Impact of interfacial dipole on carrier transport in bulk heterojunction poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester blends

The electron transport properties in various poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl C-61-butyric acid methyl ester (PC61BM) blend films, prepared by various process conditions, were investigated by admittance spectroscopy at different temperatures. It was found that the electron mobility and the dispersive transport behavior showed a strong dependence on the thermal treatment condition; the blend with the fastest growth rate had orders of magnitude reduction in the mobility and a much more dispersive transport. Using the Gaussian disorder model, it was found that the energetic disorder of the density-of-states between blends plays a significant role in the observed phenomena. It is proposed that the difference in the energetic disorder is due to the interfacial dipole effect at the P3HT/PC61BM heterojunctions in the various blend films. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3499368]