Electronic and Thermoelectric Properties of Molecular Junctions Incorporating Organometallic Complexes: Implications for Thermoelectric Energy Conversion

The electronic and thermoelectric properties of molecular junctions formed from iron and ruthenium metal acetylide were studied by using complementary experimental techniques and quantum chemical simulations. We performed physical characterizations of single-molecule and self-assembled monolayer junctions of the same molecules that allowed meaningful comparisons between the Ru and Fe adducts. In the case of the Fe-containing junctions, two distinct oxidation states are present. These junctions exhibit one of the highest Seebeck coefficients ( S ∼ 130 μV/K) reported to date for similar systems paired with broad electric conductance distribution and limited thermal conductance. As a result, the experimental thermoelectric figure of merit ZT for Fe-containing junctions reaches up to 0.4 for junctions with a relatively high conductance. This is one of the highest ZT values reported for molecular systems at room temperature.