Solution-processed organic solar cells with power conversion efficiencies of 2.5% using benzothiadiazole/imide-based acceptors

Jason T. Bloking, Xu Han, Andrew T. Higgs, John P. Kastrop, Laxman Pandey, Joseph E. Norton, Chad Risko, Cynthia E. Chen, Jean Luc Brédas, Michael D. McGehee, Alan Sellinger

Research output: Contribution to journalArticlepeer-review

234 Scopus citations

Abstract

A new series of electron-deficient molecules based on a central benzothiadiazole moiety flanked with vinylimides has been synthesized via Heck chemistry and used in solution-processed organic photovoltaics (OPV). Two new compounds, 4,7-bis(4-(N-hexyl-phthalimide)vinyl)benzo[c]1,2,5-thiadiazole (PI-BT) and 4,7-bis(4-(N-hexyl-naphthalimide)vinyl)benzo[c]1,2,5-thiadiazole (NI-BT), show significantly different behaviors in bulk heterojunction (BHJ) solar cells using poly(3-hexylthiophene) (P3HT) as the electron donor. Two-dimensional grazing incidence X-ray scattering (2D GIXS) experiments demonstrate that PI-BT shows significant crystallization in spin-coated thin films, whereas NI-BT does not. Density functional theory (DFT) calculations predict that while PI-BT maintains a planar structure in the ground state, steric interactions cause a twist in the NI-BT molecule, likely preventing significant crystallization. In BHJ solar cells with P3HT as donor, PI-BT devices achieved a large open-circuit voltage of 0.96 V and a maximum device power-conversion efficiency of 2.54%, whereas NI-BT containing devices only achieved 0.1% power-conversion efficiency.

Original languageEnglish (US)
Pages (from-to)5484-5490
Number of pages7
JournalChemistry of Materials
Volume23
Issue number24
DOIs
StatePublished - Dec 27 2011
Externally publishedYes

Keywords

  • electron acceptors
  • n-type materials
  • organic electronics
  • photovoltaic devices
  • solar cells

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry

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