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

We investigated the charge transport property of DAlq3 within the framework of the charge hopping model. The reorganization energies and charge transfer integrals of DAlq3 were calculated by density functional theory (DFT). The theoretical calculation shows that the reorganization energies of DAlq3 are smaller both for electron and hole than that of Alq3. The charge transfer integral of DAlq3 for electron transfer is larger than that of Alq3. This explains why DAlq3 has better electron transporting property and then higher EL efficiency than Alq3, which is agreement with experimental observations. The charge transfer integral is a more crucial parameter affecting the charge transfer properties of DAlq3 than the reorganization energy just as Alq3. Additionally, the electron affinity (EA) and ionization potential (IP) were also calculated. Compared with Alq3, the larger EA and smaller IP of DAlq3 implied that it is more favorable for electron transport than Alq3.