國立虎尾科技大學 |

Optical properties of conjugated polymers.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Optical properties of conjugated polymers./
Author:	Jakubiak, Rachel.
Description:	1 online resource (161 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 62-09, Section: B.
Contained By:	Dissertations Abstracts International62-09B.
Subject:	Chemistry. -
Online resource:	click for full text (PQDT)
ISBN:	9780599928770

Optical properties of conjugated polymers.
Jakubiak, Rachel.

Optical properties of conjugated polymers. - 1 online resource (161 pages)

Source: Dissertations Abstracts International, Volume: 62-09, Section: B.

Thesis (Ph.D.)--University of Rochester, 2000.

Includes bibliographical references

Electroluminescent conjugated polymers, particularly those of the PPV class, are promising candidates for light emitting display applications. In the solid state, the polymers have reduced quantum efficiency because of the formation of weakly emissive or nonemissive interchain photoexcitations. We have observed and quantified interchain emission in MEH-PPV for the first time. We conclude that excimers that are nearly nonemissive at ambient temperature can form with quantum yields approaching 50%. Excimers form because the alkoxy substutients on the MEH-PPV backbone splay out and allow cofacial approach of the polymer backbones giving rise to π - orbital overlap. We hypothesized that separation of polymer backbones in two dimensions is not sufficient to eliminate interchain interactions. To this end we have studied PPV with bulky, dendritic sidegroups that allows three-dimensional separation of polymer chains. We show that fewer interchain species are formed and consequently observe a four-fold increase in quantum efficiency. Optical spectroscopic studies of the polymers in solution revealed the importance of morphology on the photophysics of the polymers. Systematic variations of the solvent environment by changing the temperature and quality of the solvent induced or restricted the motions of the polymers. These changes were reflected in the absorption and photoluminescence of the polymers. We were able to reproduce our data quantitatively by hypothesizing two distinct configurations of polymers. Each of these species has distinct absorption and photoluminescence spectra, luminescence decay dynamics and luminescence quantum yield. These data suggest one morphology where the polymer chains behave independently of the surrounding polymer and another where the polymer chains are aggregated. Polymers in the aggregated condition have analogous photophysics to the polymers in the solid state and reduced photoluminescence. The fourfold increase in quantum yield in the first generation dendritic PPV can be attributed to the presence of a significant amount of polymer in the isolated configuration. The first generation dendritically substituted PPV has some liquid crystalline order and can be shear oriented. Selective excitation and observation of luminescence parallel and perpendicular to the backbones lead to behaviors distinct from the unoriented samples of the same polymer. We understand these differences in terms of selective excitation into distinct morphological regions of the polymer.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9780599928770Subjects--Topical Terms:

593913
Chemistry.
Subjects--Index Terms:

Conjugated polymersIndex Terms--Genre/Form:

554714
Electronic books.

Optical properties of conjugated polymers.
LDR:03957ntm a22004217 4500 001 1147925
005 20240916075431.5
006 m o d
007 cr bn ---uuuuu
008 250605s2000 xx obm 000 0 eng d
020 $a 9780599928770
035 $a (MiAaPQ)AAI9985795
035 $a AAI9985795
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Jakubiak, Rachel. $3 1473769
245 1 0 $a Optical properties of conjugated polymers.
264 0 $c 2000
300 $a 1 online resource (161 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertations Abstracts International, Volume: 62-09, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Rothberg, Lewis J.
502 $a Thesis (Ph.D.)--University of Rochester, 2000.
504 $a Includes bibliographical references
520 $a Electroluminescent conjugated polymers, particularly those of the PPV class, are promising candidates for light emitting display applications. In the solid state, the polymers have reduced quantum efficiency because of the formation of weakly emissive or nonemissive interchain photoexcitations. We have observed and quantified interchain emission in MEH-PPV for the first time. We conclude that excimers that are nearly nonemissive at ambient temperature can form with quantum yields approaching 50%. Excimers form because the alkoxy substutients on the MEH-PPV backbone splay out and allow cofacial approach of the polymer backbones giving rise to π - orbital overlap. We hypothesized that separation of polymer backbones in two dimensions is not sufficient to eliminate interchain interactions. To this end we have studied PPV with bulky, dendritic sidegroups that allows three-dimensional separation of polymer chains. We show that fewer interchain species are formed and consequently observe a four-fold increase in quantum efficiency. Optical spectroscopic studies of the polymers in solution revealed the importance of morphology on the photophysics of the polymers. Systematic variations of the solvent environment by changing the temperature and quality of the solvent induced or restricted the motions of the polymers. These changes were reflected in the absorption and photoluminescence of the polymers. We were able to reproduce our data quantitatively by hypothesizing two distinct configurations of polymers. Each of these species has distinct absorption and photoluminescence spectra, luminescence decay dynamics and luminescence quantum yield. These data suggest one morphology where the polymer chains behave independently of the surrounding polymer and another where the polymer chains are aggregated. Polymers in the aggregated condition have analogous photophysics to the polymers in the solid state and reduced photoluminescence. The fourfold increase in quantum yield in the first generation dendritic PPV can be attributed to the presence of a significant amount of polymer in the isolated configuration. The first generation dendritically substituted PPV has some liquid crystalline order and can be shear oriented. Selective excitation and observation of luminescence parallel and perpendicular to the backbones lead to behaviors distinct from the unoriented samples of the same polymer. We understand these differences in terms of selective excitation into distinct morphological regions of the polymer.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Chemistry. $3 593913
650 4 $a Materials science. $3 557839
650 4 $a Condensation. $3 592130
650 4 $a Polymers. $3 561233
650 4 $a Condensed matter physics. $3 1148471
650 4 $a Polymer chemistry. $3 1182163
650 4 $a Physical chemistry. $3 1148725
653 $a Conjugated polymers
653 $a Electroluminescent polymers
653 $a Photoluminescence
653 $a Poly(phenylene vinylene)
655 7 $a Electronic books. $2 local $3 554714
690 $a 0494
690 $a 0794
690 $a 0611
690 $a 0495
690 $a 0485
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a University of Rochester. $3 1194461
773 0 $t Dissertations Abstracts International $g 62-09B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9985795 $z click for full text (PQDT)