L-Dopa Synthesis on Conducting Polymers

With regards to the synthesis of L-Dopa (l-3,4-dihydroxy phenylalanine) two types of biosensors were designed by immobilizing tyrosinase on conducting polymers; polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT). PPy and PEDOT were synthesized electrochemically and tyrosinase immobilized by entrapment during electropolymerization. The kinetic parameters of the designed biosensors, maximum reaction rate of the enzyme (V_max) and Michaelis Menten constant (K_m) were determined. V_max were found as 0.013 for PPy matrix and 0.041 μ mol/min.electrode for PEDOT matrix. K_m values were determined as 3.7 and 5.2mM for PPy and PEDOT matrices respectively. Calibration curves for enzyme activity vs. substrate concentration were drawn for the range of 0.8 to 2.5 mM L-Tyrosine. Optimum temperature and pH, operational and shelf life stabilities of immobilized enzyme were also examined.     

Conductivity enhancement of PEDOT:PSS film via sulfonic acid modification: application as transparent electrode for ITO-free polymer solar cells

3-Hydroxy-1-propanesulfonic acid(HPSA)was applied as a modification layer on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)film via spin-coating,resulting in a massive boost of the conductivity of PEDOT:PSS film,and thus the as-formed PEDOT:PSS/HPSA bilayer film was successfully used as a transparent electrode for ITO-free polymer solar cells(PSCs).Under the optimized concentration of HPSA(0.2 mol L~(-1)),the PEDOT:PSS/HPSA bilayer film has a conductivity of 1020 S cm~(-1),which is improved by about 1400 times of the pristine PEDOT:PSS film(0.7 S cm~(-1)).The sheet resistance of the PEDOT:PSS/HPSA bilayer film was 98Ωsq~(-1),and its transparency in the visible range was over 80%.Both parameters are comparable to those of ITO,enabling its suitability as the transparent electrode.According to atomic force microscopy(AFM),UV-Vis and Raman spectroscopic measurements,the conductivity enhancement was resulted from the removal of PSS moiety by methanol solvent and HPSA-induced segregation of insulating PSS chains along with the conformation transition of the conductive PEDOT chains within PEDOT:PSS.Upon applying PEDOT:PSS/HPSA bilayer film as the transparent electrode substituting ITO,the ITO-free polymer solar cells(PSCs)based on poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]:[6,6]-phenyl C71-butyric acid methyl ester(PC_(71)BM)(PCDTBT:PC_(71)BM)active layer exhibited a power conversion efficiency(PCE)of 5.52%,which is comparable to that of the traditional ITO-based devices.     

Physical Interpretation of Mixed Ionic-electronic Conductive Polymer-coated Electrodes by a Simple Universal Impedance Model

A simple equivalent electrical circuit is used to obtain the physical parameters of electrical circuit elements from measured electrochemical impedance spectra. This model consists of four circuit elements with a clear physical meaning for each of the elements. Compared to complex models with multiple constant phase elements or Warburg impedances, our model is suitable for extracting physical values for important electrode parameters with low errors. The feasibility of the model was shown by investigating pure metal or polymer-coated electrodes. Here, gold electrodes were coated either with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT : PSS), Polypyrrole:poly(styrenesulfonate) (PPy : PSS), or (PEDOT/PPy) : PSS by means of electropolymerization. The model could demonstrate the ionic-electronic differences such as the ion accessibility of the differently coated electrodes. To prove the correctness of the model, the obtained results were compared to the literature.     

