Isomer-free: Precise Positioning of Chlorine-Induced Interpenetrating Charge Transfer for Elevated Solar Conversion

• Published in: iScience 2019-07, Vol.17, p.302-314
• Main Authors: Lai, Hanjian, Chen, Hui, Zhou, Jiadong, Qu, Jianfei, Chao, Pengjie, Liu, Tao, Chang, Xiaoyong, Zheng, Nan, Xie, Zengqi, He, Feng
• Format: Article
• Language: English
• Subjects: Chemical Synthesis; Energy Storage; Materials Characterization Techniques
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2019.06.033

The influence caused by the position of the chlorine atom on end groups of two non-fullerene acceptors (ITIC-2Cl-δ and ITIC-2Cl-γ) was intensely investigated. The single-crystal structures show that ITIC-2Cl-γ has a better molecular planarity and closer π-π interaction distance. More importantly, a 3D rectangle-like interpenetrating network is formed in ITIC-2Cl-γ and is beneficial to rapid charge transfer along multiple directions, whereas only a linear stacked structure could be observed in ITIC-2Cl-δ. The two acceptor-based solar cells show power conversion efficiencies (PCEs) over 11%, higher than that of the ITIC-2Cl-m-based device (10.85%). An excellent PCE of 13.03% is obtained by the ITIC-2Cl-γ-based device. In addition, the ITIC-2Cl-γ-based device also shows the best device stability. This study indicates that chlorine positioning has a great impact on the acceptors; more importantly, the 3D network structure may be a promising strategy for non-fullerene acceptors to improve the PCE and stability of organic solar cells. [Display omitted] •Isomer-free: improved phase purity for high-performance non-fullerene acceptor•Chlorine-substitution fine-tuned the configurations and properties of molecules•Precise Cl-atom substitution induced 3D interpenetrating network charge transfer•ITIC-2Cl-γ exhibited higher PCE of 13.03% and better stability Energy Storage; Chemical Synthesis; Materials Characterization Techniques