Synthesis and photovoltaic properties of poly(dithieno[3,2-b:2\u2032, 3\u2032-d ]germole) derivatives

A series of new dithieno[3,2-b:2\u2032,3\u2032-d]germole copolymers have been synthesized and characterized. The dithienogermole unit has been polymerized with different aromatic comonomers such as the benzothiadiazole (PGe1-C8 and PGe1-EH) and thieno[3,4-c]pyrrole-4,6-dione (PGe2). Suzuki and Stille coupling polymerizations under various conditions have been utilized. The polymers were then characterized by size-exclusion chromatography and thermal analyses (TGA, DSC), and their optical and electronic properties were investigated by UV-vis absorption spectroscopy and cyclic voltammetry. These low bandgap polymers (1.3-1.7 eV) have also been tested for photovoltaic applications; the best result was achieved with polymer PGe2, which shows a power conversion efficiency of 4.1%. \ua9 2011 American Chemical Society.Peer reviewed: YesNRC publication: Ye