Alternating copolyfluorenevinyles with polynuclear aromatic moieties: Synthesis, photophysics, and electroluminescence

Three new copolymers, namely poly(fluorenevinylene-alt-naphthalenevi- nylene) (N), poly(fluorenevinylene-alt-anthracenevinylene) (A) and poly(fluorenevinylene-alt-pyrenevinylene) (P), were synthesized by Heck coupling of 9,9-dihexyl-2, 7-divinylfluorene with a polynuclear aromatic dibromide. The 9,10-disubstituted anthracene was obtained exclusively for A while N and P were obtained as a mixture of two isomers with predominant the 1,4-disubstituted naphthalene and 1,8-disubstituted pyrene, respectively. The polymers were soluble in common organic solvents and decomposed above 370 °C Their glass transition temperature increased from 58 to 110 °C by increasing the number of the phenyl rings of the polynuclear aromatic moiety. Rather high-efficiency blue and blue-greenish photoluminescence (PL) of these copolymers in solution was largely decreased in their films, indicating the presence of concentration quenching in the solid state. The OLED using these polymers demonstrated green EL in the case of copolymers N and A, and red EL in the P derivative with ηEL = 0.26-0.31%.