Perylenediimides (PDIs) are among the most promising non-fullerene electron-acceptors for applications in organic photovoltaics (PV), providing a large scope for structural modifications. PDI-based dimers have shown the highest performances in PV devices owing to their characteristic twisted conformations that reduce their tendency to form large aggregates which are detrimental for PV operation. In this work, two fluorene-bridged perylenediimide (PDI) dimers with oligo(ethylene oxide) or alkyl chains anchored to the C9 position of the fluorene unit were synthesized and investigated in solution-processed organic bulk heterojunction (BHJ) photovoltaic cells as electron acceptors. The PDI dimer substituted with oligo(ethylene oxide) chains resulted in improved power conversion efficiencies (in 20%–53%) in solution processed bulk heterojunction (BHJ) cells with two different polymer donors, PTB7 and PffBT4T-2OD. Nevertheless, the replacement of alkyl chains by oligo(ethylene oxide) chains did not significantly affect the geometric characteristics of the PDI dimers and the optical and electrochemical properties were only marginally modified. Increased exciton dissociation and enhanced charge transport derived from a more densely packed π-π stacking in the solid state caused by ethylene oxide groups are pointed out as possible causes for the improved PV performance. The influence of 1,8-diiodooctane as solvent additive in the blend films was also investigated and allowed to further increase the efficiencies of the cells with PTB7. Overall, the results show that the simple replacement of alkyl chains by oligo(ethylene oxide) chains in PDI dimers is an efficient way to improve the PV performance without compromising the optoelectronic properties of the PDI acceptor.

ylene二酰亚胺（PDI）是有机光伏（PV）中最有前途的非富勒烯电子受体之一，为结构修饰提供了广阔的空间。基于PDI的二聚体由于其特有的扭曲构象而降低了其形成大聚集体的趋势，这在PV器件中表现出最高的性能，这不利于PV操作。在这项工作中，合成并固定了两个芴桥联的di二环氧乙烷（PDI）二聚体，其中低聚（环氧乙烷）或烷基链固定在芴单元的C9位置，并在溶液处理的有机体异质结（BHJ）光伏电池中作为电子受体进行了研究。 。用低聚（环氧乙烷）链取代的PDI二聚体在具有两种不同的聚合物供体PTB7和PffBT4T-2OD的溶液处理的本体异质结（BHJ）细胞中提高了功率转换效率（20％–53％）。但是，用低聚（环氧乙烷）链取代烷基链不会显着影响PDI二聚体的几何特征，并且光学和电化学性质仅得到少量修饰。指出了由环氧乙烷基团引起的固态中更紧密堆积的π-π堆积引起的激子解离增加和电荷传输增强，这可能是导致PV性能提高的可能原因。1，影响 还研究了8-二碘辛烷作为共混膜中的溶剂添加剂，并进一步提高了PTB7电池的效率。总体而言，结果表明，在PDI二聚体中用低聚（环氧乙烷）链简单替换烷基链是提高PV性能而不损害PDI受体光电性能的有效方法。