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.
- amplified spontaneous emission
Kuehne, A. J. C., Kaiser, M., Mackintosh, A. R., Wallikewitz, B. H., Hertel, D., Pethrick, R. A., & 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), 2564-2570. https://doi.org/10.1002/adfm.201002553