Comparison of Two D−A Type Polymers with Each Being Fluorinated on D and A Unit for High Performance Solar Cells.

Jo, Jea Woong; Bae, Seunghwan; Liu, Feng; Russell, Thomas P.; Jo, Won Ho

For the purpose of investigating the effect of fluorination position on D−A type conjugated polymer on photophysical and photovoltaic properties, two types of fluorinated polymere are synthesized, HF with fluorination on electron-donating unit and FH with fluorination on electron-accepting unit. Compared to non-fluorinated polymer, fluorinated polymers exhibit deeper HOMO energy levels without change of bandgap and stronger vibronic shoulder in UV−visible absorption, indicating that fluorination enhances intermolecular interaction. HF with fluorinated D unit exhibits well-developed fibril network, low bimolecular recombination and high hole mobility, which lead a high PCE of 7.10% in conventional single-junction solar cells, which is higher than the PCE (6.41%) of FH with fluorinated A unit. Therefore, this result demonstrates that fluorination on electron-donating unit in D−A polymers could be a promising strategy for achieving high performance polymer solar cells.

POLYMERS; FLUORINATION; SOLAR cells; FLUOROPOLYMERS; PHOTOVOLTAIC effect; FRONTIER orbitals

Advanced Functional Materials, 2015, Vol 25, Issue 1, p120

1616-301X

Academic Journal

10.1002/adfm.201402210