Stilbene like carbazole dimer-based electroluminescent materials

Two carbazole dimers (1 and 10) were synthesized from 9-ethyl-9H-carbazole-3-carbaldehyde and 6-bromo-9-ethyl-9H-carbazole-3-carbaldehyde by McMurry C-C coupling reaction. Palladium(0)-catalyzed C-N coupling reactions of 10 and various diarylamines result in the formation of stable carbazole derivatives in good yields. These compounds are fluorescent in blue to yellow region with moderate to good quantum yields. Also, they are thermally stable and capable of hole-transporting due to the presence of the carbazole moieties. The electroluminescent devices fabricated using 1, 2, and 3 as hole-transporters/emitters with a bilayer structure ITO/Cpd/TPBI or Alq(3)/LiF/Al (Cpd=1, 2, and 3) exhibit good performance (e.g., eta(ext)=1.0-2.1%; eta(p)=0.9-1.9 lm/W; eta(c)=2.4-4.8 cd/A at a current density of 100 mA/cm(2)). (c) 2006 Elsevier Ltd. All rights reserved.