Quantum-Interference-Enhanced Thermoelectricity (QUIET).
Lead Research Organisation:
Lancaster University
Department Name: Physics
Abstract
Quantum interference is a mechanism which can be used to manipulate the electrical properties of a single molecule by exploiting the property that an electron can be considered to be a wave as well as a particle. It turns out that constructive or destructive interference of electrons within individual organic molecules can be engineered precisely by the addition of various atomic groups to the molecule or by carefully selecting the connection of the molecule to external electrodes. Although the dream of manipulating quantum interference in single molecules has been discussed for many years, experimental evidence of room-temperature interference effects in single-molecule junctions was reported only recently. Building on these demonstrations of quantum interference, QuIET aims to deliver the next breakthrough by designing and realising technologically-relevant materials and devices, which exploit quantum interference at room-temperature and above.
Waste heat from information technologies currently results carbon emissions which are comparable to those of the total global aviation industry. QuIET aims to address this global challenge by inventing new materials, which efficiently convert this waste heat into useful electricity. Our target materials are thin films formed from single layers or a few layers of molecules, sandwiched between planar electrodes. Quantum interference will be used to optimise their ability to convert waste heat into electricity and for on-chip cooling. This will be achieved by designing, synthesising and measuring molecules with a high Seebeck coefficient, which determines the voltage generated when a temperature difference is applied to the two sides of a molecule or a thin film. Conversely, if a voltage is applied across a molecule, the closely-related Peltier coefficient determines the magnitude of the cooling effect that can be created.
It turns out that the Seebeck coefficient is proportional to the number of electrons within the molecule and also how the density of electronic states is distributed with energy. Both of these can be manipulated in certain families of organic molecules using quantum interference. A third property important for heat recovery (the first two being the electrical conductance and the Seebeck coefficient) is the thermal conductance, which needs to be low. Within a bulk material it is difficult to engineer simultaneously high electrical conductance and low thermal conductance. However for single molecules or thin molecular films attached to electrodes, the thermal conductance can be engineered by selecting slippery anchor groups, for binding the molecules to the electrodes and by introducing soft internal mechanical degrees of freedom, which further reduce phonon transport.
The technical challenges that this proposal addresses are four-fold. The first is to identify theoretically families of molecules that will have the propensity for large quantum interference effects, and to predict which atomic groups and which anchor groups will optimise their properties. The second is to synthesise these molecules and the third is to measure their properties at the single molecular level to feed back to the theoretic models. The fourth and final challenge is to investigate whether these superior properties persist when the molecules are turned into a vast parallel array of molecules, known as a self-assembled molecular layer. Understanding the hurdles that need to be overcome to realise quantum interference effects at room temperature in macroscopic thin-film arrays of molecules, will help identify the first steps to a new type of technology that has important societal and economic impacts in the real world and addresses pressing problems with on-chip cooling and energy-efficient heat recovery.
Waste heat from information technologies currently results carbon emissions which are comparable to those of the total global aviation industry. QuIET aims to address this global challenge by inventing new materials, which efficiently convert this waste heat into useful electricity. Our target materials are thin films formed from single layers or a few layers of molecules, sandwiched between planar electrodes. Quantum interference will be used to optimise their ability to convert waste heat into electricity and for on-chip cooling. This will be achieved by designing, synthesising and measuring molecules with a high Seebeck coefficient, which determines the voltage generated when a temperature difference is applied to the two sides of a molecule or a thin film. Conversely, if a voltage is applied across a molecule, the closely-related Peltier coefficient determines the magnitude of the cooling effect that can be created.
It turns out that the Seebeck coefficient is proportional to the number of electrons within the molecule and also how the density of electronic states is distributed with energy. Both of these can be manipulated in certain families of organic molecules using quantum interference. A third property important for heat recovery (the first two being the electrical conductance and the Seebeck coefficient) is the thermal conductance, which needs to be low. Within a bulk material it is difficult to engineer simultaneously high electrical conductance and low thermal conductance. However for single molecules or thin molecular films attached to electrodes, the thermal conductance can be engineered by selecting slippery anchor groups, for binding the molecules to the electrodes and by introducing soft internal mechanical degrees of freedom, which further reduce phonon transport.
