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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Poster: Electronic and Optical Properties of Organic Systems

CPP 12.4: Poster

Montag, 22. März 2010, 16:30–18:00, Poster C

Optical analysis of trap states in amorphous organic semiconductor films — •Harald Graaf¹, Frank Friedriszk^1,2, and Christian von Borczyskowski¹ — ¹Center of nanostructured Materials and Analytics, Chemnitz University of Technology, 09126 Chemnitz, Germany — ²Institut für Physik, Universität Rostock, 18051 Rostock, Germany

Increasing interest is drawn on thin organic semiconductor films in opto-electronic devices. While for applications like field-effect transistors and photovoltaic cells highly ordered morphologies resulting in higher charge carrier mobilities are requested, for other purposes like organic light emitting diodes amorphous arrangement of the molecules is needed. Here lower mobilities increase the recombination rate leading to a higher photon yield. In such systems trap states can influence dramatically the luminescence in its intensity and spectral regime.

We will show recent results on amorphous films of a perylene dye with a rather high concentration of trap states. These trap states act as sinks for the excitons and leads therefore to a clear shift of the luminescence to the red compared to the monomer emission. Temperature depended and time resolved measurements give a clear hint for the population of the traps from the exciton band. Comparisons with previous electrical measurements lead us to the assumption, that these traps are also dominating the charge carrier mobility within the material.