Synthesis and properties of <i>σ</i>–<i>π</i> conjugated alternating polymers consisting of carbazole and organosilicon units

Abstract

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 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‐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 10 3 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 &amp; Sons, Ltd.