductive polymers commonly used as fillers to enhance electrical properties of composite’s system. However, the low conductivity performance of conducting polymers, namely poly(3,4-ethylenedioxythiophene): poly (4-styrene sulfonate) (PEDOT: PSS), constrains their utilization in the field of conductive textile technology in inventing an advanced textiles’ fabric. Maintaining the stability of impregnated PEDOT: PSS fabrics at the microscopic level remains doubtful and unclear. Nowadays, researchers are actively pursuing the introduction of secondary dopants into PEDOT: PSS dispersion to overcome this challenge. In this study, a conductive PEDOT: PSS fabric via immersion technique was prepared and its effects on conductivity upon doped-secondarily by two different dopants; hydrochloric (HCl) and p-toluenesulfonic (p-TSA) acids was revealed. The volume percentage (vol.%) of the secondary dopants (1, 3, 5, 7, 9 vol.%) were varied to find the optimal vol.% for getting the great value of conductivity of the doped PEDOT: PSS fabrics. These fabrics were then analyzed by using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR), Electrochemical Impedance Spectroscopy (EIS), and Scanning Electron Microscopy (SEM) to investigate their conductivity performances chemically. It is found that the conductivity values were affected by varying the strength of the acids. It is concluded, that the 7 vol.% and 5 vol.% of HCl and p-TSA, respectively, gave the highest electrical conductivity values of the PEDOT: PSS fabrics. These findings can be used to provide direction and guidance to researchers in advancing the fields of textiles, electronics and advanced materials.

Raman spectroscopy and DFT calculations of PEDOT:PSS in a dipolar field.

The conductive polymer-electrolyte interface plays an important role in many electrochemical devices. An unusual situation arises when a solvent-free ionic liquid (SF-IL) is used as the electrolyte because it behaves as a molten salt rather than an electrolyte solution. On the basis of Raman spectra, it was found that the presence of ion pairs of SF-IL in the vicinity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) results in a decrease in the oxidation level of the polymer and an increase in the HOMO-LUMO gap. The process of polymer "dedoping" and the modification of the electronic structure of the polymer are illustrated by quantum chemical calculations.

プラズマ内包気泡を用いた新規PEDOT創成法の確立

Poly(3,4-ethylenedioxythiophene)(PEDOT) is known as one of the best conducting polymers and has been applied to various electronic devices. The dopants are typically used to enhance the solubility of synthesized PEDOT, however the dopants lower the conductivity of PEDOT. Then, we developed an innovative plasma enveloped bubble process to enable PEDOT synthesis with high water dispersion without introducing any dopants. The plasma polymerization process is realized in the emulsion of 3,4-ethylenedioxythiophene (EDOT) in water by plasma generated radicals inside bubbles of oxygen and argon mixture. In this study, the characteristics of plasma inside the bubbles and processed samples prepared by this innovative method were experimentally clarified. The FT-IR analysis of the synthesized sample clearly indicated the foot print of EDOT polymerization. The conductivities of the synthesized PEDOT films increased with the processing time.

Why does solvent treatment increase the conductivity of PEDOT : PSS? Insight from molecular dynamics simulations.

Poly(3,4-ethylenedioxythiophene) : polystyrene sulfonate (PEDOT : PSS) is one of the most important conducting polymers. In its pristine form its electrical conductivity is low, but it can be enhanced by several orders of magnitude by solvent treatment, e.g. dimethyl sulfoxide (DMSO). There are various (and often conflicting) explanations of this effect suggested in the experimental literature, but its theoretical understanding based on simulation and modelling accounting for the complex realistic morphology of PEDOT : PSS is missing. Here, we report Martini coarse-grained molecular dynamics simulation for the DMSO solvent treatment of the PEDOT : PSS film. We show that during solvent treatment a part of the deprotonated PSS chains are dissolved in the electrolyte. After the solvent treatment and subsequent drying, the PEDOT-rich regions become closer to each other, with a part of the PEDOT chains penetrating into the PSS-rich regions. This leads to an efficient coupling between PEDOT-rich regions, leading to the enhancement of the conductivity. Another factor leading to the conductivity improvement is the π-π stacking enhancement resulting in more π-π stacks in the film and in the increased average size of PEDOT crystallites. Our results demonstrate that course-grained molecular dynamics simulations of a realistic system represent a powerful tool enabling theoretical understanding of important morphological features of conducting polymers, which, in turn, represents a prerequisite for materials design and improvement.

