It must be noted that these results were obtained at a very low doping regime, well below the Arhkhipov trap-overlap limit (∼ 0.1 to 10%). At high doping levels, polaron localization lengths exceed the distance between ionic traps, and doping efficiency approaches 100%. However, in many polymers, such as P3HT, increased ionic loading gives a corresponding increase in microstructural disorder, which reduces the mobility even as carrier density increases. Optimum doping levels for thermoelectric applications are likely near the border between these regimes, and appear to depend sensitively on inhomogeneities in doping level between microstructral domains. Thus, an in-depth understanding of physical factors that control the nature and strength of interactions amongst ions in ion-pairs should pave the way towards efficient doping mechanisms.