Photoinduced ultrafast dynamics of Ru(dcbpy)2(NCS)2-sensitized nanocrystalline TiO2 films: The influence of sample preparation and experimental conditions

Jani Kallioinen (Corresponding Author), Gabor Benkö, Pasi Myllyperkiö, Leonid Khriachtchev, Björn Skårman, Reine Wallenberg, Markus Tuomikoski, Jouko Korppi-Tommola, Villy Sundström, Arkady P. Yartsev

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    86 Citations (Scopus)

    Abstract

    In most of the previous ultrafast electron injection studies of Ru(dcbpy)2(NCS)2-sensitized nanocrystalline TiO2 films, experimental conditions and sample preparation have been different from study to study and no studies of how the differences affect the observed dynamics have been reported. In the present paper, we have investigated the influence of such modifications. Pump photon density, environment of the sensitized film (solvent and air), and parameters of the film preparation (crystallinity and quality of the film) were varied in a systematic way and the obtained dynamics were compared to that of a well-defined reference sample:  Ru(dcbpy)2(NCS)2−TiO2 in acetonitrile. In some cases, the induced changes in the dynamics were uncorrelated to the electron injection process. High pump photon density (not in the linear response region) and exposure of the sensitized film to air altered the picosecond-time-scale kinetics considerably, and the changes were attributed mostly to degradation of the dye. In other cases, changes in the measured kinetics were related to the electron injection processes:  reducing the firing temperature of the nanocrystalline film or making the film via electron beam evaporation (EBE) resulted in a decrease of the overall crystallinity of the film, and the electron injection slowed. In the sensitized EBE films, in addition to an increased contribution of triplet excited-state electron injection, a new electron transfer (ET) process with a time constant of 200 fs was observed.
    Original languageEnglish
    Pages (from-to)6365 - 6373
    Number of pages9
    JournalThe Journal of Physical Chemistry B
    Volume108
    Issue number20
    DOIs
    Publication statusPublished - 2004
    MoE publication typeA1 Journal article-refereed

    Keywords

    • dye-sensitized solar cell
    • solar cells
    • solar energy
    • electron injection
    • electron transfer

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