Synthesis and properties of σ-π conjugated alternating polymers consisting of carbazole and organosilicon units

Abstract

We have synthesized novel σ-π conjugated polymers with an alternating organosilanylene and π-electron system, intending to utilize them for hole-transporting materials of electroluminescent (EL) devices. 3,6-Di(lithioethynyl)carbazoles were co-polymerized with organodichlorosilanes to give the corresponding polymers with molecular weights of MW = 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 Mn = 3100. The EL devices with a double-layer system composed of tris(8-quinolinolato)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 103 cd m-2. Of these, the device with the thienylene-carbazole polymers exhibited the highest luminance of 1480 cd m-2. Copyright © 2001 John Wiley & Sons, Ltd.