Organic light-emitting diodes based on a blend of poly[2-(2-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] and an electron transporting material

Organic light-emitting devices (OLEDs) containing a blend of poly[2-(2-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEH-PPV) and an electron transporting material, 2,7-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]-9,9-dihexylfluorene have been fabricated. The external quantum efficiencies of the OLEDs containing the electron transport compound were increased significantly over those obtained for devices based only on MEH-PPV. For example, the efficiency for a device incorporating 95% of electron transport compound was two orders of magnitude greater than that for a nonblended device. In all of our investigations, the electroluminescence (orange/yellow emission) originated exclusively from the MEH-PPV material, even for very high concentrations (>90%) of the electron transport component.