In this paper we focus on a new type of bis(1

3

4-oxadiazole)system and electron transportingmaterial-2

5-bis[2-(4-tert-buty/pheny/-1

3

4-oxadiazole-5-y1)]pyridine(PDPyDP).We have fabricated organic light-emitting diodes(OLED)using poly[2-methoxy-5-(2-ethy/hexoxy-1

4-pheny/ene)]

(MEH-PPV)

ITO and aluminium as the light emitting layer

anode and cathode;with and without a thermallyevaporated electron transport layer of either PDPyDP or its vinylene analog 1

2-bis[2-(4-tert-buty/pheny)-1

3

4 oxadiazole-y1]benzene(PDPDP).PDPDP is the pare isomer of OXD-7

which is a widely used electron transporting material.Electroluminescence spectra for all devices indicate that light originates only from the MEH-PPV layer.The three bilayer structure devices possess almost identical current versus electric field data

suggesting a similar electrical transport process in each device.The lowest value of the turn-on electric field for EL has been observed for the OLED incorporating PDPyDP.At a current density of 50mA/cm

2

the values of external quantum efficiency were 3×10

-3

% for the MEH-PPV single layer device

5×10

-3

% for the bilayer device using PDVDP

2×10

-2

% for the PDPDP-containing structure and 0.1% for the OLED incorporating PDPyDP.The reason of the above different EQE was analysed.It is worth noting that further improvement in the efficiency figures is possible by optimizing the device structure and material for the OLED incorporating PDPyDP.The calibrated quantum efficiency for ITO/PEDOT/MEH-PPV:Rubrene/Al device is 1.44%.