Theoretical study on charge transport properties of a dinuclear aluminum 8-hydroxyquinoline complex

We investigated the charge transport property of DAlq(3) within the framework of the charge hopping model. The reorganization energies and charge transfer integrals of DAlq(3) were calculated by density functional theory (DFT). The theoretical calculation shows that the reorganization energies of DAlq(3) are smaller both for electron and hole than that of Alq(3). The charge transfer integral of DAlq(3) for electron transfer is larger than that of Alq(3). This explains why DAlq(3) has better electron transporting property and then higher EL efficiency than Alq(3), which is agreement with experimental observations. The charge transfer integral is a more crucial parameter affecting the charge transfer properties of DAlq(3) than the reorganization energy just as Alq(3). Additionally, the electron affinity (EA) and ionization potential (IP) were also calculated. Compared with Alq(3), the larger EA and smaller IP of DAlq(3) implied that it is more favorable for electron transport than Alq(3). (C) 2008 Elsevier B.V. All rights reserved.