TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): Preparation of the monomer (I) (preferably monomer of formula (Ie)) involves functionalization of compound of formula (i) in presence of N-bromosuccinimide. Preferred Compound: The conjugated polymer (I) is preferably selected from 18 compounds as given in the specification, e.g. compound of formula (Ia)-(Ic). Preferred Definitions:    R1-R4=straight-chain or branched-chain 1-20C (thio)alkyl, 1-20C alkoxy, 2-20C alkenyl, 2-10C alkynyl, 1-20C silyl, 1-20C ester, 1-20C amino, or 1-20C fluoroalkyl;    Ar1 and Ar2=2,1,3-benzothiadiazole-4,7-diyl, 2,1,3-benzoselenadiazole-4,7-diyl, 2,3-dicyano-1,4-phenylene, 2,5-dicyano-1,4-phenylene, 2,3-difluro-1,4-phenylene, 2,5-difluoro-1,4-phenylene, 2,3,5,6-tetrafluoro-1,4-phenylene, 3,4-difluorothiophene-2,5-diyl, thieno(3,4-b)pyrazine-2,5-diyl, quinoxaline-5,8-diyl, selenophene-2,5-diyl, thiophene-2,5-diyl, thieno(3,2-b)thiophene-2,5-diyl, thieno(2,3-b)thiophene-2,5-diyl, selenopheno(3,2-b)selenophene-2,5-diyl, selenopheno(2,3-b)selenophene-2,5-diyl, selenopheno(3,2-b)thiophene-2,5-diyl, selenopheno(2,3-b)thiophene-2,5-diyl, 1,4-phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, p-p'-biphenyl, naphthalene-2,6-diyl, benzo(1,2-b:4,5-b')dithiophene-2,6-diyl, 2,2-dithiophene, 2,2-diselenophene, thiazole or oxazole (all optionally mono- or poly-substituted with R1).    SPECIFIC COMPOUNDS - 3 Compounds are disclosed as the monomer (I), i.e. 2,7-dibromo-4,9-dihydro-4,4,9,9-tetraoctyl-s-indaceno(1,2-b:5,6-b')dithiophene (Id), 2,7-dibromo-4,9-dihydro-4,4,9,9-tetrakis(hexadecyl)-s-indaceno(1,2-b:5,6-b')dithiophene, and 2,7-bis(5-bromothien-2-yl)-4,9-dihydro-4,4,9,9-tetrakis(hexadecyl)-s-indaceno(1,2-b:5,6-b')dithiophene.    EXAMPLE - To a solution of 4,9-dihydro-4,4,9,9-tetraoctyl-s-indaceno(1,2-b:5,6-6')-dithiophene (2 g) in anhydrous tetrahydrofuran (100 cm3), N-bromosuccinimide (0.98 g) was added, and the solution was heated at 50 degrees C for 2 hours and then at 40 degrees C for 17 hours. The mixture was allowed to cool and poured into water (100 cm3). The product was extracted with dichloromethane (DCM) (2x 100 cm3) and the combined organic extracts were dried over anhydrous magnesium sulfate, filtered and the solvent removed. The crude product was purified by column chromatography followed by re-crystallization from DCM/MeOH to give 2,7-dibromo-4,9-dihydro-4,4,9,9-tetraoctyl-s-indaceno(1,2-b:5,6-b')dithiophene as salmon colored crystalline solid (Yield: 1.81 g, 93%).