Regensburg 2007 – scientific programme

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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices

SYOE 8: Poster Session SYOE

SYOE 8.71: Poster

Tuesday, March 27, 2007, 18:00–20:00, Poster B

Multimode spontaneous emission of optically confined organic photonic dots — •Maik Langner, Clemens Schriever, Robert Gehlhaar, Hartmut Fröb, Vadim G. Lyssenko, and Karl Leo — Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden, Germany, www.iapp.de

We report on the preparation and photoluminescence of photonic dots of the organic semiconductor tris-(8-hydroxyquinoline) aluminum (AlQ₃). The organic material is thermally evaporated onto a distributed Bragg reflector (DBR) through a carbon film mask directly attached to the sample with micrometer sized holes. To obtain photonic dots with various lateral shapes and diameters between 1 and 5 µm, an additional DBR is grown on the top. The mirrors consisting of alternating SiO₂- and TiO₂-layers are produced by reactive electron-beam evaporation and provide maximum reflectivities with R_max>99.6 % enabling microcavities with high quality factors in vertical direction. Using a photoluminescence setup with micrometer lateral resolution, the spontaneous emission of the structured samples is studied after 407 nm cw laser excitation. This setup records the linear emission angle- and polarization-dependent using a spectrometer-CCD combination. As a result of the three dimensional optical confinement, the emission spectra show a number of discrete modes with spectral separations dependent on the structural size. The experimental results are compared with different models based on numerical methods.