Synthesis and Characteristics of Hole-transporting Materials Based on Biphenyl Diamine Derivatives with Carbazole Groups

Two hole-transporting materials containing carbazole moieties with TPD- and NPB-like structures, 4,4′-bis [N-(4-carbazolylphenyl)-N-phenylamino] biphenyl (CPB) and 4,4′-bis [N-(4-carbazolylphenyl)-N-(1-naphthyl) amino]biphenyl(CNB), were synthesized via a modified Ullmann reaction. The resulting compounds were thermally stable with high glass transition temperatures ranging from 145 to 147 °C and possessed a good electrochemical reversibility and hole-transporting properties. Typical double-layer device evaluation with the structure ITO/CPB(40 run)/Alq3(60 nm)/LiF/Al demonstrated that they were promising hole-transporting materials with a current efficiency of 5. 25 cd/A and a power efficiency of 2. 00 lm/W.