Quantum chemical investigation of cluster models for TiO 2 nanoparticles with water-derived ligand passivation: Studies of excess electron states and implications for charge transport in the Gratzel cell

Vladimir Blagojevic, Yiing-Rei Chen, Michael Steigerwald, Louis Brus, Richard A. Friesner

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We present hybrid DFT calculations for large TiO 2 cluster models in the gas phase and in solution. Two clusters are investigated, one derived from the anatase bulk structure and the second from rutile. The surfaces are passivated with hydroxyl and water ligands, and continuum solvation is used to model bulk solvent in a subset of calculations. The geometrically optimized bonding patterns, structures, and electronic properties are similar in the two clusters. The distinction between anatase and rutile is minor at this small size. The HOMO and LUMO of the clusters are delocalized, and qualitatively resemble those observed in bulk for both the anatase and rutile derived species. When an additional electron is added, the wave function is again delocalized and there is little change in geometry, and hence minimal polaronic self-trapping. Removal of a surface ligand, creating a defect in that location, does lead to localization of the wave function, but it is unclear whether this actually occurs in real nanocrystalline TiO 2 systems. Our results suggest that modeling of electron transport in TiO 2 nanocrystal photovoltaic cells may require the presence of electrolyte ions to stabilize localized trapping states.

Original languageEnglish
Pages (from-to)19806-19811
Number of pages6
JournalJournal of Physical Chemistry C
Volume113
Issue number46
DOIs
Publication statusPublished - 2009 Dec 22

Fingerprint

electron states
Passivation
Titanium dioxide
Electron energy levels
passivity
Charge transfer
Ligands
anatase
rutile
Wave functions
Nanoparticles
nanoparticles
ligands
Water
cells
water
Photovoltaic cells
trapping
Solvation
wave functions

ASJC Scopus subject areas

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

Cite this

Quantum chemical investigation of cluster models for TiO 2 nanoparticles with water-derived ligand passivation : Studies of excess electron states and implications for charge transport in the Gratzel cell. / Blagojevic, Vladimir; Chen, Yiing-Rei; Steigerwald, Michael; Brus, Louis; Friesner, Richard A.

In: Journal of Physical Chemistry C, Vol. 113, No. 46, 22.12.2009, p. 19806-19811.

Research output: Contribution to journalArticle

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