High conductivity PEDOT:PSS through laser micro-annealing: mechanisms and application

Using a 1042 nm laser, we control the conductivity of PEDOT:PSS over 3 orders of magnitude. We show that the cause of this change in conductivity is the agglomeration of the PEDOT cores, and use this process to fabricated OECTs.

Effect of Poly(Vinyl Alcohol) Concentration in the Transmittance and Sheet Resistance of Conductive Pedot:Pss/Pva Electrodes Made by Doctor Blading Deposition Technique

Effect of Poly(Vinyl Alcohol) Concentration in the Transmittance and Sheet Resistance of Conductive Pedot:Pss/Pva Electrodes Made by Doctor Blading Deposition Technique

Phase Separation to Improve the Conductivity and Work Function of the PEDOT:PSS Solution for Silicon Hybrid Solar Cells

Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is usually used as a hole-selective contact layer in photovoltaic and optoelectronic fields due to its good film-forming property and low cost. However, PSS as a dispersant is an insulating material that restricts the conductivity of PEDOT:PSS films. In this work, we modified the PEDOT:PSS solution by heat treatment to realize the double improvement of the conductivity and work function of the PEDOT:PSS film for PEDOT:PSS/Si hybrid solar cells (HSCs). It was found that phase separation occurs in the process of heat treatment of the PEDOT:PSS solution, which causes the dispersed PEDOT to agglomerate into strips to form a conductive grid. By optimizing the heat treatment temperatures, the electrical conductivity of the PEDOT:PSS film increased from 1090 to 1305 S/cm at 90 °C. In addition, the composition of the PEDOT:PSS solution was changed to increase the value of PEDOT/PSS by 55.12%, which increased the work function of the PEDOT:PSS film from 4.5 to 4.8 eV. After calculation with the finite volume method, the band bending at the Si surface of heterogeneous contact increased by 0.216 eV, which is more conducive to carrier separation. Finally, the power conversion efficiency of the heat-treated PEDOT:PSS solution applied to PEDOT:PSS/Si HSCs increased from 11.03 to 12.38% compared to that of nonheat-treated PEDOT:PSS/Si HSCs.

Solution-Processed Highly Efficient Semitransparent Organic Solar Cells with Low Donor Contents

Semitransparent organic solar cells (ST-OSCs) are promising candidates for applications in building-integrated photovoltaics (BIPV) as windows and facades. The challenge to achieve highly efficient ST-OSCs is the trade-off between power conversion efficiency (PCE) and average visible transmittance (AVT). Herein, solution-processed ST-OSCs are demonstrated on the basis a polymer donor, PM6, and a small molecule acceptor, Y6; lowering the visible-absorbing PM6 contents in blends could increase AVT and maintain PCE. Additionally, conductive polymer PEDOT:PSS is used as the top electrode due to its high transparency, good conductivity, and solution processability. Efficient ST-OSCs with 20 wt % PM6 achieve high PCE of 7.46% and AVT of 36.4%. The light utilization efficiency (LUE) of 2.72% is among the best reported values for solution-processed ST-OSCs. This work provides a straightforward approach for solution-processed ST-OSCs by combining a low fraction of visible-wavelength-selective polymer donors with near-infrared nonfullerene acceptors to achieve high PCE and AVT simultaneously.

Electrochemical oxygen reduction reaction at conductive polymer PEDOT: Insight from ab initio molecular dynamics simulations

Conducting polymers such as poly (3,4-ethylenedioxythiophene) (PEDOT) have attracted research attention as promising effective electrocatalytic materials for Oxygen Reduction Reaction (ORR). However, the complete reaction pathways leading to the hydrogen peroxide, H2O2, formation still remained unexplored. In this study, ab initio Born–Oppenheimer molecular dynamics (MD) calculations with an explicit solvent, were carried out to investigate the detailed mechanisms of the ORR on PEDOT via monitoring MD trajectories and analysing electronic energies. We confirm the outer-sphere nature of the first electron transfer and describe the essentially concerted electron–proton transfer nature of both oxygen reduction steps. Proton transfer is found to be involved in the first and second reduction steps and the role of water as an explicit solvent is outlined. Formation of the hydrogen peroxide is observed via either the reduction of hydroperoxyl radical HO2 or cleavage of its peroxo-adduct with PEDOT. It is therefore theoretically validated that the O2 reduction on a PEDOT may proceed a series pathway occurring simultaneously in acidic media. This approach provides an efficient and reliable means to rationalize and predict reaction mechanisms in solvent environment.

