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

A. J. C. Kuehne, M. Kaiser, A. R. Mackintosh, B. H. Wallikewitz, D. Hertel, R. A. Pethrick, K. Meerholz

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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.
Original languageEnglish
Pages (from-to)2564-2570
Number of pages7
JournalAdvanced Functional Materials
Volume21
Issue number13
DOIs
Publication statusPublished - 8 Jul 2011

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Keywords

  • polymer
  • Poly(9,9-DI-N-Octyl-2,7-Fluorene)
  • polyfluorene
  • lasers
  • amplified spontaneous emission
  • films
  • beam

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