Electron tunneling at the TiO2/substrate interface can determine dye-sensitized solar cell performance

Sven Rühle, David Cahen

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

The electric potential distribution in dye-sensitized solar cells plays a major role in the operation of such cells. Models based on a built-in electric field which sets the upper limit for the open circuit voltage (V ) and/or the possibility of a Schottky barrier at the interface between the mesoporous wide band gap semiconductor and the transparent conducting substrate have been presented. We show that I-V characteristics in the dark and upon illumination are very well explained by electron tunneling, rather than transport over a Schottky barrier, at this interface. Our calculations, based on tunnel currents, show that a discontinuity of the conduction band at the TiO2/FTO interface, rather than a built-in electric field, suffices for efficient electron transfer through this interface, and, thus, for efficient operation of this type of solar cell. Clearly, this will hold only if the photoinduced electrostatic potential barrier between the transparent conducting substrate and the mesoporous wide band gap semiconductor drops over a region that is sufficiently narrow to allow efficient tunneling through it.

Original languageEnglish
Pages (from-to)17946-17951
Number of pages6
JournalJournal of Physical Chemistry B
Volume108
Issue number46
DOIs
StatePublished - 18 Nov 2004
Externally publishedYes

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