Efficient and bright blue electroluminescence of poly [4,4′-biphenylene-α-(9",9"-dihexyl-3-fluorenyl)vinylene]

A blue electroluminescent polymer, poly(biphenylenevinylene) derivative containing a bulky fluorenyl group, was prepared by the nickel-catalyzed coupling reaction. The structure and properties of the polymer, PBPHFV, were analyzed by various spectroscopic methods. The obtained polymer had good solubility and thermal stability. The polymer film showed maximum absorption and emission peaks at 370 and 485 nm, respectively.-A blue electroluminescence (lambda (max) = 465 nm) was obtained with intensities of 4116 cd/m(2) when the light-emitting diodes of ITO/PEDOT/PBPHFV/LiF/Al were fabricated. The maximum efficiency of the devices was 0.22 lm/W with a turn-on voltage of 4.3 V. With the optimum ratio of PBPHFV to PVK as 1:5, the luminance and efficiency of the devices reached up to 9342 cd/m(2) and 1.66 lm/W, respectively.