A novel efficient, iodide-free redox mediator for dye-sensitized solar cells

Zhipan Zhang, Peter Chaoyu Chen, Shaik Mohammed Zakeeruddin, Jacques Edouard Moser, Michael Grätzel

Research output: Contribution to journalConference articlepeer-review


A stable organic molecular radical, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), has been electrochemically studied and employed as a new redox mediator in nanocrystalline TiO2 dye-sensitized solar cells (DSCs) when it is doped with nitrosonium tetrafluoroborate (NOBF4). Reasonable photocurrents can be achieved despite of driving force of only 0.2 eV for the TEMPO/TEMPO+ system as compared to 0.6 eV for the iodide/triiodide redox system. Judicious selections of a 5 μm photoanode made from TiO 2 mesoscopic particles (60 nm in diameter) and an organic sensitizer with high molar extinction coefficient yield an overall power conversion of 5.0 % under AM 1.5 illumination at 100 mW cm-2 and an incident photon-to-current conversion efficiencies (IPCE) in excess of 50 %.

Original languageEnglish
Pages (from-to)44-48
Number of pages5
JournalMaterials Research Society Symposium Proceedings
Publication statusPublished - 2007
EventOrganic and Nanoparticle Hybrid Photovoltaic Devices - 2007 MRS Spring Meeting - San Francisco, CA, United States
Duration: 2007 Apr 92007 Apr 13

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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