PSS Composite Films Research Articles

Nanoarchitectured Semiconducting Photoelectrodes for Enhanced Stability and Photon Conversion Efficiency

The characteristics of two dimensional (graphene), one dimensional (single walled carbon nanotube incorporated poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, composite) and zero dimensional (ZnO quantum dots) nanostructures have been systematically analyzed to elucidate the possibility of employing such nanostructures (transparent conducting corrosion resistant (TCCR)) for the passivation of the surface of a photoelectrode. Thin layer of graphene, carbon nanotubes embedded on a conductive polymer matrix (PEDOT:PSS) and ZnO quantum dots are incorporated on the surface of photoelectrode namely ‘In’ rich CuInS2 (ICIS) to act as corrosion resistant layers. The TCCR layers are found to be effective in inhibiting the surface recombination of charge carriers. Graphene exhibits a higher tendency towards the suppression of surface recombination across electrode-electrolyte interface, where an enhancement by a factor of 104 s is observed in the electron recombination life time. SWCNT/PEDOT:PSS composite films when employed as transparent conducting corrosion resistant layers enabled an enhancement of the cell stability by 95% when compared to unprotected ‘In’ rich CuInS2 electrode. The TCCR layers are found have a positive impact on the conversion efficiency of the photoelectrode and the maximum enhancement in the conversion efficiency achieved is 71% with ZnO quantum dot sensitized electrodes.

Low Cost Rice Husk Ash/PEDOT:PSS Composite Film as a Counter Electrode for Dye-Sensitized Solar Cells

Low Cost Rice Husk Ash/PEDOT:PSS Composite Film as a Counter Electrode for Dye-Sensitized Solar Cells

MoSe2 nanosheet/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) composite film as a Pt-free counter electrode for dye-sensitized solar cells

A composite film of molybdenum diselenide nanosheets and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (MoSe2 NS/PEDOT:PSS) was prepared for the counter electrode (CE) of a dye-sensitized solar cell (DSSC), via a low-cost drop-coating method. The two-dimensional (2D) nanosheets of MoSe2 (MoSe2 NS) were aimed to provide the composite film not only a large amount of electrocatalytic active sites but also orientational pathways for electron transfer, from the conducting substrate of the CE to the interface at the CE electrolyte. The PEDOT:PSS acts as the conductive matrix for the composite film, and also enables multiple interfacial electron transfer pathways between the MoSe2 NS and the substrate. Owing to the combination of the advantages of both MoSe2 NS and PEDOT:PSS, the DSSC with the composite film of MoSe2 NS/PEDOT:PSS on its CE exhibited a power conversion efficiency (η) of 7.58±0.05%, which is comparable to that of the cell with a Pt CE (7.81±0.03%). The counter electrode films were characterized by scanning electron microscopy. Various electrochemical analyses, including those with cyclic voltammetry, rotating disk electrode, Tafel polarization curves, and electrochemical impedance spectroscopy, were performed intending to quantify the electrocatalytic ability of the counter electrode films; these techniques were able to precisely distinguish the functions of MoSe2 NS and PEDOT:PSS in the composite films; the former worked as an electrocatalyst and the latter as a conductive binder. Incident photon-to-current conversion efficiency (IPCE) was used to substantiate the photovoltaic parameters. When the MoSe2 NS/PEDOT:PSS composite film was coated on a flexible titanium (Ti) foil, the pertinent DSSC showed even a higher η of 8.51±0.05%, as compared to a lower η of 8.21±0.02% using the Pt-coated Ti foil CE. The results indicate the promising potential of MoSe2 NS/PEDOT:PSS composite film to replace the expensive Pt.

