Yang Yezi, Yao Chuang, Li Lei, Bo Maolin, Zhang Jianfeng, Peng Cheng, Wang Jinshan
Key Laboratory of Extraordinary Bond Engineering and Advance Materials Technology (EBEAM) of Chongqing, School of Materials Science and Engineering, Yangtze Normal University Chongqing 408100 P. R. China
College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 P. R. China
RSC Adv. 2020 Mar 24;10(20):12004-12012. doi: 10.1039/d0ra00921k. eCollection 2020 Mar 19.
Non-fullerene acceptors have been widely investigated for organic solar cells (OSCs). In particular, fused-ring electron acceptors (FREAs), composed of two strongly electron-withdrawing end groups connected by a planar fused-ring core, have been successfully applied to develop high-performance OSCs (>16%). In this work, we proposed two novel 3D FREAs named BFT-3D and BFTT-3D, which can reduce the formation of crystalline domains and increase the interface with donors to promote exciton separation. These 3D FREAs consist of three strongly electron-withdrawing end groups linked by a central triptycene hub to form a three-bladed propeller nanostructure. In comparison with high-performance FREA (ITOIC-2F), these FREAs have stronger absorption intensity and smaller exciton binding energy. These findings demonstrated that these three-bladed propeller-shaped FREAs can absorb abundant energy from sunlight to generate excitons, easily separate excitons to free electrons and holes, and reduce the recombination of excitons. In addition, the electron mobility of BFT-3D (8.4 × 10 cm V s) is higher than that of BFTT-3D (1.0 × 10 cm V s), which indicated that the appropriate 3D core structure was conducive to the electron mobility of the three-bladed propeller-shaped FREAs. It can effectively improve the current density to enhance the performance of OSCs. These findings will provide new perspectives for experimental scientists to synthesize high-performance FREAs.
非富勒烯受体已被广泛用于有机太阳能电池（OSC）的研究。特别是，由两个通过平面稠环核心连接的强吸电子端基组成的稠环电子受体（FREA）已成功应用于开发高性能OSC（>16%）。在这项工作中，我们提出了两种新型的3D FREA，名为BFT-3D和BFTT-3D，它们可以减少晶域的形成，并增加与供体的界面以促进激子分离。这些3D FREA由三个强吸电子端基通过中心三蝶烯枢纽连接而成，形成三叶片螺旋桨纳米结构。与高性能FREA（ITOIC-2F）相比，这些FREA具有更强的吸收强度和更小的激子结合能。这些发现表明，这些三叶片螺旋桨形状的FREA可以从阳光中吸收丰富的能量来产生激子，容易将激子分离为自由电子和空穴，并减少激子的复合。此外，BFT-3D的电子迁移率（8.4×10 cm²V⁻¹s⁻¹）高于BFTT-3D（1.0×10 cm²V⁻¹s⁻¹），这表明合适的3D核心结构有利于三叶片螺旋桨形状FREA的电子迁移率。它可以有效地提高电流密度以增强OSC的性能。这些发现将为实验科学家合成高性能FREA提供新的视角。