Carbon Nanofiber/PEDOT Based Macro-Porous Composite for High Performance Multifunctional Neural Microelectrode

Brain study methods mainly rely on neurochemical detection and electrophysiology, respectively to study the molecular dynamics [1] and electrical activity [2] in the brain cellular environment. Since the brain functioning relies on careful orchestration of both neurotransmitter and neuroelectric activities, coupled monitoring of them holds great promise in elucidating the brain functioning mechanisms and its related diseases e.g. Parkinson’s, epilepsy, etc [3]. Most of the conventional implantable neural interfacing technologies are comprised of noble metals on silicon/ polymer substrates. They suffer from inferior electrical properties, mechanical tissue-electrode mismatch, incompatible surface area, and low signal-to-noise ratio [4]. To address the need, researchers around the world are developing innovative soft materials with multimodal functionalities, especially the organic flexible materials such as conductive polymers and carbon allotropes, to fuel the next-generation multimodal neural electrode devices [5].Here in this work, we present a new macro-porous, conductive, and stable nanocomposite, made up of carbon nanofibers (CNFs) and PEDOT polymer, coated on a flexible neural microelectrode array (Fig. 1A-B). A fully controlled one-shot electrodeposition strategy was developed using chronopotentiometry technique, to coat flexible Au-microelectrode surfaces with macro-porous CNF/PEDOT nanocomposite. The oxidized CNFs were used as a dopant and infused within the conductive PEDOT, electrochemically, in such a way that their excellent electronic, mechanical, chemical properties, and resulting combined performances can be exploited to yield better quality neural recordings, electrical stimulation and neurotransmitter detection. At first, CNFs were oxidized to be dispersible in water (unlike raw CNFs) by vortex and sonication. Later, CNF/PEDOT composite was deposited on Au-electrodes galvanostatically, resulted in a 3D porous and fibrous network (Fig. 1B-D). Then, CNF/PEDOT deposits were characterized through electrochemical impedance spectroscopy (EIS) and pulse current injection. The composite microelectrodes showed low impedance, 16 ± 2 kΩ for a typical electrode area of 1250 µm2, at 1kHz (value corresponding to the neuron firing frequency) (Fig. 1E). Voltage transient responses were measured, at continuous 1ms-biphasic current pulses (cathodic first) in biologically relevant aCSF media, resulted in a charge-injection limit value of 7.6 ± 1.3 mC/cm² (Fig. F). Among all reported organic nanostructured composite materials that were deposited on flexible metallic substrates, CNF/PEDOT displayed superior electrical properties and charge injection capabilities [5]. Next, the capability of CNF/PEDOT composite electrode for in-vitro Dopamine (DA) sensing was evaluated by chronoamperometry, at 130mV vs SCE (oxidation potential of DA). The current responses submitted to DA injections resulted in linear regression (Fig. 1G, R²>0.99), with a high sensitivity of 13.4pA/nM.µm², compared to similar electrochemical sensors [6]. Overall, these electrodes displayed excellent electrical properties: low impedance (16 ± 2 MΩ.µm2 at 1 kHz) and high charge injection capabilities (7.5 ± 1.3 mC/cm²) making them promising candidates for bidirectional electrophysiology, while being capable to detect neurotransmitters like dopamine. Finally, integrated upon flexible neural probes, these composite microelectrodes were tested in-vivo on mouse brain slices as recording and stimulating electrodes (Fig. 1H). They displayed excellent performances, being capable to record spontaneous activities of neurons (sharp wave-ripples and single unit action potentials) and allowed to stimulate electrically the brain slice tissues, to obtain safe and stable evoked potentials. The obtained results show a great prospect for CNF/PEDOT composites for developing next-generation microelectrodes for applications in neural therapies.Figure 1. (A) Optical micrograph of flexible neural probe. (B) CNF/PEDOT deposition on 4 Au-microelectrodes of the implant. SEM images, (C) top view and (D) cross-sectional view of the composite electrode. (E) EIS measurement on modified microelectrodes from 10 Hz to 7 MHz in aCSF at 0V Vs Ag/AgCl. (F) Voltage transient of a CNF/PEDOT microelectrode resulting from the injection of a biphasic current pulse (90 µA with 1 ms pulse width). (G) Linear regression curve of CNF/PEDOT electrode current response at 130mV vs SCE to dopamine injections. (H) Electrophysiological recordings in the hippocampal region (CA1 and CA3) of a mouse brain slice, using flexible microelectrode array modified with CNF/PEDOT composite.AcknowledgmentsAgence Nationale de la Recherche (ANR-15-CE19-0006 and ANR-19-CE19-0002-01) and French RENATECH network.References Lama R.D., Karl Charlson, Arun Anantharam, Parastoo Hashemi, Analytical Chemistry, 84(19): p 8096-101 (2012).Normann R.A. and E. Fernandez, Journal of Neural Engineering, 13(6): p 061003 (2016).Ledo A., Cátia F. Lourenço, João Laranjinha, Greg A. Gerhard, and Rui M. Barbosa, Analytical Chemistry, 89(22): p 12383-12390 (2017).Enming Song, Jinghua Li, Sang Min Won, Wubin Bai, and John A. Rogers, Nature Materials, 16, 590-603 (2020).Zaid Aqrawea, Johanna Montgomeryb, Jadranka Travas-Sejdicc,d, Darren Svirskis, Sensors and Actuators B, 257,753–765 (2018)Jong-Min Moon, Neeta Thapliyal, Khalil Khadim Hussain, Rajendra N.Goyal, Yoon-Bo Shim, Biosensors and Bioelectronics, 102 , 540-552 (2018). Figure 1

