Regensburg 2004 – wissenschaftliches Programm
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SYOH: Organic and Hybrid Systems for Future Electronics
SYOH 2: Spectroscopy
SYOH 2.4: Vortrag
Donnerstag, 11. März 2004, 15:30–15:45, H37
Up-conversion Fluorescence in Polyfluorenes doped with Metallated Macrocycles — •Stanislav Baluschev1, Panagiotis Keivanidis1, Tzenka Miteva2, Gabriele Nelles2, Ulrich Scherf3, Akio Yasuda2, and Gerhard Wegner1 — 1Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz — 2Sony International (Europe), MSL, Hedelfinger Str. 61, 70327 Stuttgart — 3Bergische Universität Wuppertal, Fach. Chemie, Gauss Str. 20, 42119 Wuppertal
In our research towards polymer lasers we achieved for the first time quasi-cw up-conversion in doped polyfluorenes (PFs). Metallated macrocycles as porphyrins and phthalocyanines were used as dopands (sensitisers). Upon excitation with 532 nm the characteristic emission of the PF (420-480 nm) was detected together with the sensitisers emission. The system was optimised for dopands type, doping level and for the side-chain pattern of the PFs. The macroscopic temperature was controlled and the efficiency of the sensitiser excitation was optimised. As a result, up-conversion at pumping densities as low as a few kWcm − 2 were achieved to be compared very favourably with the GWcm − 2 necessary for similar magnitude two-photon excited fluorescence in PFs.
From our results it is evident that the up-converted PF emission is a consequence of an energy transfer process from the sensitisers to the PF. We suggest that a mechanism involving a sequential multiphoton absorption in the macrocycles may govern this energy transfer process.