Langmuir and Langmuir–Blodgett (LB) film properties of poly(9,9-dioctylfluorene)

The Langmuir (L) and Langmuir–Blodgett (LB) properties of a prototypical member of the polyfluorene family of commercially viable organic light emitting diode (OLED) materials, namely poly(9,9-dioctylfluorene) (PFO) are reported. The Langmuir monolayer was characterised by π-A isotherms. UV–Visible absorption spectroscopy demonstrated the existence of PFO within the β-phase conformation (exhibiting extended conjugation lengths) in the Langmuir monolayer on the water surface, as evidenced by the presence of a well-resolved peak at 435 nm. A high boiling point solvent (xylene) was used in the monolayer to facilitate LB film deposition, which was performed on glass and silicon substrates. Langmuir–Blodgett films of PFO were deposited at a range of pressures (2–15 mN m−1) and deposition speeds (100–1000 mm min−1). The LB films were characterised by photoluminescence spectroscopy and decay dynamics, by fluorescence microscopy, and by UV–Visible absorption spectroscopy. The latter measurements demonstrated that the β-phase component remained present after film deposition.