In Situ Mapping of the Molecular Arrangement of Amphiphilic Dye Molecules at the TiO2 Surface of Dye-Sensitized Solar Cells

Kislon Voïtchovsky, Negar Ashari-Astani, Ivano Tavernelli, Nicolas Tétreault, Ursula Rothlisberger, Francesco Stellacci, Michael Grätzel, Hauke A. Harms

Research output: Contribution to journalArticlepeer-review

Abstract

Amphiphilic sensitizers are central to the function of dye-sensitized solar cells. It is known that the cell's performance depends on the molecular arrangement and the density of the dye on the semiconductor surface, but a molecular-level picture of the cell-electrolyte interface is still lacking. Here, we present subnanometer in situ atomic force microscopy images of the Z907 dye at the surface of TiO2 in a relevant liquid. Our results reveal changes in the conformation and the lateral arrangement of the dye molecules, depending on their average packing density on the surface. Complementary quantitative measurements on the ensemble of the film are obtained by the quartz-crystal microbalance with dissipation technique. An atomistic picture of the dye coverage-dependent packing, the effectiveness of the hydrophobic alkyl chains as blocking layer, and the solvent accessibility is obtained from molecular dynamics simulations. (Figure Presented).

Original languageEnglish
Pages (from-to)10834-10842
Number of pages9
JournalACS Applied Materials and Interfaces
Volume7
Issue number20
DOIs
Publication statusPublished - May 27 2015

Keywords

  • atomic force microscopy
  • dye-sensitized solar cells
  • liquid phase
  • molecular dynamics simulations
  • Z907

ASJC Scopus subject areas

  • Materials Science(all)

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