PEDOT Chains Research Articles

Oxygen Reduction Reaction in Conducting Polymer PEDOT: Density Functional Theory Study

An oxygen reduction reaction (ORR) mechanism in conducting polymer PEDOT is studied using the density functional theory. It is demonstrated that pure PEDOT chains possess the catalytic activity, where no platinum catalyst or external dopants are needed to sustain the electrocatalysis. This remarkable property of PEDOT is related to the formation of polaronic states, which leads to the decrease of the HOMO–LUMO gap and thus to the enhancement of the reactivity of the system. It is shown that ORR on PEDOT chains can proceed via two pathways, whether via a four-electron process when the oxygen reacts with protons and is reduced directly into water in four steps (Reaction path I) or via the two-electron process leading to formation of the hydrogen peroxide as an intermediate specimen (Reaction path II). Path I is demonstrated to be energetically preferable. This conclusion also holds for ORR on two π–π stacked chains and ORR for the case when PEDOT is reduced during the reaction. It is also found that ORR on ...

The Investigation of High Quality PEDOT:PSS Film by Multilayer-Processing and Acid Treatment

In this study, we have investigated the performance of multilayer films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) treated with one of the perfluorinated carboxylic acids, named trifluoroacetic acid (TFA). According to the increased density of the PEDOT chain under unit area conditions, the sheet resistance (Rsq) has improved from 300 to 65 Ω/sq through additional processing of PEDOT:PSS from single layer to multilayer. After the further treatment with TFA, however, the Rsq of the multilayer PEDOT:PSS was enhanced to 45 Ω/sq, leading to the decline of film thickness from 400 to 270 nm. Both conductivity and work function based on X-ray photoelectron spectroscopy results have built a breakthrough by double-processing because of the higher density of conductive PEDOT chains and the increase of 0.4 eV alternatives to typical indium tin oxide substrate, respectively. This improvement is contributed to the development of more effective transparent electrodes.

Effect of liquid immersion of PEDOT: PSS-coated polyester fabric on surface resistance and wettability

Coating of textile fabrics with poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) is one of the methods used for obtaining functional or smart applications. In this work, we prepared PEDOT:PSS polymer with certain additives such as polyethylene glycol, methanol (MeOH), and ethylene glycol on polyester fabric substrates by a simple immersion process. Surface resistance was measured and analyzed with analysis of variance to determine the coating parameters at 95% confidence level. Fourier transform infrared (FTIR) analysis and scanning electron microscopy (SEM) study of the samples were performed. Contact angle and washing fastness measurements were conducted, to observe the wettability and washing fastness of the samples, respectively. Surface resistance values were decreased by a factor of 100, due to conductive enhancers. As the immersion time and temperature condition varies, surface resistance showed no difference, statistically. FTIR analysis supports the idea that the mechanism responsible for the conductivity enhancement is the partial replacement of PSS from PEDOT chain by forming a hydrogen bond with hydroxyl ion (OH) of the conductive enhancers. A SEM images showed that PEDOT:PSS is well distributed to the surface of the fabrics. Contact angle measurements showed morphology change in the samples. The conductivity was reasonably stable after 10 washing cycles. Altogether, an effective simple immersion of coated polyester fabric is presented to achieve functional textiles that offer a broad range of possible applications.

Conductivity Enhancement of PEDOT:PSS via Addition of Chloroplatinic Acid and Its Mechanism

Readily obtained highly conductive, transparent, and flexible poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films is urgently needed in printing of flexible transparent electrodes. A simple and facile method to enhance the electrical conductivity of PEDOT:PSS films is reported. The conductivity is increased by four orders of magnitude after adding solid chloroplatinic acid (H2PtCl6) into the pristine PEDOT:PSS solution. The H2PtCl6‐doped PEDOT:PSS film exhibits a sheet resistance of 44 ± 5 Ω □‐1 and a transmittance of 84 ± 1% at 550 nm, corresponding to a figure of merit of 47 ± 4. Comparative study shows addition of solid acid like H2PtCl6 is more effective in conductivity enhancement than addition of polar organic solvents, such as dimethyl sulfoxide or ethylene glycol. The mechanism for the conductivity enhancement is attributed to both in situ doping and phase separation of PEDOT:PSS. PEDOT is oxidized and doped by Pt4+ of H2PtCl6, which is reduced simultaneously to Pt2+. Proton transfer from H2PtCl6 to PSS− of PEDOT:PSS causes formation of neutral PSSH, leading to phase separation between insulating PSS and conducting PEDOT. Such a phase separation results in conformational changes of PEDOT chains and reduction in energy barrier for charge hopping.

