PEDOT bilayer

Since the ionization potential of 238 matches closely the work function of PEDOT (5.1-5.3 eV) [335], the hole injection is dramatically improved. Accordingly, the device ITO/PEDOT/237 238(7 3)/Al has a significantly improved EL efficiency, tjel= 1.5cd/A, two orders of magnitude higher than that of single-layer PLED with 237, six times higher than that of bilayer PLED with triarylamine polymer HTL, and almost twice as high as that of PF blends with low molecular triphenylamine HT materials (in device with Ca electrode) [321]. 

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].

This view of Voc generation is additionally supported by the fact that the values of the temperature coefficient dUoc/dT = -(1.40-1.65) mVK-1 for the cells under the present study (with bilayer LiF/Al and ITO/PEDOT contacts) coincide with those for polymer/fullerene bulk heterojunction solar cells of the previous generation (with the same components of the active layer but without LiF and PEDOT contact layers) [156]. In this picture, the temperature dependence of Voc is directly correlated with the temperature dependence of the quasi-Fermi levels of the components of the active layer under illumination, i.e., of the polymer and the fullerene. Therefore, the temperature dependence of Voc over a wide range, and in particular V),c(0 K), are essential parameters for understanding bulk hetero junction solar cells. 

The basic structure of a typical dc-biased bilayer OLED is shown in Figure 1.5. The first layer above the glass substrate is a transparent conducting anode, typically indium tin oxide (ITO). Flexible OLEDs, in which the anode is made of a transparent conducting organic compound, e.g., doped polyaniline (see Fig. 1.2),44 or poly(3,4-ethylene dioxy-2,4-thiophene) (PEDOT)-polystyrene sulfonate (PEDOT-PSS) (see Fig. 1,2)45 deposited on a suitable plastic, e.g., transparency plastic, have also been reported. 

With molecular structures similar to the MEH-PPV CN-PPV system, the intensively studied M3EH-PPV CN-ether-PPV system—either as a blend or as a bilayer—resulted more recently in higher efficiencies under full AM 1.5 illumination (lOOmW/cm ) (Fig. 46) [35,223-225]. The first blend devices incorporated either a flat sintered titanium dioxide (Ti02) or a PEDOT PSS interlayer at the ITO interface. Blend devices with PEDOTiPSS and Ca electrodes led to power conversion efficiencies of 1% and EQEs of up to 23%. 

Gallegos AK.C. and Rincon M., Carbon nanofiberand PEDOT-PSS bilayer systems as eiectrodes for symmetric and asymmetric electrochemical capacitor ceiis,/ Power Sources, 2006,162, lAZ-lAl. 

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... 

FIGURE 20.21 Absorption spectroelectrochemistry for a 40-bilayer film of a composite of poly(hexyl viologen) and PEDOT-PSS at potentials between —0.9 and 0.5 V vs. SCE. Absorbance values are normalized to the polymer film thickness. (From DeLongchamp, D., Chem. Mater., 15, 1575, 2003. With permission.)... 

Non-destructive surface-functionalization of carbon nanofibers can be achieved by using poly(3,4-ethylenedioxythiophene) (PEDOT) since PEDOT is an electron donor and carbon nanofiber is an electron acceptor [40]. PEDOT/carbon nanofiber nanocomposites can be prepared by chemical polymerization process. This includes an initial adsorption of EDOT monomers on the carbon nanofibers, which is followed by the polymerization process. The adsorption of monomers on the fiber surface occurs due to the electrostatic n-n interaction. PEDOT poly(styrenesulfonate) (PEDOT PSS)/carbon nanofiber bilayer system is used particularly for electrode applications [41]. Such bilayer systems can be easily prepared with dip-coating technique.The advantage of dip-coating is that only a small amount of polymer will be adsorbed on the carbon nanofiber surface and hence nanometer thick coating is achievable. The surface area of electroactive materials can be enhanced in such bilayer systems prepared with carbon nanofibers. 

Figure 4.29 Scan rate dependence of PAH-PEDOT-S multilayer films of 10-50 bilayers. Cyclic voltammograms were scanned between —0.7V and 0.6 V (vs Ag/AgCl) at scan rates ranging from 20-1000 mV/s inNaS04 (O.2M/H2O). (Reproduced from Advanced Materials, 2002, 14, 684, C. A. Cutler, M. Bouguettaya, T. S. Kang, J. R. Reynolds, with permission from Wiley-VCH.)...

There are two main types of PSCs including bilayer heterojunction and bulk-heterojunction [7]. Bulk-heterojunction PSCs are more attractive due to their high surface area junction that increases conversion efficiency. This type of polymer solar cell consists of Glass, ITO, PEDOT PSS, active layer, calciiun and aluminum in which conjugated polymer are used as active layer [8]. The organic solar cells with maximum conversion efficiency about 6% still are at the begiiming of development and have a long... 

The general structure of the bilayer solar cells is similar to the light-emitting diodes (LEDs). The devices are fabricated in sandwich geometry (Fig. 11.9). The active layer is sandwiched between two contacts an indium-tin-oxide electrode (ITO) (cathode) coated with a hole transport layer/glass or plastic foil. The blend polymer/PCBM solution was doctor-bladed on top of the hole conductor PEDOT PSS [poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid]. It improves the surface quality of ITO electrode. On the top of this polymer, about 100-nm aluminum layer is placed as an electrode (anode). 

Taccola et al. (2013) have employed the spin-coating technique to build bilayer polymer actuators, which are in the form of microfingers, consisting of a PEDOT/ PSS film spin-coated with SU-8, which is the structural passive layer in the bilayer configuration. 

Wu Y, Alici G, Madden JDW, Spinks GM, Wallace GG (2007) Soft mechanical sensors through reverse actuation in polypyrrole. Adv Funct Mater 17 3216-3222 Zainudeen UL, Careem MA, Skaamp S (2007) Actuators based on pedot and PPy conducting polymer bilayers and trilayers. In Industrial and information systems, 2007. ICIIS 2007. International conference on, 9-11 Aug 2007. Peradeniya, pp 461-464 Zhou D, Wallace GG, Spinks GM, Liu L, Cowan R, Saunders E, Newbold C (2003) Actuators for the cochlear implant Synth Met 135-136 39-40... 

Bilayer and trilayer actuators Characterizations of Electrochemical cell Experimental procedure Materials Conducting polymers (CPs) Liquid electrolyte Open air Cyclic voltammetry Dibutyltin dilaurate Electronic conducting polymers (ECPs) Interpenetrating polymer network (IPN) Poly (3,4-ethylenedioxythiophene) (PEDOT) Polypyrrole (PPY) Actuation mechanism of Electrogeneration of Electropolymerization of pyrrole monomer Oxidation and reduction reaction of Polyvinylidene fluoride (PVDF) Solid polymer electrolyte (SPE) membrane Force characterizations IPNs Load curves and metrics PVDF membrane Strain characterizations... 

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