New star-shaped luminescent triarylamines: Synthesis, thermal, photophysical, and electroluminescent characteristics

A series of 3,6-disubstituted carbazole and 1,3,5-trisubstituted benzene derivatives incorporating thienyl aromatic (phenyl, fluorenyl, and carbazolyl) conjugation and end-capped diphenylamine were synthesized by iterative C-N and C-C coupling procedures. The carbazole derivatives emit blue light and the star-shaped benzene derivatives emit either blue or bluish green color depending on the conjugation segment. In general, they possess high glass transition temperatures (>120 degreesC) and decomposition temperatures (> 520 degreesC). Double-layer organic light-emitting devices were successfully fabricated using these novel molecules as hole-transporting and emitting materials. Devices of the configuration ITO/HTM/TPBI/Mg:Ag display blue to green emission from the HTM layer while in the devices of the configuration ITO/HTM/Alq(3)/Mg:Ag, a typical green emission from the Alq(3) layer was observed.