Electron injection mechanisms of the luminance efficiency of green organic light-emitting devices (OLEDs) fabricated utilizing a cesium carbonate (Cs(2)CO(3))/fullerene (C(60)) heterostructure acting as an electron injection layer (EIL) were investigated. Current density-voltage and luminance-voltage measurements showed that the current densities and the luminances of the OLEDs with a Cs(2)CO(3) or Cs(2)CO(3)/C(60) EIL were higher than that of the OLEDs with a Liq EIL. The luminance efficiency of the OLEDs with a Cs(2)CO(3) EIL was almost three times higher than that of the OLEDs with a Liq EIL Because the electron injection efficiency of the Cs(2)CO(3) layer in OLEDs was different from that of the C(60) layer, the luminance efficiency of the OLEDs with a double EIL consisting of a Cs(2)CO(3) layer and a C(60) layer was smaller than that of the OLEDs with a Cs(2)CO(3) EIL The electron injection mechanisms of OLEDs with a Cs2CO3 and C60 double EIL are described on the basis of the experimental results. (C) 2010 Elsevier B.V. All rights reserved.