Mario Caironi "Mapping charge transport in high-mobility polymer field-effect transistors via polarised charge modulation microscopy"

Structure-property relationships are of fundamental importance in order to develop quantitative models to describe charge transport in organic semiconductors based electronic devices which are among the best candidates for future flexible and cost-effective electronic applications. Here we make use of polarized charge modulation micro-spectroscopy (p-CMM) to unveil sub-micrometer textures [1] in the map of charge induced features [2] within the accumulation layer of high-mobility polymer field-effect transistors. In combination with density functional theory (DFT) and time-dependent DFT calculations, we demonstrate that the polarization dependent differential transmission signals can be unambiguously associated to the local preferential alignment of the polymer backbones. With respect to polarised optical density measurements, which provide average information on the bulk property of a polymer thin film, p-CMM allows to selectively map only those domains probed by mobile charges in the transistor accumulation layer, revealing preferential transport pathways.

[1] C. Sciascia et al., Adv. Mater. 23, 5086, 2011

[2] M. Caironi et al., Adv. Funct. Mater. 21, 3371, 2011