Polymer light-emitting devices (PLEDs) using poly(9,9-dihexyl-9H-fluorene-2,7-diyl-vinylene)(PPV-D) as electroluminescent layer, with TiO2 and with Ti as electron injecting layers were prepared. Experimental results show that the efficiency of device with cathode buffer layers is increased in comparison without buffers. The structure using titanium as injection layer is less sensitive in injection efficiency to the film thickness than that using TiO2. Titanium based buffers are also very effective as an electron injection layer for poly((9,9-dihexyl-9H-fluorene-2,7-vinylene)-co-(1-methoxy-4-(2-ethylhexy loxy)-2,5-phenylenevinylene)) (PVF) based PLED. The effect of the buffer layers on the electron injection enhancement is evaluated by current-voltage and brightness-voltage characteristics measurements. Turn-on voltage decrease with similar to 2 V after cathode buffer insertion and the structure conductivity increase to 120 mu A/cm(2). The maximum brightness become twice higher and reaches 120 cd/m(2) at injection efficiency 1.3 cd/A. (C) 2011 Elsevier Ltd. All rights reserved.