Design, synthesis, and electroluminescent property of CN-poly(dihexylfluorenevinylene) for LEDs

Abstract

A new green electrolumineseence polymer, CN-poly(dihexylfluorenevinylene) (CN-PDHFV), which denotes poly [(9,9-dihexyl-9H-fluorene-2,7-diyl)(1-cyanoethene-1,2-diyl)(9,9-dihexyl-9H-fluorene-2,7-diyl)(2-cyaoethene-1,2-diyl)], was synthesized by condensation polymerization utilizing the Knoevenagel reaction. The resulting polymer exhibits good solubility in common organic solvents such as chloroform, THF, and ODCB. The polymer is also easily cast on a glass plate to green film. The UV-vis spectrum of the polymer exhibits characteristically a broad absorption band at 440 nm. This polymer shows photoluminescence around lambda(max) = 535 nm (exciting wavelength 410 nm) and green electroluminescence around.. = 530 nm. The current-voltage-luminance (I-V-L) characteristics of the polymer show a turn-on voltage of 4.8 V and a brightness of 600 cd/m(2) at 5.8 V in the Al/polymer/PEDOT/ITO device. The highest efficiency was observed to be 0.85 1m/W at 5.6 V.