BODIPY based A-D-A molecules: Effect of CF3 group substitution at meso phenyl group

Justin Johnson, Bryon Larson, Gourav Tarafdar, Praveen Ramamurthy

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8 Scopus Citations


Two pairs of A-D-A molecules have been synthesized with fluorene and benzodithiophene as the central donor subunits and terminal BODIPY units, functionalized with either a 4-methylphenyl or 4-trifluoromethylphenyl group at the meso position. The effect of the para substituent of the meso phenyl group on the photophysical properties of these molecules is studied through steady state absorption and fluorescence spectroscopy as well as femtosecond transient absorption and time resolved fluorescence spectroscopy techniques. Applicability of these molecules as donors in solution processed solar cell active layers was investigated through time resolved microwave conductivity measurements on blends with PC60BM acceptor, which shows a varying yield of charge transfer with choice of substituent. Transient absorption spectroscopy is then employed to investigate the role of the 4-trifluoromethylphenyl group in altering the efficiency of charge transfer from these A-D-A molecules to PC60BM. The results show a consistent picture of picosecond charge transfer and a component of a few hundred ps geminate recombination that results in a small yield of long-lived free charges optimized for the methylphenyl derivatives.

Original languageAmerican English
Article number108289
Number of pages9
JournalDyes and Pigments
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2020 Elsevier Ltd

NREL Publication Number

  • NREL/JA-5900-75359


  • donor-acceptor
  • solar-photochemistry
  • time-resolved microwave conductivity
  • transient absorption


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