A triazole containing co-polymer for use as an electron transport material in multilayer LEDs

We report investigations into a poly(1,20-(10,13-didecyl)distyrylbenzene-co-1,2-[p-ethylphenyl)]triazole) (TRIDSB) electron transport material and its incorporation into single and multilayer LEDs. Multilayer devices have been investigated with poly(p-phenylenevinylene) (PPV) and poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) as hole transport layers (HTLs). The incorporation of the polymer into an ITO/PPV/TRIDSB/Al LED facilitates electron injection into the hole transporting emissive layer and results in a ten fold increase in the external quantum efficiency for electroluminescence (EL) of the PPV layer from 0.008% to 0.08-0.1%. In an ITO/I-MEHPPV/TRIDSB/Al device the corresponding increase in the quantum efficiency for EL from the I-MEHPPV is fifty fold, from 0.002% to between 0.06-0.11%. The polymer has been shown to be thermally stable with no glass transition temperature or melting point detected within the range 25-250 degrees C.