TRIPHENYLAMINE-BASED STAR-SHAPED ABSORBERS WITH TUNABLE ENERGY LEVELS FOR ORGANIC PHOTOVOLTAICS


Hammond S. R. , Garcia A., Nardes A., Knoll E., Kose M. E. , Larsen R., ...More

35th IEEE Photovoltaic Specialists Conference, Hawaii, United States Of America, 20 - 25 June 2010, pp.1607-1610 identifier

  • Publication Type: Conference Paper / Full Text
  • Doi Number: 10.1109/pvsc.2010.5616496
  • City: Hawaii
  • Country: United States Of America
  • Page Numbers: pp.1607-1610

Abstract

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 C-61 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.