Binder-free Printing Ultra-stable PEDOT Sensor on Multiple Fabrics Using Oxidative Chemical Vapor Deposition

With the dramatic progress of Internet-of-Things technology and Artificial Intelligence (AI) algorithms, portable healthcare monitoring has been highlighted as a facile pre-diagnosing strategy for tracking individual health status without hospitalization. In this regard, a wide range of wearable sensors, which extract bio-information such as body temperature, blood pressure, or respiratory patterns, have been developed so far. Although numerous factors are considered during sensor development depending on the types of analytes or target locations in the human body, acquiring sufficient flexibility must be a priority to endure uncontrollable stress caused by the surrounding conditions.Diverse flexible materials have been exploited as suitable substrates for wearable sensors that fulfill the desired mechanical stability. Among them, textiles have tremendous advantages in terms of remarkable stability, skin compatibility, lightweight, and breathability. However, owing to their inherently rough surface, high porosity, and surface hydrophobicity, the formation of a uniform sensing film on fabric has been regarded as a much daunting task compared to a flat and rigid substrate. Liquid-phase coating methods such as spin-coating, dip-casting, or doctor-blading have failed to create a uniform and reproducible film on a fabric. Additives like binders are sometimes effective for improving conformability, but creating thin layers, which is significant for high-performance sensors, still remains challenging. Vapor phase coating methods are, arguably, the most efficient tactics for coating sensing films on fabrics. Inorganic or metallic materials, deposited by a comprehensive deposition tool based on physical vapor deposition, chemical vapor deposition, or atomic layer deposition techniques, have been typically considered as active materials for strain sensors, thermometers, or pressure sensors. However, the inorganic materials with poor flexibility or stretchability are vulnerable to be cracked readily even under mild mechanical stress. Thus, exploring materials and contriving their proper coating methods should be further progressed for realizing desired fabric-based wearable sensors.Herein, we utilize the oxidative chemical vapor deposition (oCVD) technique for creating a conformal Poly(3,4-ethylene dioxythiophene) (PEDOT) layer on multiple fabrics (nylon, polyester, and cotton) without any binder or additives. The oCVD is capable of creating a highly conductive PEDOT (nominally, 1-10 S cm-1 on cotton fabric; 500-1500 S cm-1 on glasses) of which thickness is readily controllable from 50 nm to 1 μm by varying the deposition time. Moreover, the mechanical stability, breathability, and lightness of fabrics are consistent even after PEDOT coating, implying the oCVD could form a promising sensing material while maintaining all advantages of fabrics. Based on the unique properties of excellent conformality, high conductivity, and good mechanical flexibility1-5, we fabricate simple resistive-typed sensors by directly printing the PEDOT on a commercial glove and disposable mask, consisting of polymers such as polypropylene or polyester. The glove and mask sensors are capable of extracting blood pressure information and respiratory rates in real-time with remarkable precision. This is the first report proving the usability of the oCVD method on fabric-based sensors, thus, paving the way for developing versatile healthcare devices.This work was partly supported by the NSF Award No. ECCS-1931088.References Lee, S.; Song, H. W.; Cho, J. Y.; Radevski, N.; Truc, L. N. T.; Sung, T. H.; Jiang, Z. T.; No, K., Mobility of Air-Stable p-type Polythiophene Field-Effect Transistors Fabricated Using Oxidative Chemical Vapor Deposition. Journal of Electronic Materials 2020, 49 (6), 3465-3471.Drewelow, G.; Wook Song, H.; Jiang, Z.-T.; Lee, S., Factors controlling conductivity of PEDOT deposited using oxidative chemical vapor deposition. Applied Surface Science 2020, 501, 144105.Lee, S.; Borrelli, D. C.; Jo, W. J.; Reed, A. S.; Gleason, K. K., Nanostructured Unsubstituted Polythiophene Films Deposited Using Oxidative Chemical Vapor Deposition: Hopping Conduction and Thermal Stability. Advanced Materials Interfaces 2018, 5 (9).Lee, S.; Gleason, K. K., Enhanced Optical Property with Tunable Band Gap of Cross-linked PEDOT Copolymers via Oxidative Chemical Vapor Deposition. Adv. Funct. Mater. 2015, 25 (1), 85-93.Lee, S.; Paine, D. C.; Gleason, K. K., Heavily Doped poly(3,4-ethylenedioxythiophene) Thin Films with High Carrier Mobility Deposited Using Oxidative CVD: Conductivity Stability and Carrier Transport. Adv. Funct. Mater. 2014, 24 (45), 7187-7196. Figure 1

