Control of Thickness of PEDOT Electrodeposits on Glass/ITO Electrodes from Organic Solutions and its Use as Anode in Organic Solar Cells

Poly-ethylendioxythiophene (PEDOT) was electropolymerized from the monomer EDOT in acetonitrile (ACN) containing Bu₄N⁺ClO₄^-, BF₄^- or PF₆^- ions as supporting electrolyte. The electrode used was transparent electrodes (Glass/ITO) in order to generate the anode of an organic solar cell (OSC). Potentiodynamic and potentiostatic electropolymerization techniques were used to make the conducting polymer deposits (E-PEDOT), which were obtained as a thin film onto the ITO surface. It was possible to control the thickness of the electrodeposited films in the range of 15 to 200 nm measured by AFM. With the thinner films (until 100 nm), it was observed that its absorbance at 700 nm was linearly dependent with their thickness and it was possible to obtain an equation that was used to measure the films thickness of future experiments. The E-PEDOT films were successfully used for constructing OSC's and the efficiency values found were equivalent or slightly superior to those found with the classical PEDOT:PSS anode.     

An effective approach to enhanced thermoelectric properties of PEDOT:PSS films by a DES post‐treatment

As conventional organic solvents present inherent toxicity, deep eutectic solvents (DES) have been considered as excellent candidates due to their green characteristics. In this work, thermoelectric properties enhancement of PEDOT:PSS films is achieved by introducing DES as an additive and post‐treatment reagent. Direct addition and post‐treatment approaches lead to a maximum Seebeck coefficient of 29.1 μV K^?1 and electrical conductivity of 620.6 S cm^?1, respectively. In addition, an optimal power factor is obtained by DES post‐treatment, reaching up to 24.08 μW m^?1 K^?2, which is approximately four orders of magnitude higher than the pure PEDOT:PSS. Assuming a thermal conductivity of 0.17 W m^?1 K^?1, the maximum ZT value is estimated to be 0.042 at 300 K. Further, atomic force microscopy and X‐ray photoelectron spectroscopy are performed and suggest that the remarkably enhanced electrical conductivity originates from the removal of the excess insulating PSS and the phase separation between the PEDOT and PSS chains. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 885–892     

Influence of imidazole‐based acidity control of PEDOT:PSS on its electrical properties and environmental stability

Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been studied for a wide range of applications due to its potential as a transparent electrode. Herein, the use of imidazole and its derivatives as a neutralizing additive for PEDOT:PSS dispersion and in‐depth studies of their effects in terms of electrical properties and stability is reported. Although the neutralization in general reduces the electrical conductivity of PEDOT:PSS, the conductivity after imidazole treatment (685.2 S cm^?1) is higher than that after treatment of other derivatives. Spectroscopic and thermoelectric studies show that the de‐doping effect resulted in the conductivity reduction. As a trade‐off of the conductivity reduction, greatly enhanced long‐term stability and noncorrosive characteristics are obtained after neutralization. The change in sheet resistance of imidazole‐treated PEDOT:PSS after 500 h under harsh conditions (85 °C and 85% humidity) is half that of the untreated samples, demonstrating the great enhancement of the stability. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1530–1536     

Enhanced functionalities of DNA thin films by facile conjugation with conducting polymers

In this study, we discuss a method to embed PEDOT:PSS into DNA with a designated concentration of PEDOT:PSS and construction of PEDOT:PSS-embedded DNA thin films. In order to shed light on the interaction between PEDOT:PSS and DNA, optical spectroscopy measurements were performed. DNA-PEDOT:PSS thin films showed a broad absorption band around 800 nm which was associated with PEDOT:PSS. The electrical properties of DNA-PEDOT:PSS thin films were assessed. A significant enhancement in current for DNA-PEDOT:PSS thin films DNA was observed which agreed with the decrement in band gap of DNA-PEDOT:PSS thin films. For the energy storage capability and dielectric constant of DNA-PEDOT:PSS thin films, capacitance measurements were conducted. Frequency-dependent capacitance indicated enhancement in the capacitance and dielectric constant by electric polarization of PEDOT:PSS in a DNA thin film. Our approach may assist in development of various biosensors and electronic devices with specific functionalities based on biomaterials and conducting polymer complexes.     

PEDOT‐Modified Microelectrodes. Preparation,Characterisation and Analytical Performances

Poly(3,4‐ethylenedioxythiophene) (PEDOT) modified microelectrodes were prepared by electropolymerisation of the relevant monomer from CH₃CN or H₂O solutions. The electrochemical behaviour of the obtained coatings was investigated by cyclic voltammetry in both organic and aqueous media. The anodic responses obtained for a typical benchmark analyte such as ascorbic acid was used to test the different coatings; calibration curves were built up in order to evaluate the repeatability of the response and the reproducibility of the prepared sensing system. Moreover, the ability of the modified microelectrodes to work in low conductivity media was studied, and exploratory tests in dense food matrix was performed.     

