Concurrent Enhancement of Thermopower and Conductivity via Modulation of Diacetylide-Electrode Coupling in Molecular Junctions

The
study of molecular thermoelectricity offers fundamental insights
into charge transport via tunneling through organic and organometallic
systems, with implications for nanoscale energy conversion technologies.
Here, we investigate how molecule–electrode coupling strength
influences thermoelectric performance in molecular junctions incorporating
self-assembled monolayers of π-extended Ru(dppe)2-diacetylide complex. Surface modification of gold electrode with
monatomic Pt and Pd layers via underpotential deposition enabled precise
tuning of the strength of molecule–electrode contact. This
tuning enhanced electronic interaction with the remotely positioned
Ru core, promoted cumulene-like π-delocalization along the molecular
backbone, reorganized frontier orbitals, and simultaneously enhanced
the Seebeck coefficient and electrical conductivity to amplify the
power factor by up to 111-fold compared to unmodified junctions. These
findings highlight the broader potential of diacetylide complex to
translate subtle orbital interactions into significant energy-conversion
functions.