Tuning the degree of oxidation and electron delocalization of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) with solid-electrolyte

We report on the effects of ionic interaction on the electronic structure of PEDOT:PSS where the oxidation state of PEDOT is an import aspect for various applications. Additional ionic interactions are introduced and controlled by varying the fraction of poly(ethylene oxide) (PEO). These interactions are balanced against the inherent cohesive forces within each of the polymers constituting intertwined networks. Raman spectra evidenced a peak-shift as high as ∼14cm−1 for CC vibrational region which suggested increasing degree of oxidation of PEDOT for higher PEO fractions. Changes to the single and bipolaronic absorption bands support the results from the Raman spectra. For highest PEO fraction neutral-PEDOT and lowered bipolaron density is attributed to localization of PEDOT chains within PEO matrix. Interestingly, for higher PEO fractions the electronic density of states (DOS) of HOMO and core-levels (S2p, C1s and O1s) suggested increased degree of oxidation and electron localization on PEDOT. Near and below (∼12eV) Fermi level, contribution to the O2p and C2p atomic orbitals depicted significantly different DOS. Also we note energetic shift for O2s/C2s and bonding σCC atomic and molecular DOS, respectively. The correlation between some surface and bulk-related properties suggests the uniformity of the blend material which might be vital for the application in electrochemical devices.

A Strategy to Enhance the Electrode Performance of Novel Three-Dimensional PEDOT/RVC Composites by Electrochemical Deposition Method.

In this article, three-dimensional (3D) microstuctured poly(3,4-ethylenedioxythiophene) (PEDOT)/reticulated vitreous carbon (RVC) composite electrodes with varying amount of PEDOT loadings were successfully prepared by electrochemical deposition method. The composites were characterized by Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and cyclic voltammetry. Raman spectra suggest that there is a strong interaction between the RVC and backbone of PEDOT chain. It is revealed from the SEM images that the PEDOT amount, thickness, surface roughness, porosity, and globular structure on RVC electrode are increased with the increase in polymerization time. The capacitance of PEDOT/RVC electrode has increased by a factor of 2230 compared to a bare RVC electrode when polymerization is carried out for 120 min. Moreover, the capacitance of PEDOT was found to be very high compared with other PEDOT studies. The electrodes also show good cyclic stability. This substantial increase in capacitance of RVC electrode is due to the rough, highly porous, and honeycomb-like fine structure of PEDOT coating, which shows a flower-like morphology, consisting of numerous thin flakes with numbers of macropores and micropores. This interesting morphology has enhanced the performance of PEDOT because of increased electrode surface area, specific capacitance, and macroporous structure of RVC electrode.

Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances. The electrical conductivity of PEDOT:PSS@DOH films was markedly improved compared with that of PEDOT:PSS. The PEDOT:PSS@DOH film exhibited excellent optical characteristics, appropriate work function alignment, and good surface properties in BHJ-PSCs. When a poly(3-hexylthiohpene):[6,6]-phenyl C61-butyric acid methyl ester blend system was applied as the photoactive layer, the power conversion efficiency of the resulting PSCs with PEDOT:PSS@DOH(1.0%) reached 3.49%, outperforming pristine PEDOT:PSS, exhibiting a power conversion enhancement of 20%. The device fabricated using PEDOT:PSS@DOH (1.0 wt%) also exhibited improved thermal and air stability. Our results also confirm that DOH, a basic pyridine derivative, facilitates adequate hydrogen bonding interactions with the sulfonic acid groups of PSS, induces the conformational transformation of PEDOT chains and contributes to the phase separation between PEDOT and PSS chains.