ZnO flower/PEDOT:PSS thermoelectric composite films

ZnO flower/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared by spin-coating dimethyl sulfoxide doped PEDOT:PSS on the ZnO flowers grown on glass substrate. The thermoelectric properties of the ZnO flower/PEDOT:PSS composite films were measured at room temperature. As the number of spin coated PEDOT:PSS layer increased, the electrical conductivity of the ZnO flower/PEDOT:PSS composite films increases dramatically from 1-layer (177.3 S/m) to 4-layer (910.4 S/m), however, all the composite films have almost the same Seebeck coefficient (~20–22 μV/K). A maximum power factor of ~0.4 μWm−1 K−2 at room temperature was obtained from the composite film with 4-layer PEDOT:PSS.

Fabrication of conductive polymer/inorganic nanoparticles composite films: PEDOT:PSS with exfoliated tin selenide nanosheets for polymer-based thermoelectric devices

Organic polymer based thermoelectric films consisting of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with inorganic tin selenide (SnSe) nanosheets were fabricated. Two-dimensional SnSe nanosheets were prepared by Li intercalation and subsequent exfoliation process from the synthesized bulk ingot. Different amounts of SnSe nanosheets were evenly distributed in the PEDOT:PSS matrix, producing various SnSe/PEDOT:PSS composites. The thermal conductivity of the composites was found to be insensitive to the addition of SnSe nanosheets. The power factor of the composite film was greatly enhanced by the addition of an optimal content of SnSe nanosheets, which significantly increased the Seebeck coefficient, and the solvent treatment, which dramatically improved the electrical conductivity. The maximum power factor of 386μW/mK2 was obtained for the 5vol.% dimethyl sulfoxide (DMSO)-treated SnSe/PEDOT:PSS composite film with 20wt.% of SnSe nanosheet content, which is ∼257 times higher than that of the pristine PEDOT:PSS film. The use of conductive PEDOT:PSS matrix mixed with inorganic SnSe nanosheets and the subsequent solvent treatment appear a promising strategy to achieve high-performance polymer-based thermoelectric devices.

Graphene-doped PEDOT:PSS nanocomposite thin films fabricated by conventional and substrate vibration-assisted spray coating (SVASC)

In this paper, successful fabrication of highly conductive transparent graphene-doped PEDOT:PSS composite thin films is reported for the first time, using conventional and substrate vibration-assisted ultrasonic spray coating (SVASC). To suppress the challenges associated with spraying of the precursor solution containing graphene, graphene sheets were broken by sonication and were uniformly dispersed and stabilized in PEDOT:PSS aqueous solution using isopropyl alcohol (IPA). The mechanism of dispersion of graphene in PEDOT:PSS aqueous solution using IPA is elucidated. The maximum electrical conductivity of 298 S.cm−1 was obtained for a graphene-doped PEDOT:PSS thin film, which compared to the pristine PEDOT:PSS thin films shows a ten-fold increase, with a transparency comparable to that of the indium tin oxide (ITO)-coated glass.

Lift-off patterning of multi-walled carbon nanotube and PEDOT:PSS composite films with fluorinated polymer templates

This paper reports a micro patterning method for multi-walled carbon nanotubes (MWCNTs), whose patterns were defined by a poly(1H,1H,2H,2H-perfluorodecyl methacrylate) (PFDMA) mask in a lift-off process. The PFDMA layer on the patterned polydimethylsiloxane (PDMS) mold was transferred to a polyethylene naphthalate (PEN) film using a Micro-Contact Printing (μCP) technique. In contrast to conventional photoresist masks, the PFDMA polymer template was not damaged by the solvent used for the MWCNT dispersion, isopropyl alcohol (IPA), which enabled the precise and clean deposition of MWCNTs. Moreover, a hydrofluoroether solvent, which was used to remove the PFDMA template, did not show any signal for chemical interactions with the PEN substrate or poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). This orthogonal character led to the successful lift-off patterning of MWCNTs/PEDOT:PSS composite films. The micro-patterned composite films could be examined further as a thin film heater with a bending radius of 15mm, generating enough heat to reach a maximum temperature of 53°C with an applied voltage of 30V.

