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1587625 
Journal Article 
Power-Law Kinetics in the Photoluminescence of Dye-Sensitized Nanoparticle Films: Implications for Electron Injection and Charge Transport 
Mcneil, IanJ; Ashford, DL; Luo, H; Fecko, CJ 
2012 
Yes 
Journal of Physical Chemistry C
ISSN: 1932-7447
EISSN: 1932-7455 
116 
30 
15888-15899 
WOS:000306989500004 
Dye-sensitized solar cells have provided a model to
inexpensively harness solar energy, but the underlying physics that limit their efficiency are
still not well understood. We probe electron injection in sensitized nanocrystalline TiO2 films
using time-correlated single photon counting (TCSPC) to measure time-dependent chromophore
photoluminescence quenching. The time-dependent emission exhibits kinetics that become faster and
more dispersive with increasing ionic concentrations in both water and acetonitrile; we quantify
these trends by fitting the data using several kinetic models. Even more notably, we show that
the residual emission under conditions that favor efficient electron injection exhibits a power-
law decay in time. We attribute this highly dispersive kinetic behavior to electron injection
from the dye into localized acceptor states of the TiO2 nanoparticle film, which exhibits a
distribution of injection rate constants that depend on the energetic distribution of sub-band-
gap trap states.