Higher PEDOT Molecular Weight Giving Rise to Higher Thermoelectric Property of PEDOT:PSS: A Comparative Study of Clevios P and Clevios PH1000.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a promising candidate as the next-generation thermoelectric (TE) material. Its TE properties are strongly dependent on its chemical and electronic structures. In this paper, we investigated the effect of PEDOT molecular weight on the TE properties of PEDOT:PSS films by a comparative study on two commercial grades of PEDOT:PSS, Clevios P, and Clevios PH1000. Dynamic light scattering (DLS) and Raman spectra imply that the PEDOT of Clevios PH1000 possesses longer conjugated chains than that of Clevios P. The TE properties of both the Clevios P and Clevios PH1000 films can be significantly enhanced through various post treatments, including solvent treatment, germinal diol treatment, organic solution treatment, and acid treatment. After these treatments, the treated Clevios PH1000 films constantly show both superior Seebeck coefficients and electrical conductivities over the treated Clevios P films. It is attributed to the higher molecular weight of PEDOT for the former than the latter. For the treated Clevios PH1000, longer PEDOT chains result in large PEDOT domains, facilitating the charge conduction a semimetallic behavior. Tuning the oxidation level of PEDOT:PSS is a facile way to enhance their TE property. A base treatment with sodium hydroxide was subsequently performed on both the treated Clevios P and Clevios PH1000 films. The power factors of both grades of PEDOT:PSS films were remarkably increased by a factor of 1.2-3.6. Still, both the conductivity and the Seebeck coefficient of a based-treated Clevios PH1000 film are superior over those of a control Clevios P film. The highest power factor the former is 334 μW/(m K2) for the former while only 11.4 μW/(m K2) for the latter. They are different by a factor of about 30 times.

Influence of ethylene glycol vapor annealing on structure and property of wet-spun PVA/PEDOT:PSS blend fiber

In this study, blend fibers composed of poly(vinyl alcohol) and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) were prepared via wet-spinning technology. Ethylene glycol (EG) vapor annealing was employed to improve the electrical conductivity and tensile properties of blend fibers. The effects of EG vapor annealing on structures and properties of blend fibers were investigated in detail by analyzing the changes in chemical constituent and structure, molecular structure, surface morphology, surface chemical composition, electrical conductivity, and tensile properties. FTIR spectroscopy indicates that EG vapor annealing does not change the chemical constituent and structure of blend fibers. Raman spectroscopy shows that vapor annealing leads to conformational changes of PEDOT chains from benzoid structure to quinoid structure. AFM and SEM images show that surface morphology of blend fibers become smoother after vapor annealing. XPS measurement shows that EG vapor annealing induces significant phase separation between PEDOT and PSS, forming an enriched PSS layer on the surface of blend fibers, thus leading to a thinner insulating PSS layer between PEDOT grains. This conformational change is beneficial to improve the electrical conductivity of blend fibers. The resultant blend fiber reached conductivity up to 20.4 S cm−1. The mechanical properties of blend fibers were also improved by EG vapor annealing, with the Young’s modulus and tensile strength increasing from 3.6 GPa and 112 MPa to 4.4 GPa and 132.7 MPa, respectively.

Effect of Secondary Doping Using Sorbitol on Structure and Transport Properties of PEDOT–PSS Thin Films

Poly(3,4-ethylene dioxythiophene):poly(styrenesulphonate) (PEDOT–PSS) in the recent past has emerged as one of the most fascinating conducting polymers for many device applications. The unique feature of PEDOT–PSS is its transparency in the entire visible spectrum with excellent thermal stability. The PEDOT–PSS as prepared as an aqueous dispersion has very low conductivity, and it hinders the performance of a device. In this work we report the conductivity enhancement of PEDOT–PSS thin films through secondary doping using a polar organic solvent such as sorbitol. The mechanism of conductivity enhancement was studied through various physical and chemical characterizations. The effect of sorbitol concentration on structure and transport properties of PEDOT–PSS thin films was investigated in detail. The structural and morphological modifications in PEDOT–PSS due to the addition of sorbitol was studied through Fourier transform spectroscopy, Ultra Violet–visible spectroscopy, theromogravimetric analysis, scanning electron microscopy and atomic force microscopy. The interactions resulting from conformational changes of PEDOT chains that changes from coiled to linear structure due to the sorbitol treatment significantly improves the conductivity of PEDOT–PSS films. The secondary doping of sorbitol reduces the energy barrier that facilitates the charge carrier hopping leading to enhanced conductivity. We have observed that the conductivity of PEDOT–PSS thin films was increased by two fold due to sorbitol treatment when compared to conductivity of pure PEDOT–PSS. We have carried out detailed analysis of dielectric parameters of sorbitol-treated PEDOT–PSS films and found that sorbitol treatment has a significant effect on various dielectric attributes of PEDOT–PSS films. Hence, secondary doping using sorbitol could be a useful way to effectively tailor the conductivity and dielectric properties of PEDOT–PSS thin films that can be used as flexible electrodes in optoelectronic devices.

