title: Implication of Fluorine Atom on Electronic Properties, Ordering Structures, and Photovoltaic Performance in Naphthobisthiadiazole-Based Semiconducting Polymers.
abstract: The development of semiconducting polymers is imperative to improve the performance of polymer-based solar cells (PSCs). In this study, new semiconducting polymers based on naphtho[1,2-c:5,6-c']bis[1,2,5]thiadiazole (NTz), PNTz4TF2 and PNTz4TF4, having 3,3'-difluoro-2,2'-bithiophene and 3,3',4,4'-tetrafluoro-2,2'-bithiophene, respectively, are designed and synthesized. These polymers possess a deeper HOMO energy level than their counterpart, PNTz4T, which results in higher open-circuit voltages in solar cells. This concequently reduces the photon energy loss that is one of the most important issues surrounding PSCs. The PNTz4TF4 cell exhibits up to 6.5% power conversion efficiency (PCE), whereas the PNTz4TF2 cell demonstrates outstanding device performance with as high as 10.5% PCE, which is quite high for PSCs. We further discuss the performances of the PSCs based on these polymers by correlating the charge generation and recombination dynamics with the polymer structure and ordering structure. We believe that the results provide new insights into the design of semiconducting polymers and that there is still much room for improvement of PSC efficiency.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University , 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan.|RIKEN Center for Emergent Matter Science (CEMS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Kawashima
authors.affiliation: Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Kyoto 615-8510, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Fukuhara
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Suda
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI) , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Koganezawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshida
authors.affiliation: Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Kyoto 615-8510, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Ohkita
authors.affiliation: RIKEN Center for Emergent Matter Science (CEMS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Itaru
authors.initials: I
authors.lastname: Osaka
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University , 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan.|RIKEN Center for Emergent Matter Science (CEMS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Takimiya