Threshold Reduction in Polymer Lasers Based on Poly(9,9-dioctylfluorene) with Statistical Binaphthyl Units
| Autor: | Eike Becker, Thomas Riedl, Wolfgang Kowalsky, Torsten Rabe, H.-H. Johannes, Benjamin S. Nehls, D. Schneider, M. Hoping, Thomas Weimann, Peter Hinze, Tony Farrell, J. Wang, Ullrich Scherf |
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| Rok vydání: | 2005 |
| Předmět: |
chemistry.chemical_classification
Photoluminescence Materials science Polymer Dihedral angle Condensed Matter Physics Laser Electronic Optical and Magnetic Materials law.invention Biomaterials chemistry law Polymer chemistry Electrochemistry Copolymer Physical chemistry Thin film Lasing threshold Excitation |
| Zdroj: | Advanced Functional Materials. 15:1188-1192 |
| ISSN: | 1616-3028 1616-301X |
| Popis: | We introduce novel statistical copolymers of poly(9,9-dioctylfluorene), PFO, which contain various concentrations of 6,6'-(2,2'-octyloxy-l ,1 '-binaphthyl) spacer groups. We demonstrate that, owing to the large dihedral angle (> 60°) between neighboring naphthalene units, we could hinder the formation of the highly ordered β-phase in thin films of the copolymers. In low-temperature photoluminescence measurements, the typical signature of the PFO p-phase at 442 nm is no longer observed for copolymers with a binaphthyl concentration of about 12%. Moreover, the optical properties of the copolymers resembled those of the glassy α-phase PFO. Second-order distributed feedback (DFB) lasers based on thin films of the homopolymer PFO showed a minimum lasing threshold of 11.7 μJ cm - 2 (λ m a x = 452 nm, excitation at λ = 337 nm with 500 ps pulses). With increasing binaphthyl concentration in the copolymer backbone, the lasing threshold steadily decreased to 3 μJcm - 2 for a binaphthyl concentration of about 12%. Therefore, our novel copolymers provide a vast improvement for PFO-based optoelectronics. |
| Databáze: | OpenAIRE |
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