title: Understanding the Impact of Hierarchical Nanostructure in Ternary Organic Solar Cells.
abstract: Ternary organic solar cells (OSCs), which blend two donors and fullerene derivatives with different absorption ranges, are a promising potential strategy for high-power conversion efficiencies (PCEs). In this study, inverted ternary OSCs are fabricated by blending a highly crystalline small molecule BDT-3T-CNCOO in a low band gap polymer PBDTTT-C-T:PC71BM. As the small molecule is introduced, the overall PCEs increase from 7.60% to 8.58%. The morphologies of ternary blends are studied by combining transmission electron microscopy and X-ray scattering techniques at different length scales. Hierarchical phase separation is revealed in the ternary blend, which is composed of domains with sizes of ≈88, ≈50, and ≈20 nm, respectively. The hierarchical phase separation balances the charge separation and transport in ternary OSCs. As a result, the fill factors of the devices significantly improve from 58.4% to 71.6%. Thus, ternary blends show higher hole mobility and higher fill factor than binary blends, which demonstrates a facile strategy to increase the performance of OSCs.
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China; University of Chinese Academy of Sciences Beijing 100049 P. R. China.
authors.forename: Jin
authors.initials: J
authors.lastname: Fang
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China; State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 P. R. China.
authors.forename: Zaiyu
authors.initials: Z
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China.
authors.forename: Jianqi
authors.initials: J
authors.lastname: Zhang
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China.
authors.forename: Yajie
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China; University of Chinese Academy of Sciences Beijing 100049 P. R. China.
authors.forename: Dan
authors.initials: D
authors.lastname: Deng
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China.
authors.forename: Kun
authors.initials: K
authors.lastname: Lu
authors.affiliation: State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.affiliation: CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology Beijing 100190 P. R. China.
authors.forename: Zhixiang
authors.initials: Z
authors.lastname: Wei
keywords: conjugated polymers; conjugated small molecules; hierarchical nanostructures; morphology; ternary organic solar cells