High-efficiency blue light-emitting polymers based on 3,6-silafluorene and 2,7-silafluorene

A novel blue-emitting polymer based on 3,6-silafluorene and 2,7-silafluorene was synthesized via the Suzuki polycondensation. The resulting polymers are readily soluble in common organic solvents, such as toluene, xylene, THF, and chloroform. The thermal, electrochemical, photophysical, and electroluminescence properties of the resulting polymers were investigated. The device fabricated from the copolymer with a configuration of ITO/PEDOT:PSS/PVK/polymer/Ba/Al exhibited an external quantum efficiency of 1.95%, a luminous efficiency of 1.69 cd A(-1) and a maximal brightness of 6000 cd m(-2). It has been found that the incorporation of the 3,6-silafluorene unit into the poly(2,7-silafluorene) main chain can not only improve the color purity of the devices from the resulting copolymer but also enhance its device efficiency. Moreover, no undesired long-wavelength green emission was observed in the PL spectra of P36-27SiF90 compared to that of PFO with a dominating emission at 500-600 mn after thermal annealing at 200 degrees C for 8 h. (c) 2007 Wiley Periodicals, Inc.