Volume 26, Issue 43 p. 9506-9517
Full Paper

Long-Lived Photocharges in Supramolecular Polymers of Low-Band-Gap Chromophores

Dr. Regina J. Hafner

Dr. Regina J. Hafner

Institute of Materials, Ecole Polytechnique Fédérale de Lausanne (EPFL), EPFL-STI-IMX-LMOM, MXG 037, Station 12, 1015 Lausanne, Switzerland

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Dr. Daniel Görl

Dr. Daniel Görl

Institute of Materials, Ecole Polytechnique Fédérale de Lausanne (EPFL), EPFL-STI-IMX-LMOM, MXG 037, Station 12, 1015 Lausanne, Switzerland

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Dr. Andrzej Sienkiewicz

Dr. Andrzej Sienkiewicz

Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), EPFL-SB-IPHYS-LPMC, PH L 1 491, Station 3, 1015 Lausanne, Switzerland

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Dr. Sandor Balog

Dr. Sandor Balog

Adolphe Merkle Institute, Université de Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland

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Prof. Holger Frauenrath

Corresponding Author

Prof. Holger Frauenrath

Institute of Materials, Ecole Polytechnique Fédérale de Lausanne (EPFL), EPFL-STI-IMX-LMOM, MXG 037, Station 12, 1015 Lausanne, Switzerland

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First published: 09 March 2020
Citations: 8

Graphical Abstract

1D matters! Low-band-gap chromophores that self-assemble into one-dimensional helical nanowires show light-induced formation of polarons with unusual lifetimes exceeding hours. The accumulation of these charge carriers at concentrations close to that of the metal–insulator transition is reflected by profound macroscopic charge-transport properties and photoconductivity in these confined organic semiconductor systems.

Abstract

Photoinduced charge separation in supramolecular aggregates of π-conjugated molecules is a fundamental photophysical process and a key criterion for the development of advanced organic electronics materials. Herein, the self-assembly of low-band-gap chromophores into helical one-dimensional aggregates, due to intermolecular hydrogen bonding, is reported. Chromophores confined in these supramolecular polymers show strong excitonic coupling interactions and give rise to charge-separated states with unusually long lifetimes of several hours and charge densities of up to 5 mol % after illumination with white light. Two-contact devices exhibit increased photoconductivity and can even show Ohmic behavior. These findings demonstrate that the confinement of organic semiconductors into one-dimensional aggregates results in a considerable stabilization of charge carriers for a variety of π-conjugated systems, which may have implications for the design of future organic electronic materials.

Conflict of interest

The authors declare no conflict of interest.