Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: POSTER: INTERNAL SYMPOSIUM Optical Spectrosopy

CPP 22.7: Poster

Wednesday, March 28, 2007, 16:00–18:30, Poster B

Optical properties of rubrene crystals and films as a function of temperature — Olga Krylova¹, Domink Berg¹, •Matthias Müller¹, Jens Pflaum², and Moritz Sokolowski¹ — ¹Institut für Physikalische und Theoretische Chemie, Universität Bonn, — ²3. Physikalisches Institut, Universität Stuttgart

We have investigated the optical absorption and photoluminescence (PL) of high quality rubrene (Rub) single crystals and thin vacuum deposited Rub films as a function of temperature. Interestingly, very strong changes are found in the PL spectra of Rub crystals upon cooling. Whereas room temperature (RT) spectra show the strongest emission at about 2000 cm⁻¹ below the electronic origin, spectra at low temperatures (LT), i.e., 5 K, have a very strong emission on the electronic origin and are very similar to spectra of thin Rub films. Going to low T increases the PL yield by a factor of more than 100. These results are tentatively interpreted with an emission from H-aggregates at RT and from J-aggregates at LT. A detailed comparison with the spectra of Rub films and Rub in solution will be given. Funding by the DFG research unit 557 is acknowledged.