| Abstract
| - The first series of monodisperse nematic oligofluorenes was synthesized following a divergent−convergent approach. With optimized structural parameters, a Tg close to 150 °C and a Tc beyond 375 °C were achieved. This material class is characterized by its ability to form monodomain glassy nematic films. Upon thermal annealing under relatively mild conditions, the highly ordered spin-cast films were found to yield a fluorescence dichroic ratio up to 17 with superior stability in morphology and blue emission.
- The first series of monodisperse glass-forming, nematic oligofluorenes was synthesizedfollowing a divergent−convergent approach. Both chain length and pendant structure werefound to affect solid morphology and phase transition temperatures. With optimizedstructural parameters, a Tg close to 150 °C and a Tc beyond 375 °C were achieved. Thismaterial class is characterized by its ability to form monodomain glassy nematic films viaspin-coating, thermal annealing at 10 to 20 °C above Tg for 15−30 min, and cooling to roomtemperature without encountering crystallization. The absorption and emission dichroicratios of 80−90-nm-thick films increase from 7 to 17 with an increasing molecular aspectratio, while the photoluminescence quantum yield varies erratically from 43 to 60%. Superiorstability of emissive color and of emission dichroic ratio and that against thermally activatedcrystallization were also demonstrated through prolonged heating of a film at 10 °C aboveTg under argon.
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