title: Asymmetrical Squaraines Bearing Fluorine-Substituted Indoline Moieties for High-Performance Solution-Processed Small-Molecule Organic Solar Cells.
abstract: Two novel asymmetrical squaraines based on the indoline unit, ASQ-5-F and ASQ-5-DF, with one and two fluorine substituents, have been developed to investigate the effect of fluorine substituted on small-molecule bulk-heterojunction (BHJ) organic solar cells (OSCs). In comparison with non-fluorine-substituted ASQ-5, both fluorine-substituted ASQ-5-F and ASQ-5-DF possess analogous absorption band gaps but 0.05 and 0.10 eV lowered highest occupied molecular orbital (HOMO) energy levels, respectively. Single-crystal analysis exhibits that ASQ-5-DF shows more desirable intermolecular packing patterns for the hole-carrier collection than ASQ-5 does; hence, higher hole mobility could be acquired. Therefore, solution-processed small-molecule BHJ OSCs fabricated with ASQ-5-F/PC71BM and ASQ-5-DF/PC71BM blends exhibit extremely higher power conversion efficiency (PCE; 5.0% and 6.0%, respectively) than that of ASQ-5/PC71BM (4.5%). The much improved PCE could be attributed to the simultaneously enhanced Voc, Jsc, and FF relative to those of the ASQ-5-based device. To our knowledge, this is the highest PCE (6.0%) among squaraine-based solution-processed BHJ OSCs and the highest PCE in OSCs based on the fluorinated donor segment of small molecules.
authors.affiliation: †Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.|‡Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, Yonezawa 992-8510, Japan.
authors.forename: Daobin
authors.initials: D
authors.lastname: Yang
authors.affiliation: †Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.affiliation: †Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: †Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Jiao
authors.affiliation: ‡Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, Yonezawa 992-8510, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Igarashi
authors.affiliation: †Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Chen
authors.affiliation: †Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Lu
authors.affiliation: †Key Laboratory of Green Chemistry and Technology (Ministry of Education), College of Chemistry, Sichuan University, Chengdu 610064, People's Republic of China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Pu
authors.affiliation: ‡Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, Yonezawa 992-8510, Japan.
authors.forename: Hisahiro
authors.initials: H
authors.lastname: Sasabe
authors.affiliation: ‡Department of Organic Device Engineering, Research Center for Organic Electronics, Yamagata University, Yonezawa 992-8510, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Kido
keywords: asymmetrical squaraines; fluorine-substituted; packing pattern; small-molecule organic solar cells; solution-processed