十字交叉型π共轭分子3,6-二苯-1,2,4,5-(2′,2″-二苯基)-苯并二噁唑的电子结构和电荷传输性质的理论研究

采用密度泛函理论的B3LYP方法, 在6-31G(d)基组水平下研究了以三联苯和二苯基苯并噁唑构成的十字交叉型共轭分子3,6-二苯基-1,2,4,5-(2′,2″-二苯基)-苯并二噁唑的电子结构和电荷传输性质. 通过对分子的重组能和晶体中分子间电荷传输积分的计算得到该分子的空穴迁移率为0.31 cm²·V^-1·s^-1, 电子迁移率为0.11 cm²/(V·s). 计算结果表明, 空穴的传输主要是通过三联苯方向上两端苯环的“边对面”的相互作用以及分子中心π体系的错位重叠相互作用来实现的. 而电子的传输路径主要是通过苯并噁唑方向的π-π重叠相互作用来实现. 通过分析分子正负离子态的Mulliken电荷发现, 正电荷较多分布在三联苯方向上, 而负电荷较多分布在苯并噁唑方向上. 计算结果表明, 电子和空穴的传输分别在分子相互交叉的不同方向上, 有利于电子和空穴的平衡传输.

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.