Conjugated polymers PEDOT

Stephan Kirchmeyer and colleagues, in Chapter 14, start the device application part of the book, through the introduction of the most industrially important conjugated polymer, PEDOT and showing a wide variety of its applications, such as transparent conductors, antistatic coatings, hole-injecting layers for OLEDs and photovoltaics. 

The unique property of conjugated polymers to uptake/release the anions upon transformation from oxidized to reduced state can be used for the targeted deposition of NPs. To demonstrate the principal viability of such approach, VCL/AAEM/PEDOT microgels have been used as templates for the incorporation of AuNPs [148], Figure20 shows the procedure of AuNP deposition into microgels filled with PEDOT nanorods. 

The first conducting polymer was trans-polyacetylene which was doped with bromine and was produced at 1970s. Soon other conjugated polymers such as poly (p-phenylene), polypyrrole (PPy), polyethylene dioxythiophene (PEDOT) and polyaniline (PANi) and their derivatives which are stable and processable were synthesized. The molecular structures of a few ICPs are shown in Figurel. 

The development of suitable contacts for polymer solar cells has directly profited from the developments in light-emitting diodes, due to the injec-tion/extraction similarity. Due to its lower barrier for hole transfer between most conjugated polymers and PEDOT PSS as compared to ITO, this highly doped polymer electrode was applied at an early stage in solar cells as... 

Other studies in 2000 by Drew et al. reported that it is very difficult to spin fibers of PANI complexed to sulfonated polystyrene (PANFSPS), even when solutions containing sodium chloride and dodecyl benzene sulfonic acid sodium salt were used to lower the surface tension and thereby enhance electrospinning [16,17]. However, PANFSPS nanofibers can be produced by adding a carrier polymer such as PEO, polyacrylonitrile, or polyurethane. Also reported was the use of electrostatically layered sulfonated polystyrene as a template for the surface polymerization of conjugated polymers in their conducting form. Enzymatic synthesis of PANI and a copolymer of pyrrole and PEDOT was done on electrospun nanofiber... 

Secondly, appropriate orthogonal solvents for the selective template dissolution had to be found. Because of the same reason mentioned above, these solvents are not allow to even slightly swell the nanostructured conjugated polymers, otherwise the desired stractural features are inevitable lost. Diethyl ether and xylene were identified as ideal solvents for PEDOT and PPy, respectively. Chlorobenzene was reported to have no effect on the nanostructure of electrodeposited P3MT, but in this study the opposite was found [13]. Instead, pure diethyl ether or a 2 1 mixture of diethyl ether and hexane were used. 

Figure 7.3a shows the profound impact a so-called non-solvent for PT, such as chlorobenzene, can have on the nanostructure. Although chlorobenzene does not dissolve the polymer film, no obvious mesoporous nanostructure is left after template removal. This is most probably due to diffusion of solvent molecules into the conjugated polymer which destabilize the about 11 nm thick gyroidal network struts and eventually leads to the structural collapse. Using diethyl ether as solvent for the template dissolution instead resulted in mesoporous and highly ordered films. However, the free-surface did not show the same degree of order and porosity as the bulk of the film, see Fig. 7.3c. This behavior at the free-surface was more pronounced in the case of PEDOT and PPy, and will be discussed in more detail in the following to sections.

In this spirit, we will smdy the performance of structured PEDOT films in batteries and/or supercapacitors as well as the application of dedoped PT and P3MT in bulk heterojunction solar cells in the near future [12-15]. Furthermore, thenanostructured conjugated polymer films may find application in thermoelectric devices [47-50],... 

Based on this composite electrode, PLECs were fabricated by an all-solution process. The PLEC devices were made in four steps. (1) A thin PEDOT PSS layer was spin coated onto AgNW-PUA composite electrode with 15 Qsq sheet resistance as the anode. (2) A solution of a conjugated polymer (Super Yellow) and electrolyte blend was then spin-coated onto the anode. (3) The resulting film was laminated with a second 15 Qsq AgNW-PUA composite electrode (as cathode) to complete the device fabrication. (4) Finally, the device was laminated between a pair of precross-linked urethane liquid rubber compound layers to accomplish the encapsulation. 

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