The technical challenges that this proposal addresses are four-fold. The first is to identify theoretically families of molecules that will have the propensity for large quantum interference effects, and to predict which atomic groups and which anchor groups will optimise their properties. The second is to synthesise these molecules and the third is to measure their properties at the single molecular level to feed back to the theoretic models. The fourth and final challenge is to investigate whether these superior properties persist when the molecules are turned into a vast parallel array of molecules, known as a self-assembled molecular layer. Understanding the hurdles that need to be overcome to realise quantum interference effects at room temperature in macroscopic thin-film arrays of molecules, will help identify the first steps to a new type of technology that has important societal and economic impacts in the real world and addresses pressing problems with on-chip cooling and energy-efficient heat recovery.
Planned Impact
Recent experimental demonstrations of quantum interference (QI) in single-molecule devices at room temperature have opened up the possibility that QI could be exploited to design new molecular materials with the ability to convert waste heat into electricity with unprecedented efficiency. To realise this potential in the laboratory, this project aims to demonstrate that room-temperature QI-enhanced thermoelectricity, high electrical conductance and low thermal conductance in single molecules can be transferred without significant degradation in parallel arrays of self-assembled molecular layers (SAMs), thereby setting the groundwork for high-performance thermoelectric thin film devices. The planned work in this program is fundamental in nature, because although all molecules of a given kind are identical, their atomic-scale environments are all different and therefore the effect of intermolecular interactions, defects in the electrodes and imperfections in molecular arrays needs to be built into any design strategy for molecular-scale thermoelectric films. In addition, the control of QI in parallel arrays of molecules sandwiched between parallel planar electrodes has yet to be established, the molecules needed to achieve this control have to be synthesised and the principles needed to achieve the delicate balance between high electrical conductance and low thermal conductance, combined with a high Seebeck coefficient in molecular thin films have to be demonstrated.
Once established, the design rules we identify will enable future economic and societal impacts, which would be realisable in the next 5-10 years in areas such as on-chip cooling and waste heat recovery, particularly from data farms and the environment for powering the internet of things. These long-term impacts will require further multi-disciplinary translational research beyond the scope of the project, which takes the molecular films and devices from our laboratory demonstrations to real-world application. IBM, NPL and Sigma Aldrich will provide advice on maximising the impact of our outputs, and we plan to engage with other industries through 'Energy Lancaster', Imperial's 'Energy Futures Lab' and the Knowledge Transfer Partnership on Thermoelectricity (TEMPEST).
In the nearer term, we plan to develop a set of experimental and theoretical methodologies that will have a more immediate impact in academic and industrial research laboratories. In particular, we will fill a UK capability gap, since there are no UK groups currently measuring thermopower in molecular-scale thin films. Such thermopower measurements, as well as providing insight into the thermoelectric properties of molecular materials, are particularly instructive for probing the mechanism of charge transport. The underpinning QI effects have not been experimentally applied to SAMs and our project will deliver the first experimental measurements of thermopower in such systems. In addition, we will develop and disseminate theoretical methods beyond the present state-of-the-art for modelling the thermoelectric and electrical properties of complex molecular junctions and their environments.
The project will also have direct impact on our early career researchers, as their research training and experience in chemical synthesis, theory and molecular-scale measurements will allow them to contribute to future developments in molecular and organic electronics, molecular thermoelectrics and molecular sensors and to the commercial exploitation of the new disruptive technologies emerging from the science.
Workshops held in months 18 and 36 will contribute to the dissemination of our outputs to end users in academia and industry.
Once established, the design rules we identify will enable future economic and societal impacts, which would be realisable in the next 5-10 years in areas such as on-chip cooling and waste heat recovery, particularly from data farms and the environment for powering the internet of things. These long-term impacts will require further multi-disciplinary translational research beyond the scope of the project, which takes the molecular films and devices from our laboratory demonstrations to real-world application. IBM, NPL and Sigma Aldrich will provide advice on maximising the impact of our outputs, and we plan to engage with other industries through 'Energy Lancaster', Imperial's 'Energy Futures Lab' and the Knowledge Transfer Partnership on Thermoelectricity (TEMPEST).
