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Title: Photorefractive conjugated polymer-liquid crystal composites

Abstract

A new mechanism for space-charge field formation in photorefractive liquid crystal composites containing poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV) and the electron acceptor N,N{prime}-dioctyl-1,4:5,8-naphthalenediimide, NI, is observed. Using asymmetric energy transfer (beam coupling) measurements that are diagnostic for the photorefractive effect, the direction of beam coupling as a function of grating fringe spacing inverts at a spacing of 5.5 {micro}m. The authors show that the inversion is due to a change in the dominant mechanism for space-charge field formation. At small fringe spacings, the space-charge field is formed by ion diffusion in which the photogenerated anion is the more mobile species. At larger fringe spacings, the polarity of the space charge field inverts due to dominance of a charge transport mechanism in which photogenerated holes are the most mobile species due to hole migration along the BEH-PEV chains coupled with interchain hole hopping. Control experiments are presented, which use composites that can access only one of the two charge transport mechanisms. The results show that charge migration over long distances leading to enhanced photorefractive effects can be obtained using conjugated polymers dissolved in liquid crystals.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab., IL (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
755876
Report Number(s):
ANL/CHM/CP-101877
TRN: AH200021%%89
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: Materials Research Society 1999 Fall Meeting, Boston, MA (US), 11/29/1999--12/03/1999; Other Information: PBD: 15 May 2000
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COMPOSITE MATERIALS; LIQUID CRYSTALS; POLYMERS; REFRACTION; CHARGE TRANSPORT; SIGNAL CONDITIONING; OPTICAL EQUIPMENT

Citation Formats

Wasielewski, M. R., Yoon, B. A., Fuller, M., Wiederrecht, G. P., Niemczyk, M. P., and Svec, W. A. Photorefractive conjugated polymer-liquid crystal composites. United States: N. p., 2000. Web.
Wasielewski, M. R., Yoon, B. A., Fuller, M., Wiederrecht, G. P., Niemczyk, M. P., & Svec, W. A. Photorefractive conjugated polymer-liquid crystal composites. United States.
Wasielewski, M. R., Yoon, B. A., Fuller, M., Wiederrecht, G. P., Niemczyk, M. P., and Svec, W. A. Mon . "Photorefractive conjugated polymer-liquid crystal composites". United States. https://www.osti.gov/servlets/purl/755876.
@article{osti_755876,
title = {Photorefractive conjugated polymer-liquid crystal composites},
author = {Wasielewski, M. R. and Yoon, B. A. and Fuller, M. and Wiederrecht, G. P. and Niemczyk, M. P. and Svec, W. A.},
abstractNote = {A new mechanism for space-charge field formation in photorefractive liquid crystal composites containing poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV) and the electron acceptor N,N{prime}-dioctyl-1,4:5,8-naphthalenediimide, NI, is observed. Using asymmetric energy transfer (beam coupling) measurements that are diagnostic for the photorefractive effect, the direction of beam coupling as a function of grating fringe spacing inverts at a spacing of 5.5 {micro}m. The authors show that the inversion is due to a change in the dominant mechanism for space-charge field formation. At small fringe spacings, the space-charge field is formed by ion diffusion in which the photogenerated anion is the more mobile species. At larger fringe spacings, the polarity of the space charge field inverts due to dominance of a charge transport mechanism in which photogenerated holes are the most mobile species due to hole migration along the BEH-PEV chains coupled with interchain hole hopping. Control experiments are presented, which use composites that can access only one of the two charge transport mechanisms. The results show that charge migration over long distances leading to enhanced photorefractive effects can be obtained using conjugated polymers dissolved in liquid crystals.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {5}
}

Conference:
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