PMID- 17136272
OWN - NLM
STAT- MEDLINE
DCOM- 20070206
LR  - 20061130
IS  - 1463-9076 (Print)
IS  - 1463-9076 (Linking)
VI  - 8
IP  - 47
DP  - 2006 Dec 21
TI  - Photoluminescence spectra of a conjugated polymer: from films and solutions to 
      single molecules.
PG  - 5569-76
AB  - 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 approximately 20 
      nm to the value corresponding to well-separated single molecules (SMS sample). 
      The thickness variation resulted in a strong ( approximately 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.
FAU - Mirzov, O
AU  - Mirzov O
AD  - Chemical Physics, Lund University, P.O. Box 124, 22100 Lund, Sweden.
FAU - Scheblykin, I G
AU  - Scheblykin IG
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20061108
PL  - England
TA  - Phys Chem Chem Phys
JT  - Physical chemistry chemical physics : PCCP
JID - 100888160
RN  - 0 (Polymers)
RN  - 0 (Polyvinyls)
RN  - 0 (Solutions)
SB  - IM
MH  - Luminescence
MH  - Polymers/*chemistry
MH  - Polyvinyls/*chemistry
MH  - Solutions
MH  - Spectrometry, Fluorescence
EDAT- 2006/12/01 09:00
MHDA- 2007/02/07 09:00
CRDT- 2006/12/01 09:00
PHST- 2006/12/01 09:00 [pubmed]
PHST- 2007/02/07 09:00 [medline]
PHST- 2006/12/01 09:00 [entrez]
AID - 10.1039/b612073c [doi]
PST - ppublish
SO  - Phys Chem Chem Phys. 2006 Dec 21;8(47):5569-76. doi: 10.1039/b612073c. Epub 2006 
      Nov 8.