Electrodeless method for ultra-low mobility with carrier-resolution of nanochannel

As the channel lengths of electronic devices are scaled down to the nanometer range, the conventional methods to evaluate charge-carrier mobility approach a technical limit that is imposed by interfering effects of the electrode and forcing field. In this study, we demonstrate that electron spectroscopy provides additional (yet hidden) information on unipolar charge transport, which is free from conventional problems. We demonstrate that the estimated effective diffusion current through the target sample allows the measurement that is precise enough (10^-4 cm²/V s) to obtain the mobility of electrons µ_electron and holes µ_hole in nanolength organic channels. Using this method, we show how µ_electron and µ_hole are correlated with the local structural order of poly(3-hexylthiophene) at the nanoscale. This method enables in situ charge-resolved observations of µelectron and µhole by eliminating the need for electrode and forcing field and will help to expand our understanding of charge conduction in nanoscale materials.