Degradation phenomena and degradation mechanisms for highly conductive PEDOT:PSS films

Poly (3, 4 – ethylenedioxythiophene) – poly (styrenesulfonate) (PEDOT: PSS) thin film has caught much attention because of its high electrical conductivity, optical transmittance and mechanical flexibility. Reducing the PSS content can improve the conductivity of PEDOT: PSS film effectively. However, few studies have been reported on the corresponding degradation behaviors and mechanisms for the PEDOT: PSS films with different PSS contents. Here, we studied the degradation phenomena under various aging conditions. Our results indicated that the degradation behaviors are determined by the content of PSS, and the degradation mechanism is related to the change of molecular configuration of PEDOT chains under various aging conditions.

Green ink formulation for inkjet printed transparent electrodes in OLEDs on biodegradable substrates

In this manuscript we present a green ink formulation for inkjet-printed and blade coated highly conductive PEDOT:PSS thin film. By the addition of a biodegradable surfactant we reduced the surface tension of a water-based PEDOT:PSS formulation enabling the deposition of high quality layers. Finally, we demonstrate the use of inkjet printed PEDOT:PSS films on the basis of these formulation as bottom transparent electrode of organic light-emitting diodes deposited on a biodegradable cellulose acetate (CA) substrate. Our devices outperformed a reference fabricated with a commercially available low-ST PEDOT:PSS that includes unknown additives.

Polymer Blends and Polymer Nanocomposites for Photovoltaic (PV) Cells and an Investigation of the Material Deposition Techniques in PV Cell Fabrication

Polymer photovoltaics (PV) offer the advantage of low-cost, mass-produced, flexible PV films, but they generally suffer from a low-power conversion efficiency (PCE) compared to silicon. This paper studies ITO/PEDOT:PSS/bulk heterojunction/Al PV cells, where two different bulk heterojunction blends are researched: P3HT/PC61BM and PCDTBT/PC70BM. The addition of multiwall carbon nanotubes (CNT) is explored as a conductive network to accelerate the electron transport and extraction to the outer aluminium current collector while reducing the chance of charge recombinations. Several layer deposition techniques are investigated: spin coating and casting, as well as techniques that would induce transverse orientation of polymer grains, including inkjet printing, electrophoresis and the application of a transverse AC field during annealing. Transverse orientation techniques produced architectures that would facilitate charge transport without recombinations, but it is recommended to avoid such techniques for the deposition of conductive PEDOT:PSS and CNT layers as they create a high surface roughness that leads to short circuiting. The best performing PV cell is the ITO/PEDOT:PSS/PCDTBT/PC70BM/CNT/Al structure with a PCE of 11%.

