Electronic structure investigations of organic and hybrid semiconductors

Dr Selina Olthof - Materials Science, Experimental Physics – University of Cologne

Research on novel semiconducting materials for application in optoelectronic devices like solar cells or light emitting diodes has gained increasing interest in the last years as these technologies have several advantages over the standard silicon applications; these include, e.g., the processability from solution or the application in flexible devices. In this talk I want to look at two of these material classes, which are the rather well established organic semiconductors as well as the recently established organic/inorganic halide perovskites.

The stack architectures of these novel semiconductor devices are rather different from their inorganic (e.g. silicon) counterparts. In the resulting complex multilayer structures, function and performance depend crucially on the proper alignment of the energy level landscape throughout the device, i.e. allowing for efficient charge transport across the various interfaces. Here, an advantage of these novel semiconductors is that the electronic structure and band gap energy can be readily tuned, either by molecular design or composition tuning. But in order to optimize interfaces in a device in a non-trial-and-error fashion, one needs to access the relative conduction band and valence band positions.

In this talk I will discuss how measurements by photoelectron spectroscopy can help us to understand the basic properties of these materials and shed light on interface processes in order to unravel and improve the working mechanisms in devices.

Host: Dr Moritz Riede

Audrey Wood Seminar Room, Clarendon Laboratory

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