He Chengliang, Li Yaokai, Li Shuixing, Yu Zhi-Peng, Li Yuhao, Lu Xinhui, Shi Minmin, Li Chang-Zhi, Chen Hongzheng
MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
Department of Physics, The Chinese University of Hong Kong, New Territories, Kowloon, Hong Kong 999077, P. R. China.
ACS Appl Mater Interfaces. 2020 Apr 8;12(14):16700-16706. doi: 10.1021/acsami.0c00837. Epub 2020 Mar 25.
The absorption of nonfullerene acceptors (NFAs) at near-infrared (NIR) regions is crucial for obtaining high current densities in organic solar cells (OSCs). Herein, two narrow-band gap NFAs with unfused backbones possessing broad (600-900 nm) and strong absorption are developed by the conjugation of a benzothiadiazole core to halogenated end groups through a cyclopentadithiophene bridge. Compared with the fluorinated counterpart BCDT-4F, the chlorinated NFA BCDT-4Cl shows stronger J-aggregation and closer molecular packing, leading to an optimized blend morphology when paired with the polymer donor, PBDB-T. Thus, an obvious improvement in external quantum efficiency response was obtained for BCDT-4Cl-based OSCs, presenting a higher efficiency of 12.10% than those (9.65%) based on BCDT-4F. This work provides a design strategy for NIR acceptors in the combination of electron-deficient core and halogenated terminal in unfused backbones, which results in not only fine-tuning the optoelectronic properties but also simplifying the synthetic complexities of molecules.
非富勒烯受体（NFAs）在近红外（NIR）区域的吸收对于在有机太阳能电池（OSCs）中获得高电流密度至关重要。在此，通过环戊二噻吩桥将苯并噻二唑核心与卤化端基共轭，开发了两种具有未融合主链、具有宽（600 - 900 nm）且强吸收的窄带隙NFAs。与氟化类似物BCDT - 4F相比，氯化NFA BCDT - 4Cl表现出更强的J - 聚集和更紧密的分子堆积，当与聚合物供体PBDB - T配对时，导致优化的共混形态。因此，基于BCDT - 4Cl的OSCs获得了明显的外量子效率响应改善，其效率为12.10%，高于基于BCDT - 4F的OSCs（9.65%）。这项工作为未融合主链中缺电子核心和卤化末端相结合的近红外受体提供了一种设计策略，这不仅可以微调光电性能，还可以简化分子的合成复杂性。
