Conjugated polymers electron-accepting with tethered moieties as ambipolar materials for photovoltaics

Conjugated polymers are of increasing interest as semiconductors for soft (opto) electronic devices, including photovoltaic elements. A promising conversion of solar energy into electrical energy is possible with blends of soluble electron donor-type conjugated polymers and fullerenes as electron-acceptor, transporting component. This approach, called bulk-heterojunction, suggested the preparation of intrinsic ambipolar materials to control simultaneously the electronic and morphological properties. On these bases, the covalent grafting of acceptor moieties onto conjugated backbones seemed attractive for the preparation of intrinsically ambipolar polymeric materials ('double-cable' polymers) as an alternative to donor-acceptor composites. The design, characterisation and application of this novel class of polymers are reviewed taking into account the current understanding of organic photovoltaics. (c) 2007 Society of Chemical Industry.