Engineering Interfacial Donor−Acceptor Molecular Cocrystals

Y6 is a high-performance non-fullerene acceptor widely used in organic solar cells. The assembly behavior of Y6 atinterfaces, however, remains mostly unknown and respective in-depth investigations are missing. Here, we use room temperaturescanning tunneling microscopy to investigate the self-assembly of Y6 at the solid−liquid interface. We show how coadsorption ofpolycyclic aromatic hydrocarbon donor molecules leads to the formation of a series of donor−acceptor interfacial cocrystals withtailored molecular structure and order on a graphite surface. The gained understanding of the intricate interplay of the underlyingintermolecular interactions should facilitate the engineering of multicomponent interfacial nanostructures and help to potentiallyimprove charge separation and transport in organic (opto)electronic devices.