Synthesis and electroluminescence property of new hexaphenylbenzene derivatives including amine group for blue emitters

Three new blue-emitting compounds of 5P-VA, 5P-VTPA, and 5P-DVTPA for organic light-emitting diode (OLED) based on hexaphenylbenzene moiety were demonstrated. Physical properties by the change of the substitution groups of the synthesized materials were systematically examined. Photoluminescence spectrum of the synthesized materials showed maximum emitting wavelengths of about 400 to 447 nm in solution state and 451 to 461 nm in film state, indicating deep blue emission color. OLED devices were fabricated by the synthesized compounds using vacuum deposit process as an emitting layer. The device structure was ITO/2-TNATA 60 nm/ NPB 15 nm/ EML 35 nm/ TPBi 20 nm/ LiF 1 nm/ Al 200 nm. External quantum efficiencies and CIE values of 5P-VA, 5P-VTPA, and 5P-DVTPA were 1.89%, 3.59%, 3.34%, and (0.154, 0.196), (0.150, 0.076), (0.148, 0.120), respectively. 5P-VTPA and 5P-DVTPA exhibited superior highly blue quality and thermal property such as high T_d of 448°C and 449°C.