Bartelt, Andreas F. Schütz, Robert Strothkämper, Christian Schaff, Joachim Janzen, Stephan Reisch, Paja Kastl, Ivo Ziwritsch, Manuel Eichberger, Rainer Fuhrmann, Gerda Danner, David Scheller, Lars-Peter Nelles, Gabriele Efficient Electron Injection from Acyloin-Anchored Semisquarylium Dyes into Colloidal TiO<sub>2</sub> Films for Organic Dye-Sensitized Solar Cells Semisquarylium dyes use a novel acyloin anchor group to strongly bind to TiO<sub>2</sub> semiconductors. Efficient acyloin anchor mediated electron injection into nanocrystalline TiO<sub>2</sub> is demonstrated, allowing highly efficient dye-sensitized solar cells with IPCEs > 80%. The acyloin anchor can thus be viewed as a true alternative to the standard carboxylic acid anchor group. The opto-electronic and electron injection properties of the most basic semisquarylium dye <b>SY404</b> are compared to the modified semisquarylium dye <b>DD1</b> and the carboxylic acid anchored indoline dye <b>D131</b> using a combination of ultrafast and photoemission spectroscopy. For <b>SY404</b>, ultrafast injection times of ∼50 fs are found despite a small energetic driving force between dye excited states and TiO<sub>2</sub> conduction band minimum. This is possible due to the strong electronic coupling of the semisquarylium dyes to the TiO<sub>2</sub> surface mediated by the acyloin anchor. For a better overlap with the solar spectrum, the semisquarylium dyes are modified by substitution with a larger donor moiety (<b>DD1</b>). While for <b>DD1</b> the overall absorption increases, the injection process slightly slows down; however, it still proves fast enough for very efficient injection. Compared to the carboxylic acid anchored indoline dye <b>D131</b>, the <b>SY404</b> dye injects more than seven times faster despite a ∼150 meV smaller driving force. indoline dye D 131;semisquarylium dye SY 404;TiO 2 surface;electron injection properties;carboxylic acid;nanocrystalline TiO 2;novel acyloin anchor group;TiO 2 semiconductors;Efficient acyloin anchor;carboxylic acid anchor group;semisquarylium dyes;semisquarylium dye DD 1;Efficient Electron Injection;acyloin anchor;TiO 2 conduction band;SY 404 dye;Colloidal TiO 2 Films;IPCE 2014-04-03
    https://acs.figshare.com/articles/journal_contribution/Efficient_Electron_Injection_from_Acyloin_Anchored_Semisquarylium_Dyes_into_Colloidal_TiO_sub_2_sub_Films_for_Organic_Dye_Sensitized_Solar_Cells/2309602
10.1021/jp4125364.s001