Blending MEH-PPV conjugate polymers with single-walled carbon nanotubes for polymer light-emitting diodes

We report the effects of blending poly[2-methoxy-5-(2′-ethyl- hexyloxy)-p-phenylene-vinylene] (MEH-PPV) conjugate polymers with single-walled carbon nanotubes (SWNTs). The blend ratio of MEH-PPV/SWNT composites for polymer light-emitting diodes (PLEDs) ranged from 0 wt% to 1 wt% SWNTs. From time-of-flight (TOF) measurements, the electron mobility was observed to increase gradually with the weight percent of SWNTs while the hole mobility remained almost unchanged. According to the Poole-Frenkel model, an increase in the weight percent of SWNTs lowers the zero-field activation energy, suggesting that SWNTs effectively reduce the oxygen trap density. At a 0.2-wt% SWNTs concentration, the electron and the hole mobilities could be tuned for the highest external quantum efficiency.