Efficient Electron Injection from Acyloin-Anchored Semisquarylium Dyes into Colloidal TiO2 Films for Organic Dye-Sensitized Solar Cells

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• 作者：Andreas F. Bartelt ; Robert Sch眉tz ; Christian Strothk盲mper ; Joachim Schaff ; Stephan Janzen ; Paja Reisch ; Ivo Kastl ; Manuel Ziwritsch ; Rainer Eichberger ; Gerda Fuhrmann ; David Danner ; Lars-Peter Scheller ; Gabriele Nelles
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：April 3, 2014
• 年：2014
• 卷：118
• 期：13
• 页码：6612-6623
• 全文大小：611K
• 年卷期：v.118,no.13(April 3, 2014)
• ISSN：1932-7455

文摘

Semisquarylium dyes use a novel acyloin anchor group to strongly bind to TiO₂ semiconductors. Efficient acyloin anchor mediated electron injection into nanocrystalline TiO₂ 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 SY404 are compared to the modified semisquarylium dye DD1 and the carboxylic acid anchored indoline dye D131 using a combination of ultrafast and photoemission spectroscopy. For SY404, ultrafast injection times of 50 fs are found despite a small energetic driving force between dye excited states and TiO₂ conduction band minimum. This is possible due to the strong electronic coupling of the semisquarylium dyes to the TiO₂ 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 (DD1). While for DD1 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 D131, the SY404 dye injects more than seven times faster despite a 150 meV smaller driving force.