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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs.

Strathprints serves world leading Open Access research by the University of Strathclyde, including research by the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), where research centres such as the Industrial Biotechnology Innovation Centre (IBioIC), the Cancer Research UK Formulation Unit, SeaBioTech and the Centre for Biophotonics are based.

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Sub-micrometer patterning of amorphous- and β-phase in a crosslinkable poly(9,9-dioctylfluorene) : dual-wavelength lasing from a mixed-morphology device

Kuehne, A. J. C. and Kaiser, M. and Mackintosh, A. R. and Wallikewitz, B. H. and Hertel, D. and Pethrick, R. A. and Meerholz, K. (2011) Sub-micrometer patterning of amorphous- and β-phase in a crosslinkable poly(9,9-dioctylfluorene) : dual-wavelength lasing from a mixed-morphology device. Advanced Functional Materials, 21 (13). pp. 2564-2570. ISSN 1616-301X

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Abstract

The metastable β-phase morphology, inherent to most polyfluorene homo-polymers, is of interest due to its superior optical and electrical characteristics compared to its amorphous analogue. Here, a polyfluorene with vinyl-ether-functionalized aliphatic side-chains that allow crosslinking is reported. It is demonstrated that the previously induced conformational morphology is preserved in the resulting polyfluorene network, which enables subsequent wet thin-film processing. Electron-beam lithography provides a means for sub-(optical)-wavelength patterning of the crosslinkable polyfluorene films. As a specific demonstration, optically-pumped distributed-feedback (DFB) lasers made from surface-relief gratings in amorphous and β-phase polyfluorene are presented. By backfilling gratings of one morphology by the other, devices are demonstrated that exhibit lasing at two wavelengths with a threshold (<1 μJ cm−2) at least an order of magnitude lower compared with previous data.