Synthesis, molecular and photovoltaic properties of an indolo[3,2-b]indole- based acceptor-donor-acceptor small molecule

Yu Ying Lai, Jyun Ming Yeh, Che En Tsai, Yen-Ju Cheng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Indolo[3,2-b]indole, containing two fused indole units, is an unexplored but promising electron-rich molecule for constructing donor-acceptor materials due to its planar, symmetric, and extended conjugated structure. We have successfully developed a new synthetic pathway to prepare 2,7-diboronic ester-indolo[3,2-b]indole, which was then reacted with dithienodiketopyrrolo- pyrrole acceptor to afford a new acceptor-donor-acceptor (A-D-A) conjugated molecule, 2,7-bis(dithienodiketopyrrolo-pyrrole)indolo[3,2-b]indole (2,7-DPPIIDPP). II is used to stand for indolo[3,2-b]indole in order to emphasize that this compound is constructed from two indole units. The A-D-A linkage through the 2,7-positions of II not only preserves the phenylene units in the para-conjugation but also renders stronger electron-donating strength. This material exhibited good thermal stability, high crystallinity, and broad UV/Vis absorption. The solution-processed bulk heterojunction device using the configuration of ITO/PEDOT:PSS/2,7-DPPIIDPP:PC71BM/Ca/Al exhibited a Voc of 0.72 V, a Jsc of 6.88 mA/cm2, and an FF of 49.6 %, leading to a power conversion efficiency (PCE) of 2.45 %. A new acceptor-donor-acceptor conjugated molecule, 2,7-bis(dithienodiketopyrrolo- pyrrole)indolo[3,2-b]indole (2,7-DPPIIDPP) was designed and synthesized. This material exhibited good thermal stability, high crystallinity, and broad UV/Vis absorption. The solution-processed bulk heterojunction device using the configuration of ITO/PEDOT:PSS/ 2,7-DPPIIDPP:PC71BM/Ca/Al was characterized.

Original languageEnglish
Pages (from-to)5076-5084
Number of pages9
JournalEuropean Journal of Organic Chemistry
Issue number23
DOIs
StatePublished - 4 Jul 2013

Keywords

  • Conjugation
  • Donor-acceptor systems
  • Nitrogen heterocycles
  • Photophysics
  • Semiconductors

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