In this report we discuss the great potential of Eutectic Gallium Indium (EGaIn) as conformal soft top electrode. EGaIn is a liquid eutectic supporting a skin (∼ 1 nm-thick) of self-limiting oxide Ga2O3 as a non-damaging,
conformal top-contact. In the last half of decade EGaIn has been used by several group to form molecular junctions and study charge transport properties in self-assembled monolayer (SAMs). We compared the current density (J) versus applied bias (V) for three different self-assembled monolayers (SAMs) of ethynylthiophenol- functionalized anthracene derivatives with approximately the same thickness and diverse conjugation: linear- conjugation (AC), cross-conjugation (AQ), and broken-conjugation (AH) by using liquid eutectic Ga-In (EGaIn). This skin imparts non-Newtonian rheological properties that distinguish EGaIn from other top-contacts, however it may also have limited the maximum values of J observed for AC. We measure values of J for AH and AQ which
are not significantly different (J ≈ 10-1 A/cm2 at V = 0.4 V). For AC, however, J is one (using log-averages) or two (using Gaussian mean) orders of magnitude higher than both AH and AQ. Our results are also in good qualitative agreement with gDFTB calculations on single AC, AQ, and AH molecules transport calculation, based on chemisorbed between Au contacts which predict currents, I, that are two orders of magnitude higher
for AC than AH at 0 < |V| < 0.4 V. We ascribe these observations to quantum-interference effects. The
agreement between the theoretical predictions on single-molecules and the measurements on SAMs suggest that
molecule-molecule interactions do not play a significant role in the transport properties of AC, AQ, and AH.