10,15-Dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole

10,15-Dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole, also known as triazacycloheptene (TAT), is a rotameric structure formed by fusing three indoles in orthogonal positions to a single benzene ring, or it can be viewed as a carbazole structure formed by fusing two indoles. In contrast to the carbazole unit, it is a C3 symmetric planar π-extended conjugated structure with a strong electron-carrying capacity, and usually acts as an electron-carrying component either alone or as part of a more complex structure. The triazatriene structure is an indole cyclic trimer with an extended non-localised π-system in which the three indole units form an overlapping framework. Due to the disc-like core, triazatricyclic heptene is highly susceptible to extended π planes, forming a columnar supramolecular arrangement. Organic semiconductors based on triazatricycloheptene have high hole mobility and are most often used as hole transport layer materials due to their strong π-π stacking ability.