Novel perylene diimides for improved photophysical and electrochemical properties

In this study, ortho-terphenyl groups were introduced at the 1- and 7-bay positions of PDI (PDI–TP), and their effect on the photophysical and electrochemical properties were studied along with density functional theory calculations. The PDI core in PDI–TP became highly twisted and exhibited a dihedral angle 12°; while, the unsubstituted PDI compound maintained a planar structure. Furthermore, PDI–TP exhibited a distorted geometry, which reduced the intermolecular π-π stacking between the PDI core and terphenyl group, as evidenced by its increased solubility in common organic solvents. Finally, ternary OSCs were fabricated using PDI–TP as a third component and evaluated in an indoor lighting environment. The ternary OSCs exhibited a power conversion efficiency of up to 20.02%, which is improved by about 28% in comparison to binary OSCs under same condition. This indicates that PDI−TP play an important role as third components in ternary OSCs.