Effect of water-soluble vitamins on the structure and properties of poly(3,4-ethylenedioxythiopehene):poly(styrenesulfonate)

Intrinsically conducting polymers can have important application in biology because they can be conductive and have good biological compatibility. Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) has been the most popular conductive polymer in biological application due to its solution processability in water. PEDOT:PSS can be used as electrode materials or active materials of biological devices or circuits. It is important to study the effect of biomaterials on the structure and properties of PEDOT:PSS films. In this work, water-soluble vitamins that are biomaterials needed for organisms are used to treat PEDOT:PSS. They can significantly enhance the conductivity of PEDOT:PSS from 0.3 S cm−1 up to higher than 1000 S cm−1. The conductivity enhancement depends on the structure of vitamins. The highest conductivity enhancement was observed for PEDOT:PSS treated with vitamin B3. The vitamin-induced changes in the structure and properties of PEDOT:PSS were studied by UV–Vis absorption spectroscopy, temperature-dependence of resistance measurements, atomic force microscopy and cyclic voltammetry. The characterizations indicate that vitamins can induce phase segregation between PEDOT and PSS and the conformational change of the PEDOT chains. These discoveries are important to understand the application of PEDOT:PSS in biology and the development of new biological application of PEDOT:PSS.

Fabrication and gas sensing behavior of poly(3,4-ethylenedioxythiophene) coated polypropylene fiber with engineered interface

Conductive composite fibers were successfully fabricated by coating poly(3,4-ethylenedioxythiophene) (PEDOT) layers on the surface of polypropylene-graft-poly(acrylic acid) (PP-g-PAA) fibers through in situ chemical oxidative polymerization. It was found that the adhesion between the conductive PEDOT layers and the modified PP fiber substrates was significantly enhanced due to the electrostatic attractions between PEDOT chains and carboxylic groups of grafted PAA. In this study, we investigated the influence of the 3,4-ethylenedioxythiophene (EDOT) concentration and the oxidant species on the electrical conductivity of the composite fibers, and the result show that the maximum conductivities of PP-g-PAA/PEDOT composite fibers prepared with FeCl3 and iron(III) p-toluenesulfonate (FepTS) as oxidants reached 0.069S/cm and 10.09S/cm, respectively. The composite fibers were applied as a sensor for HCl and NH3 gas detection and exhibited a rapid and reversible response. The influence of the oxidant species on the sensing properties for HCl and NH3 gas detection is further discussed, and some features such as fast response time (less than 2s) and high relative resistance changes (63% for HCl and 110% for NH3 gas) were achieved.

Triumphing over Charge Transfer Limitations of PEDOT Nanofiber Reduction Catalyst by 1,2-Ethanedithiol Doping for Quantum Dot Solar Cells.

Charge transfer between a conducting polymer-based counter electrode (CE) and a polysulfide (S2-/Sn2-) electrolyte mediator is a key limitation to improvements of solar energy conversion efficiency (ECE) in quantum-dot-sensitized solar cells (QDSCs). In this paper, 1,2-ethanedithiol (EDT) was doped into nanofibrous poly(3,4-ethylenedioxythiophene) (PEDOT NF) to overcome the charge transfer limitation between PEDOT NF and S2-/Sn2-. EDT not only helps to reduce the aggregation and thus enhance the linearization of the PEDOT chains but also changes the molecular conformation of the PEDOT chains from a benzoid to a quinoid structure. EDT-doped PEDOT NF-based CEs showed almost 3.7 times higher conductivity, better electrocatalytic activity, and improved compatibility with S2-/Sn2- in an aqueous electrolyte. As a result, the charge transfer resistance between the polymer-based CE and the S2-/Sn2- electrolyte was significantly reduced, resulting in over 3% ECE in QDSCs, more than double that of a bare PEDOT NF-based CE.

