Outer-sphere redox couples as shuttles in dye-sensitized solar cells. performance enhancement based on photoelectrode modification via atomic layer deposition

Thomas W. Hamann, Omar K. Farha, Joseph T. Hupp

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150 Citations (Scopus)

Abstract

Atomic layer deposition (ALD) has been used to create conformal TiO 2 blocking layers on fluorine-doped tin-oxide substrates in dye-sensitized solar cells (DSSCs), effectively eliminating shunting. ALD has also been used to deposit, in controlled fashion, ultrathin coatings of alumina on nanoparticle-based TiO 2 DSSC photoanodes. These modified electrodes enable ferrocenium/ferrocene, an outer-sphere redox couple, to be used as a shuttle. The photovoltaic performance and interfacial charge-transfer dynamics were investigated in DSSCs employing this shuttle. It was found that a single ALD cycle is able to passivate surface states, resulting in a dramatic improvement in photovoltaic performance. Subsequent alumina deposition resulted in exponentially increasing electron lifetimes as a function of alumina layer thickness, indicating that the layers behave as barriers to electron tunneling. The characterization of DSSC photovoltaic performance and interfacial charge-transfer dynamics was extended to cells employing derivatives of ferrocenium and ferrocene featuring more positive redox potentials; these cells yielded larger open-circuit photovoltages.

Original languageEnglish
Pages (from-to)19756-19764
Number of pages9
JournalJournal of Physical Chemistry C
Volume112
Issue number49
DOIs
Publication statusPublished - Dec 11 2008

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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