Thermally stable carbazole-diimides as hole transport materials for organic light-emitting devices

We synthesized new carbazole-diimide hole-transporting materials with different dianhydride groups by thermal imidization. The imide moieties were introduced to improve thermal stability of a carbazole hole transport molecule. Result showed that the carbazole-diimdes exhibit good thermal stability with glass transition temperature of 142-182 degrees C and degradation temperature of approximately 450 degrees C as well as good optical transparency in the visible region. The organic light-emitting device (OLED) using alicyclic diimide (CBCZ) shows maximum luminance approximately 8,600 cd/m2 at 12 V and current efficiency of 2.1 cd/A. With optimization of fabricating conditions, the thermally stable CBCZ is expected to be used as a promising hole-transporting material with higher efficiency and durability.