Zinc Tetraphenylporphyrin-Fluorene Branched Copolymers: Synthesis and Light-Emitting Properties

Three novel branched zinc tetraphenylporphyrin (ZnTPP)-fluorene copolymers P12, P100, and P1000, with different ZnTPP content, were designed and synthesized by a A(2) + A(2)' + B-4 approach based oil a facile one-pot Suzuki polycondensation reaction. The molar ratio of ZnTPP to fluorene units in the copolymers is 5.50% for P12, 0.91% For P100, and 0.08% for P1000. The copolymers are thermally stable, readily soluble in common organic solvents, and show ZnTPP content-dependent absorption and emission properties. The hand gap of the copolymers decreased with increasing content of ZnTPP from P1000 to P12, and the emission color of the copolymers changed from purplish pink to red. The OLED device using 1112 as emitter showed pure red emission (CIE coordinates of x = 0.64, y = 0.30) with a maximum luminance of 740 cd/m(2), which is among the highest values for pure red light-emission OLEDs based on porphyrin-containing copolymers. It is noteworthy that these devices all show reasonably stable efficiency over a broad Current range, which is a satisfactory performance meeting the need for active-matrix-driven devices.