Fluorinated conjugated polymers in organic bulk heterojunction photovoltaic solar cells

The photovoltaic technology represents a major renewable energy source to harnes the solar power. Over the last two decades, the development of solution-processed bulk heterojunction polymer solar cells has attracted a considerable interest. This has resulted in a significant efficiency improvement through innovation of device architectures and molecular structure design of donor polymers. In this regard, the introduction of fluorinated units along the conjugated backbone has emerged as a successful strategy for further fine-tuning the physical and chemical properties of conducting polymers. In this review, we highlight recent strategies aiming at improving the solar cell performance by variable fluorine substitution of repeating units. Fluorination was found to achieve a modulation of HOMO and LUMO energy levels and optical properties to some extent. Moreover, intermolecular interactions involving fluorine atoms have a significant influence on blend film morphology. The resulting organic photovoltaic solar cells endowed some of the highest power conversion efficiency values reported to date.