title: Tuning the thermoelectric properties of metallo-porphyrins.
abstract: We investigated the thermoelectric properties of metalloporphyrins connected by thiol anchor groups to gold electrodes. By varying the transition metal-centre over the family Mn, Co, Ni, Cu, Fe, and Zn we are able to tune the molecular energy levels relative to the Fermi energy of the electrodes. The resulting single-molecule room-temperature thermopowers range from almost zero for Co and Cu centres, to +80 μV K(-1) and +230 μV K(-1) for Ni and Zn respectively. In contrast, the thermopowers with Mn(II) or Fe(II) metal centres are negative and lie in the range -280 to -260 μV K(-1). Complexing these with a counter anion to form Fe(III) and Mn(III) changes both the sign and magnitude of their thermopowers to +218 and +95 respectively. The room-temperature power factors of Mn(II), Mn(III), Fe(III), Zn and Fe(II) porphyrins are predicted to be 5.9 × 10(-5) W m(-1) K(-2), 5.4 × 10(-4) W m(-1) K(-2), 9.5 × 10(-4) W m(-1) K(-2), 1.6 × 10(-4) W m(-1) K(-2) and 2.3 × 10(-4) W m(-1) K(-2) respectively, which makes these attractive materials for molecular-scale thermoelectric devices.
authors.affiliation: Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK. c.lambert@lancaster.ac.uk qusiyalgaliby@gmail.com and Physics Department, Al-Qadisiyah University, Diwaniyah, 58002, Iraq.
authors.forename: Qusiy H
authors.initials: QH
authors.lastname: Al-Galiby
authors.affiliation: Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK. c.lambert@lancaster.ac.uk qusiyalgaliby@gmail.com.
authors.forename: Hatef
authors.initials: H
authors.lastname: Sadeghi
authors.affiliation: Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK. c.lambert@lancaster.ac.uk qusiyalgaliby@gmail.com and College of Basic Education, Sumer University, Al-Refayee, Thi-Qar 64001, Iraq.
authors.forename: Laith A
authors.initials: LA
authors.lastname: Algharagholy
authors.affiliation: Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK. c.lambert@lancaster.ac.uk qusiyalgaliby@gmail.com.
authors.forename: Iain
authors.initials: I
authors.lastname: Grace
authors.affiliation: Quantum Technology Centre, Lancaster University, Lancaster LA1 4YB, UK. c.lambert@lancaster.ac.uk qusiyalgaliby@gmail.com.
authors.forename: Colin
authors.initials: C
authors.lastname: Lambert