Double-cables

The majority of the synthetic studies towards the construction of novel photodiodes of fullerene-based double-cable polymers concern either electropolymerization of suitable aromatic monomeric units or copolymerization of two monomeric units, one carrying the fullerene moiety and one designed to improve solubility. Most of the electropolymerized conjugated polymeric materials bearing fullerenes that have been obtained consist of bithiophene units with low oxidation potential that favor electropolymerization [162-164]. On the other hand, the preparation of some photodiodes based on novel chemically synthesized double-cable polymers was recently reported and studied using their photophysical properties [165-170]. For example, the structures of some conju-gated-backbone hybrids covalently linked with organofullerene moieties are shown in Scheme 8. 

Novel hybrid materials have been realized in which fullerenes participate in composite films with 7r-conjugated-polymer electron donors such as oligothio-phenes. Established studies have already shown that the photoinduced electron transfer is rather enhanced between 7r-conjugated polymers and fullerenes, while back electron transfer is considerably slower [145,149,171,172].Electrosynthe-sized polythiophene with pendant fullerene substituents was recently obtained from the corresponding biothiophene-fulleropyrrolidine dyad [173]. The novel material described has the potential of a double-cable polymer, heavily loaded with fullerene electron-conducting moieties. 

Scheme 5.3 Carbodithioate-functionalized poly(octylthiophene) (left) and its hybrid with 3 nm CdSe nanocrystals (middle). Idealized double-cable structure allowing for efficient electron (e ) and hole (h+) transport (right).112 (Reprinted with permission from C. Querner et al., Chem. Mater. 2006,18, 4817-4826. Copyright 2006 American Chemical Society.)...

P. Samori, X. Yin, N. Tchebotareva, Z. Wang, T. Pakula, F. Jackel, M.D. Watson, A. Venturini, K. MuUert, J.P. Rabe, Self-assembly of electron donor-acceptor dyads into ordered architectures in two and three dimensions surface patterning and columnar double cables . J. Am. Chem. Soc. 126, 3567-3575 (2004)... 

Cravino, A., G. Zerza, M. Maggini, S. Bucella, M. Svensson, M.R. Andersson, H. Neugebauer, and N.S. Sariciftci. 2000. A novel polythiophene with pendant fullerenes Toward donor/acceptor double-cable polymers. Chem Commun 2487-2488. 

Giacalone, R, J.L. Segura, N. Martin, M. GateDani, S. Luzzati, and N.-O. Lupsac. 2003. Synthesis of soluble donor-acceptor double-cable polymers based on polythiophene and tetracyanoanthraqui-nodimethane (TCAQ). Org Lett 5 1669-1672. 

A. Cravino and N. S. Sariciftci, Double-cable polymers for fuUerene based organic optoelectronic applications, J. Mater. Chem., 12, 1931-1943 (2002). 

F. Zhang, M. Svensson, M. R. Andersson, M. Maggini, S. BuceUa, E. Menna, O. Inganas, Soluble polythiophenes with pendant fullerene groups as double cable materials for photodiodes, Adv. Mater., 13, 1871—1874 (2001). 

Wang C-L, Zhang W-B, Van Horn RM et al (2011) A potphyrin-fullerene dyad with a supramolecular double-cable structure as a novel electron acceptor for bulk heterojunction polymer solar cells. Adv Mater 23(26) 2951-2956... 

Double-cable and single-cable systems are available. In the latter, one and the same cable (wire rope) serves to support as well as to tow the buckets. Ropeways can be used for virtually any distance from, say, 1 km to 100 km. The speed of the buckets is about 4m/second. 

FIGURE 2.40 (a) Most used fullerene derivative in solar cells PCBM, (b) example of double-cable polymer, and (c) supramolecular polymer assembled through hydrogen bonding. 

Ouhib, R, Khoukh, A., Ledeuil, J.-B. et al. (2008a) Diblock and random donor/acceptor double cable polythiophene... 

In this subclass of side-chain polymers, the main chain always consists of a n-conjugated backbone with electron-donating characteristics, the so-called p-type cable, to which several electron-accephng fullerene cages, or an n-type cable, are covalently linked. Owing to its intrinsic electronic properties, numerous double-cable-polymers (D-C) have been employed in electro-optical devices, namely photovoltaic devices (Chapters 7 and 8) [50]. 

Figure 7.6 Some soluble double-cables compounds.

We first, briefly, introduce the concept of bulk heterojunchon solar cells, with the aim of pointing out the importance of the nanomorphology and the degree of D-A separation within the photoactive layer. Then, with no claims of completeness, we select examples of polyfullerene double-cables from the recent literature. 

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