Conducting polymer acceptors

Conducting polymers with p-phenylene groups in the backbone can be generated by the metathetical reaction shown in Eq. 14.1. Doping of these polymers with acceptors such as h. Bra, or AsFs increases the conductivity to ca. lO " cm. ... 

Robinson, T., L. D. Kispert et al. (1985). EPR study of acceptor dopedp-terphenyl crystals The oriented radical cation precursor for a conducting polymer. J. Chem. Phys. 82 1539-1542. 

Note 1 The bulk electrical conductivity of an intrinsically conducting polymer is comparable to that of some metals and results from its macromolecules acquiring positive or negative charges through oxidation or reduction by an electron acceptor or donor (charge-transfer agent), termed a dopant. 

The materials studied for 2PA properties involve a number of types of conjugated structures with donor and acceptor groups from stryl to cyanine dyes. Our group is particularly interested in conjugated fluorene derivatives. Fluorene derivatives have been used in conducting polymers, more recently in... 

It is seen from Table 5.1 that the values of the conversion efficiency in bilayer solar cells also is quite low. As mentioned in the introduction it is difficult to dissociate excitons in the conducting polymers. The Donor/Acceptor (D/A) junction between the polymer and the fullerene is rectifying and can be used for designing photovoltaic cells or photodetectors. In this bilayer cell also the conversion efficiency is low. The cause of the low efficiency is that the charge separation occurs only at the D/A interface that results low collection efficiency. The diffusion length of the exciton is a factor 10, lower than the typical penetration depth of the photon. 

K. Yoshino, K. Tada, A. Fujii, E.M. Conwell, A. Zakhidov, Novel photovoltaic devices based on donor-acceptor molecular and conducting polymer systems, IEEE Trans. Electron Devices 44 (1997) 1315-1324. 

Many other air-stable conducting polymers followed (Fig. 12.10) polypyrrole, polythiophene, polyaniline (which had been known since the nineteenth century as "aniline black"), and so on (Table 12.4). These polymers are semiconducting, not metallic, when "doped" with electron donors or acceptors the individual conjugated chains have finite length, so the conductivity is limited by chain-to-chain hopping. Also, if the individual strands exceed four or so oligomers, the conjugation tends to decrease, as the strand tends to adopt a screw-type distortion. The transport within each strand is attributed to polarons and bipolarons. 

The discovery of photoinduced electron transfer in composites of conducting polymers (as donors, D) and buckminsterfullerene, C q, and its derivatives (as acceptors. A) opened a number of new opportunities for semiconducting polymers [149,174]. A schematic description of the photoinduced electron transfer process is displayed in Fig. VC-1. 

The choice of counterion (anion or cation) has a major effect on the stability of conducting polymers. The stability of donor- (36) and acceptor-doped (37, 38) polyacetylenes, polypyrrole (39), poly(alkylthiophene)s (40), and other polymers (40) has been studied by using thermogravimetric anal-... 

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