Ionic‐Liquid Induced Morphology Tuning of PEDOT:PSS for High‐Performance Organic Electrochemical Transistors

AbstractThe ability to operate in aqueous environments makes poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, based organic electrochemical transistors (OECTs) excellent candidates for a variety of biological applications. Current research in PEDOT:PSS based OECTs is primarily focused on improving the conductivity of PEDOT:PSS film to achieve high transconductance (gm). The improved conductivity and electronic transport are attributed to the formation of enlarged PEDOT‐rich domains and shorter PEDOT stacking, but such a change in morphology sacrifices the ionic transport and, therefore, the doping/de‐doping process. Additionally, little is known about the effect of such morphology changes on the gate bias that makes the maximumgm(), threshold voltage (VT), and transient behavior of PEDOT:PSS based OECTs. Here, the molecular packing and nanostructure of PEDOT:PSS films are tuned using ionic liquids as additives, namely, 1‐Ethyl‐3‐methylimidazolium (EMIM) as cation and anions of chloride (Cl), trifluoromethanesulfonate (OTF), bis(trifluoromethylsulfonyl)imide (TFSI), and tricyanomethanide (TCM). It is demonstrated that an optimal morphology is realized using EMIM OTF ionic liquids that generate smaller fibril‐like PEDOT‐rich domains with relatively loose structures. Such optimal morphology improves ion accessibility, lowering the gate bias required to completely de‐dope the channel, and thus enabling to achieve high transconductance, fast transient response, and at lower gate bias window simultaneously.

Carbon Nanofiber/PEDOT Based Macro-Porous Composite for High Performance Multifunctional Neural Microelectrode

Brain study methods mainly rely on neurochemical detection and electrophysiology, respectively studying the molecular dynamics and electrical activity in the brain cellular environment. The combined and simultaneous use of both study modes holds great promises for patients and researchers, in line with the treatment research but rely on multifunctional platforms (materials, devices, techniques…) still to be developed. Here, we present a new macro-porous composite material made up of PEDOT and carbon nanofibers (CNFs), coated on a flexible neural microelectrode array. A fully controlled one-shot electrodeposition strategy was developed to coat flexible Au-microelectrode surfaces with macro-porous CNF/PEDOT nanocomposite. The oxidized CNFs were used as a dopant and infused within the conductive PEDOT, electrochemically, in such a way that their excellent electronic, mechanical, chemical properties, and resulting combined performances can be exploited to yield better quality neural recordings, electrical stimulation and neurotransmitter detection.

High‐Efficiency Stable Flexible Organic Solar Cells with PEDOT:PSS Electrodes via Superacid Fumigation Treatment

Strong acid treatment is regarded as the most effective approach to increase the electrical conductivity of poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) electrodes. However, the conventional soaking treatments of strong acids have drawbacks, including limited flexibility of PEDOT:PSS electrodes coated on thermoplastic underlying substrates, high preparation cost with large acid consumption, and moderate stability of flexible organic solar cells (OSCs). Herein, a unique and cost‐effective fumigation treatment using trifluoromethanesulfonic acid (CF3SO3H) vapors is proposed. The CF3SO3H fumigation treatment leads to a highly conductive, smooth, homogeneous, and flexible PEDOT:PSS electrode. On the basis of the CF3SO3H‐fumigated PEDOT:PSS electrodes, the inverted flexible OSCs yield a high power conversion efficiency (PCE) of 13.62%. Moreover, the flexible solar cells maintain most (≈91%) of the initial efficiency in long‐term storage. This work provides a novel route to make solution‐processed flexible OSCs simultaneously have a high PCE and good storage stability.

