Investigation on Copper Liberation in the Multilayer CuPc/Li/Al Cathode of Organic Light-Emitting Diodes

摘要

An interlayer Li inserting between copper phthalocyanine (CuPc) and Al improves both electric and luminous properties of an organic light-emitting diode (OLED). X-ray photoelectron spectroscopy (XPS) surface analysis technique is employed to investigate chemical binding conditions of CuPc/Li interface. At varying thicknesses of Li deposited on CuPc, we have studied C_(1s) and Cu_(2p) XPS of CuPc films. Investigation demonstrates that Cu atoms are liberated from CuPc with increasing Li thicknesses. The results reveal that an OLED with an indium tin oxide glass/triphenyldiamine derivative/tris(8-hydroxyquinoline)aluminum/CuPc/Li/Al structure employing a 2 nm thick Li exhibits optimum performance. It can satisfy commercial demands in not only good reproducibility but also a large area of uniformality.