左旋多巴和N,N-二甲基亚砜共掺杂PEDOT:PSS作为空穴传输层的高性能p-i-n型钙钛矿太阳能电池

在p-i-n型的钙钛矿太阳能电池中,聚3, 4-乙烯二氧噻吩：聚苯乙烯磺酸盐(PEDOT:PSS)作为最常用的空穴传输层(HTL)材料之一,由于其存在着吸湿性强以及能级与钙钛矿层不匹配等缺点,限制了它的应用。基于此,本文拟采用将左旋多巴(DOPA)和N, N-二甲基亚砜(DMSO)共同掺杂于PEDOT:PSS作为HTL的简单方法制备高性能p-i-n型钙钛矿太阳能电池。研究结果表明,DOPA和DMSO共掺杂PEDOT:PSS可以有效的调节HTL的能级并提高其导电性,器件的能量转化效率由13.35%显著提高到了17.54%。进一步研究发现,相比于未掺杂或单一掺杂的PEDOT:PSS,在DOPA和DMSO共掺杂的PEDOT:PSS上更有利于生长大尺寸、高结晶度的钙钛矿晶体;同时稳态/瞬态荧光和交流阻抗测试表明器件的内部载流子分离和传输更加有效。     

Synthesis of Poly(3,4‐ethylenedioxythiophene) latexes using poly(N‐vinylpyrrolidone)‐based copolymers as reactive stabilizers

The synthesis by oxidative polymerization of well‐defined poly(3,4‐ethylenedioxythiophene) (PEDOT) nano‐objects in the presence of modified and unmodified poly(N‐vinylpyrrolidone)‐based copolymers used as stabilizers in aqueous media is reported. Ammonium persulfate or a mixture of ammonium persulfate with CuCl₂ or CuBr₂ was used as oxidants. The effects of several parameters such as the molar mass and the concentration of the stabilizer as well as the nature of the oxidants on the size, morphology, and the conductivity of the PEDOT particles have been investigated. The distribution of the reactive moieties along the copolymer stabilizer backbone was shown to be crucial to get well‐defined PEDOT nano‐objects. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3841–3855, 2010     

Polymer Optoelectronic Devices with High‐Conductivity Poly(3,4‐Ethylenedioxythiophene) Anodes

Abstract

The conductivity of poly(3,4‐ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) film can be enhanced by more than two orders in magnitude by adding a compound with two or more polar groups, such as ethylene glycol (EG), meso‐erythritol (IUPAC name: 1,2,3,4‐tetrahydroxybutane), or 2‐nitroethanol, into the PEDOT:PSS aqueous solution. The mechanism of the increase in conductivity for PEDOT:PSS has been studied using Raman spectroscopy and atomic force microscope (AFM). Here we propose that the change in conductivity is due to the conformational change of PEDOT chains in the film. In untreated PEDOT:PSS films, coil, linear, or expanded‐coil conformations of the PEDOT chains may be present. In treated PEDOT:PSS films, the linear or expanded‐coil conformations may becomes the dominant form for PEDOT chains. This conformational change results in the enhancement of charge‐carrier mobility in the film and leads to enhanced conductivity. The high‐conductivity PEDOT:PSS film is ideal as the electrode for polymer optoelectronic devices. In this article, we report on the fabrication of polymer light‐emitting diodes (PLEDs) and photovoltaic cells (PVs) made using a highly conductive form of PEDOT:PSS as anode, and we demonstrate its performance relative to that of similar device using indium‐tin oxide (ITO) as the anode.     

Influence of doped anions on poly(3,4-ethylenedioxythiophene) as hole conductors for iodine-free solid-state dye-sensitized solar cells

Poly(3,4-ethylenedioxythiophene) (PEDOT) is an excellent hole-conducting polymer able to replace the liquid I(-)/I3(-) redox electrolyte in dye-sensitized solar cells (DSCs). In this work we applied the in situ photoelectropolymerization technique to synthesize PEDOT and carried out a careful analysis of the effect of different doping anions on overall solar cell performance. The anions analyzed in this work are ClO4(-), CF3SO3(-), BF4(-), and TFSI(-). The best solar cell performance was observed when the TFSI(-) anion was used. Photoelectrochemical and impedance studies reveal that the doped anions in the PEDOT hole conductor system have great influences on I-V curves, conductivity, and impedance. The optimization of these parameters allowed us to obtain an iodine-free solid-state DSC with a maximum J(sc) of 5.3 mA/cm2, V(oc) of 750 mV, and a conversion efficiency of 2.85% which is the highest efficiency obtained so far for an iodine-free solid-state DSC using PEDOT as hole-transport material.     

