关键词: 受体, 共轭聚合物, 异质结太阳能电池, 含氟受体

Two conjugated copolymers poly[4-(4,4'-dinonyl-2,2'-bithiazol-5-yl)-7-(4,4'-dinonyl-5'-(9-octyl-9H-carbazol- 2-yl)-2,2'-bithiazol-5-yl)benzo[c][1,2,5]thiadiazole] (HSD-5) and poly[9-octyl-2-(5-(2,3,5,6-tetrafluoro-4-(3-undecylthieno- [3,2-b]thiophen-2-yl)phenyl)-6-undecylthieno[3,2-b]thiophen-2-yl)-9H-carbazole] (HSD-7) were synthesized and their photophysical and photovoltaic properties were studied. The electrochemical characterization results showed that these two polymer possessed wide band-gaps of 2.16 and 2.53 eV, respectively. Solar cell devices based on polymer/PC71BM gave a power conversion efficiency (PCE) of 0.36% and 0.73% for HSD-5 and HSD-7, respectively. For the fluorine containing polymer HSD-7, the strong electronegativity of fluorine induces a strong dipole moment along the C—F bond, which resulted in a strong inter/intramolecular interaction and displayed significant influnce on the morphology of the active layer. Meanwhile, the large torsion angles between the acceptor blocks destroyed the conjugation and the electron delocalization. Finally, the structure-activity relationship was also discussed to understand the reason of the low power conversion efficiency (PCE).

Key words: acceptor, conjugated polymer, bulk-heterojunction solar cells, fluorinated blocks