In the nearer term, we plan to develop a set of experimental and theoretical methodologies that will have a more immediate impact in academic and industrial research laboratories. In particular, we will fill a UK capability gap, since there are no UK groups currently measuring thermopower in molecular-scale thin films. Such thermopower measurements, as well as providing insight into the thermoelectric properties of molecular materials, are particularly instructive for probing the mechanism of charge transport. The underpinning QI effects have not been experimentally applied to SAMs and our project will deliver the first experimental measurements of thermopower in such systems. In addition, we will develop and disseminate theoretical methods beyond the present state-of-the-art for modelling the thermoelectric and electrical properties of complex molecular junctions and their environments.
The project will also have direct impact on our early career researchers, as their research training and experience in chemical synthesis, theory and molecular-scale measurements will allow them to contribute to future developments in molecular and organic electronics, molecular thermoelectrics and molecular sensors and to the commercial exploitation of the new disruptive technologies emerging from the science.
Workshops held in months 18 and 36 will contribute to the dissemination of our outputs to end users in academia and industry.
People |
ORCID iD |
| Colin Lambert (Principal Investigator) |
Publications
Liu SX
(2023)
Signatures of Room-Temperature Quantum Interference in Molecular Junctions.
in Accounts of chemical research
El Abbassi M
(2020)
Controlled Quantum Dot Formation in Atomically Engineered Graphene Nanoribbon Field-Effect Transistors.
in ACS nano
Almughathawi R
(2021)
Conformation and Quantum-Interference-Enhanced Thermoelectric Properties of Diphenyl Diketopyrrolopyrrole Derivatives.
in ACS sensors
Planje IJ
(2021)
Selective Anchoring Groups for Molecular Electronic Junctions with ITO Electrodes.
in ACS sensors
Chen Z
(2022)
Modulating Quantum Interference Between Destructive and Constructive States in Double N-Substituted Single Molecule Junctions
in Advanced Electronic Materials
Evangeli C
(2019)
Nanoscale Thermal Transport in 2D Nanostructures from Cryogenic to Room Temperature
in Advanced Electronic Materials
Famili M
(2017)
Toward High Thermoelectric Performance of Thiophene and Ethylenedioxythiophene (EDOT) Molecular Wires
in Advanced Functional Materials
Ferri N
(2019)
Hemilabile Ligands as Mechanosensitive Electrode Contacts for Molecular Electronics
in Angewandte Chemie
O'Driscoll LJ
(2020)
Carbazole-Based Tetrapodal Anchor Groups for Gold Surfaces: Synthesis and Conductance Properties.
in Angewandte Chemie (International ed. in English)
Li X
(2020)
Structure-Independent Conductance of Thiophene-Based Single-Stacking Junctions.
in Angewandte Chemie (International ed. in English)
Alqahtani J
(2018)
Breakdown of Curly Arrow Rules in Anthraquinone.
in Angewandte Chemie (International ed. in English)
Jiang F
(2019)
Turning the Tap: Conformational Control of Quantum Interference to Modulate Single-Molecule Conductance.
in Angewandte Chemie (International ed. in English)
Ferri N
(2019)
Hemilabile Ligands as Mechanosensitive Electrode Contacts for Molecular Electronics.
in Angewandte Chemie (International ed. in English)
Famili M
(2019)
Self-Assembled Molecular-Electronic Films Controlled by Room Temperature Quantum Interference
in Chem
Jia C
(2020)
Redox Control of Charge Transport in Vertical Ferrocene Molecular Tunnel Junctions
in Chem
Ge L
(2022)
Hydrogen-bond-induced quantum interference in single-molecule junctions of regioisomers.
in Chemical science
Wang X
(2021)
Optimised power harvesting by controlling the pressure applied to molecular junctions.
in Chemical science
Ismael A
(2020)
Tuning the thermoelectrical properties of anthracene-based self-assembled monolayers.
