Origin of the luminance efficiency enhancement in organic light-emitting devices fabricated utilizing a co-host electron transport layer consisting of a 4,7-diphenyl-1,10-phenanthroline and an aluminum tris(8-hydroxyquinoline)

摘要

The electrical and the optical properties of organic light-emitting devices (OLEDs) utilizing a 4,7-diphenyl-1,10-phenanthroline (BPhen) and aluminum tris(8-hydroxyquinoline) (Alq_3) co-host electron transport layer (ETL) has been investigated to clarify the origin of the luminance efficiency enhancement. The luminance efficiency of the OLEDs was significantly enhanced by utilizing a BPhen:Alq_3 co-host ETL The electron-only-devices for OLEDs with a BPhen:Alq_3 co-host ETL or an Alq_3 ETL were fabricated to investigate the electron injection and transport properties in the co-host or single ETL The enhancement of the luminescence efficiency in OLEDs fabricated utilizing a co-host ETL consisting of a BPhen and an Alq_3 were attributed to the decrease in the electron injection barrier and the increase in the hole blocking barrier. The origin of the luminescence efficiency enhancement in OLEDs fabricated utilizing a co-host ETL consisting of a BPhen and an Alq_3 were described on the basis of the experimental results.