A number of other analogues containing two carbazole donors were also prepared by Lee et al. The different substitution patterns of the two carbazoles for six emitters 23CT, 24CT, 25CT, 26CT, 34CT and 35CT (here DCzTRZ was renamed as 35CT) are correlated with their photophysical properties. Ortho-substitution to the triazine acceptor induces a large dihedral angle between the carbazole and triazine moieties, thus leading to a stronger charge transfer state and smaller DEST, which is evident by comparing 23CT (DEST: -0.02 eV, 1 wt% in Zeonex), 24CT (DEST: 0.11 eV, 1 wt% in Zeonex), 25CT (DEST: 0.07, 1 wt% in Zeonex), 26CT (DEST: