Sensitized hole injection of phosphorus porphyrin into NiO: Toward new photovoltaic devices

Magnus Borgström, Errol Blart, Gerrit Boschloo, Emad Mukhtar, Anders Hagfeldt, Leif Hammarström, Fabrice Odobel

Research output: Contribution to journalArticle

160 Citations (Scopus)

Abstract

This paper describes the preparation and the characterization of a photovoltaic cell based on the sensitization of a wide band gap p-type semiconductor (NiO) with a phosphorus porphyrin. A photophysical study with femtosecond transient absorption spectroscopy showed that light excitation of the phosphorus porphyrin chemisorbed on NiO particles induces a very rapid interfacial hole injection into the valence band of NiO, occurring mainly on the 2-20 ps time scale. This is followed by a recombination in which ca. 80% of the ground-state reactants are regenerated within 1 ns. A photoelectrochemical device, prepared with a nanocrystalline NiO electrode coated with the phosphorus porphyrin, yields a cathodic photocurrent indicating that electrons indeed flow from the NiO electrode toward the solution. The low incident-to-photocurrent efficiency (IPCE) can be rationalized by the rapid back recombination reaction between the reduced sensitizer and the injected hole which prevents an efficient regeneration of the sensitizer ground state from the iodide/ triiodide redox mediator. To the best of our knowledge, this work represents the first example of a photovoltaic cell in which a mechanism of hole photoinjection has been characterized.

Original languageEnglish
Pages (from-to)22928-22934
Number of pages7
JournalJournal of Physical Chemistry B
Volume109
Issue number48
DOIs
Publication statusPublished - Dec 8 2005

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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