Thermoelectric properties of the PEDOT/SWCNT composite films prepared by a vapor phase polymerization

The poly(3,4-ethylenedioxythiophene)/single walled carbon nanotube (PEDOT/SWCNT) composite films with various SWCNT contents (0–50wt.%) have been prepared by a vapor phase polymerization technique for the first time. The Seebeck coefficients of the composite films increase with the SWCNT contents. The maximum power factor is 37.8μWmK−2 for a composite film with 35wt% SWCNT, which is 1.7 times as high as that of the film without SWCNTs. The composite film with 35wt% SWCNT has then been treated with a 0.04wt% NaBH4/DMSO solution and the power factor increases to 44.1μWmK−2 after the treatment. The PEDOT chains are more orderly arranged and with decreased doping level by forming composites with SWCNT and may be de-doped further after further treated with NaBH4/DMSO. Therefore, the Seebeck coefficient of the composite film has been further enhanced.

The effect of counterion in polymer sulfonates on the synthesis and properties of poly-3,4-ethylenedioxythiophene

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of the salt and acid forms of polymer sulfonates with different polymer-chain flexibility is studied. The dependence of the rate of synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on the nature of polysulfonate counterion that determines the type and distribution density of the charge in the polyelectrolyte chain is demonstrated. For the Н+ form of a rigid-chain polysulfonate, it is found that the specific interactions between parts of its macromolecules lead to destabilization of EDOT•+ radical cations, hinder the growth of PEDOT chains, and favor the formation of structures with the high degree of charge localization.

Manipulating the molecular structure of PEDOT chains through controlling the viscosity of PEDOT:PSS solutions to improve the photovoltaic performance of CH3NH3PbI3 solar cells

A series of alcohols (methanol, ethanol and isopropyl alcohol) were added to poly(3,4-ethylenedioxythiophene): (polystyrene sulfonate) (PEDOT: PSS) aqueous solutions in order to manipulate the molecular structure of the PEDOT chains in PEDOT: PSS hole transporting materials (HTMs) and thus to improve the power conversion efficiency of CH3NH3PbI3 based solar cells. The structural and electronic characteristics of the resultant PEDOT: PSS HTMs were analyzed using atomic-force microscopy, contact angle measurement, Raman scattering spectrometry and photoelectron spectrometry. The properties of the PEDOT: PSS thin films could be controlled by tuning the viscosity of the PEDOT: PSS solutions. High viscosity PEDOT: PSS solutions resulted in linear structured PEDOT chains, which increased the work function of the PEDOT: PSS HTMs thereby improving the open-circuit voltage of the CH3NH3PbI3 solar cells. The surface roughness and surface free energy of the PEDOT: PSS HTMs influence the structural properties of CH3NH3PbI3 thin films, which determines the exciton dissociation at the CH3NH3PbI3/PEDOT: PSS interface (short-circuit current density) and the carrier recombination at the CH3NH3PbI3/[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) interface (fill factor). In addition, it is predicted that the power conversion efficiency can be further improved by increasing the crystallinity of the CH3NH3PbI3 thin film.

Improvement in Half-Life of Organic Solar Cells by Using a Blended Hole Extraction Layer Consisting of PEDOT:PSS and Conjugated Polymer Electrolyte.

In this study, we fabricated conventional structured organic solar cells (OSCs) by introducing a hole extraction layer (HEL) that consisted of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and conjugated polymer electrolyte (CPE) poly[9,9-bis(4'-sulfonatobutyl)fluorene-alt-thiophene] (PFT-D). PFT-D has a -SO3- functional group that acts as a conjugate base against the -SO3H of PSS. In addition, the molecular dipole of PFT-D can screen the Coulombic attraction between PEDOT chains and PSS chains. By blending PEDOT:PSS and PFT-D, the acidity of the HEL solution and changes to the surface morphology and potential of the HEL film as a function of exposure time in air were reduced. As a result, the half-life of the OSC fabricated with blended HEL was five times better at room temperature and 40% humidity without encapsulation as compared to the pristine PEDOT:PSS-based device.

