Photophysical Processes Occurring in a Zn-phthalocyanine in Ethanol Solution and on TiO2 Nanostructures

Alessandro Iagatti, Sandra Doria, Agnese Marcelli, Nicola Angelini, Sara Notarantonio, Anna Maria Paoletti, Giovanna Pennesi, Gentilina Rossi, Gloria Zanotti, Giuseppe Calogero, Paolo Foggi

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The photophysics of 9(19),16(17),23(24)-tri-tert-butyl-2-[ethynyl-(4-carboxymethyl)phenyl] phthalocyaninatozinc(II) (ZnPc) in solution and adsorbed on TiO2 and ZrO2 nanoparticle films is characterized by stationary and time-resolved spectroscopies in the subpicosecond to nanosecond time interval. The comparison between the solution and the solid substrate data allows us to identify different pathways of the energy and electron relaxation. On the solid substrate, the presence of H-aggregates adds a further nonradiative deactivation channel competing with the charge injection into the TiO2-conducting band, thus providing an explanation of the reduced efficiency of the charge transfer processes. The comparison between the kinetics recorded after excitation of the S0-S2 transition and those recorded after excitation of the S0-S1 transition provides an estimate of the internal conversion between S2 and S1 which occurs very efficiently and on an ultrafast (<50 fs) time scale. The ground-state recovery characterized by the decay of the bleaching band in the transient spectra slows down in TiO2 samples and is taken as evidence of the charge injection in this kind of sample.

Original languageEnglish
Pages (from-to)20256-20264
Number of pages9
JournalJournal of Physical Chemistry C
Volume119
Issue number35
DOIs
StatePublished - 12 Aug 2015
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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