Observation of diffusion and tunneling recombination of dye-photoinjected electrons in ultrathin TiO2 layers by surface photovoltage transients

Iván Mora-Seró, Thomas Dittrich, Abdelhak Belaidi, Germa Garcia-Belmonte, Jüan Bisquert

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Surface photovoltage transients were used to monitor both the short time dynamics (> 10 ns) and the spatial distribution of electrons photoinjected in thin (2-20 nm) TiO2 layers from dye molecules adsorbed at the surface. At low temperatures (100-250 K), the dynamics are governed exclusively by spatially dependent tunneling recombination, with a rate that varies with the distance from the surface x as exp(-2x/a), and an initial exponential distribution of photoinjected electrons, n0 exp(-x/b). This model is confirmed by the observation of power law decay in time t-a/2b with a ratio alb = 0.28 ± 0.04. The stability of cis-di-(isothiocyanato)-Af- bis(2,2′-bipyridine-4,4′-dicarboxy) ruthenium(II) (N3) dye molecules on TiO2 during treatment in a vacuum at high temperatures was proven. For high temperatures (250-540 K), the thickness dependence of the decays indicates that the dynamics of surface recombination are retarded by the diffusion of electrons toward the interior of the film. The implications for thin layer coating in dye-sensitized solar cells are discussed.

Original languageEnglish
Pages (from-to)14932-14938
Number of pages7
JournalJournal of Physical Chemistry B
Volume109
Issue number31
DOIs
Publication statusPublished - 11 Aug 2005
Externally publishedYes

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photovoltages
Coloring Agents
Dyes
dyes
Electrons
electrons
Molecules
Ruthenium
decay
Temperature
Spatial distribution
ruthenium
molecules
spatial distribution
solar cells
Vacuum
coatings
Coatings
vacuum

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Observation of diffusion and tunneling recombination of dye-photoinjected electrons in ultrathin TiO2 layers by surface photovoltage transients. / Mora-Seró, Iván; Dittrich, Thomas; Belaidi, Abdelhak; Garcia-Belmonte, Germa; Bisquert, Jüan.

In: Journal of Physical Chemistry B, Vol. 109, No. 31, 11.08.2005, p. 14932-14938.

Research output: Contribution to journalArticle

Mora-Seró, Iván ; Dittrich, Thomas ; Belaidi, Abdelhak ; Garcia-Belmonte, Germa ; Bisquert, Jüan. / Observation of diffusion and tunneling recombination of dye-photoinjected electrons in ultrathin TiO2 layers by surface photovoltage transients. In: Journal of Physical Chemistry B. 2005 ; Vol. 109, No. 31. pp. 14932-14938.
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