Nafion-Modified PEDOT:PSS as a Transparent Hole-Transporting Layer for High-Performance Crystalline-Si/Organic Heterojunction Solar Cells with Improved Light Soaking Stability.

We demonstrate the chemistry of amphiphilic perfluorosulfonic copolymer Nafion-coated conductive poly(3,4-ethyelenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and its effect on the photovoltaic performance of PEDOT:PSS/crystalline Si (c-Si) heterojunction solar cells. The highly hydrophilic sulfonate group of insulating, chemically stable Nafion interacts with PSS in PEDOT:PSS, which reduce the Coulombic interaction between PEDOT and PSS. The highly hydrophobic fluorocarbon backbone of Nafion favorably interacts with hydrophobic PEDOT of PEDOT:PSS. These factors give rise to the extension of π-conjugation of PEDOT chains. Silver paste used as a top grid electrode diffused into the Nafion layer and contacted with underneath Nafion-modified PEDOT:PSS layer. As a consequent, solution-processed Nafion-coated PEDOT:PSS/c-Si heterojunction solar cells exhibited a higher power conversion efficiency of 14.0% with better stability for light soaking rather than that of the pristine PEDOT:PSS/c-Si device by adjusting the layer thickness of Nafion. These findings originate from the chemical stability of hydrophobic fluorocarbon backbone of Nafion, diffusivity of silver paste into Nafion and contact with PEDOT:PSS, and Nafion as an antireflection layer.

Ultraviolet-Visible-Near Infrared and Raman spectroelectrochemistry of poly(3,4-ethylenedioxythiophene) complexes with sulfonated polyelectrolytes. The role of inter- and intra-molecular interactions in polyelectrolyte

Poly(3,4-ethylenedioxythiophene) (PEDOT) films were electrodeposited in galvanostatic mode in the presence of salt or acid forms of sulfonated polyelectrolytes distinguished by different rigidity of the polymer main chain and presence of amid fragments in their stricture. The films obtained were characterized by cyclic voltammetry, as well as Ultraviolet-Visible-Near Infrared and Raman spectroelectrochemistry at fixed potentials in non-aqueous and aqueous media, respectively. It was found that bipolaronic fragments of PEDOT are hardly to be formed at high anodic potentials in the films prepared in the presence of acid forms of the rigid-chain amid-containing polyelectrolytes as distinct from all other polyelectrolytes regardless of amide-groups content. In situ Raman studies during PEDOT electrodeposition in the presence of the acid forms of the rigid-chain amid-containing polyelectrolytes showed domination and retarded delocalization of radical cations being the moving force of the electropolymerization. The results are discussed in terms of possibility/impossibility of proton-transfer inter- and intra-molecular interactions between sulfonic and amid groups in the polyelectrolytes. These result in the appearance of positive charges (confirmed by ζ-potential measurements) on the polyelectrolyte chain, which create barriers for radical cations delocalization, their recombination into bipolarons, as well as prevents growth of long PEDOT chains. The prepared materials were studied as a hole-transport (buffer) layer in organic photovoltaic cells. The influence of polyelectrolyte structure on the cells performance is discussed.

Significant Enhancement in the Thermoelectric Properties of PEDOT:PSS Films through a Treatment with Organic Solutions of Inorganic Salts.

PSS) films through a treatment with organic solutions of inorganic salts. N,N-Dimethylformamide (DMF) and a common inorganic salt like zinc chloride (ZnCl2) are used as the solvent and solute of the solutions, respectively. The treatments can significantly increase both the Seebeck coefficient and electrical conductivity of the PSS films. The thermoelectric properties of the PSS films are sensitive to the experimental conditions, such as the salt concentration, treatment temperature, and the cation of the salts. After treatment at the optimal experimental conditions, the PSS films can exhibit a Seebeck coefficient of 26.1 μV/K and an electrical conductivity of over 1400 S/cm at room temperature. The corresponding power factor is 98.2 μW/(m·K(2)). The mechanism for the enhancement in the thermoelectric properties is attributed to the segregation of some PSSH chains from PSS and the conformation change of PEDOT chains as a result of the synergetic effects of inorganic salts and DMF.