PEDOT/PSS films

Figure 2.31 Effect of film thickness on the absorbance response of a PXV/PEDOT PSS films bearing (a) 20 (b) 30 (c) 40 (d) 50 and (e) 60 bilayers. Square-wave potential between 0.5 V and —0.9 V and a period of 20s was employed. Taken from [196].

Fig.6 IP values of 20 nm PEDOT PSS films at different delay times to baking after spincoating on ITO, and IP of neutral PEDOT (taken from [76])...

Fig. 9.1. (Left) the architecture of the PEDOT PSS-based OECT is illustrated viewed from the top and at a cross section, respectively. The area of the PEDOT PSS film, in between the source and drain contact, that is capped by the electrolyte, defines the transistor channel. (Right) the current vs. voltage characteristics of the PEDOT PSS-based OECT. At zero gate voltage, the transistor is in the ON state and at Vg = 0.8 V the channel current is suppressed by more than two orders of magnitude as compared to the ON state current...

Figure 3.7 i-V curves for dye-sensitized plastic photocells using various counter electrode materials coated on ITO-PEN plastic substrate. A, Ti02-IT0/PED0T-PSS film B, ITO/PEDOT-PSS film C, PEDOT-PSS... 

L. S. C. Pingree, B.A. MacLeod, and D.S. Ginger, The changing face of PEDOT PSS films Substrate, bias, and processing effects on vertical charge transport. J. Phys. Chem. C, 112,7922 (2008). 

Figure 10.6 Procedure for polymer nanowire fabrication. An aqueous PEDOTtPSS solution was spin-coated on a substrate patterned with a 1.3 ym period grating, then coated with a thin Si02 layer and a PDMS homopolymer brush. A PS-PDMS block-copolymer thin film was then spin-coated and solvent-annealed. The self-assembled block-copolymer patterns were transferred into the underlying PEDOT-.PSS film through a series of reactive ion etching steps employing CF4 and O2 plasmas. (Reprinted with permission from Nano Letters, Nanowire Conductive Polymer Gas Sensor Patterned Using Self-Assembled Block Copolymer Lithography by Y. S. Jung et al., 8, 11. Copyright (2008) American Chemical Society)...

A humidity-sensitive conducting polymer actuator made up of PEDOT doped with poly(4-styrenesulfonate) (PEDOT/PSS) was fabricated [47]. Water vapor sorption and electro-active actuating behavior of free-standing PEDOT/PSS films were investigated by sorption isotherm and electromechanical analyses. The non-porous PEDOT/PSS film, with a specific surface area of 0.13 m g sorbed water vapor of 1,080 cm (STP)g , corresponding to 87 wt%, at relative water... 

Fig. 7 Time profiles of electric current, surface temperature, and length change of PEDOT/PSS films (50 mm long, 2 mm wide, and 10 pm thick) under 10 V measured at 50% RH and various temperatures. Reproduced with permission from [47]...

PEDOT PSS represents one of the most explored conductive polymers and is available for some commercial applications in the fabrication of low-cost, flexible, and printable electronic devices. Although the PEDOTrPSS films are also widely investigated for high electrical conductivities (Liu et al., 2015), they remain obviously lower than their inorganic counterparts (Dobbelin et al., 2007). Even worse, the performances, such as efficiency and lifetime of the electronic devices are deteriorated as PSS is strongly acidic and hygroscopic. Therefore, it is critical to further improve the electrical conductivity and stability of the PEDOT PSS film. 

FIGURE 3.4 (A) Fabrication of polymer solar cell from PEDOTiPSS thin film. (B) Fabrication of a three-dimensional (3D) nonwoven nanofabric-based organic solar cell. (A) Reproduced with permission from reference Oh, J.Y., Shin, M., Lee, J.B., Ahn, J.-H., Baik, H.K., Jeong, U., 2014. Effect ofPEDOT nanofibril networks on the conductivity, flexibility, and coatability of PEDOT PSS films. ACSAppl. Mater. Interfaces 6, 6954-6961. Copyright 2014, Royal Society of Chemistry. 

D., 2007. Influence of ionic liquids on the electrical conductivity and morphology of PEDOT PSS films. Chem. mater. 19,2147-2149. 

McCarthy, J.E., Hanley, C.A., Brerman, L.J., Lambertini, V.G., Gun ko,Y.K., 2014. Fabrication of highly transparent and conducting PEDOT PSS films using a formic acid treatment. 1. Mater. Chem. C 2, 764-770. 

Reyes-Reyes, M., Cruz-Cruz, L, L Pez-Sandoval, R., 2010. Enhancement of the electrical conductivity in PEDOT PSS films by the addition of dimethyl sulfate. J. Phys. Chem. C 114,20220-20224. 

Vosgueritchian, M., Lipomi, D.L, Bao, Z., 2012. Highly conductive and transparent PEDOT PSS films with a fluorosurfactant for stretchable and flexible transparent electrodes. Adv. Eunct. Mater. 22,421-428. 