Emulsion synthesis of nanoparticles containing PEDOT using conducting polymeric surfactant: Synergy for colloid stability and intercalation doping

Poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) is a widely used conductive aqueous dispersion synthesized by using emulsion polymerization method. To further enhance its solution processability and conductivity of PEDOT derivatives, we proposed to replace the nonconductive PSS with conductive poly[2‐(3thienyl)‐ethoxy‐4‐butylsulfonate] (PTEB) as surfactant for the emulsion polymerization of PEDOT. The reaction involved colloid stabilization and doping in one step, and yielded PEDOT:PTEB composite nanoparticles with high electrical conductivity. Contrary to its counterpart containing nonconductive surfactant, PEDOT: PTEB showed increasing film conductivity with increasing PTEB concentration. The result demonstrates the formation of efficient electrical conduction network formed by the fully conductive latex nanoparticles. The addition of PTEB for EDOT polymerization significantly reduced the size of composite particles, formed stable spherical particles, enhanced thermal stability, crystallinity, and conductivity of PEDOT:PTEB composite. Evidence from UV–VIS and FTIR measurement showed that strong molecular interaction between PTEB and PEDOT resulted in the doping of PEDOT chains. X‐ray analysis further demonstrated that PTEB chains were intercalated in the layered crystal structure of PEDOT. The emulsion polymerization of EDOT using conducting surfactant, PTEB demonstrated the synergistic effect of PTEB on colloid stability and intercalation doping of PEDOT during polymerization resulting in significant conductivity improvement of PEDOT composite nanoparticles. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2536–2548, 2008     

Free-Standing,Flexible Nanofeatured Polymeric Films Prepared by Spin-Coating and Anodic Polymerization as Electrodes for Supercapacitors

Flexible and self-standing multilayered films made of nanoperforated poly(lactic acid) (PLA) layers separated by anodically polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) conducting layers have been prepared and used as electrodes for supercapacitors. The influence of the external layer has been evaluated by comparing the charge storage capacity of four- and five-layered films in which the external layer is made of PEDOT (PLA/PEDOT/PLA/PEDOT) and nanoperforated PLA (PLA/PEDOT/PLA/PEDOT/PLA), respectively. In spite of the amount of conducting polymer is the same for both four- and five-layered films, they exhibit significant differences. The electrochemical response in terms of electroactivity, areal specific capacitance, stability, and coulombic efficiency was greater for the four-layered electrodes than for the five-layered ones. Furthermore, the response in terms of leakage current and self-discharge was significantly better for the former electrodes than for the latter ones.     

Enzymatic‐catalyzed polymerization of water‐soluble electrically conductive polymer PEDOT:PSS

Water‐soluble electrically conductive polymer poly(3,4‐ethylenedioxythiophene) (PEDOT) was synthesized by the enzymatic‐catalyzed method using 3,4‐ethylenedioxythiophene (EDOT) as monomer, poly(styrenesulfonate) (PSS) as water‐soluble polyelectrolyte, horseradish peroxidase enzyme as catalyst, and hydrogen peroxide (H₂O₂) as oxidant. Fourier transform infrared spectra and UV–vis absorption spectra confirm the successful enzymatic‐catalyzed polymerization of PEDOT. Dynamic light scattering data confirm the formation of a stable PEDOT:PSS aqueous dispersion. The thermo gravimetric data show that the obtained PEDOT is stable over a fairly high range of temperatures. The atomic force microscopy height images show that the PEDOT:PSS aqueous dispersion can form excellent homogeneous and smooth films on various substrates by conventional solution processing techniques, which renders this PEDOT:PSS aqueous dispersion a very promising candidate for various application in electronic devices. This enzymatic polymerization is a new approach for the synthesis of optical and electrical active PEDOT polymer, which benefits simple setting, high yields, and environmental friendly route. Copyright © 2014 John Wiley & Sons, Ltd.     

