title: High-performance thermoelectricity in edge-over-edge zinc-porphyrin molecular wires.
abstract: If high efficiency organic thermoelectric materials could be identified, then these would open the way to a range of energy harvesting technologies and Peltier coolers using flexible and transparent thin-film materials. We have compared the thermoelectric properties of three zinc porphyrin (ZnP) dimers and a ZnP monomer and found that the "edge-over-edge" dimer formed from stacked ZnP rings possesses a high electrical conductance, negligible phonon thermal conductance and a high Seebeck coefficient of the order of 300 μV K-1. These combine to yield a predicted room-temperature figure of merit of ZT ≈ 4, which is the highest room-temperature ZT ever reported for a single organic molecule. This high value of ZT is a consequence of the low phonon thermal conductance arising from the stacked nature of the porphyrin rings, which hinders phonon transport through the edge-over-edge molecule and enhances the Seebeck coefficient.
authors.affiliation: Quantum Technology Centre, Department of Physics, Lancaster University, Lancaster LA1 4YB, UK. h.sadeghi@lancaster.ac.uk c.lambert@lancaster.ac.uk and Department of Physics, College of Science, Thi-Qar University, Thi-Qar, Iraq.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Noori
authors.affiliation: Quantum Technology Centre, Department of Physics, Lancaster University, Lancaster LA1 4YB, UK. h.sadeghi@lancaster.ac.uk c.lambert@lancaster.ac.uk.
authors.forename: Hatef
authors.identifier: http://orcid.org/0000-0001-5398-8620
authors.initials: H
authors.lastname: Sadeghi
authors.affiliation: Quantum Technology Centre, Department of Physics, Lancaster University, Lancaster LA1 4YB, UK. h.sadeghi@lancaster.ac.uk c.lambert@lancaster.ac.uk.
authors.forename: Colin J
authors.identifier: http://orcid.org/0000-0003-2332-9610
authors.initials: CJ
authors.lastname: Lambert