Polythiophenes blends

More recently, as pointed out earlier, doped PAn and blends of doped PAn have become commercially available in large quantities. They show superior electromagnetic shielding properties compared with previous materials [100,101]. The blends are easier to process than metal flake or fibre-filled polymers, and are non-abrasive. They also exhibit uniform and higher conductivities than is possible with carbon black fillers. It seems very likely that polythiophene blends that are currently being developed [102,103] may be used for similar purposes. 

Ohkita H, Cook S, Astuti Y, Duffy W, Tierney S, Zhang W, Heeney M, McCulloch I, Nelson J, Bradley DDC, Durrant JR (2008) Charge carrier formation in polythiophene/fullerene blend films studied by transient absorption spectroscopy. J Am Chem Soc 130 3030... 

Drori T, Holt J, Vardeny ZV (2010) Optical studies of the charge transfer complex in polythiophene/fullerene blends for organic photovoltaic apphcations. Phys Rev B 82 075207... 

Coated materials are evaluated in S-SBR and in 50 50 blends of S-SBR and EPDM rubbers. In blends, the partitioning of fillers and curatives over the phases depends on differences in surface polarity. In S-SBR, polythiophene-modified silica has a strong positive effect on the mechanical properties because of a synergistic reaction of the sulfur-moieties in the polythiophene coating with the sulfur cure system. In S-SBR/EPDM blends, a coating of polyacetylene is most effective because of the chemical similarity of polyacetylene with EPDM. The effect of... 

For silica in SBR, a polyacetylene coating gives the lowest filler-filler interaction, a good filler-polymer interaction, and the best dispersion compared to untreated and the other plasma-treated samples. However, for the stress-strain properties, the polythiophene-treated sample gives the best results. This shows the importance of sulfur moieties on the surface of the filler, which form a secondary network in the cured materials. In the blend of S-SBR and EPDM rubbers, the situation is less conclusive. The Payne effect, the bound rubber, and... 

Composites can also be prepared by electropolymerization from solutions containing dissolved polymer 307). Since films of polypyrrole or polythiophene are normally porous, it seems most likely that the dissolved polymer is simply entrained in the pores. Similarly, composites have been prepared by polymerization of pyrrole in the presence of acrylic latex, giving blends with 10-30 % polypyrrole that are conducting yet processable 808). Presumably the polypyrrole is distributed throughout the latex particles. 

Blends between thiazole yellow and the polythiophene 534 have been reported (07MI275). The polythiophene showed an absorption band at 520 nm. Electrical and photovoltaic properties have been studied. 

The inclusion of 5 wt% PCBM [l-(3-methoxycarbonyl)propyl-l-phe-nyl-[6,6]C6i] in the spin-coating solutions resulted in efficient polymer emission quenching for all the polythiophenes studied. The transient absorption spectra of the amorphous poly(541)/PCBM blend film. At 10 ps exhibited an absorption peak around 700 nm, similar to that observed for the poly(541) pristine film. The shape of the transient spectrum varied with time, with the absorption peak shifting from 700 nm at 10 is to 900 nm for time delays >100 (is, demonstrating the formation of two distinct transient species in the blend film. The monoexponential lifetime was t = 8 (is under Ar atmosphere and significantly shortened under 02 atmosphere. Monoexponential phase is therefore assigned to the decay of poly(541) triplet excitons. 

It was shown earlier that the efficiency of the diode depends significantly on the thicknesses of the layers due to the optical field distribution inside the device, caused by the interference of the incoming light with light reflected from the mirror cathode. The blend diode is always more efficient than the neat diode. The excitation created by absorption in the PPV phase is transferred to the polythiophene, where a more efficient charge separation process is possible, as is clear from Figs. 6.10 and 6.11. 

We have also studied photodiodes with the polymer blend (BEHP-PPV polythiophene) but without Ceo- We find very small photocurrents and no ev-... 

Thermally activated PCBM diffusion and formation of crystalhne aggregates within blends with PPV derivatives were observed even at moderate temperatures [55,68,137]. In contrast, polythiophene based polymer-fullerene solar cells had an overall performance improvement upon thermal anneahng steps [171,172]. This improvement has been mainly correlated with an improved order in the film. This is especially true in the case of polythiophene, which is known to convert to a more ordered phase upon... 

Rud et al. applied electric fields for the improved vertical orientation of SWNTs in a blend with a water-soluble polythiophene derivative [323]. A profound increase of both the conductance and the photocurrent was observed for the devices where CNTs were aligned. The orientation of MWNTs in composites with polymers can also be influenced by application of large magnetic fields [324]. 

Gadisa A, Svensson M, Andersson MR, Ingantls O (2004) Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/fullerene derivative. Appl Phys Lett 84 1609... 

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