Regulating the Packing of Non-Fullerene Acceptors via Multiple Noncovalent Interactions for Enhancing the Performance of Organic Solar Cells

Three
noncovalently fused-ring electron acceptors (FOC6-IC, FOC6-FIC, and FOC2C6-2FIC) are synthesized. Single
crystals of FOC6-IC and FOC2C6-2FIC are
prepared, and structure analyses reveal that the molecular backbone
can be planarized via the formation of the intramolecular noncovalent
interactions. These acceptor molecules can be packed closely in the
solid state via π–π stacking and static interactions
between the central phenylene unit and the terminal group with a distance
of 3.3–3.4 Å. Besides, multiple intermolecular noncovalent
interactions can be observed in the single crystal structure of the
fluorinated acceptor FOC2C6-2FIC, which help increase
the crystallinity of acceptors and the charge mobility of the blends.
Photovoltaic devices based on FOC2C6-2FIC give a power
conversion efficiency of 12.36%, higher than 12.08% for FOC6-FIC and 10.80% for FOC6-IC.