TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The acceptor group comprises at least one acceptor conjugated ring structure such as aromatic structure. The tuning group comprises at least one donor conjugated ring structure e.g. aromatic structure. The tuning group has highest occupied molecular orbital, in isolation from acceptor group. The acceptor conjugated ring structure is fused to one or more tuning groups through tuning conjugated ring structure. The acceptor group comprises nitrogen-containing structures of formulae (I)-(V). Tuning groups contain at least one thiophene ring. The thiophene ring is fused directly to the acceptor group through one or more conjugated aromatic ring structure. The tuning group comprises two or more conjugated ring structure in which at least one is thiophene ring. Tuning group comprises thiophene ring-container structures of formulae (VI)-(XI). Species contain polycyclic ring structures of formulae (XII)-(XXV). Species further contain small molecule. The small molecule further comprises solvating groups such as alkyl chain and/or silyl group, which optionally coupled to the species by alkenyl and/or alkynyl linker groups, and polymeric species such as polymer or oligomer comprising fluorene or fluorine-based repeating unit. Species are optionally substituted by two or more reactive groups comprising halogen and/or boronic ester for Suzuki reaction, or halogen and/or organo tin groups for performing stille reaction.X=S or O;R1,R2=H or optionally substituted linear, branched or cyclic alkyl or 1-20C alkenyl, alkoxy, amino, amide, silyl, alkylsilyl or acyl;Y'=halo, nitro or electron withdrawing group;andR3-R26=1-20C optionally substituted linear, branched or cyclic alkyl, alkenyl, alkynyl aromatic, alkoxy, amino or amido.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: At least one portion of tuning groups and acceptor groups, is in the polymer structure. The copolymer comprises 30-70 mol% of fluorine residue. The polymer further comprises repeating unit (b) comprising fluorene residue, a repeating unit (c), and optionally repeating units (d)-(f). The molar ratio of repeating unit (a) with respect to repeating unit (b) is 50:50. The solution further comprises donor polymer such as poly(3-hexylthiophene).