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Photoluminescence spectra of a conjugated polymer: from films and solutions to single molecules

Mirzov, Oleg LU and Scheblykin, Ivan LU orcid (2006) In Physical Chemistry Chemical Physics 8(47). p.5569-5576
Abstract
The purpose of this work is to address the issue of applicability of single-molecule spectroscopy (SMS) results for conjugated polymers to "bulk" samples, e.g. conjugated polymer films. Also, some apparent inconsistencies in the literature on SMS regarding the photoluminescence spectral position of conjugated polymers are discussed. We present a series of photoluminescence spectra of thin films of the conjugated polymer poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) with a wide range of varying thickness. The thickness was varied from similar to 20 nm to the value corresponding to well-separated single molecules (SMS sample). The thickness variation resulted in a strong (similar to 2000 cm(-1)) blue-shift and... (More)
The purpose of this work is to address the issue of applicability of single-molecule spectroscopy (SMS) results for conjugated polymers to "bulk" samples, e.g. conjugated polymer films. Also, some apparent inconsistencies in the literature on SMS regarding the photoluminescence spectral position of conjugated polymers are discussed. We present a series of photoluminescence spectra of thin films of the conjugated polymer poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) with a wide range of varying thickness. The thickness was varied from similar to 20 nm to the value corresponding to well-separated single molecules (SMS sample). The thickness variation resulted in a strong (similar to 2000 cm(-1)) blue-shift and broadening of the spectrum. The result was reproduced on isolated molecules embedded into a PMMA matrix. This effect cannot be explained by a decrease in energy transfer "freedom" alone. We performed a comprehensive comparison of presented and elsewhere published spectra of MEH-PPV polymer and oligomers in different samples: films, solutions, isolated-molecule coatings and standard SMS samples. The comparison allows that the main reason behind the blue shift is conformational disorder, which is largely dependent on the sample. We also discuss some experimental aspects of SMS, such as representativeness of detected molecules, spectral sensitivity of a setup and temperature. Together with differences in sample preparation method, these issues can explain the existing inconsistencies in the literature. (Less)
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author
and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Chemistry Chemical Physics
volume
8
issue
47
pages
5569 - 5576
publisher
Royal Society of Chemistry
external identifiers
  • wos:000243193900023
  • scopus:33751517102
ISSN
1463-9084
DOI
10.1039/b612073c
language
English
LU publication?
yes
additional info
The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Chemical Physics (S) (011001060)
id
a97d33e3-3152-4d9f-8d4a-ff9f064b22da (old id 679901)
date added to LUP
2016-04-01 15:58:21
date last changed
2020-09-23 05:20:29
@article{a97d33e3-3152-4d9f-8d4a-ff9f064b22da,
  abstract     = {The purpose of this work is to address the issue of applicability of single-molecule spectroscopy (SMS) results for conjugated polymers to "bulk" samples, e.g. conjugated polymer films. Also, some apparent inconsistencies in the literature on SMS regarding the photoluminescence spectral position of conjugated polymers are discussed. We present a series of photoluminescence spectra of thin films of the conjugated polymer poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) with a wide range of varying thickness. The thickness was varied from similar to 20 nm to the value corresponding to well-separated single molecules (SMS sample). The thickness variation resulted in a strong (similar to 2000 cm(-1)) blue-shift and broadening of the spectrum. The result was reproduced on isolated molecules embedded into a PMMA matrix. This effect cannot be explained by a decrease in energy transfer "freedom" alone. We performed a comprehensive comparison of presented and elsewhere published spectra of MEH-PPV polymer and oligomers in different samples: films, solutions, isolated-molecule coatings and standard SMS samples. The comparison allows that the main reason behind the blue shift is conformational disorder, which is largely dependent on the sample. We also discuss some experimental aspects of SMS, such as representativeness of detected molecules, spectral sensitivity of a setup and temperature. Together with differences in sample preparation method, these issues can explain the existing inconsistencies in the literature.},
  author       = {Mirzov, Oleg and Scheblykin, Ivan},
  issn         = {1463-9084},
  language     = {eng},
  number       = {47},
  pages        = {5569--5576},
  publisher    = {Royal Society of Chemistry},
  series       = {Physical Chemistry Chemical Physics},
  title        = {Photoluminescence spectra of a conjugated polymer: from films and solutions to single molecules},
  url          = {http://dx.doi.org/10.1039/b612073c},
  doi          = {10.1039/b612073c},
  volume       = {8},
  year         = {2006},
}