Implication of Fluorine Atom on Electronic Properties, Ordering Structures, and Photovoltaic Performance in Naphthobisthiadiazole-Based Semiconducting Polymers

Kazuaki Kawashima, Tomohiro Fukuhara, Yousuke Suda, Yasuhito Suzuki, Tomoyuki Koganezawa, Hiroyuki Yoshida, Hideo Ohkita, Itaru Osaka, Kazuo Takimiya

Research output: Contribution to journalArticle

204 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)10265-10275
Number of pages11
JournalJournal of the American Chemical Society
Volume138
Issue number32
DOIs
Publication statusPublished - 2016 Aug 17
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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