Huang Jinfeng, Li Sunsun, Qin Jinzhao, Xu Lei, Zhu Xiaozhang, Yang Lian-Ming
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
ACS Appl Mater Interfaces. 2021 Sep 29;13(38):45806-45814. doi: 10.1021/acsami.1c11412. Epub 2021 Sep 15.
Electron acceptors with nonfused aromatic cores (NCAs) have aroused increasing interest in organic solar cells due to the low synthetic complexity and flexible chemical modification, but the corresponding device performance still lags behind. Herein, we designed and synthesized two new quinoxaline-based NCAs, namely, QOC6-4H and QOC6-4Cl. Although both NCAs show good backbone coplanarity, QOC6-4Cl with chlorinated end groups exhibits higher extinction coefficient, enhanced crystallinity, and more compact π-π stacking, which is correlated with the stronger intermolecular interactions induced by chlorine atoms. Benefiting from the broader and stronger optical absorption, improved carrier mobilities, and suppressed charge recombination, a notable power conversion efficiency (PCE) of 12.32% with a distinctly higher short-current density () of 22.91 mA cm and a fill factor (FF) of 69.01% could be obtained for the PBDB-T:QOC6-4Cl-based device. The PCEs of PBDB-T:QOC6-4H were only lower than 8%, which could mainly be attributed to the unsymmetric charge transport. Our work proves that the chlorination of end groups is a facile and effective strategy to enhance the intermolecular interactions and thus the photovoltaic performance of NCAs, and a careful modulation of the intermolecular interactions plays a vital role in further developing both high-performance and low-cost organic photovoltaic materials.
具有非稠合芳香核的电子受体（NCA）由于合成复杂度低和化学修饰灵活，在有机太阳能电池中引起了越来越多的关注，但相应的器件性能仍然滞后。在此，我们设计并合成了两种基于喹喔啉的新型NCA，即QOC6-4H和QOC6-4Cl。尽管这两种NCA都表现出良好的主链共面性，但带有氯化端基的QOC6-4Cl表现出更高的消光系数、增强的结晶度和更紧密的π-π堆积，这与氯原子诱导的更强分子间相互作用相关。受益于更宽更强的光吸收、改善的载流子迁移率和抑制的电荷复合，基于PBDB-T:QOC6-4Cl的器件可获得12.32%的显著功率转换效率（PCE），其短路电流密度（）明显更高，为22.91 mA cm，填充因子（FF）为69.01%。PBDB-T:QOC6-4H的PCE仅低于8%，这主要归因于不对称的电荷传输。我们的工作证明，端基氯化是一种简便有效的策略，可增强分子间相互作用，从而提高NCA的光伏性能，并且仔细调节分子间相互作用对于进一步开发高性能和低成本的有机光伏材料起着至关重要的作用。
