Synthesis and properties of sigma-pi conjugated alternating polymers consisting of carbazole and organosilicon units

We have synthesized novel sigma-pi conjugated polymers with an alternating organosilanylene and pi -electron system, intending to utilize them for hol e-transporting materials of electroluminescent (EL) devices. 3,6-Di(lithioe thynyl)carbazoles were co-polymerized with organodichlorosilanes to give th e corresponding polymers with molecular weights of M-W = 2000-5000. Another type of polymer with a thienylene unit was also synthesized by the nickel- catalyzed reaction of the di-Grignard reagent of 1,2-bis[2-(5-bromothienyl) ]tetraethyldisilane with 3,6-dibromocarbazole, the molecular weight being M -n = 3100. The EL devices with a double-layer system composed of tris(8-qui nolinolato)aluminum(III) and the present polymers as the emitting-electron- transporting and hole-transporting layers, respectively, emit green EL with a maximum intensity of the order of 10(3) cd m(-2). Of these, the device w ith the thienylene-carbazole polymers exhibited the highest luminance of 14 80 cd m(-2). Copyright (C) 2001 John Wiley & Sons, Ltd.