Systems Chemistry Approach in Organic Photovoltaics

The common approach in organic materials science is dominated by the perception that the properties of the bulk materials are virtually determined by the properties of the molecular building blocks. In this Concept Article, we advocate for taking into account supramolecular organization principles for all kinds of organic solid-state materials, irrespective of them being crystalline, liquid crystalline, or amorphous, and discuss a showcase example, that is, the utilization of merocyanine dyes as p-type organic semiconductors in bulk heterojunction (BHJ) solar bells. Despite their extraordinarily large dipole moments, which are considered to be detrimental for efficient charge carrier transport, BM organic photovoltaic materials of these dyes with fullerenes have reached remarkable power conversion efficiencies of meanwhile nearly 5%. These at the first glance contradictory properties are, however, well-understandable on the systems chemistry level.