TECHNOLOGY FOCUS - POLYMERS - Preferred Components: At least one of the monomer is a heterocycle. The monomer further comprises at least one and at most 8 condensed cycles. The monomer is of formula (I). The basic structure of the monomer is formula (II)-(VII). The monomer, in a desired selected sequence, forms the oligomer. The monomer further has: a carbon-sulfur-carbon, carbon-CR3R4-carbon, carbon-NR3-carbon or carbon-oxygen-carbon-bridge for direct bonding over carbon-carbon, and has a basic structure of formula (VIII); or a further bridge over a benzene ring and has a basic structure of formula (IX) or (X). The oligomer further contains one or more side chain with less than 3 atoms of carbon, silicon, oxygen, sulfur, selenium, nitrogen or phosphorus in linear sequence. The oligomer comprises acceptor-donor-acceptor- or donor-acceptor-donor-molecule. The oligomer comprises a molecule having 4 or 6 side chains and has mirror and/or point symmetry. The oligomer is: a molecule having 5 or 6 consecutive conjugated monomers, where the monomer comprises either a non-conjugated side chain, or one or two side chains, or two non-conjugated side chains; or a molecule having at least two n-propyl groups, as a side chain, or a monomer of formula (XI); or a molecule with a nitrile group of formula (C((C?=N)2)=CH(R)) or (C((C?=N)2)=C(CH3)(R)), as an acceptor terminal group or an acceptor monomer with or without additional peripheral substituents of cyano-bicyano or tricyano-vinylene, bridged dithiophene unit with electron-withdrawing bridge, benzothiadiazole, oxadiazole, triazole, benzimidazole, quinoline, quinoxaline, pyrazoline, naphthalene-dicarboxylic acid-anhydride, naphthalene-dicarboxylic acid-imide, naphthalene-dicarboxylic acid-imidazole, halogenated homo- and heterocycle, di- or triarylboryl, dioxaborinane derivatives, quinoid structure, arylene with ketone- or dicyanomethane-substituents.X, Y1 = O, S, Se, CR3R4 or N-R3;R1-R4 = H or a non-conjugated linear chain, where the basic structure of the non-conjugated linear chain contains 3 atoms of C, Si, O, S, Se, N or P in linear sequence;Z = S, CR3R4, NR3 or O; andR = not defined.Where: simultaneously at least one of R1-R4 is not H.