An asymmetric heptacyclic electron-donating core, namely DTPPSe, was developed by integrating selenophene and dithieno[3,2-b:2′,3′-d]pyrrole (DTP) building blocks. Three DTPPSe-based narrow band gap asymmetric fused-ring acceptors (FRAs) (ca.DTPPSe-IC, DTPPSe-2F and DTPPSe-4F) have been synthesized to specifically explore the effect of fluorinated end groups on their photovoltaic performance. The two fluorinated FRAs (ca.DTPPSe-2F and DTPPSe-4F) exhibit red-shifted absorption and significantly deeper energy levels relative to non-fluorinated DTPPSe-IC. When blending with a PBDB-T donor, the DTPPSe-2F blend films show a better miscibility with fibrous and uniformly ordered phase separation morphology compared with the other two counterparts. As a result, a maximum power conversion efficiency (PCE) of 13.76% was achieved for DTPPSe-2F based organic solar cells (OSCs) with a low energy loss (E_loss) of 0.60 eV. To the best of our knowledge, this PCE is among the highest values for OSCs in the literature using selenophene-containing FRAs. Our results not only indicate the great potential of the asymmetric heptacyclic donating core DTPPSe for developing efficient FRAs, but also demonstrate the fluorination of the end groups of FRAs as key to modulate the energy levels in molecular engineering.

中文翻译：

---

硒烯集成的双硫杂[3,2-b：2'，3'-d]吡咯不对称受体可实现13.76％的非富勒烯太阳能电池效率

通过整合硒烯和双硫杂[3,2- b：2'，3'- d ]吡咯（DTP）构件开发了不对称的七环给电子核，即DTPPSe 。合成了三种基于DTPPSe的窄带隙不对称稠环受体（FRA）（约DTPPSe-IC，DTPPSe-2F和DTPPSe-4F）以专门研究氟化端基对其光电性能的影响。相对于非氟化的DTPPSe-IC，两个氟化的FRA（约DTPPSe-2F和DTPPSe-4F）显示出红移的吸收，并且能级明显更深。与PBDB-T混合时与其他两个对应物相比，DTPPSe-2F共混膜与纤维和均匀有序的相分离形态表现出更好的混溶性。结果，对于基于DTPPSe-2F的有机太阳能电池（OSC），具有0.60 eV的低能量损失（E _loss），获得了13.76％的最大功率转换效率（PCE）。据我们所知，该PCE在使用含硒烯的FRA的文献中是OSC的最高值之​​一。我们的结果不仅表明不对称的七环捐赠核心DTPPSe具有开发高效FRA的巨大潜力，而且还证明了FRA端基的氟化是调节分子工程中能级的关键。