Interface formation between tris(8-hydroxyquinoline) aluminum and ZnO nanowires and film

摘要

The energy level alignments at the interface between tris(8-hydroxyquinoline) aluminum (Alq_3) and ZnO nanowires and thin film were studied with in situ x-ray and ultraviolet photoemission spectroscopy. The changes of work functions, highest occupied molecular orbitals, and core levels were measured with step-by-step deposition of Alq_3 on each ZnO substrate. Although both substrates show similar electronic structures, a larger interface dipole is induced at the interface between Alq_3 and ZnO nanowires. This results in the reduction of the electron injection barrier at the interface of Alq_3/ZnO nanowires. Thus, the ZnO nanowire substrate is expected to show better performance than that of ZnO film when used as a cathode. We discussed the different interface dipole formation at each interface.