Polymer poly-3-hexylthiophene

Nowadays the best performing organic photovoltaic cell is represented by a bulk heterojunction (BHJ) solar cell based on the polymer poly(3-hexylthiophene) (P3HT) and the fullerene derivative [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM), with reproducible efficiencies approaching 5% [262,263], However, a serious drawback for the preparation of efficient organic photovoltaic cells is represented by the low optical absorbance in the red/near-infrared region of the lightharvesting component(s), as well as their low extinction coefflcient(s). 

That detection limit was recently improved by Wang et al. [20]. The authors replaced the 16 mm vacuum-deposited CuPc-Ceo bilayer devices by 1 mm solution-processed polymer devices based on a 1 1 blend by weight of the conjugated polymer poly(3-hexylthiophene) (P3HT) and 6,6-phenyl-C6i-butyric acid methyl ester (PCBM), a soluble derivative of Ceo- The device has an active area of 1 mm and an external quantum efficiency of more than 50 % between 450 and 550 nm (Fig. 12). The device... 

S. Holdcroft. Photochain scission of the soluble electronicaUy conducting polymer poly(3-hexylthiophene). Macromolecules 24(8), 2119-2121 (1991). 

Barrau and co-workers have found that amphiphilic palmitic add could be favorable for an efSdent dispersion of CNTs in an epoxy matrix. The hydrophobic part of palmitic acid was absorbed onto the surface of CNTs, whereas the hydrophilic head group induced electrostatic repulsions between CNTs, effeaively preventing their aggregation. The cosolvent has also been found to affect the dispersion of CNTs in polymer matrix. Very recently, Camponeschi a reported the use of trifluoroacetic acid as a cosolvent for the dispersion of MWNTs in a conjugated polymer poly (3-hexylthiophene) and PMMA via a solution process. SEM, optical microscopy, and light transmittance studies indicated that a better dispersion of CNTs in polymer matrices was obtained by using trifluoroacetic acid. Many other polymer composites such as polyurethane/CNT, PS/CNT, epoxy/ CNT, poly(vinyl alcohol)/CNT, " P(MMA-co-EMA)/ CNT, polyacrylonitrile/CNT, and polyethylene/CNT have also been fabricated by this method. ... 

FIGURE 13.7 Tapping mode AFM phase images of polymer thin films (a) poly(3-hexylthiophene) (b) poly(3-hexylthiophene)-b-polystyrene (c) poly(hexylthiophene)-fc-poly(butylacrylate) (d) poly(3-hexylthiophene)- -poly(methylacrylate) (e) poly(3-dodecylthiophene-ran-3-methylthiophene). Reprinted with permission from [83], Copyright 2006 American Chemical Society. 

S. Amou, O. Haba, K. Shirato, T. Hayakawa, M. Ueda, K. Takeuchi, and M. Asai, Head-to-tail regioregularity of poly(3-hexylthiophene) in oxidative coupling polymerization with FeCl3, J. Polym. Sci., Part A Polym. Chem., 37 1943-1948, 1999. 

Y. Li, G. Vamvounis, J. Yu, and S. Holdcroft, A novel and versatile methodology for functionalization of conjugated polymers. Transformation of poly(3-bromo-4-hexylthiophene) via palladium-catalyzed coupling chemistry, Macromolecules, 34 3130-3132, 2001. 

Thus, many polymers with different conductivity were synthesized. To cite a few, these are polythiophene [158], 3-methylthiophene [159], polymers of 3-thiophene-acetic acid and methyl 3-thiophene-acetate [160], poly(2,5-thienylenevinylene) [161], poly(benzo[h]-thiophene) [162], poly(naphto[2,3-c]thio-phene) [163], poly(dithieno[3,2-h 2, 3 -fii]-thiophene) [164], poly(3- -hexylthiophene)... 

The soluble polythiophenes are the first conducting polymers that can be taken above their glass transition without decomposition and it will be interesting to study morphology-property relationships. Heeger et al.262) have recently described conformational changes in solutions of poly-3-hexylthiophene which seem to involve a coil-helix transformation as the temperature is decreased or a poor solvent is added. 

Fig. 1.16. Regio-regular poly-3-hexylthiophene with edge-on orientation of the polymer chains. Redrawn from Ref. [74].

Polymers (CH), PPA Poiy(o-Me3SiPA) PPY DP-PPY PPY PAN PNA EM LM NA PTH PPS PBT PBiT PMeT PHeT PPV PPP P2VP P4VP PVK polyacetylene polyphenylacetylene poly[[o-(trimethylsilyl)phenyl]acetylene] polypyrrole deprotonated (25%) polypyrrole fully reduced polypyrrole polyaniline pernigraniline emeraldine leucoemeraldine nigraniline polythiophene poly(phenylene sulfide) polybenzothiophene poly(2,2 -bithiophene) poly(3-methylthiophene) poly(3-hexylthiophene) poly(phenylene vinylene) poly( p-phenylene) poly(2-vinylpyridine) poly(4-vinylpyridine) poly(A-vinylcarbazole)... 

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