Current projects

Current research projects of Schlettwein group:

Kinetic Investigations of Electrochromic Thin Films for the Application in Smart Windows

Worked on by Thi Hai Quyen Nguyen

Tungsten oxide and perfluorinated phthalocyanines are investigated as electrochromic materials for the application in smart windows. The electrochromic thin films are prepared by spin-coating and physical vapor deposition. The aim is to optimize the charge transport at the interface of the electrolyte and the electrochromic film and to enhance the switching behaviour between the bleached and the colored state of the film by varying the film properties. Thus, the inner structure and the composition of the film play a crucial role in the electrochromic switching process.

Porous layers for the preparation of photoanodes in dye-sensitized solar cells

Worked on by Andreas Ringleb

Zink oxide (ZnO) is used for the preparation of porous layers in dye-sensitized solar cells. The incorporation of Mg-Atoms in place of Zn in the crystall lattice of ZnO leads to a widening of the band gap depending on the Mg-content. This variability can be used for the reduction of injection losses and can lead to a higher voltage output of the solar cell. Syntesis of ZnO and MgZnO can be done wet-chemically in form of nanoparticles or by means of atomic layer deposition (ALD).

Electrical Contact Formation in Organic Semiconducting Devices (OLED & OFET)

Worked on by Pascal Schweitzer

Contact resistances crucially limit the performance of hybrid-organic semiconducting devices. Energy barriers for charge carrier transport and inappropriate contact quality at the interfaces of organic light emitting diodes (OLED) induce energy losses and reduced light intensity. For building efficient devices, an optimization of these interfaces and the device architecture as well as adjustment of the energy levels of the materials in contact is key. The (less well-known) organic field-effect transistors (OFET) offer the possibility to study these contact resistances, e.g. locally resolved using Kelvin probe force microscopy (KPFM), to identify crucial parameters, also influencing OLED efficiency.

DFG-funded research projects:

Mechanistic analysis of dye regeneration and recombination processes at dye-sensitized solar cells using microelectrochemical experiments (Link)

Investigations of charge separation and migration in lead-free perovskite-based thin films and devices for photovoltaics using ultrafast broadband optical techniques and electrical characterization methods (Link)

Worked on by Jonas Horn

Lead halide perovskite materials were successfully used as absorber layers in thin film photovoltaics during the last decade, however, are at cost of intrinsic instabilities of the absorber layer as well as the toxicity of water-soluble lead salts. Therefore, the aim of this project is to investigate alternative lead-free perovskite materials. The particular focus is, besides the structural stability of the absorbing layer, in its contact formation as well as the properties of the interface with adjacent electron and hole selective layers, as they are essential for the solar cell function.

DFG-Graduiertenkolleg 2204