Bis[4-(N,N-di-p-tolylamino)phenyl] Chalcogenides--Synthesis of Novel Hole Transport Materials Containing Chalcogen Atom and Their Application to Organic Electroluminescence Devices--

Takashi OKAI, Yoshio ASO†, Tetsuo OTSUBO*, Jun-ichi HORI and Heiju UCHIIKE††

Faculty of Engineering, Hiroshima University; Higashi-Hiroshima-shi 739-8527 Japan
† Institute for Fundamental Research of Organic Chemistry, Kyushu University; Fukuoka-shi 812-8581 Japan
†† Present address: Faculty of Science and Engineering, Saga University; Saga-shi 840-8502 Japan

The title novel hole transport materials (HTM) (1--3) have been synthesized in good yields by the modified Ullmann coupling reaction of the corresponding bis(4-aminophenyl) chalcogenides with p-iodotoluene in the presence of Cu, K2CO3 and 18-crown-6 in o-dichlorobenzene. From the electrochemical and spectroscopic measurements, it was evaluated that the HOMO levels of these materials are nearly the same as that of TPD, the most typical hole transport material, while the LUMO levels are fairly higher. Electroluminescence devices with the layer structure ITO/HTM(50 nm)/Alq3(50 nm)/Al(500 nm) were fabricated by successive vapor deposition of the materials under vacuum onto an ITO-coated glass. All the devices utilizing 1--3 emitted green light from Alq3 and showed higher luminous efficiency than the device using TPD. In particular, the highest luminance of 2298 cd/m2 was observed for the device of the sulfide-derivative(1).


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