Electrochemical synthesis of poly(3,4‐ethylenedioxythiophene) nanotube arrays using ZnO templates

A new method toward vertically oriented poly(3,4‐ethylenedioxythiophene) (PEDOT) nanotube arrays on transparent conductive oxide substrates is presented. The approach is based on the use of ZnO nanowire arrays as templates for the electropolymerization of PEDOT. Robust arrays of vertically oriented PEDOT nanotubes with different lengths and wall thicknesses were obtained by modifying the ZnO nanowire length and charge density passed during the electropolymerization, respectively. Furthermore, PEDOT nanotubes with different morphologies (top‐closed and mushroom‐like) were successfully designed by varying the PEDOT electropolymerization kinetics or monomer diffusion or both. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and electro‐optical characterization of new conducting PEDOT/Au‐nanorods nanocomposites

This paper describes a new strategy to obtain PEDOT/Au‐nanorods nanocomposites with different PEDOT: Au ratio. A polymeric ionic liquid (PIL) was used as stabilizer during the chemical synthesis of PEDOT dispersions. PEDOT/Au‐nanorods dispersions in organic media were obtained. Electrochemical characterization of PEDOT/Au‐nanorods nanocomposites revealed that the addition of Au nanorods modified the electroactivity of the conducting films by reducing the oxidation potential from +0.33 to +0.23 V (versus Ag/AgCl). Optical contrast (ΔT%) of the films decreased from 17% for neat PEDOT films to 8% for PEDOT/Au‐nanorods nanocomposites films (3:1 (v/v)) while switching times (from 1 to 4 sec) were similar to neat PEDOT. Conductivity of the films increased from 0.027 S/cm for neat PEDOT to 0.691 S/cm for PEDOT/Au‐nanorods nanocomposites. Nanoscale morphology and contact potential of PEDOT/Au‐nanorods nanocomposites were investigated in detail by Scanning Force Microscopy. Electrical measurements show a clear contact potential difference between the ITO substrate and the PEDOT/Au‐nanorods film. On the film, no contact potential inhomogeneity is observed indicating that the Au‐nanorods are uniformly dispersed in the film. Copyright © 2010 John Wiley & Sons, Ltd.     

Poly(pyrrole) versus poly(3,4-ethylenedioxythiophene): amperometric cholesterol biosensor matrices

Two conducting polymers, poly(pyrrole) (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) were used as immobilization matrices for cholesterol oxidase (ChOx). The amperometric responses of the enzyme electrodes were measured by monitoring oxidation current of H₂O₂ at +0.7 V in the absence of a mediator. Kinetic parameters, such as K _m and I _max, operational and storage stabilities, effects of pH and temperature were determined for both entrapment supports. K _m values are found as 7.9 and 1.3 mM for PPy and PEDOT enzyme electrodes, respectively; it can be interpreted that ChOx immobilized in PEDOT shows higher affinity towards the substrate.     

Synthesis of high performance,conductive PEDOT‐coated polyester yarns by OCVD technique

