TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No preparation method is given. Preferred Definitions:    Ch=benzo (1,2,5)thiadiazol-4,7-diyl or a benzo(1,2,5)selena-diazol-4,7-diyl group or group of formula (A) as HOMO-LUMO gap; or (poly)thienylfluorene group including 1-3 thienylfluorene, carbazolyl, fused thienylthiophene-based group, thiophene-based group, group of formula (B) or a derivative obtained by substituting at least one H-atom with a 1-4C alkyl group, as polyaromatic chromophore;    X=S or Se;    R1-R3=H or 1-4C alkyl;    D=dialkylamino or diarylamino containing at least one Ph, 1-naphthyl, 9-anthracenyl or 1-pyrenyl;    Acc=2-cyanovinyl;    Y=carboxylic acid, or;    Acc+Y=2-cyanoacrylic acid;    Sp1=p-phenylene, 2,5-thienylene, or group of formula (Sp1a) or (Sp1b);    n=2 or 3; and    Sp2=2,5-thienylene, butadien-1,4-diyl that optionally has a side chain on 3-carbon atom forming a 5- or 6-member ring with the acceptor group Acc, a pyrimidine-2,5-diyl, or trans-vinylene-2,5-thiazolylene.    SPECIFIC COMPOUNDS - 12 Compounds (1) are specifically claimed, e.g. group of formulae (2) and (4)-(7).    EXAMPLE - A dialkylamino or diarylamino donor group was attached to the core by either Stille or Suzuki coupling reactions to produce disubstituted side products as well. Monocapped compounds can be easily separated by column chromatography. In the next step, this bromo-exposed intermediate was reacted with (5-(1,3-dioxolan-2-yl)thiophen-2yl)tributyl stannane under Stille coupling conditions, and subsequent cleavage of the 1,3-dioxalane protecting group in aqueous acetic acid produced the free aldehydes. These aldehydes, on reaction with cyanoacetic acid in the presence of ammonium acetate catalyst in acetic acid, produced the required dyes. The dyes were dark red or black in the solid state and freely dissolve in tetrahydrofuran to produce a red or violet solution. The dye-sensitized solar cells were constructed using these dyes as a sensitizer for nano-crystalline anatase titanium dioxide.