title: Using cyclopenta[2,1-b:3,4-c']dithiophene-4-one as a building block for low-bandgap conjugated copolymers applied in solar cells.
abstract: A novel electron-accepting unit cyclopenta[2,1-b:3,4-c']dithiophene-4-one (CPDTO-c'), which is an isomer of CPDTO-b' was developed. CPDTO-c' can be incorporated into the D-A backbone through 5, 7 positions. The 2 position of CPDTO-c' can be easily functionalized with an electron-withdrawing chain. By copolymerizing CPDTO-c' with four different donor units: benzo[1,2-b:4,5-b']dithiophene (BDT), dithieno[3,2-b:2',3'-d]silole (DTS), carbazole, and fluorene, four new conjugated copolymers P1-P4 were obtained. All these polymers have good solubility and low-lying HOMO energy levels (-5.41 ∼ -5.92 eV). Among them, P1 and P2 exhibit broad absorption and narrow optical bandgaps of 1.91 and 1.72 eV, respectively. Solar cells based on P1/PC(71) BM afforded a PCE up to 2.72% and a high V(oc)  up to ∼0.9 V.
authors: National Center for Nanoscience and Technology, Beijing, China.
authors: Wei
authors: W
authors: Zhang
authors: Jiamin
authors: J
authors: Cao
authors: Ying
authors: Y
authors: Liu
authors: Zuo
authors: Z
authors: Xiao
authors: Weiguo
authors: W
authors: Zhu
authors: Qiqun
authors: Q
authors: Zuo
authors: Liming
authors: L
authors: Ding
mesh_terms: D011211:Electric Power Supplies; D015394:Molecular Structure; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D012993:Solar Energy; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D011108:Polymers; D013876:Thiophenes