Voltammetric determination of phytoinhibitor maleic hydrazide using PEDOT:PSS composite electrode

Maleic hydrazide (MH) was successfully detected using a novel electrochemical sensor based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)-carboxymethyl cellulose-single-walled carbon nanotubes modified glassy carbon electrode (PEDOT:PSS-CMC-SWCNT/GCE). A commercially available aqueous PEDOT:PSS dispersion with good processability and conductivity was used as electrode modified substrate material, while a water-soluble and adhesive CMC was selected as both binder and dopant to improve the long-term electrode stability in water of the PEDOT:PSS composite film and obtain synergistically enhanced electrocatalytic ability for analytes. A commercially available SWCNT dispersion with good processability, enhanced electrocatalytic ability and large rough surface area was selected as enhancer to improve the sensing performance of PEDOT:PSS composite electrode. The properties of the prepared composite film and its electrode were characterized and employed for the electrochemical detection of MH. The electrochemical behaviors of MH, optimum experimental parameters, and the performance of sensing electrode were investigated. The fabricated PEDOT:PSS-CMC-SWCNT/GCE accelerated electron transfer, enhanced synergistically electrocatalytic ability toward MH oxidation and displayed excellent sensing performance such as wide linear range (0.8–51μM) and a low limit of detection (0.1μM) and good sensing stability.

Lift-off patterning of Ag nanowire/PEDOT:PSS composite films for transparent electrodes using a fluoropolymer structure

This paper describes a lift-off method of Ag nanowire (Ag NW) patterning using a poly(1H,1H,2H,2H-perfluorodecyl methacrylate) polymer (PFDMA) structure as a mask which is prepared by micro-contact printing. Unlike a conventional photoresist mask, the PFDMA polymer is inert to the dispersion solvent of Ag NW. In addition, the hydrofluoroether solvent used for removing the mask layer of patterned PFDMA films after Ag NW deposition does not chemically affect the polyethylene naphthalate (PEN) substrate or poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) coated on Ag NW layer. In this method, Ag NW/PEDOT:PSS composite films were patterned and the effects of the hot-press method were examined to further improve the electrical and optical properties of the composite films. Moreover, the hot-press method at 110°C has an advantage of applying low pressure to make Ag NW/PEDOT:PSS embedded into PEN films compared to that of pressing samples without heating. The ratio of resistance change of patterned and hot-pressed composite film was only below 1% after repeated bending test.

Bistable electrical switching and nonvolatile memory effect in carbon nanotube-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite films.

PSS and single-wall carbon nanotubes (SWCNTs) composite thin films have been investigated. The effect of doping level on electrical conductance switching behavior of an indium tin oxide/ PSS + SWCNTs/aluminum (ITO/PEDOT:PSS + SWCNTs/Al) sandwich structure has been reported. The ITO/(PEDOT:PSS + SWCNTs)/Al devices show current bistability. Moreover, the ON/OFF state current ratio is in an extent of 10(2)-10(4). The OFF state current increased with the decreasing SWCNTs content in the composite film, and the ON/OFF state current ratio of the device increases with the increase in SWCNTs content of the composite film. Thus, by varying the doping level of SWCNTs in PSS composite thin films, the electrical conductance switching behavior of ITO/PEDOT:PSS + SWCNTs/Al can be modulated in a controlled manner.

Efficient preparation of ultralarge graphene oxide using a PEDOT:PSS/GO composite layer as hole transport layer in polymer-based optoelectronic devices

