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

Abstract

Enhancement mechanisms of the luminance efficiency in green organic light-emitting devices (OLEDs) fabricated utilizing a cesium fluoride (CsF)/fullerene (C-60) 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/C-60 heterostructure acting as an EIL was higher than that in the green OLEDs fabricated utilizing a CsF, a Liq, or a C-60 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/C-60 heterostructure acting as an EIL.