TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The ink comprises at least one halogenated or non-halogenated solvent which is the majority solvent component by weight percentage; comprises at least one non-halogenated or halogenated aromatic solvent as the primary solvent; comprises a solids content of 1-30 (preferably 1.5-5) wt.%; comprises at least one n-type material which is fullerene derivative; and comprises at least one additive.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The first acceptor moiety or monomer is of formulae (II)-(VII). The copolymer further comprises at least one second acceptor moiety different from the first acceptor moiety which is of formula (VIII); is soluble and has a molecular weight of at least 10000; and has number average molecular weight of at least 10000. The donor comprises at least one fused ring system; and comprises benzodithiophene moiety. The donor moiety comprises at least one thiophene ring or at least two thiophene rings; and comprises at least three fused rings.R1, R2 and R'=H or solubilizing group;andR'a=solubilizing group.Preferred Composition: In the composition (C3), the copolymer is of formulae (IIa)-(XIIa). The donor comprises at least one fused ring system.R1a-R5a=solubilizing groups (including optionally substituted alkyl, aryl or halo (such as F atom)), or H.Preferred Method: In the method (M1), the functionalizing with polymerization reaction sites occurs at X1 and X2. The functionalizing with reaction sites occurs at Y1 and Y2. The polymerization reaction sites are halogen or bromine. The providing step involves providing first fluorinated compound comprising first ring, followed by carrying out a ring closure reaction to generate second ring fused to the first ring; or involves providing first fluorinated compound comprising first ring functionalized with at least two amino groups, followed by carrying out ring closure reaction with the amino groups to generate second ring fused to the first ring; or providing first fluorinated compound comprising first ring functionalized with at least two primary amino groups in an ortho position on the ring, followed by carrying out ring closure reaction with the primary amino groups to generate second ring fused to the first ring. In the method (M2), the polymerization reaction sites are halogeno sites. The two fluorine atoms are adjacent to each other on the ring. The functionalizing is carried out on the first ring or the second ring. The first ring is benzene ring or thiophene ring. The second ring is heterocyclic ring. Preferred Definitions:    Z'=B, C, N, O, P, S, Se, or Si.    EXAMPLE - No suitable example given.