Luminescence Dynamics of Alq3-Based Multilayer Structures in Terms of HOMO and LUMO Energy Discontinuity

Abstract

ABSTRACTOptical properties of organic multilayer structures with type-I and type-II energy lineups with respect to the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels were investigated and compared. The fast energy transfer followed by carrier confinement in the material with lower HOMO-LUMO energy difference was proved for the structures with type-I energy lineup, while the tendency of separation of excited states, i.e., electrons and holes generated in the excited molecules, was demonstrated for those with type-II. These results indicate that the luminescence dynamics of organic multilayer structures are well discussed in terms of HOMO and LUMO energy lineups similarly to valence and conduction band energies in inorganic semiconductors.