Narrow band-gap oligomer for solution-processed heterojunction organic solar cells

A novel diphenylaminofluorenyl-capped narrow band-gap oligomer 4,7-[bis-5-(9,9-bis(octyl)-7-diphenylaminofluorene-2-yl)-thiophen-2-yl]-[2,1,3]benzo thiadiazole (DPAFL-DBT-DPAFL which is further abbreviated to DDBTD, presented in first scheme of the article) has been synthesized and characterized. The obtained molecule absorbs light from 300 to 650 nm. Photovoltaic cell by using the blend of the obtained oligomer and PCBM as a active layer was fabricated by spin-coating method. The maximum energy conversion efficiency reached 0.22% and photocurrent response was extended over 700 nm.