Production of high performance conductive textile yarn fibers for different electronic applications has become a prominent area of many research groups throughout the world. We have used oxidative chemical vapor deposition (OCVD) technique to coat flexible and high strength polyester yarns with conjugated polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT) in presence of ferric (III) chloride (FeCl₃) oxidant. OCVD is an efficient solvent free technique used to get uniform, thin, and highly conductive polymer layers on different substrates. In this paper, PEDOT‐coated polyester (PET) yarns were prepared under specific reaction conditions, and the electrical, mechanical and thermal properties were compared to previously studied PEDOT‐coated viscose yarns. Scanning electron microscopy (SEM) and FT‐IR analysis revealed that polymerization of PEDOT on the surface of the polyester yarns has been taken place successfully and structural analysis showed that PEDOT has strong interactions with viscose yarns as compared to PET yarns. The voltage–current (V–I) characteristics showed that PET yarns are more conductive than PEDOT‐coated viscose yarns. The variation in the conductivity of PEDOT‐coated yarns and the heat generation properties during the flow of current through coated yarns for longer period of time, was studied by time–current (t–I) characteristics. Thermogravimeteric analysis (TGA) was employed to investigate the thermal properties and the amount of PEDOT in PEDOT‐coated PET yarns compared to PEDOT‐coated viscose. The effect of PEDOT coating and ferric (III) chloride concentration on the mechanical properties of coated yarns was evaluated by tensile testing. The obtained PEDOT‐coated conductive polyester yarns could be used in smart clothing for medical and military applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Electrochemistry of conductive polymers 38. Electrodeposited poly(3,4-ethylenedioxy-thiophene) studied by current sensing atomic force microscopy

Electrical and morphological properties of poly(3,4-ethylenedioxythiophene) (PEDOT) thin films electrodeposited on gold-on-silicon electrodes by galvanostatic, potentiostatic, and potentiodynamic methods have been determined using current sensing atomic force microscopic experiments. Surface morphologies and vertical conductivities of PEDOT films were affected by the experimental parameters including the preparation method, the current density, the potential, and the potentiodynamic cyclic number. Band gaps obtained from current-voltage curves of dedoped PEDOT were in excellent agreement with those obtained from absorption spectra. When the film thickness was increased on the gold-on-silicon electrode, the topographic images were not very well defined due to the high roughness but conductivities increased significantly in all the galvanostatically, potetiostatically, and potentiodynamically grown PEDOT films.     

聚(3,4-乙烯二氧噻吩):聚苯乙烯磺酸盐热电性能的 提升策略研究进展

近十年,有机聚合物及其复合热电材料与柔性器件取得了显著进展,在废热回收利用、可穿戴电子学、软体机器人和物联网等领域有广泛的应用.其中,聚(3,4-乙烯二氧噻吩):聚苯乙烯磺酸(PEDOT:PSS)是迄今研究最多也是性能最高的聚合物体系.本文对近年来有关PEDOT:PSS热电性能有效提升主要策略的文献报道进行了总结.首先,从PEDOT:PSS的二次掺杂/去掺杂、酸或碱处理和离子液体处理方面等,重点论述了掺杂/去掺杂策略的研究进展;然后,分别从改善聚集态结构、构筑PEDOT微纳米结构和与碳纳米材料复合等3个方面,重点介绍了采用此3种策略提升PEDOT:PSS热电性能的研究进展;最后,对该领域进行总结,提出了开展进一步研究的建议,并对其未来发展前景进行展望.     

Preparation and spectroelectrochemical characterization of composite films of poly(3,4-ethylenedioxythiophene) with 4-(pyrrole-1-yl) benzoic acid

The possibility of incorporation of 4-(pyrrole-1-yl) benzoic acid, PyBA, during electrodeposition of poly(3,4-ethylenedioxythiophene), PEDOT, is demonstrated here. The resulting novel composite material has been fabricated as moderately thin (ca 200–300 nm thick) PEDOT/PyBA film on electrode surface. As evidenced from scanning tunneling microscopy (STM) and scanning electron microscopy (SEM), morphology of the composite film is dense and granular, and it is composed of larger granules in comparison to the PyBA-free PEDOT film. It is apparent from infrared reflectance absorption spectroscopy and spectroelectrochemical measurements that the PEDOT/PyBA composite film cannot be viewed as simple mixtures of PEDOT and PyBA components. Some specific (chemical) interactions between PEDOT and PyBA can be expected. The conducting polymer serves as a robust, positively charged conductive polmer matrix for anionic (carboxylate-group derivatized) partially polymerized PyBA structures. Upon incorporation of PyBA, the overall stability of PEDOT film (resistance to dissolution during prolonged voltammetric potential cycling) has been improved. The fact, that the composite PEDOT/PyBA film is capable of preconcentrating (under open circuit conditions) both cations (Cu²⁺) or anions implies the presence of both free (available for binding) carboxylate groups and positively charged PEDOT sites. The presence of PyBA in PEDOT seems to facilitate charge propagation in the composite film. “Contribution to the International Workshop on Electrochemistry of Electroactive Materials (WEEM-2006), Repino, Russia, 24–29 June 2006”.     

