The role of driving energy and delocalized states for charge separation in organic semiconductors
File(s)1310.1759v1.pdf (759.21 KB)
Accepted version
Author(s)
Type
Journal Article
Abstract
The electron-hole pair created via photon absorption in organic photoconversion systems must overcome the Coulomb attraction to achieve long-range charge separation. We show that this process is facilitated through the formation of excited, delocalized band states. In our experiments on organic photovoltaic cells, these states were accessed for a short time (<1 picosecond) via infrared (IR) optical excitation of electron-hole pairs bound at the heterojunction. Atomistic modeling showed that the IR photons promote bound charge pairs to delocalized band states, similar to those formed just after singlet exciton dissociation, which indicates that such states act as the gateway for charge separation. Our results suggest that charge separation in efficient organic photoconversion systems occurs through hot-state charge delocalization rather than energy-gradient–driven intermolecular hopping.
Date Issued
2012-03-16
Date Acceptance
2012-02-10
Citation
Science, 2012, 335 (6074), pp.1340-1344
ISSN
0036-8075
Publisher
American Association for the Advancement of Science
Start Page
1340
End Page
1344
Journal / Book Title
Science
Volume
335
Issue
6074
Copyright Statement
© 2012 American Association for the Advancement of Science. This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science 335(6074):1340-1344, 16 Mar 2012, DOI: https://doi.org/10.1126/science.1217745
Subjects
cond-mat.mes-hall
cond-mat.mtrl-sci
MD Multidisciplinary
General Science & Technology
Publication Status
Published
Date Publish Online
2012-02-23