TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer comprises a donor-acceptor structure, where the acceptor comprises backbone moiety of formula VIII. The polymer is soluble. The fused ring systems comprise at least one thiophene fused ring, where the thiophene ring is directly linked to the cyclic polymer substructure of formula IX. The polymer is represented by one of diketopyrrolopyrrole-based structures of formula (X-A) to (X-J). Additionally, the polymer comprises donor-acceptor structure, and the donor comprises at least one of the donors given in the specification (Figure 1). It is a random copolymer or an alternating copolymer. The polymer comprises a donor-acceptor structure, but does not comprise equal amounts of donor and acceptor; the polymer comprises a donor-acceptor structure, and comprises more acceptor than donor; the polymer comprises a donor-acceptor structure, and comprises more donor than acceptor; or the polymer comprises a donor-acceptor structure comprising units D1, D2, A1, and/or A2 and is represented by at least one of polymeric structures of formulae 1-7. The n-type material comprises a fullerene derivative. A1 and/or A2 comprises thiophene ring directly covalently linked to cyclic polymer substructure of formula IX, and at least one of the carbonyl groups shown in backbone moiety of formula VIII interact with thiophene sulfur of the thiophene ring directly covalently linked to cyclic polymer substructure of formula IX. The polymer comprises donor-acceptor structure, and A1 and A2 comprise the donor which comprises at least one tricyclic unit comprising three fused rings; the polymer comprises donor-acceptor structure, and A1 and A2 comprise the donor which comprises at least four fused rings; the polymer comprises donor-acceptor structure, and the donor comprises a silole; the polymer comprises donor-acceptor structure, and the polymer comprises at least one acceptor represented by backbone moiety of formula VIII and at least one donor which is a triarylamine; the polymer comprises donor-acceptor structure, and the donor is a symmetrical moiety; or the polymer comprises donor-acceptor structure, and A1 and/or A2 comprises the donor which comprises at least one tricyclic unit comprising three fused rings, where two of the rings are thiophene rings and one of the rings is a benzene ring. The polymer is free of protecting groups. It exhibits vibronic structure as measured by UV-vis absorption spectroscopy. The composition comprises at least one of diketopyrrolopyrrole-based moieties of formulae XI-n, XI-o, and XI-p. The at least two fused rings form part of the backbone and none of the fused rings form side groups to the backbone. Preferred Composition: The polymer comprises a molecular weight Mn of at least 10000 or 20000. Preferred Device: The device is a photovoltaic device and demonstrates a power conversion efficiency of at least 3%. The device further comprises at least one hole collection layer. Preferred Method: The method further comprises polymerizing the modified compound. Preferred Definitions:    R1 and R2=are adapted to provide the polymer with solubility, each comprise optionally substituted alkyl, optionally substituted linear alkyl, optionally substituted branched alkyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted alkylaryl, optionally substituted arylalkyl, optionally substituted alkoxy, or optionally substituted aryloxy, and optionally, where R groups R1 and R2 further comprises fluorine, preferably R1 and R2 are the same;    A=a nitrogen atom; and    A1 and A2=the same.    EXAMPLE - No suitable example given.