Highly enhanced thermoelectric performance of WS2 nanosheets upon embedding PEDOT:PSS

Two‐dimensional (2D) WS₂ nanosheets (NSs) as a promising thermoelectric (TE) material have gained great concern recently. The low electrical conductivity significantly limits its further development. Herein, we reported an effective method to enhance the TE performance of WS₂ NSs by combining poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS). The restacked WS₂ NSs thin film with 1T phase structure obtained by a common chemical lithium intercalation show a high Seebeck coefficient of 98 μV K^?1 and a poor electrical conductivity of 12.5 S cm^?1. The introduction of PEDOT:PSS with different contents obviously improve the electrical conductivity of WS₂ NSs thin films. Although a declining Seebeck coefficient was observed, an optimized TE power factor of 45.2 μW m^?1 k^?1 was achieved for WS₂/PEDOT:PSS composite thin film. Moreover, the as‐prepared WS₂/PEDOT:PSS thin film can be easily peeled off and transferred to other substrate leading to a more promising application. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 997–1004     

Systematic study on chemical oxidative and solid‐state polymerization of poly(3,4‐ethylenedithiathiophene)

Systematic research on the synthesis, chemical oxidative polymerization of 3,4‐ethylenedithiathiophene (EDTT) in the presence of surfactants or not, and solid‐state polymerization of 2,5‐dibromo‐3,4‐ethylenedithiathiophene (DBEDTT) and 2,5‐diiodo‐3,4‐ethylenedithiathiophene (DIEDTT) under solventless and oxidant‐free conditions has been investigated. Effects of oxidants (Fe³⁺ salts, persulfate salts, peroxides, and Ce⁴⁺ salts), solvents (H₂O, CH₃CN/H₂O, and CH₃CN), surfactants, and so forth on polymerization reactions and properties of poly(3,4‐ethylenedithiathiophene) (PEDTT) were discussed. Characterizations indicated that FeCl₃ was more suitable oxidant for oxidative polymerization of EDTT, while CH₃CN was a better solvent to form PEDTT powders with higher yields and electrical conductivities. Dispersing these powders in aqueous polystyrene sulfonic acid (PSSH) solution showed better stability and film‐forming property than sodium dodecylsulfate and sodium dodecyl benzene sulfonate. Oxidative polymerization of EDTT in aqueous PSSH solutions formed the solution processable PEDTT dispersions with good storing stability and film‐forming performance. Solvent treatment showed indistinctive effect on electrical conductivity of free‐standing PEDTT films. As‐formed PEDTT synthesized from solid‐state polymerization showed similar electrical conductivity, poorer stability, but better thermoelectric property than oxidative polymerization. Contrastingly, PEDTT synthesized from DIEDTT showed higher electrical conductivity (0.18 S cm^?1) than DBEDTT which showed better thermoelectric property with higher power factor value (6.7 × 10^?9 W m^?1 K^?2). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Ionic liquid assisted growth of poly(3,4-ethylenedioxythiophene)/reduced graphene oxide based electrode: An improved electro-catalytic performance for the detection of organophosphorus pesticides in beverages

An enzyme based nanocomposite host matrix comprising of Poly(3,4-ethylenedioxythiophene) and 1-Butyl-3-methylimidazolium trifluoromethanesulfonate based ionic liquid functionalized reduced graphene oxide (PEDOT/ILRGO) has been designed for the electrochemical detection of organophosphorus pesticides (OPs). Interactions between reduced graphene oxide and ionic liquid have resulted in better loading of the same onto the PEDOT matrix. A detail redox analysis highlights the increased surface area and more number of charge carriers enabling the redox inhibition mechanism more efficient in the designed electrode. The biosensor works on the principle of generation of thiocholine by reaction between acetylcholinesterase (AChE) and substrate acethylthiocholine iodide (ATChI), which undergoes oxidation resulting in redox peaks. Under the optimized conditions, three different OPs chlorpyrifos (CP), malathion (ML) and methyl parathion (MP) were analyzed by varying concentrations with limit of detection calculated to be 0.04 ng ml⁻¹, 0.117 ng ml⁻¹ and 0.108 ng ml⁻¹ respectively, all below 0.2 µg ml⁻¹ concentration which is their maximum residual limit, hence exhibiting good sensitivity. The prepared sensor offers 91.7% of reactivation and good stability for 15–20 days with 95.7% of initial current response retainment, reflecting its excellent potency as an organophosphorus pesticide sensor.     

Voltammetric Determination of L‐Dopa on Poly(3,4‐ethylenedioxythiophene)‐Single‐Walled Carbon Nanotube Composite Modified Microelectrodes

In the present communication, it is shown that platinum microelectrodes electrochemically coated with a composite of poly(3,4‐)ethylenedioxythiophene and single‐walled carbon nanotubes (PEDOT/SWNT) enable determinations of 3,4‐dihydroxy‐L ‐phenylalaines (L ‐dopa) in neutral phosphate buffer solutions containing an excess of ascorbic acid. The interpenetrated networked nanostructure of the composite was characterized by scanning electron microscope (SEM) and Raman spectroscopy. It is shown that the presence of the composite gives rise to an increase in the electroactive area of an order of magnitude in compared to the area for the bare microelectrodes. The composite film‐coated microelectrode, which yielded reversible cyclic voltammograms for the ferro/ferricyanide redox couple for scan rates between 0.01 and 0.10 V s^?1, also gave rise to two well‐resolved oxidation peaks for L ‐dopa and ascorbic acid (AA). The latter effect, which was not seen in the absence of the composite, enabled differential pulse voltammetric determinations of L ‐dopa in the concentration range between 0.1 to 20 μM with a detection limit of 100 nM.     

Specific recognition of a nucleobase-functionalized poly(3,4-ethylenedioxithiophene) (PEDOT) in aqueous media

In this Letter we report the synthesis, characterization, and electrochemical investigation of a 3,4-ethylenedioxythiophene (EDOT) derivative covalently linked to the nucleobase uracil. The successful electrochemical polymerization of this derivative has provided modified electrodes with a novel functional poly(3,4-ethylenedioxythiophene) derivative. Recognition experiments in aqueous media have shown the specific recognition of the complementary base adenine. The electrochemical detection of the selective binding of nucleobases to this PEDOT derivative in aqueous media can be of particular interest for electrochemical sensor applications in physiological media.