Polyfluorene derivatives pending iridium complexes: Improved optoelectronic properties by introducing D‐A units and altering pendent mode

To study influence of the donor(D)-acceptor(A) units and pendent mode of phosphorescent moiety on the opto-electronic properties for its resulting copolymers, two D-A-based polyfluorene derivatives (P1 and P2) pending the red-emitting iridium bi(phenylisoquilonato) (picolinato) [Ir(Piq)2(pic)] unit and a polyfluorene derivative (P3) only pending Ir(Piq)2(pic) unit were synthesized and characterized, in which the donor of carbazole, the acceptor of oxadiazole are grafted into the C-9 position of fluorene, the Ir(Piq)2(pic) unit is pended into either the C-9 position for P1 and P3 or the end for P2 of fluorene by unconjugated linkage, respectively. Their opto-electronic properties were significantly influenced by the D-A units and pendent mode of the Ir(Piq)2(pic) unit. In the polymer light-emitting devices with a configuration of ITO/PEDOT/polymers/LiF/Al, the P1 showed best electroluminescent properties than the P2 and P3. The maximum current efficiency of 0.72 cd/A and the highest luminance of 1398 cd/m2 were obtained in the P1-based device, which are 1.3 and 1.5 times higher than those in the P2-based device, respectively. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

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