Blue light-emitting diodes based on novel polyfluorene copolymers

Paper in proceeding, 2007

This study presents the synthesis and characterization of a series of fluorene-based conjugated copolymers, together with the prepn. and characterization of the corresponding light-emitting devices. The polymers consist of alkoxyphenyl-substituted fluorene units together with different amts. of a hole-transporting triphenylamine-substituted fluorene unit: 0%, 10%, 25% and 50%. All polymers (P0, P1, P2, and P3) show high photoluminescence efficiency (hPL) and light emission (both PL and EL) in the blue spectral region. Electrochem. studies show improved hole injection as the ratio of the triphenylamine-substituted segment is increased. The electroluminescence quantum efficiencies (EQEs) of the devices increase six times going from P0 to P1. Compared with P1, polymers P2 and P3 show lower efficiencies in devices. These findings indicate the presence of an optimal polymer compn., where balance between the charge-carrier mobilities has been reached. [on SciFinder (R)]