Deposition of Au and Ag nanoparticles on PEDOT

The deposition of Au and Ag, locally and from bulk solution, on poly(3,4-ethylenedioxythiophene) (PEDOT) was studied. Specifically, PEDOT was electrochemically polymerized onto a glassy carbon (GC) electrode and used for bulk deposition of Au and Ag from their respective ions dissolved in the solution as well as for the local deposition of these metals using scanning electrochemical microscopy (SECM). These two sets of experiments were utilized to investigate the difference between Au and Ag electrochemical deposition on PEDOT. In particular, SECM experiments, which were conducted by the controlled anodic dissolution of Au and Ag microelectrodes close to GC/PEDOT, probed the effect of different PEDOT oxidation states on local deposition. The current-time transients recorded during the deposition, combined with scanning electron microscopy and EDX analysis provided insight into the reduction processes. AuCl(4)(-) and Ag(+) ions were electrochemically reduced at a potential equal to and more negative than the ions redox potentials (0.4 and 0.2 V, respectively) and more positive than -0.7 V, where the PEDOT starts transforming into the reduced, i.e. insulating, state. We found that the electroreduction of Ag(+) ions was diffusion-controlled and the PEDOT film served as a simple conductor. On the other hand, the reduction of AuCl(4)(-) ions was enhanced on GC/PEDOT as compared with bare GC, indicating that PEDOT catalyzes the reduction of AuCl(4)(-) to Au.     

New CNT/poly(brilliant green) and CNT/poly(3,4-ethylenedioxythiophene) based electrochemical enzyme biosensors

A combination of the electroactive polymer poly(brilliant green) (PBG) or conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) with carbon nanotubes to obtain CNT/PBG and CNT/PEDOT modified carbon film electrodes (CFE) has been investigated as a new biosensor platform, incorporating the enzymes glucose oxidase (GOx) as test enzyme, alcohol oxidase (AlcOx) or alcohol dehydrogenase (AlcDH). The sensing parameters were optimized for all biosensors based on CNT/PBG/CFE, CNT/PEDOT/CFE platforms. Under optimized conditions, both GOx biosensors exhibited very similar sensitivities, while in the case of AlcOx and AlcDH biosensors, AlcOx/CNT/PBG/CFE was found to give a higher sensitivity and lower detection limit. The influence of dissolved O₂ on oxidase-biosensor performance was investigated and was shown to be different for each enzyme. Comparisons were made with similar reported biosensors, showing the advantages of the new biosensors, and excellent selectivity against potential interferents was successfully demonstrated. Finally, alcohol biosensors were successfully used for the determination of ethanol in alcoholic beverages.     

Preparation and Characterization of Carbon Nano‐Onion/PEDOT:PSS Composites

Composites of unmodified or oxidized carbon nano‐onions (CNOs/ox‐CNOs) with poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are prepared with different compositions. By varying the ratio of PEDOT:PSS relative to CNOs, CNO/PEDOT:PSS composites with various PEDOT:PSS loadings are obtained and the corresponding film properties are studied as a function of the polymer. X‐ray photoelectron spectroscopy characterization is performed for pristine and ox‐CNO samples. The composites are characterized by scanning and transmission electron microscopy and differential scanning calorimetry studies. The electrochemical properties of the nanocomposites are determined and compared. Doping the composites with carbon nanostructures significantly increases their mechanical and electrochemical stabilities. A comparison of the results shows that CNOs dispersed in the polymer matrices increase the capacitance of the CNO/PEDOT:PSS and ox‐CNO/PEDOT:PSS composites.