Synthesis and electroluminescent properties of para- and meta-tolyl carbazyl derivatives

A series of para and meta-tolyl substituted carbazole derivatives (dimer, trimer and tetramer) were synthesized to be applied as hole transporting materials (HTM) in multilayer electroluminescent devices. To evaluate electroluminescent properties, multilayer organic-emitting devices were fabricated using these materials as hole transporting layer and Alq3 as emitting layer. All of these EL devices showed a green light emission about 520 nm due to Alq3 emission. The HOMO levels of synthesized materials appear in the range of 5.07∼5.50 eV. These materials have a wide energy band gap.