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

TL;DR

This study investigates the electronic and thermoelectric properties of iron and ruthenium molecular junctions, revealing high Seebeck coefficients and ZT values, with implications for thermoelectric energy conversion at the molecular scale.

Contribution

It provides a comparative analysis of Fe and Ru molecular junctions, highlighting high thermoelectric performance of Fe-based systems through experimental and quantum chemical methods.

Findings

Fe junctions exhibit high Seebeck coefficient (~130 μV/K).

Fe junctions achieve ZT up to 0.4 at room temperature.

Distinct oxidation states are observed in Fe junctions.

Abstract

The electronic and thermoelectric properties of molecular junctions formed from iron and ruthenium metal-acetylide were studied 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 ca. 130 {\mu}V/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 relatively high conductance. This is one of the highest ZT values reported for molecular systems at room temperature.