Figure 6.20 SEM images of PEDOT PSS films (a) PEDOT PSS, (b) PEDOTiPSS + 10 wt.% Bi TCj, and (c) PEDOT PSS + 70 wt.% Bi TOj. Adapted with permission from Ref. [31], Copyright 2013 IEEE.

Liu et al. successfully prepared p-type PEDOT-ESS/Ca Co Og composite films by casting the mixed solution of Ca Co Og powder and PEDOT-PSS solution on polypropylene (PP) substrate [33]. The surfaces of the freestanding PEDOT-PSS films were smooth and compact (Figure 6.21a),... 

The two electrons transferred from TDAE to PEDOT-PSS are expected to undope the conjugated polymer chains. Since TDAE diffuses into PEDOT-PSS, long exposures to the electron donor induce changes in the optical properties of the polymer film. Optical absorption experiments on 200 nm thick PEDOT-PSS films coated onto a transparent polyethylene terephthalate (PET) substrate. The pol5mier film was exposed to the TDAE vapor in an inert nitrogen atmosphere and shows the difference in absorption spectrum between a film exposed to TDAE and the pristine PEDOT-PSS layer (Figs. 3.10 and 3.11). The modification of the optical properties and the sheet resistance of the pol5mier layer were recorded versus exposure time. The two absorption features at 550 nm and... 

The conductivity of a PEDOT-PSS film can be enhanced by more than 2 orders of magnitude by the addition of polar group containing compounds like ethylene glycol, into an aqueous solution of PEDOT-PSS. The additive induces a conformational change in the PEDOT chains of the PEDOT-PSS film. 

Both coil and linear or expanded-coil conformations exist in untreated PEDOT-PSS films, whereas the linear or expanded-coil conformation becomes dominant in high-conductivity PEDOT-PSS films. This conformational change results in an increase in the intrachain and interchain charge carrier mobility, so the conductivity is enhanced. ... 

The reaction at room temperature results in a dark-blue, aqueous PEDOT/PSS dispersion, which is commercially available from Bayer AG under the trade name BAYTRON P and from ELECON under the trade name ELEFLEX13 2000. After dr5dng of BAYTRON P and ELEFLEX 2000, the remaining PEDOT/PSS film is highly conducting, transparent, mechanically durable, and insoluble in any common solvent. 

Working in collaboration with Reynolds, we have fabricated organic photovoltaic devices in which the active materials were assembled by using the LbL method [53]. In this work, the donor and hole transporting materials were the anionic CPEs PPE-SOs and PPE-EDOT-SO , whereas the acceptor and electron transport material was a cationic fullerene derivative, Cso-NHa (Scheme 14.13). The active layers were constructed atop an ITO substrate that was precoated with a PEDOT-PSS film (spin-coated). The PPE(—)/C6o—NHa bilayers were deposited through the LbL method, and the effect of active layer thickness on device performance was explored. Figure 14.20 shows a schematic... 

The absorptive/transmissive-type ECD operates with a reversible switching of the electrochromic materials between a colored state and a bleached state. Both working electrode and counter electrode are transparent so that light can pass through the device [4,5,15,250]. For flexible devices, ITO, SWNT, or PEDOT/PSS deposited onto a plastic such as poly(ethylene terepthalate) (PET) have been used [258,259]. When deposited in the doped form and dried, PEDOT/PSS films, to a thickness of 300 nm, are relatively transmissive in the visible region ( 75% T), have a relatively low resistivity (500 fi/D), and adhere to the plastic substrate in most common electrolyte solutions. The polymer films were demonstrated to be useable over the operating range of the device with no loss in conductivity or transmissivity. 

In this section, several PES studies on selected properties of PEDOT-PSS that are relevant to certain applications in organic electronics are reviewed. The unique initial-state binding energies of the sulfur atoms in the PEDOT and the PSS portions of the polymer blend make it possible to distinguish PEDOT from PSS within PEDOT-PSS films. We focus on the analysis of the elemental composition, the PEDOT-to-PSS ratio, some aspects of the granular morphology, and some additional chemical information (for example, an estimate of the doping level). 

The 0(ls) spectrum of a PEDOT-PSS film is shown in Figure 21.17b. Again, a number of different chemical species are expected to contribute to the core-level signal. In analogy to the S(2p) spectrum, a combination of the a priori knowledge of the chemical composition and the measurements performed... 

As discussed, the electropolymerized PEDOT-PSS (o- = 80 S cm , 1 s/t ratio = 0.68) has a completely different composition than the chemically polymerized PEDOT-PSS (Electrochemical quartz crystal microbalance (EQCM) analyses have shown that the composition of the electropolymerized PEDOT-PSS is not dependent on the anion concentration [135]. This indicates that the mechanism of synthesis of the polymer strongly influences its composition. During electropolymerization, the first formed (and doped) oligomers are very close to the metal electrode as charge transfer occurs at a tunnel distance. Consequently, those doped oligomers interact electrostatically with the closest sulfonate anions of a PSS chain at the vicinity of the electrode. This mechanism leads to a high concentration of PEDOT in the PEDOT-PSS film, independent on the anion concentration. 

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