Rights statement: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © 2017 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.7b03736
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Research output: Contribution to Journal/Magazine › Letter › peer-review
Research output: Contribution to Journal/Magazine › Letter › peer-review
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TY - JOUR
T1 - Field-Effect Control of Graphene–Fullerene Thermoelectric Nanodevices
AU - Gehring, Pascal
AU - Harzheim, Achim
AU - Spiece, Jean
AU - Sheng, Yuewen
AU - Rogers, Gregory
AU - Evangeli, Charalambos
AU - Mishra, Aadarsh
AU - Robinson, Benjamin James
AU - Porfyrakis, Kyriakos
AU - Warner, Jamie H.
AU - Kolosov, Oleg Victor
AU - Briggs, Andrew
AU - Mol, Jan A.
N1 - This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © 2017 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.7b03736
PY - 2017/11/8
Y1 - 2017/11/8
N2 - Although it was demonstrated that discrete molecular levels determine the sign and magnitude of the thermoelectric effect in single-molecule junctions, full electrostatic control of these levels has not been achieved to date. Here, we show that graphene nanogaps combined with gold microheaters serve as a testbed for studying single-molecule thermoelectricity. Reduced screening of the gate electric field compared to conventional metal electrodes allows control of the position of the dominant transport orbital by hundreds of meV. We find that the power factor of graphene–fullerene junctions can be tuned over several orders of magnitude to a value close to the theoretical limit of an isolated Breit–Wigner resonance. Furthermore, our data suggest that the power factor of an isolated level is only given by the tunnel coupling to the leads and temperature. These results open up new avenues for exploring thermoelectricity and charge transport in individual molecules and highlight the importance of level alignment and coupling to the electrodes for optimum energy conversion in organic thermoelectric materials.
AB - Although it was demonstrated that discrete molecular levels determine the sign and magnitude of the thermoelectric effect in single-molecule junctions, full electrostatic control of these levels has not been achieved to date. Here, we show that graphene nanogaps combined with gold microheaters serve as a testbed for studying single-molecule thermoelectricity. Reduced screening of the gate electric field compared to conventional metal electrodes allows control of the position of the dominant transport orbital by hundreds of meV. We find that the power factor of graphene–fullerene junctions can be tuned over several orders of magnitude to a value close to the theoretical limit of an isolated Breit–Wigner resonance. Furthermore, our data suggest that the power factor of an isolated level is only given by the tunnel coupling to the leads and temperature. These results open up new avenues for exploring thermoelectricity and charge transport in individual molecules and highlight the importance of level alignment and coupling to the electrodes for optimum energy conversion in organic thermoelectric materials.
KW - electroburning
KW - graphene
KW - molecular conductance
KW - molecular thermopower
KW - single molecule
KW - thermoelectrics
U2 - 10.1021/acs.nanolett.7b03736
DO - 10.1021/acs.nanolett.7b03736
M3 - Letter
VL - 17
SP - 7055
EP - 7061
JO - Nano Letters
JF - Nano Letters
SN - 1530-6984
IS - 11
ER -