Polythiophenes electronic properties

Polythiophene [78] is a promising material for certain future electronic applications, due to its relatively high stability and processability in the substituted form [79-81]. Upon substitution, with e.g. alkyl side-chains [79, 80], polythiophene exhibit properties such as solvalochromism [82] and thermochromism [83]. Presently, a large variety of substituted polythiophenes with various band gaps exists (for example see Ref. [81 ]). 

Related Polymer Systems and Synthetic Methods. Figure 12A shows a hypothetical synthesis of poly (p-phenylene methide) (PPM) from polybenzyl by redox-induced elimination. In principle, it should be possible to accomplish this experimentally under similar chemical and electrochemical redox conditions as those used here for the related polythiophenes. The electronic properties of PPM have recently been theoretically calculated by Boudreaux et al (16), including bandgap (1.17 eV) bandwidth (0.44 eV) ionization potential (4.2 eV) electron affinity (3.03 eV) oxidation potential (-0.20 vs SCE) reduction potential (-1.37 eV vs SCE). PPM has recently been synthesized and doped to a semiconductor (24). 

Polythiophenes (including oligothiophenes) are one of the most studied and important classes of linear conjugated polymers [444,445], Versatile synthetic approaches to PTs (chemical [446] and electrochemical [447]), easy functionalization and unique, widely tunable electronic properties have been the source of tremendous interest in this class of polymers. 

The polymerization of thiophene, to yield intractable polythiophene 48, was first carried out in a controlled manner in the early 1980s [185-188]. Even in such an unyielding form, this polymer displayed many promising optical and electronic properties. Unfortunately, its lack of processibility precluded further exploration of these attractive attributes. Since then, the synthesis of soluble pol-... 

Optical Properties of Polythiophenes Electronic Band Structure and UV-Visible Spectra... 

Mardalen, J. et al.. Structure and electronic-properties of polythiophene and poly(3-alkylthiophene) films electropolymerized on indium tin oxide (Ito) glass at elevated potentials, Macwmol. Chem. Phys. 194, 2483-2495, 1993. 

Polythiophenes constitute a particularly important class of conjugated polymers, which has been extensively studied for the relation between the geometrical structure and the optic and electronic properties. Wliile... 

In all eases, Al atoms arc found to react with the conjugated systems by forming new Al-carbon covalent bonds. As a consequence, the carbon atoms involved in the bonding adopt an p hybridization. The n electron conjugation is dramatically perturbed and the corresponding wavcfunction delocalization, which constitutes the basis for the electronic properties of these materials, is significantly reduced in polytmcs or even disrupted in polythiophenes. ... 

Bredas, J.L., G.B. Street, B. Themans, and J.M. Andre. 1985. Organic polymers based on aromatic rings (polyparaphenylene, polypyrrole, polythiophene) Evolution of the electronic properties as a function of the torsion angle between adjacent rings. J Chem Phys 83 1323-1329. 

Barbarella, G., L. Favaretto, G. Sotgiu, M. Zambianchi, C. Arbizzani, A. Bongini, and M. Mas-tragostino. 1999. Controlling the electronic properties of polythiophene through the insertion of nonaromatic thienyl S,S-dioxide units. Chem Mater 11 2533-2541. 

Synthesis of a poly[tetra(2,3-thienylene)] P4.16 was realized by typical Ni°-catalyzed cross-coupling polymerization of metalated tetramer 4.16, which in turn was prepared effectively from quaterthiophene 4.15 by oxidative coupling in 48% yield (Scheme 1.37) [366, 367]. The polymer, a poly( [8]annulene), which was soluble in organic solvents due to the butyl side-chains, showed electronic properties typical for polythiophenes a measurement of actuation, however, could not be obtained. 

Aromatic heterocyclic polymers such as polypyrrole and polythiophene have low ionization potentials and low electron affinities [1, 2]. An early theoretical study on the electronic properties of these polymers indicated that electron affinity is mainly affected by substitution on the heteroatom whereas ionization potential is mainly affected by substitution on the backbone [9], Later theoretical studies on polythiophene indicated that chemical transformation of thienyl sulfur to the corresponding thienyl-5-oxide or thienyl-5,5-dioxide would deeply affect the electronic properties of the polymer as a result of the increase in both electron affinity (EA) and ionization potential (IP) [10, 11],... 

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