Sub-Micrometer Patterning of Amorphous- and beta-Phase in a Crosslinkable Poly(9,9-dioctylfluorene): Dual-Wavelength Lasing from a Mixed-Morphology Device

[摘要]：The metastable beta-phase morphology, inherent to most polyfluorene homopolymers, 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 beta-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 mu J cm(-2)) at least an order of magnitude lower compared with previous data.

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