Electron injection mechanisms of green organic light-emitting devices fabricated utilizing a double electron injection layer consisting of cesium carbonate and fullerene

Abstract

Electron injection mechanisms of the luminance efficiency of green organic light-emitting devices (OLEDs) fabricated utilizing a cesium carbonate (Cs2CO3)/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 Cs2CO3 or Cs2CO3/C-60 EIL were higher than that of the OLEDs with a Liq EIL. The luminance efficiency of the OLEDs with a Cs2CO3 EIL was almost three times higher than that of the OLEDs with a Liq EIL Because the electron injection efficiency of the Cs2CO3 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 Cs2CO3 layer and a C-60 layer was smaller than that of the OLEDs with a Cs2CO3 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.