Low‐Work‐Function PEDOT Formula as a Stable Interlayer and Cathode for Organic Solar Cells

AbstractCathode with low work‐function (WF) is a vital unit in optoelectronic devices. Yet, the stable cathode is still a big challenge. Here, PEDOT:PSS‐TBA is reported among series of PEDOT:PSS‐M, where PEDOT:PSS denotes poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate), M refers to monovalent cation and TBA is tetrabutylammonium specifically, as a stable cathode. The PEDOT:PSS‐TBA is synthesized via ion exchange with WF of 4.1–4.2 eV and its conductivity can be improved to 300 S cm−1 by the additive. Meanwhile, PEDOT:PSS‐TBA is stable even under plasma, heat, or isopropanol sonication. Organic solar cells (OSCs) are fabricated with indium tin oxide (ITO)/PEDOT:PSS‐TBA and highly conductive PEDOT:PSS‐TBA (with additive, hc‐PEDOT:PSS) electrodes respectively. The OSCs display superior stability than the reference with ITO/ZnO as the cathode. As a proof of concept, solution‐processed OSCs are demonstrated with a three‐layered structure (hc‐PEDOT:PSS‐TBA/active layer/PEDOT:PSS), which proves PEDOT:PSS‐TBA as a promising cathode for printable optoelectronic with a simplified structure.

A Cu2O/PEDOT/graphene-modified electrode for the enzyme-free detection and quantification of glucose

• Cu 2 O/PEDOT/rGO/GCE were fabricated by a simple electrodeposition process. • Cu 2 O/PEDOT/rGO/GCE displayed showed excellent glucose detection activity. • The unique PEDOT/rGO structure enhanced the glucose oxidation activity of Cu 2 O. A cuprous oxide decorated poly(3,4-ethylenedioxythiophene) multi-layer graphene modified glassy carbon electrode (Cu 2 O/PEDOT/rGO/GCE) was fabricated via a stepwise electrodeposition process, then used as a non-enzymatic sensor for glucose detection. The structure and morphology of Cu 2 O/PEDOT/rGO film were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical tests showed that the Cu 2 O/PEDOT/rGO/GCE offered excellent performance for the detection of glucose, including high sensitivity of 4700 μA cm −2 mM −1 in the linear range from 0.004 to 3.2 mM, and low detection limit of 0.14 μM. These results suggest that Cu 2 O/PEDOT/rGO/GCE is an outstanding non-enzymatic sensor for the detection of glucose. The excellent response can be attributed to the unique multi-layered graphene structure of the modified electrode, in which highly conductive PEDOT enhances the electrocatalytic oxidation activity of cuprous oxide nanoparticles.

Conductive PEDOT:PSS/cellulose nanofibril paper electrodes for flexible supercapacitors with superior areal capacitance and cycling stability

PEDOT:PSS has been widely used as the electrode materials for supercapacitors. However, processing PEDOT:PSS bulk films with good flexibility and mechanical stability is still challenging. The present study is aimed at providing a facile and low-cost strategy for the preparation of mechanically strong and conductive PEDOT:PSS based bulk films by using Cellulose nanofibrils (CNF) as building blocks. PEDOT:PSS/CNF suspension was firstly prepared via a simple in situ polymerization process. Afterwards, flexible and conductive PEDOT:PSS/CNF nanopaper (PEDOT:PSS/CNP) were prepared from the PEDOT:PSS/CNF suspension by vacuum filtration and Dimethyl sulfoxide (DMSO) post-treatment. Results showed that the optimized PEDOT:PSS/CNP exhibited excellent flexibility, high tensile strength (72 MPa), and high electrical conductivity (66.67 S/cm). Finally, a symmetric supercapacitor was assembled using the PEDOT:PSS/CNP as electrodes. The assembled supercapacitor could deliver the maximum areal specific capacitance of 854.4 mF cm−2 (corresponding to 122.1F cm−3) at 5 mV/s and offer the highest areal energy density of 30.86 μWh cm−2 (corresponding to 4.41 mWh cm−3), which are among the highest values reported for PEDOT:PSS based supercapacitors. More importantly, the assembled supercapacitor showed remarkable cycling stability with the capacitance retention of 95.8% after 10,000 charge/discharge cycles. Considering the good mechanical properties and excellent electrochemical performance, the PEDOT:PSS/CNP could be a promising electrode material for flexible supercapacitors.