Luminance Efficiency Enhancement in Green Organic Light-Emitting Devices Fabricated Utilizing a Cesium Fluoride/Fullerene Heterostructure Electron Injection Layer

Enhancement mechanisms of the luminance efficiency in green organic light-emitting devices (OLEDs) fabricated utilizing a cesium fluoride (CsF)/fullerene (C60) heterostructure acting as an electron injection layer (EIL) were investigated. The luminance efficiencies as functions of the current density showed that the luminance efficiency in the green OLEDs fabricated utilizing a CsF/C60 heterostructure acting as an EIL was higher than that in the green OLEDs fabricated utilizing a CsF, a Liq, or a C60 single EIL. The interfacial dipole existing at the CsF layer decreased the electron injection barrier, and the stability of the OLEDs with a CsF EIL was enhanced due to the lower diffusion rate of Cs atoms in comparison with Li atoms. The enhancement of the luminance efficiency of the OLEDs with a heterostructure EIL was attributed to the increase in the electron injection. These results can help improve understanding of the enhancement mechanisms of the luminance efficiency in green OLEDs utilizing a CsF/C60 heterostructure acting as an EIL.