[en] Controlling carrier transport in light-emitting polymers is extremely important for their efficient use in organic opto-electronic devices. Here, we show that the interactions between single-wall carbon nanotubes (SWNTs) and conjugated polymers can be used to modify the overall mobility of charge carriers within nanotube- polymer nanocomposites. By using unique, double-emitting organic light-emitting diodes (DE-OLEDs), we characterized the hole transport within electroluminescent nanocomposites (nanotubes in poly (m-phenylene vinylene-co-2,5-dioctoxy-p-phenylene) or PmPV). We showed, using this idea, that single devices with color tunability can be fabricated. SWNTs in PmPV are seen to be responsible for hole trapping, leading to shifts in the emission wavelengths. Our results could lead to improved organic optical amplifiers, semiconducting devices, and displays.