Theoretical study of electronic and charge transport properties of cruciform π-conjugated 3, 6-diphenyl-1,2,4,5- (2', 2"-diphenyl)-benzobisazole

The electronic and charge transport properties of a cruciform π-conjugated molecule 3,6-diphenyl-1,2,4,5-(2', 2"-diphenyl)-benzobisazole were investigated with density functional theory at B3LYP/6-31G (d) level. The molecular reorganization energy and charge transfer integral between the nearest neighbour molecule were calculated. The hole and electron mobilities are 0.31 and 0.11 cm²·V^-1·s^-1, respectively. Hole transport is mainly through the benzene "edge-to-face" interaction at terphenyl directions and displaced π-π stacking interaction of molecular center. While the main path for electron transport is the π-π stacking interaction in the benzobisazole direction. Mulliken charge analysis for the cationic and ionic state of molecule reveal that the hole and electron are mainly delocalized at terphenyl and benzobisazole directions, respectively. Such hole and electron transport at cruciform direction would be benefit for the balanced charge and electron transport, which might give the hints for practical applications in organic photoelectronic devices and design of novel charge transport materials.