A new π-conjugated star-shaped polymer comprising of full fluorene units: An efficient blue emitter without reduction of color purity undergoing an annealing

A new star-shaped polymer comprising of full fluorene units was synthesized by Suzuki polycondensation between an A3 type monomer and an AB type monomer. For comparison, a fluorene-based linear polymer was also prepared. The star-shaped polymer was soluble in common organic solvents and gave the number-average molecular weight, Mn, of more than 12,000 and the weight-average molecular weight, Mw, of exceeded 22,000. The polymer showed similar optical behavior both in solution and in the solid state. After an annealing process, the linear fluorene-based polymer showed an additional bathochromic emission at about 550 nm, whereas such red-shifted emission was fully eliminated for the fluorene-based star-shaped polymer. Cyclic voltammetry (CV) measurement of the polymer indicated that the polymer was reversible under p-doping.