| 초록 |
A new series of polymers (PBDT-DFBI) based on difluoro-alkyl benzoimidazole (DFBI) electron-acceptor unit and an electron-donor segment of benzo[1,2-b:4,5-b']dithiophene (BDT) in which (2-octyldodecyl)oxyl chain was used as side chain, were designed and synthesized according to palladium catalyzed the Stille coupling reaction. Fluorine atoms (F atoms) were introduced onto the A-units of D–A polymers to tune their molecular energy levels. The resulting polymers were characterized in paralled by absorption spectroscopy, Thermogravimetric analysis (TGA), Gel Permeation Chromatography (GPC), and photovoltaic measurements. The polymer has good thermal stability and poor solubility in common types of organic solvents. The polymer based on benzoimidaozole units show λmax at 365 nm ~ 508 nm, HOMO energy levels at -5.17 eV~ -5.63eV. With a highest occupied molecular orbital (HOMO) energy level around -5.20 eV, these polymers exhibit a narrow bandgap of 1.75 ~ 1.87 eV. |
