One Electron Changes Everything. A Multispecies Copper Redox Shuttle for Dye-Sensitized Solar Cells

William L. Hoffeditz, Michael J. Katz, Pravas Deria, George E. Cutsail, Michael J. Pellin, Omar K. Farha, Joseph T. Hupp*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Dye-sensitized solar cells (DSCs) are an established alternative photovoltaic technology that offers numerous potential advantages in solar energy applications. However, this technology has been limited by the availability of molecular redox couples that are both noncorrosive/nontoxic and do not diminish the performance of the device. In an effort to overcome these shortcomings, a copper-containing redox shuttle derived from 1,8-bis(2′-pyridyl)-3,6-dithiaoctane (PDTO) ligand and the common DSC additive 4-tert-butylpyridine (TBP) was investigated. Electrochemical measurements, single-crystal X-ray diffraction, and absorption and electron paramagnetic resonance spectroscopies reveal that, upon removal of one metal-centered electron, PDTO-enshrouded copper ions completely shed the tetradentate PDTO ligand and replace it with four or more TBP ligands. Thus, the Cu(I) and Cu(II) forms of the electron shuttle have completely different coordination spheres and are characterized by widely differing Cu(II/I) formal potentials and reactivities for forward versus reverse electron transfer. Notably, the coordination-sphere replacement process is fully reversed upon converting Cu(II) back to Cu(I). In cells featuring an adsorbed organic dye and a nano- and mesoparticulate, TiO2-based, photoelectrode, the dual species redox shuttle system engenders performance superior to that obtained with shuttles based on the (II/I) forms of either of the coordination complexes in isolation.

Original languageEnglish (US)
Pages (from-to)3731-3740
Number of pages10
JournalJournal of Physical Chemistry C
Volume120
Issue number7
DOIs
StatePublished - Feb 25 2016

Funding

O.K.F. and J.T.H. gratefully acknowledge support from the U.S. Dept. of Energy, Office of Science, Basic Energy Sciences (Grant No. DE-FG02-87ER13808) and Northwestern University. G.E.C. acknowledges Prof. Brian M. Hoffman (Northwestern University) for access to instrumentation and funding for EPR measurements. This work was supported by the National Institutes of Health (GM111097 to B.M.H.).

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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