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  4. Unusually Long-Lived Photocharges in Helical Organic Semiconductor Nanostructures
 
research article

Unusually Long-Lived Photocharges in Helical Organic Semiconductor Nanostructures

Hafner, Regina J.  
•
Tian, Liangfei  
•
Brauer, Jan C.  
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September 1, 2018
Acs Nano

Photocharge generation and formation of long-lived charge carriers are relevant in photosynthesis, photocatalysis, photovoltaics, and organic electronics. A better understanding of the factors that determine these processes in synthetic polymer semiconductors is crucial, but difficult due to their morphological inhomogeneity. Here, we report the formation of exceptionally long-lived photocharges in one-dimensional organic semiconductor nanostructures. These nanostructures consist of chiral oligopeptide-substituted thienothiophene-based chromophores and exhibit a well-defined helical arrangement of these chromophores at their core. The chromophores give rise to spectroscopic H-aggregates and show strong intermolecular excitonic coupling. We demonstrate that all of these parameters are the prerequisites required for the nanostructures to show the efficient formation of polaron-like photocharges upon irradiation with a low-power white light source. The observed charge carriers in the helical nanowires show an unusually long lifetime on the order of several hours and are formed at high concentrations of up to 3 mol % in the absence of any dedicated electron acceptor. They are observed in solution as well as in film and furthermore give rise to a light-induced increase of the macroscopic charge transport. By contrast, no such photocharge generation is observed either in non-aggregating reference systems of the same chromophores or in aggregated but non-helical systems that do not form one-dimensional nanostructures. Our results thus demonstrate a clear correlation between nanoscopic confinement and the generation of long-lived photocharges.

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Type
research article
DOI
10.1021/acsnano.8b03165
Web of Science ID

WOS:000445972400030

Author(s)
Hafner, Regina J.  
Tian, Liangfei  
Brauer, Jan C.  
Schmaltz, Thomas  
Sienkiewicz, Andrzej  
Balog, Sandor
Flauraud, Valentin  
Brugger, Juergen  
Frauenrath, Holger  
Date Issued

2018-09-01

Publisher

AMER CHEMICAL SOC

Published in
Acs Nano
Volume

12

Issue

9

Start page

9116

End page

9125

Subjects

Chemistry, Multidisciplinary

•

Chemistry, Physical

•

Nanoscience & Nanotechnology

•

Materials Science, Multidisciplinary

•

Chemistry

•

Science & Technology - Other Topics

•

Materials Science

•

organic semiconductor nanostructures

•

thiophene-based semiconductors

•

organic nanowires

•

helical nanostructures

•

photocharges

•

long-lived charge carriers

•

polarons

•

electron-spin-resonance

•

conjugated polymers

•

charge separation

•

perylene bisimide

•

supramolecular polymers

•

solar fuels

•

light

•

states

•

nanofibers

•

transport

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

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Available on Infoscience
December 13, 2018
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/152057
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