Bias-driven conductance increase with length in porphyrin tapes

Leary, Edmund and Limburg, Bart and Alanazy, Asma and Sangtarash, Sara and Grace, Iain and Swada, Katsutoshi and Esdaile, Louisa J. and Noori, Mohammed and González, M. Teresa and Rubio-bollinger, Gabino and Sadeghi, Hatef and Hodgson, Andrew and Agraït, Nícolas and Higgins, Simon J. and Lambert, Colin J. and Anderson, Harry L. and Nichols, Richard J. (2018) Bias-driven conductance increase with length in porphyrin tapes. Journal of the American Chemical Society. ISSN 0002-7863

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Abstract

A key goal in molecular electronics has been to find molecules that facilitate efficient charge transport over long distances. Normally molecular wires become less conductive with increasing length. Here we report a series of fused porphyrin oligomers for which the conductance increases substantially with length by > 10-fold at a bias of 0.7 V. This exceptional behavior can be attributed to the rapid decrease of the HOMO-LUMO gap with the length of fused porphyrins. In contrast, for butadiyne-linked porphyrin oligomers with moderate inter-ring coupling, a normal conductance decrease with length is found for all bias voltages explored (± 1 V), although the attenuation factor (β) decreases from ca. 2 nm-1 at low bias to < 1 nm-1 at 0.9 V, highlighting that β is not an intrinsic molecular property. Further theoretical analysis using density functional theory underlines the role of inter-site coupling and indicates that this large increase in conductance with length at increasing voltages can be generalized to other molecular oligomers.

Item Type:
Journal Article
Journal or Publication Title:
Journal of the American Chemical Society
Additional Information:
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/jacs.8b06338
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1500/1503
Subjects:
ID Code:
127696
Deposited By:
Deposited On:
27 Sep 2018 10:18
Refereed?:
Yes
Published?:
Published
Last Modified:
27 Sep 2020 04:47