Phosphine oxide-functionalized polyfluorene derivatives: Synthesis, photophysics, electrochemical properties, and electroluminescence performance

A series of phosphine oxide-functionalized polyfluorene derivatives, PFH-PO-40-1 ( P1 ), PFH-PO-20-1 ( P2 ), PFH-PO-10-1 ( P3 ), and PFH-PO-1-1 ( P4 ), were prepared via a palladium-mediated Suzuki cross-coupling reaction. The structures and purities of all polymers were fully characterized by 1 H and 13 C NMR, UV-vis and photoluminescent spectroscopy, gel permeation chromatography, and TGA/DSC. Their emission features showed single broad peaks at about 445 nm in film, compared with those in dilute solutions, which might be caused by some degree of aggregation in the excited states of the backbones. The best electroluminescence (EL) performance of these polymers with configuration of ITO/PEDOT:PSS/Polymer/Alq 3 /LiF/Al was obtained from P1 (current efficiency was 4.2 Cd/A at 6V).