Polymer diodes with a blend of MEH-PPV and conjugated polyquinoline

A polymer blend containing MEH-PPV and a conjugated polyquinoline, poly(2,6-(4-phenylquinoline)), PQ, is obtained by first dissolving PQ in common organic solvents by complexation with a functionalized protonic acid and then mixing with a solution of poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene), MEH-PPV. Transmission electron microscopy (TEM) of blend films reveals an extremely homogeneous and fine fibrillar interconnected dispersion of the PQ-complex for blends containing ~1% PQ, suggesting that there is a large interfacial area between the MEH-PPV and PQ-complex regions. In devices with the simple structure ITO/polymer blend/Al, EL external quantum efficiency is significantly enhanced by the blending, reaching a value of 0.08% photons/electron for blend films with a nominal PQ content of about 1.5%. This is greater than that of ITO/MEH-PPV/A1 devices by a factor of more than 20.