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Fine Particles Science and Technology pp 343–370Cite as

Directed Photocurrents in Nanostructured SnO2/TiO2/Ru(II)L2(CNS)2 Heterojunctions

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Part of the book series: NATO ASI Series ((ASHT,volume 12))

Abstract

An electrochemical photovoltaic cell utilizing a nanoporous dye sensitized TiO2 electrode has been described displaying higher efficiency for current collection when exposure is through the SnO2(F-doped) conducting glass support for the TiO2 as compared to exposure from the reverse side [1]. Using the same electrode components, time resolved photocharge, TRPC, measurements are used to ascertain the vectorial directions of transient photocurrents, with and without dye sensitization of the nanoporous TiO2 for coatings on glass and on transparent conducting glass.

The use of UV and visible laser light pulses, with and without CW UV-Visible illumination, make possible the evaluation of the presence and polarity of space charge fields. TiO2 contact with a transparent conducting layer and an adsorbed sensitizing dye, upon equilibration of Fermi levels of the individual phases, spontaneously creates a field across the TiO2 which aids in directing photoelectron currents toward the SnO2(F-doped) electrode, regardless of sample orientation with respect to the incident light - explaining observed TRPC polarity reversals. When exposure is through the conducting glass, the proximity of the region of greatest light absorption to the electrode enhances photoelectron collection by the SnO2(F-doped) coated glass.

Energy band structures are proposed for the various structures investigated, which are consistent with the TRPC results, and with other relevant information available in the literature. For the SnO2(F-doped)-TiO2(nanoporous)-Ru(II)L2(CNS)2 system, a combined n-i-p/quantum well band structure is proposed. The n-i-p segment is considered to consist of SnO2(F-doped) in contact with bulk property TiO2, to which dye is adsorbed on the available surface not in contact with the SnO2. The quantum wells are comprised of nanoporous TiO2 aggregates surrounded by adsorbed Ru(II)L2(CNS)2 aggregates.

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Authors and Affiliations

  1. Department of Chemistry, Boston University, Boston, MA, 02215, USA

    B. Levy & W. Liu

  2. Institute of Physical Chemistry, Swiss Federal Institute of Technology, Ecublens, CH-1015, Lausanne, Switzerland

    S. Gilbert

Authors
  1. B. Levy
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  2. W. Liu
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  3. S. Gilbert
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Editors and Affiliations

  1. Dipartimento di Chimica Analitica, Università di Torino, Torino, Italy

    Ezio Pelizzetti

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© 1996 Kluwer Academic Publishers

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Levy, B., Liu, W., Gilbert, S. (1996). Directed Photocurrents in Nanostructured SnO2/TiO2/Ru(II)L2(CNS)2 Heterojunctions. In: Pelizzetti, E. (eds) Fine Particles Science and Technology. NATO ASI Series, vol 12. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0259-6_26

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  • DOI: https://doi.org/10.1007/978-94-009-0259-6_26

  • Publisher Name: Springer, Dordrecht

  • Print ISBN: 978-0-7923-4047-8

  • Online ISBN: 978-94-009-0259-6

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