We design and synthesize two novel PDI based acceptors VDP-Se and NDP-Se. VDP-Se with a central vinylene core presents a slightly twisted molecular conformation; whereas, the fused NDP-Se possesses a distorted naphthalene core, an X-shaped skeleton and two planar PDI units. The twisted conformations of these two acceptors can effectively prevent them from forming large aggregates when blended with the polymer donor. Photovoltaic characterizations demonstrate PCEs of 6.01% and 6.85% for VDP-Se and NDP-Se based devices, respectively. Higher and more balanced charge carrier mobility of NDP-Se based devices can account for its better photovoltaic performance. The morphology of PBDB-T:NDP-Se blend films can be slightly optimized by the addition of DIO and an improved PCE of 7.41% (V_oc = 0.94 V, J_sc = 12.68 mA/cm² and FF = 61.89%) is finally achieved. Our studies demonstrate that the twisted core can effectively suppress the exhausted intermolecular aggregation and the planar PDI units can form better charge transporting channels. Such combined planar and twisted strategy can be an effective way to design PDI based acceptors for high efficiency PSCs.

我们设计和合成了两种新颖的基于PDI的受体VDP-Se和NDP-Se。具有中心亚乙烯基核的VDP-Se呈现出轻微扭曲的分子构象；熔融NDP-Se具有扭曲的萘芯，X形骨架和两个平面PDI单元。当与聚合物供体混合时，这两个受体的扭曲构象可以有效地防止它们形成大的聚集体。光伏特性表明，基于VDP-Se和NDP-Se的器件的PCE分别为6.01％和6.85％。NDP-Se更高，更平衡的电荷载流子迁移率基于基础的设备可以解释其更好的光伏性能。通过添加DIO可以稍微优化PBDB-T：NDP-Se共混薄膜的形态，将PCE改善为7.41％（V _oc  = 0.94 V，J _sc  = 12.68 mA / cm ²和FF  = 61.89％）终于实现了。我们的研究表明，扭曲的磁芯可以有效地抑制耗尽的分子间聚集，而平面PDI单元可以形成更好的电荷传输通道。这种组合的平面和扭曲策略可以是设计用于高效PSC的基于PDI受体的有效方法。