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.

本研究合成了三种非共价稠环电子受体（noncovalently fused-ring electron acceptors），分别为FOC6-IC、FOC6-FIC与FOC2C6-2FIC。成功制备了FOC6-IC与FOC2C6-2FIC的单晶，结构表征分析表明，分子骨架可通过分子内非共价相互作用的形成实现平面化。这类受体分子在固态下可通过π-π堆积（π–π stacking）以及中心亚苯基单元与端基间的静电相互作用实现紧密堆积，堆积间距为3.3~3.4埃。此外，在氟化受体FOC2C6-2FIC的单晶结构中可观察到多种分子间非共价相互作用，此类作用有助于提升受体的结晶度以及共混膜的电荷迁移率。基于FOC2C6-2FIC的光伏器件功率转换效率可达12.36%，高于FOC6-FIC的12.08%与FOC6-IC的10.80%。