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The conducting polymer, poly(3,4-ethylenedioxythiophene)–polystyrenesulfonic acid (PEDOT:PSS), is certainly one of the most important substitute materials for indium tin oxide in organic devices. Its metallic conductivity and transmittance bring favorable perspectives for organic photovoltaic applications. Although graphene oxide (GO) is not a good conductor, it can form high-quality thin films and can be transparent, and additionally, GO is an inexpensive material and can be easily synthesized. This study investigated how the conductivity of a composite film of graphene oxide (GO) and different amounts of PEDOT:PSS can be modified. The effects of GO:PEDOT:PSS composites with several PEDOT:PSS proportions were analyzed in regards to the composite molecular structure and ordering, charge transfer dynamics (in the femtosecond range), electrical properties and morphology. For the best conductivity ratio GO found with 5% PEDOT:PSS, a solvent treatment was also performed, comparing the resistivity of the film when treated with dimethyl sulfoxide (DMSO) and with ethylene glycol. [ABSTRACT FROM AUTHOR]

Herein, polypyrrole (PPy) films are prepared via electrochemical deposition in a mixture of 1-n-butyl-3-methylimidazolium methanesulfonate (BMI·CH3SO3) ionic liquid (IL) and dodecyl sulfate (DS). The physico-chemical properties of the films have been investigated by a wide range of characterization techniques. PPy films synthesized in DS or IL have shown larger and irregular granules as compared to PPy films prepared in the mixture of DS and IL. This result is related to the preferential dissolution of pyrrole monomers in micelle templates formed by the IL and a co-assembly of IL and dodecyl-sulfate (DS), thereby decreasing the granule size and affecting the structural arrangement of the polymer chain. The template behavior of the IL in combination with DS promotes the selective formation of polaron and bipolaron states in the PPy films. This effect has been investigated by UV-Vis spectrophotometry, Raman spectroscopy, electrochemical impedance spectroscopy (EIS), cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, and electrical conductivity measurements. The synergy of IL–DS has helped to decrease the resistivity of the PPy film from 2.17 × 102Ω cm for PPy–IL to 2.44 Ω for PPy–IL–DS. EIS has also shown a decreased interfacial charge transfer resistance for PPy–IL–DS when compared to PPy–IL. The cyclic voltammetry curves have shown that the PPy films are electrocatalytically active for the I−/I3− redox reaction, and therefore, can be applied as a counter electrode (CE) in dye sensitised solar cells. The PPy based CEs resulted in nearly the same photocurrent and energy conversion efficiencies as that obtained from a conventional Pt CE. [ABSTRACT FROM AUTHOR]

Abstract: A synergistic effect resulting from the interaction of small (2.4–3.1 nm) naked Pt nanoparticles (NPs) imprinted on N‐doped carbon supports is evidenced by structural, electronic and electrochemical characterization. The size and distribution of the sputtered Pt NPs are found to be related to the nature of the support because Pt NPs are preferentially located at Ngraphitic sites. In addition, Rutherford backscattering shows that a deeper penetration of the Pt NPs is obtained in the N‐doped carbon support with larger pore diameters. The ligand effect of the N‐doped carbon supports is found to occur by electron donation from Npyrrolic and Ngraphitic sites to the Pt NPs and the electron acceptor behavior of the C=Npyridinic sites. The carbon matrix acquires a basic characteristic (electron‐richer, metallic behavior) capable of interacting with metallic NPs akin to a bimetallic‐like system. The imprinted Pt NPs are active catalysts for oxidation, although displaying poor catalytic activity for reduction reactions. The catalyst N‐doped carbon supports play an important role in the overall catalytic process, rather than only acting as a simple active phase carrier. [ABSTRACT FROM AUTHOR]

In this work, poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) was used as active layer in bilayer solar cell with C60 as electron acceptor. As cast devices already show reasonable power conversion efficiency (PCE) that increases to 4% upon annealing at 100 ℃C. Space charge limited measurements of the hole mobility (l) in PSiF-DBT give μ~1.0×10-4 cm²/(V s) which does not depend on the temperature of the annealing treatment. Moreover, positron annihilation spectroscopy experiments revealed that PSiFDBT films are well stacked even without the thermal treatment. The variations in the transport of holes upon annealing are then small. As a consequence, the PCE rise was mainly induced by the increase of the polymer surface roughness that leads to a more effective interface for exciton dissociation at the PSiF-DBT/fullerene heterojunction. [ABSTRACT FROM AUTHOR]

The search for new structures, new synthetic paths, and new processing technologies is crucial for the future of electronic devices. In this context, this work reports a novel and simple miniemulsion-way to achieve nanostructured polymers in aqueous solution using graphene oxide (GO) as a surfactant for electronic applications. The materials were prepared using the Pickering emulsion concepts, where the graphene oxide colloidal dispersion was sonicated along with toluene solutions of the organic semiconductive polymer poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl) benzo-2,1,3-thiadiazole] (PSiF-DBT). We have investigated various PSiF: GO ratios as well as the effect of the pH on the thin film preparation, by the liquid-liquid interfacial method. Scanning and transmission electron microscopy (SEM and TEM) and atomic force microscopy (AFM) images showed that the morphology of the films is strongly dependent on both the amount of the polymer and the pH. Infrared spectroscopy suggests the anchoring of Si atoms from the PSiF-DBT in some oxygenated groups of graphene oxide, explaining better the angle-resolved near-edge X-ray absorption fine structure (NEXAFS) results, that indicate an upright-standing molecular orientation for the thiophene units and a lying-down orientation for the benzothiadiazole units. UV–Vis molecular absorption and resonant Auger spectroscopies indicated that the charge transfer is faster the higher are the ratio of PSiF: GO in the film. Image 1 • Innovative method to prepare polymeric nanoparticles using graphene oxide as surfactant. • Polymer concentration and pH influences the morphology and the electronic properties. • Simpler synthesis, ability to modulate the morphology and electronic structure. • Charge transfer by controlling the synthesis variables. • Thin film deposition via liquid-liquid interfacial method at ambient conditions. [ABSTRACT FROM AUTHOR]

In this work, poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) was used as active layer in bilayer solar cell with C60 as electron acceptor. As cast devices already show reasonable power conversion efficiency (PCE) that increases to 4% upon annealing at 100 ℃C. Space charge limited measurements of the hole mobility (l) in PSiF-DBT give μ~1.0×10-4 cm²/(V s) which does not depend on the temperature of the annealing treatment. Moreover, positron annihilation spectroscopy experiments revealed that PSiFDBT films are well stacked even without the thermal treatment. The variations in the transport of holes upon annealing are then small. As a consequence, the PCE rise was mainly induced by the increase of the polymer surface roughness that leads to a more effective interface for exciton dissociation at the PSiF-DBT/fullerene heterojunction. [ABSTRACT FROM AUTHOR]