| 초록 |
Among various semiconducting polymers for polymer solar cells, poly{9,9-bis-alkylfluorene-2,7-diyl-alt-[4,7-bis-(thien-2-yl)-2,1,3-benzothiadiazole]-5´,5˝-diyl} (PFDTBT) shows relatively low PCEs of 2-5% with moderate JSCs due to a large bandgap of 1.9 eV although it exhibits a high VOC of 1 V due to their low-lying HOMO energy level. In this study, for the purpose to lower the bandgap, we introduce strong electron-donating oxygen atom into the fluorene unit, which is expected to increase the HOMO energy level, to form dibenzopyran (DBP) unit, although VOC is sacrificed to some extent. DBP was polymerized with the electron deficient DTBT to form a low bandgap polymer (PDBPDTBT). Chemical structures and electrochemical properties of the two polymers (PFDTBT, PDBPDTBT) are measured by NMR, GPC, UV-vis absorption spectroscopy and cyclic voltammetry. The solar cell performances of the cells based on the two polymers are measured and compared. |
