TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No preparation method is given. Preferred Components: The furan derivatized benzo(1,2-b:3,4-b')dithiophene-thienothiophene based polymer is poly(4,8-bis(5-(2-ethyhexyl)furan-2-yl)-benzo(1,2-b:4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno(3,4-b)thiophene)-2-carboxylate-2-6-diyl or poly(4,8-bis(5-hexylfuran-2-yl)-benzo(1,2-b:4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-3-fluorothieno(3,4-b)thiophene)-2-6-diyl. The bulk heterojunction material comprises at least one selenophene derivatized benzo(1,2-b:3,4-b')dithiophene-thienothiophene based polymer including poly(4,8-bis(5-(2-ethyhexyl)selenophen-2-yl)-benzo(1,2-b:4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-3-fluorothieno(3,4-b)thiophene)-2-6-diyl or poly(4,8-bis(5-(2-ethyhexyl)selenophen-2-yl)-benzo(1,2-b:4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno(3,4-b)thiophene)-2-carboxylate-2-6-diyl. The acceptor is phenyl C70 butyric acid methyl ester (PC70BM), bisindene-C70, bisPC70BM, bisbenzene-C70, trisPC70BM or phenyl C76 butyric acid methyl ester (PC76BM). SPECIFIC COMPOUNDS - 4 Compounds (I) are disclosed i.e. derivatized benzo(1,2-b:3,4-b')dithiophene-thienothiophene based polymer of formulae (Q1)-(Q4).    EXAMPLE - 0.1275 g of 2-Ethylhexyl-4,6-dibromo-3-fluorotheino(3,4-b)thiophene-2-carboxylate and a 0.2697 g of (4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo(1,2-b:4,5-b')dithiophene-2,6-diyl)bis(trimethylstannane) were dissolved in 5.5 ml of toluene with 1.1 ml of dimethyformamide. The reaction mixture was purged with argon for 10 minutes. 12.5 mg of Palladium-tetrakis(triphenylphosphine) catalyst was added to the reaction mixture. After being purged with argon for an additional 20 minutes, the reaction mixture was refluxed for 16 hours under an argon atmosphere. The reaction mixture was cooled to room temperature. The polymer was precipitated by addition of 100 ml of methanol. The polymer precipitate was re-dissolved in chloroform and the polymer was re-precipitated by addition of hexane. The polymer residue was dried over vacuum to afford a 0.163 g of (Q2) with a yield of 61.5%.