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Ultrafast conductivity in a low-band-gap polyphenylene and fullerene blend studied by terahertz spectroscopy

Nemec, Hynek LU ; Nienhuys, Han-Kwang; Perzon, Erik; Zhang, Fengling; Inganas, Olle; Kuzel, Petr and Sundström, Villy LU (2009) In Physical Review B (Condensed Matter and Materials Physics) 79(24).
Abstract
Time-resolved terahertz spectroscopy and Monte Carlo simulations of charge-carrier motion are used to investigate photoinduced transient conductivity in a blend of a low-band-gap polyphenylene copolymer and fullerene derivative. The optical excitation pulse generates free holes delocalized on polymer chains. We show that these holes exhibit a very high initial mobility as their initial excess energy facilitates their transport over defects (potential barriers) on polymer chains. The conductivity then drops down rapidly within 1 ps, and we demonstrate that this decrease occurs essentially by two mechanisms. First, the carriers loose their excess energy and they thus become progressively localized between the on-chain potential barriers-this... (More)
Time-resolved terahertz spectroscopy and Monte Carlo simulations of charge-carrier motion are used to investigate photoinduced transient conductivity in a blend of a low-band-gap polyphenylene copolymer and fullerene derivative. The optical excitation pulse generates free holes delocalized on polymer chains. We show that these holes exhibit a very high initial mobility as their initial excess energy facilitates their transport over defects (potential barriers) on polymer chains. The conductivity then drops down rapidly within 1 ps, and we demonstrate that this decrease occurs essentially by two mechanisms. First, the carriers loose their excess energy and they thus become progressively localized between the on-chain potential barriers-this results in a mobility decay with a rate of (180 fs)(-1). Second, carriers are trapped at defects (potential wells) with a capture rate of (860 fs)(-1). At longer time scales, populations of mobile and trapped holes reach a quasiequilibrium state and further conductivity decrease becomes very slow.</p>. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
polymer blends, photoconductivity, Monte Carlo methods, hole mobility, energy gap, fullerenes, terahertz wave spectra, time, resolved spectra
in
Physical Review B (Condensed Matter and Materials Physics)
volume
79
issue
24
publisher
American Physical Society
external identifiers
  • wos:000267699700102
  • scopus:68949127448
ISSN
1098-0121
DOI
10.1103/PhysRevB.79.245326
language
English
LU publication?
yes
id
245c6667-66e7-47b3-9795-5a4c5dc6fb25 (old id 1462372)
date added to LUP
2009-08-20 12:30:17
date last changed
2017-09-17 06:52:18
@article{245c6667-66e7-47b3-9795-5a4c5dc6fb25,
  abstract     = {Time-resolved terahertz spectroscopy and Monte Carlo simulations of charge-carrier motion are used to investigate photoinduced transient conductivity in a blend of a low-band-gap polyphenylene copolymer and fullerene derivative. The optical excitation pulse generates free holes delocalized on polymer chains. We show that these holes exhibit a very high initial mobility as their initial excess energy facilitates their transport over defects (potential barriers) on polymer chains. The conductivity then drops down rapidly within 1 ps, and we demonstrate that this decrease occurs essentially by two mechanisms. First, the carriers loose their excess energy and they thus become progressively localized between the on-chain potential barriers-this results in a mobility decay with a rate of (180 fs)(-1). Second, carriers are trapped at defects (potential wells) with a capture rate of (860 fs)(-1). At longer time scales, populations of mobile and trapped holes reach a quasiequilibrium state and further conductivity decrease becomes very slow.&lt;/p&gt;.},
  author       = {Nemec, Hynek and Nienhuys, Han-Kwang and Perzon, Erik and Zhang, Fengling and Inganas, Olle and Kuzel, Petr and Sundström, Villy},
  issn         = {1098-0121},
  keyword      = {polymer blends,photoconductivity,Monte Carlo methods,hole mobility,energy gap,fullerenes,terahertz wave spectra,time,resolved spectra},
  language     = {eng},
  number       = {24},
  publisher    = {American Physical Society},
  series       = {Physical Review B (Condensed Matter and Materials Physics)},
  title        = {Ultrafast conductivity in a low-band-gap polyphenylene and fullerene blend studied by terahertz spectroscopy},
  url          = {http://dx.doi.org/10.1103/PhysRevB.79.245326},
  volume       = {79},
  year         = {2009},
}