Amine groups-functionalized alcohol-soluble polyfluorene derivatives: Synthesis, photophysical properties, and self-assembly behaviors

A polyfluorene derivative with primary amine groups on side chains, poly(9,9-bis(6′-aminohexyl)fluorene) (PF-NH2), was prepared through de-protection of its analogue polymer poly(9,9-bis(6′-butoxylcarbonylaminohexyl)fluorene) (PF-BOC) with hydrochloric acid followed by neutralizing the salt form of poly(6,6′-(9H-fluorene-9,9-diyl)dihexan-1-aminium chloride) (PF-NION). PF-NION had good solubility in methanol, DMSO, and DMF. Scanning electron microscopic images of PF-NH2 in thin films revealed that intramolecular/intermolecular hydrogen bonding and π-π stacking interactions probably played an important role in the formation of special surface morphologies, which might be beneficial to the molecular ordering and device fabrication. The electroluminescence property of PF-NION was recorded on a simple polymer light-emitting diode (PLED) device configuration of ITO/PEDOT/Polymer/Al. Pure blue electroluminescence is achieved from double-layer PLEDs based on PF-NION as the active material with the CIE of (0.16, 0.08).