We herein report an investigation of ultralarge graphene oxide (UL-GO) sheet/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin composite layers fabricated by spin coating on an indium–tin-oxide (ITO) anode as hole transport layer (HTL) in polymer light-emitting diodes (PLEDs), as well as polymer solar cells (PSCs). Monolayer UL-GOs were first synthesized based on a novel solution-phase method involving pre-exfoliation of graphite flakes which were then mixed into the PEDOT:PSS solution in various specific amounts. The PEDOT:PSS composite film mixed with 0.04 wt% UL-GO by weight exhibits a conductivity of 749.4 S cm−1 and a transmittance of 88.6% at 550 nm. The PEDOT:PSS/GO HTL shows enhanced charge carrier transport because of improved conductivity by the weakening of the coulombic attraction between PEDOT and PSS by the functional groups on GO nanosheets, and the formation of an extended conductive network. Moreover, it can effectively block electrons and reduce resistance in the HTL, leading to better injection and transport of holes and lower turn-on voltage and resulting in a higher overall efficiency in PLEDs. Similarly, it remarkably increases the short circuit current (Jsc), and PSC efficiency because of a remarkable reduction of exciton quenching that results in higher charge extraction in PSCs. The optimized PLEDs and PSCs with a PEDOT:PSS/GO composite HTL layer show a maximum luminosity of 725.6 cd m−2 (at 10.6 V) for PLEDs, as well as a power conversion efficiency of 3.388% for PSCs, which were improved by ∼11% and 12%, respectively, compared to reference PLEDs and PSCs with a PEDOT:PSS layer.

Preparation and thermoelectric properties of reduced graphene oxide/PEDOT:PSS composite films

Reduced graphene oxide/poly(3,4-ethylene-dioxythiophene):poly(4-styrenesulfonate) (r-GO/PEDOT:PSS) composite films have been prepared by in situ reducing graphene oxide (GO)/PEDOT:PSS films prepared via a simple wet-chemical route. The as-prepared films have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and field emission scanning electron microscopy (FESEM). The in-plane electrical conductivity and Seebeck coefficient of the films have been measured at room temperature, and a maximum power factor is ∼32.6μW/mK2 for a 3wt% GO/PEDOT:PSS film after reduction, which is about 1.5 times as high as that of a neat PEDOT:PSS film prepared by the same method.

Cover Picture: Electrocatalytic SiC Nanoparticles/PEDOT:PSS Composite Thin Films as the Counter Electrodes of Dye‐Sensitized Solar Cells (ChemElectroChem 6/2014)

Cover Picture: Electrocatalytic SiC Nanoparticles/PEDOT:PSS Composite Thin Films as the Counter Electrodes of Dye‐Sensitized Solar Cells (ChemElectroChem 6/2014)

Electrocatalytic SiC Nanoparticles/PEDOT:PSS Composite Thin Films as the Counter Electrodes of Dye‐Sensitized Solar Cells

AbstractThe front cover artwork is provided by Professor Kuo‐Chuan Ho’s Electro‐optical Materials Lab at the Department of Chemical Engineering, National Taiwan University. The image shows a Pt‐free composite of silicon carbide nanoparticles/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (SiC‐NPs/PEDOT:PSS) as the counter electrode in a dye‐sensitized solar cell (DSSC), which has a good electrocatalytic ability for I‐/I3‐. Read the full text of the article at 10.1002/celc.201300242.

Electrocatalytic SiC Nanoparticles/PEDOT:PSS Composite Thin Films as the Counter Electrodes of Dye‐Sensitized Solar Cells

AbstractA composite film consisting of silicon carbide nanoparticles and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (SiC‐NPs/PEDOT:PSS) is deposited on a fluorine‐doped tin oxide substrate and used as the counter electrode (CE) material for a dye‐sensitized solar cell (DSSC). The content of SiC is optimized to be 5 wt % with respect to PEDOT:PSS to obtain the best power conversion efficiency (η) of 7.25 % for the pertinent DSSC. The η of the best DSSC (7.25 %) is found to be slightly lower than that of the cell with a sputtered‐Pt CE (η=7.98 %). The films are characterized by using field‐emission scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Electrocatalytic parameters of the CEs are obtained by using cyclic voltammetry, rotating disk electrode, and Tafel polarization curves. Electrochemical impedance spectroscopy and incident photon‐to‐current conversion efficiency curves are used to substantiate the photovoltaic parameter.