in Chemical science
Bennett TLR
(2022)
Multi-component self-assembled molecular-electronic films: towards new high-performance thermoelectric systems.
in Chemical science
Wilkinson LA
(2022)
Assembly, structure and thermoelectric properties of 1,1'-dialkynylferrocene 'hinges'.
in Chemical science
Yang G
(2017)
Protonation tuning of quantum interference in azulene-type single-molecule junctions.
in Chemical science
Bock S
(2017)
Single-Molecule Conductance Studies of Organometallic Complexes Bearing 3-Thienyl Contacting Groups.
in Chemistry (Weinheim an der Bergstrasse, Germany)
Baghernejad M
(2020)
Constructive Quantum Interference in Single-Molecule Benzodichalcogenophene Junctions
in Chemistry - A European Journal
Jiang W
(2021)
Single-Molecule Charge-Transport Modulation Induced by Steric Effects of Side Alkyl Chains.
in Chemphyschem : a European journal of chemical physics and physical chemistry
Famili M
(2017)
Suppression of Phonon Transport in Molecular Christmas Trees.
in Chemphyschem : a European journal of chemical physics and physical chemistry
Ismael A
(2019)
Single-molecule conductance oscillations in alkane rings
in Journal of Materials Chemistry C
Wang X
(2020)
Scale-Up of Room-Temperature Constructive Quantum Interference from Single Molecules to Self-Assembled Molecular-Electronic Films.
in Journal of the American Chemical Society
Zhang C
(2023)
Enhanced p-p Stacking between Dipole-Bearing Single Molecules Revealed by Conductance Measurement.
in Journal of the American Chemical Society
Li P
(2022)
Quantum Interference-Controlled Conductance Enhancement in Stacked Graphene-like Dimers.
in Journal of the American Chemical Society
Algethami N
(2018)
The Conductance of Porphyrin-Based Molecular Nanowires Increases with Length.
in Nano letters
Mosso N
(2019)
Thermal Transport through Single-Molecule Junctions.
in Nano letters
Plaszkó NL
(2020)
Quantum Interference and Nonequilibrium Josephson Currents in Molecular Andreev Interferometers.
in Nanomaterials (Basel, Switzerland)
Chen H
(2020)
Exploring the thermoelectric properties of oligo(phenylene-ethynylene) derivatives.
in Nanoscale
Wu C
(2020)
In situ formation of H-bonding imidazole chains in break-junction experiments.
in Nanoscale
Wu Q
(2018)
MoS2 nano flakes with self-adaptive contacts for efficient thermoelectric energy harvesting.
in Nanoscale
Gantenbein M
(2019)
Exploring antiaromaticity in single-molecule junctions formed from biphenylene derivatives.
in Nanoscale
Wu Q
(2018)
A single-molecule porphyrin-based switch for graphene nano-gaps.
in Nanoscale
Hou S
(2019)
Thermoelectric properties of oligoglycine molecular wires.
in Nanoscale
Li B
(2018)
Cross-plane conductance through a graphene/molecular monolayer/Au sandwich.
in Nanoscale
Audi H
(2020)
Electrical molecular switch addressed by chemical stimuli.
in Nanoscale
Ismael A
(2020)
Molecular-scale thermoelectricity: as simple as 'ABC'.
in Nanoscale advances
O'Driscoll LJ
(2023)
Planar aromatic anchors control the electrical conductance of gold|molecule|graphene junctions.
in Nanoscale advances
Alshammari M
(2022)
Orientational control of molecular scale thermoelectricity.
in Nanoscale advances
Wang X
(2022)
Electrostatic Fermi level tuning in large-scale self-assembled monolayers of oligo(phenylene-ethynylene) derivatives.
in Nanoscale horizons
Ismael AK
(2020)
Molecular-scale thermoelectricity: a worst-case scenario.
in Nanoscale horizons
Ismael AK
(2022)
Exploring seebeck-coefficient fluctuations in endohedral-fullerene, single-molecule junctions.
in Nanoscale horizons
Tang JH
(2019)
Single-molecule level control of host-guest interactions in metallocycle-C60 complexes.
in Nature communications