A general overview of the optoelectronic properties of π -conjugated polymers is presented. Two types of polymer are discerned: interchangeable structures of the same energy (degenerate), such as polyacetylene; and non-degenerate polymers, such as poly(para-phenylene). The band structures of degenerate and non-degenerate polymers are related to their conductivities in doped and non-doped states. In both cases, disorder and impurities play an important role in conductivity. Polarons, bipolarons and excitons are detailed with respect to doping and charge transfers. Given the fibrillic nature of these materials, the variable range hopping (VRH) law for semiconducting polymers is modified to account for metallic behaviours. Optoelectronic properties-electroluminescence and photovoltaic activity-are explained in terms of HOMO and LUMO bands, polaron-exciton and charge movement over one or more molecules. The properties of H-or J-type aggregates and their effects on transitions are related to target applications. Device structures of polymer light-emitting diodes are explicitly linked to optimising polaron recombinations and overall quantum efficiencies. The particularly promising use of π -conjugated polymers in photovoltaic devices is discussed.

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A simple overview of the methods used and the expected benefits of block copolymers in organic photovoltaic devices is given in this review. The description of the photovoltaic process makes it clear how the detailed self-assembly properties of block copolymers can be exploited. Organic photovoltaic technology, an inexpensive, clean and renewable energy source, is an extremely promising option for replacing fossil fuels. It is expected to deliver printable devices processed on flexible substrates using high-volume techniques. Such devices, however, currently lack the long-term stability and efficiency to allow organic photovoltaics to surpass current technologies. Block copolymers are envisaged to help overcome these obstacles because of their long term structural stability and their solid-state morphology being of the appropriate dimensions to efficiently perform charge collection and transfer to electrodes.

π-Conjugated block copolymers have been prepared from terminal azide functionalized polystyrenes (PS) and alkyne functionalized poly(3-hexylthiophene)s (P3HT) via a copper(I) catalyzed Huisgen [3 + 2] dipolar cycloaddition reaction. The functionalized α-azido-PS homopolymer was prepared by atom transfer radical polymerization from a specifically designed initiator bearing the azide function, whereas ω-ethynyl-P3HT and α,ω-pentynyl-P3HT were synthesized by a modified Grignard metathesis polymerization using alkynyl Grignard derivatives. The electronic environment of the alkynyl end groups was shown to be decisive in determining triazole ring formation.