Application of a CdS nanostructured layer in inverted solar cells

An inverted solar cell has been constructed by the growth of a CdS layer on an indium tin oxide (ITO)/glass substrate followed by spin-coating of organic poly(3-hexylthiophene) : [6,6]-phenyl C61-butyric acid methyl ester (P3HT : PCBM) or a zinc phthalocyanine derivative (ZnPc-4R): PCBM composite layer and using a free-standing PEDOT : PSS composite film as the top electrode. It has been found that CdS plays the role of an electron-selective (hole-blocking) layer to rectify the electron flow from the P3HT : PCBM or ZnPc-4R : PCBM bulk heterojunction to the ITO electrode. By changing the morphology of the CdS layer from a textured continuous film to a nanowire array we demonstrate an improved collection efficiency of charge carriers due to the increased organic–inorganic interface area. Thus, a bifunctional role of the CdS nanostructured layer as a bottom electrode with better electron affinity than ITO and as a means to increase the interface for better electron collection from the organic active layer has been demonstrated.

Synthesis of Urchin-like Tungsten Oxide and Its Supercapacitive Performance

Tungsten-oxide nanourchins (NUs) consisting of nanowires added to a spherical shell were prepared by using the hydrothermal synthesis method. The detailed morphology and crystallinity depended on the synthesis time and the synthesis temperature. The electrochemical (EC) properties of an EC double layer capacitor using tungsten-oxide NUs/PEDOT:PSS composite films and a 1-M H3PO4 electrolyte were examined. The capacitance of tungsten-oxide NUs with relatively longer nanowires was 50% higher than that with shorter nanowires. Controlling the morphologing of nanostructures is important for improving the performance of a supercapacitor.

Functionalized graphene/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate as counter electrode catalyst for dye-sensitized solar cells

A (grapheme/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) graphene/PEDOT:PSS composite film was electrodeposited on fluorine-doped tin oxide conductive substrate by one-step electrochemical polymerization method. The low-cost and platinum-free film was used as counter electrode in (dye-sensitized solar cell) DSSC. The cyclic voltammetry, electrochemical impedance spectroscopy and Tafel measurements indicate that the graphene/PEDOT:PSS composite film has low charge-transfer resistance on the electrolyte/electrode interface and high catalytic activity for the reduction of triiodide to iodide and. As a result, the DSSC based on the graphene/PEDOT:PSS counter electrode showed high power conversion efficiency of 7.86% under a simulated sunlight illumination of 100 mW cm−2 (AM 1.5), which is comparable with the performance of the DSSC based on Pt counter electrode (7.31%).

Annealing-free, flexible silver nanowire–polymer composite electrodes via a continuous two-step spray-coating method

For the realization of high-efficiency flexible optoelectronic devices, transparent electrodes should be fabricated through a low-temperature process and have the crucial feature of low surface roughness. In this paper, we demonstrated a two-step spray-coating method for producing large-scale, smooth and flexible silver nanowire (AgNW)-poly3,4-ethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) composite electrodes. Without the high-temperature annealing process, the conductivity of the composite film was improved via the lamination of highly conductive PEDOT:PSS modified by dimethyl sulfoxide (DMSO). Under the room temperature process condition, we fabricated the AgNW-PEDOT:PSS composite film showing an 84.3% mean optical transmittance with a 10.76 Ω sq(-1) sheet resistance. The figure of merit Φ(TC) was higher than that obtained from the indium tin oxide (ITO) films. The sheet resistance of the composite film slightly increased less than 5.3% during 200 cycles of tensile and compression folding, displaying good electromechanical flexibility for use in flexible optoelectronic applications.

The thermoelectric performance of carbon black/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) composite films

Carbon black/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (CB/PEDOT:PSS) composite films have been prepared by a spin-coating method. The morphology of the composite films was investigated by field emission scanning electron microscopy and atomic force microscopy. The thermoelectric properties of CB/PEDOT:PSS composite films were measured at room temperature. As the content of CB increased from 0 to 11.16 wt%, the electrical conductivity of the composite films first increased sharply and then decreased, while the Seebeck coefficient increased slowly. A highest power factor of 0.96 μWm−1 K−2 was obtained.