| 초록 |
For many efficient donor polymers, halogenation is an effective way to modify the energy levels and the band gaps of the polymers. Fluorination has been applied organic solar cells (OSCs) for recent years due to its advantages such as providing more planar backbones and exhibiting more ordered packing. However, on the basis of previous reports, fluorinated polymers have drawbacks of low yields in the fluorine exchange reactions and severe aggregation. So, we need methods to overcome this disadvantages, such as chlorination. Compared to fluorinated ones, chlorinated polymers are simple to synthesize with higher yields and intermolecular interactions will be partly restrained due to the bigger atomic radius of the chlorine atom. At the same time, chlorine atom has large dipole moment and it lied lowest unoccupied molecular orbital (LUMO), highest occupied molecular orbital (HOMO) levels of polymers and changed the band gaps eventually pushing the PCE to a higher value. |
