title: Molecular origin of differences in hole and electron mobility in amorphous Alq3--a multiscale simulation study.
abstract: In order to determine the molecular origin of the difference in electron and hole mobilities of amorphous thin films of Alq(3) (meridional Alq(3) (tris(8-hydroxyquinoline) aluminium)) we performed multiscale simulations covering quantum mechanics, molecular mechanics and lattice models. The study includes realistic disordered morphologies, polarized site energies to describe diagonal disorder, quantum chemically calculated transfer integrals for the off-diagonal disorder, inner sphere reorganization energies and an approximative scheme for outer sphere reorganization energies. Intermolecular transfer rates were calculated via Marcus-theory and mobilities were simulated via kinetic Monte Carlo simulations and by a Master Equation approach. The difference in electron and hole mobility originates from the different localization of charge density in the radical anion (more delocalized) compared to the radical cation (more confined). This results in higher diagonal disorder for holes and less favourable overlap properties for the hole transfer integrals leading to an overall higher electron mobility.
authors.affiliation: BASF SE, Department of Computational Chemistry, 67056 Ludwigshafen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fuchs
authors.forename: Thomas
authors.initials: T
authors.lastname: Steinbrecher
authors.forename: Mario S
authors.initials: MS
authors.lastname: Mommer
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nagata
authors.forename: Marcus
authors.initials: M
authors.lastname: Elstner
authors.forename: Christian
authors.initials: C
authors.lastname: Lennartz
mesh_terms: D004583:Electrons; D008567:Membranes, Artificial; D056004:Molecular Dynamics Simulation; D009010:Monte Carlo Method; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D009942:Organometallic Compounds; C500391:tris(8-quinolinolato-N1,O8)aluminum