Fig. 3

a A schematic energy diagram of poly-3-hexylthiophene (P3HT)/carbon nanotube (CNT) films, I-V characteristics of b electron-only and c hole-only devices. The slope of the I–V curve in logarithmic scale is shown in the two insets of (b) and (c). Reprinted with permission from Lee et al. [46], © 2011, Wiley