Crystal Engineering in Organic Photovoltaic Acceptors: A 3D Network Approach

The power conversion efficiency of organic solar cell (OSC) devices has surpassed 18% rapidly. In order to further promote OSC development, it is necessary to understand the packing information at the atomic level to help develop acceptor systems with superior performance. The packing arrangements and intermolecular interactions of these acceptors in the solid state, observed by single crystal X‐ray crystallography, are often used to design materials with expected physicochemical properties. In this review, the chemical structures of acceptors revealed by single crystal X‐ray crystallography are summarized, and the relationship between structural design, packing arrangement, and device properties is discussed. In addition, the concept of “3D network packing” in acceptor systems is proposed, which offers better charge transfer properties in reported chlorinated, fluorinated, brominated, and trifluoromethylated systems, an understanding of 3D network transport also provides guidance in high‐performance materials design. Finally, some current issues related to single crystal studies in OSCs are discussed, with an emphasis on the significance of developing acceptors by understanding and adjusting the aggregation states and intermolecular interactions of materials by single crystal analysis. The relationship between structure design, packing arrangement, and molecular property of organic photovoltaic (OPV) acceptors is explored, in which the 3D network packing originating from non‐covalent intermolecular interactions and aggregation states, is found to promote OPV device performance. This review sheds light on charge transport processes in acceptors and provides a guideline for developing new generation OPV materials.