Triphenylamine-Based Star-Shaped Absorbers with Tunable Energy Levels for Organic Photovoltaics

Scott R. Hammond, Andres Garcia, Alexandre Nardes, Eric Knoll, Muhammet Kose, Ross Larsen, Nikos Kopidakis, Zbyslaw Owczarczyk, Dana C. Olson, David S. Ginley

Research output: Contribution to conferencePaperpeer-review


A new family of soluble low-bandgap star-shaped molecules based upon triphenylamine (TPA) and containing benzothiadiazole (BTD) acceptor moieties have been designed and synthesized for organic photovoltaic (OPV) applications. The design results in the lowest unoccupied molecular orbital (LUMO) being spatially distributed on the periphery of the molecule, allowing facile photo-induced electron transfer to the fullerene phenyl C61 butyric acid methyl ester (PCBM). Photoluminescence quenching studies indicate efficient quenching of excitons, while time-resolved microwave conductivity experiments demonstrate effective separation of charges. Adjunct electron-withdrawing moieties allow tuning of the LUMO level. Theoretical calculations indicate three derivatives with LUMO levels in varying proximity to that of PCBM, which allows empirical testing of the theorized need for a 0.3 eV LUMO offset to ensure efficient charge transfer to PCBM. Design, characterization and bulk heterojunction device results for the new materials will be presented.

Original languageAmerican English
Number of pages4
StatePublished - 2010
Event35th IEEE Photovoltaic Specialists Conference, PVSC 2010 - Honolulu, HI, United States
Duration: 20 Jun 201025 Jun 2010


Conference35th IEEE Photovoltaic Specialists Conference, PVSC 2010
Country/TerritoryUnited States
CityHonolulu, HI

NREL Publication Number

  • NREL/CP-520-47698


  • absorption
  • organic photovoltaics
  • photoluminescence


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