A cobalt complex redox shuttle for dye-sensitized solar cells with high open-circuit potentials

Research output: Contribution to journalArticlepeer-review


  • Jun-Ho Yum
  • Florian Kessler
  • Thomas Moehl
  • Shahzada Ahmad
  • Takeru Bessho
  • Arianna Marchioro
  • Elham Ghadiri
  • Jacques-E Moser
  • Chenyi Yi
  • Md K Nazeeruddin
  • Michael Grätzel

Colleges, School and Institutes


Dye-sensitized solar cells are a promising alternative to traditional inorganic semiconductor-based solar cells. Here we report an open-circuit voltage of over 1,000 mV in mesoscopic dye-sensitized solar cells incorporating a molecularly engineered cobalt complex as redox mediator. Cobalt complexes have negligible absorption in the visible region of the solar spectrum, and their redox properties can be tuned in a controlled fashion by selecting suitable donor/acceptor substituents on the ligand. This approach offers an attractive alternate to the traditional I(3)(-)/I(-) redox shuttle used in dye-sensitized solar cells. A cobalt complex using tridendate ligands [Co(bpy-pz)(2)](3+/2+)(PF(6))(3/2) as redox mediator in combination with a cyclopentadithiophene-bridged donor-acceptor dye (Y123), adsorbed on TiO(2), yielded a power conversion efficiency of over 10% at 100 mW cm(-2). This result indicates that the molecularly engineered cobalt redox shuttle is a legitimate alternative to the commonly used I(3)(-)/I(-) redox shuttle.


Original languageEnglish
Pages (from-to)631
JournalNature Communications
Publication statusPublished - 2012