Polymers semiconduction

Zhang Y, de Boer B, Blom PWM (2009) Controllable molecular doping and charge transport in solution-processed polymer semiconducting layers. Adv Funct Mater 19 1901... 

Future studies should concentrate on four types of silicon-based polymers semiconducting polymers, functional polymers, metallic polymers, and ideal low-dimensional materials for pure physics. The range of Si-based polymers should be expanded rapidly to include high-dimensional polymers, one-dimensional superlattices, and unsaturated polymers. 

FIGURE 3.1.15 Precursor polymers. Semiconducting polymers can be made by either thermal or chemical treatment of preformed solution-cast films. 

Controlled radical polymerizations as versatile synthetic routes for conjugated rod-coil block copolymers and their use as active polymer semiconducting materials in flexible organic electronic devices and systems... 

Key words chemical warfare agents (CWA), polymer, semiconducting device, SAW-type sensor, principal component analysis (PCA). 

Polymer Semiconducting Heterostructure Devices by Nitrene-Mediated Photocrosslinking of Alkyl Side Chains. Nat. Mater. 2010,9,152-158. 

Arias, A.C., et al. 1999. Doped conducting-polymer-semiconducting-polymer interfaces Their use in organic photovoltaic devices. Phys Rev B 60 1854. 

PNG 10] Png R.-Q., Chia P.-J., Tang J.-C. et al., High-performance polymer semiconducting heterostincture devices by nitrene-mediated photocrosslinking of alkyl side chains , Nature Materials, vol. 9, no. 2, pp. 152-158, 2010. 

The purpose of this chapter is to illustrate the type of information that can be obtained about organic conjugated polymers, semiconducting and conducting, through the use of photoelectron spectroscopic measurements. Thus it presents a background to the application of photoelectron spectroscopy for conducting poly-... 

Polymers. The Tt-conjugated polymers used in semiconducting appHcations are usually insulating, with semiconducting or metallic properties induced by doping (see Flectrically conductive polymers). Most of the polymers of this type can be prepared by standard methods. The increasing use of polymers in devices in the last decade has led to a great deal of study to improve the processabiUty of thin films of commonly used polymers. 

Polyaniline (PANI) can be formed by electrochemical oxidation of aniline in aqueous acid, or by polymerization of aniline using an aqueous solution of ammonium thiosulfate and hydrochloric acid. This polymer is finding increasing use as a "transparent electrode" in semiconducting devices. To improve processibiHty, a large number of substituted polyanilines have been prepared. The sulfonated form of PANI is water soluble, and can be prepared by treatment of PANI with fuming sulfuric acid (31). A variety of other soluble substituted AJ-alkylsulfonic acid self-doped derivatives have been synthesized that possess moderate conductivity and allow facile preparation of spincoated thin films (32). 

Both the polymers are dark in color and exhibit semiconductivity and paramagnetism. The electric conductivity measurements are performed on peUets and on thin films in sandwich and surface ceUs. 

The polysdanes are normally electrical insulators, but on doping with AsF or SbF they exhibit electrical conductivity up to the levels of good semiconductors (qv) (98,124). Conductivities up to 0.5 (H-cm) have been measured. However, the doped polymers are sensitive to air and moisture thereby making them unattractive for practical use. In addition to semiconducting behavior, polysilanes exhibit photoconductivity and appear suitable for electrophotography (qv) (125—127). Polysdanes have also been found to exhibit nonlinear optical properties (94,128). 

The carbon black in semiconductive shields is composed of complex aggregates (clusters) that are grape-like stmctures of very small primary particles in the 10 to 70 nanometer size range (see Carbon, carbon black). The optimum concentration of carbon black is a compromise between conductivity and processibiUty and can vary from about 30 to 60 parts per hundred of polymer (phr) depending on the black. If the black concentration is higher than 60 phr for most blacks, the compound is no longer easily extmded into a thin continuous layer on the cable and its physical properties are sacrificed. Ionic contaminants in carbon black may produce tree channels in the insulation close to the conductor shield. 

The most important parameter that affects the resistivity is the amount of carbon black particles, and of secondary importance is the type and especially the shape of the carbon black particles. The susceptibiUty of the carbon black to oxidation may possibly lead to high resistivity of insulation shields. The type of polymer used in a semiconducting material is also an important parameter that can affect resistivity. 

About the time that synthetic metals reached their apogee, twenty years ago, research began on semiconducting polymers. Today, at the turn of the century, such polymers have taken the center of the stage, and indeed promise some of the most important applications of polymers. 

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