Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

SYOO: Organic Optoelectronics and Photonics

SYOO 6: Poster

SYOO 6.60: Poster

Montag, 7. März 2005, 18:00–20:00, Poster TU A

Threshold reduction in polymer lasers based on poly(9,9-dioctylfluorene) with statistical binaphthyl units — •Matthias Hoping¹, Torsten Rabe¹, Daniel Schneider¹, Eike Becker¹, Hans-Hermann Johannes¹, Wolfgang Kowalsky¹, Thomas Weimann², Jing Wang², Peter Hinze², Benjamin Nehls³, Ullrich Scherf³, Tony Farell³, and Thomas Riedl¹ — ¹Institut für Hochfrequenztechnik, Technische Universität Braunschweig,Schleinitzstrasse 22, 38092 Braunschweig — ²Physikalisch Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig — ³Bergische Universität Wuppertal, Gauss Strasse 20, 42097 Wuppertal

We introduce novel statistical copolymers of poly(9,9-dioctylfluorene) (PFO) which contain binaphthyl spacer groups in different concentrations. The incorporation of these spacer groups results in a large dihedral angle between neighbouring naphthalene units and leads to a suppression of the highly ordered β-phase formation in thin films of the copolymers. In low temperature photoluminescence measurements we observed a shift of the spectra from the typical signature of the β-phase PFO at 442 nm to smaller wavelengths with a binaphthyl concentration of ca. 12 percent. The beneficial effect of the suppressed β-phase is reflected in the minimum lasing thresholds of second order distributed feedback (DFB) lasers based on thin films of the copolymers. While the minimum lasing threshold energy of the homopolymer is found at 11.7 µJ/cm² an incorporation with binaphthyl units in the copolymer backbone leads to a lasing threshold of 3 µJ/cm² for a binaphthyl concentration of ca. 12%.