Amphiphilic 4-Hydroxy-1,3-thiazoles - On The Way to Hierarchical Structured Active Layers in Organic Solar Cells and OLED's

Martin Kaufmann1,  Felix Herrmann2,  Torsten Sachse2,  Stefan Fischer2,  Dieter Weiß3,  Benjamin Dietzek2,  Rainer Beckert3,  Martin Presselt2
1Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, D-07743 Jena, Germany ; Institute of Physical Chemistry, Friedrich Schiller University Jena, D-07743 Jena, Germany, 2Institute of Physical Chemistry, Friedrich Schiller University Jena, D-07743 Jena, Germany, 3Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University Jena, D-07743 Jena, Germany

Abstract

Low-cost high-efficiency alternatives to conventional semiconductor-based solar cells are highly needed for a decentralized energy supply and might be provided by organic or dye-sensitized solar cells (DSSCs). Hence, much research has been devoted to improvement of power conversion efficiencies, especially to the development of new chromophores. For each new material system elaborate and mostly empirical optimization within the manifold of device fabrication parameters is necessary for reliable material evaluation and occasional new record power conversion efficiencies. In view of this large effort, mostly devoted morphology tuning, and the fact that the morphology will change towards the thermodynamic minimum upon operation, i.e. probably away from the performance optimum, usage self-organizing substances is a promising way to significantly reduce morphology optimization efforts and to stabilize morphologies on a long term. In our research we utilize amphiphilicity of dyes to control supra-molecular geometries and to stabilize interfaces. Furthermore, amphiphilic dyes can be deposited as smooth mono-layers for fabrication of model devices with well-defined interfaces and tunable molecular order, thus enabling in-depth studies of the ultra-fast photo-induced processes at donor-acceptor interfaces. As donor chromophores we use 4-hydroxy-1,3-thiazoles, an class of chromophores which experienced a renaissance in last years[3]. These thiazoles are photochemically stable, possess high molar extinction coefficients as well as fluorescence quantum yields up to 95% and in addition, exhibit solvatochromism and were successfully tested in DSSCs[4,5,6,7]. We present the synthesis and characterization of amphiphilic dyes for development of improved organic solar cells and in OLED's.

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