Photoinduced Absorption in Poly(p-phenylene vinylene)

Bradley, Donal D. C.; Friend, R. H.; Pratt, F. L.; Wong, K S; Hayes, W.; Lindenberger, H.; Roth, S.

doi:10.1007/978-3-642-83284-0_20

Cited by 9 publications

(7 citation statements)

References 15 publications

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“…The preparation of PPV by in-vacuo thermal conversion of a sulphonium polyelectrolyte precursor is outlined in figure 1. Such a synthetic approach gives considerable flexibility in polymer processing and through a suitable choice of preparation conditions (see Bradley (1987b) for a recent review) high quality material of controlled morphology, crystallinity, orientation and length of uninterrupted conjugated sequences may be obtained. Of particular importance to the study reported here is the ability to vary the extent of the formation of conjugated sequences by controlling the temperature at, and time for which the conversion of the initially non-conjugated precursor (I) is carried out.…”

Section: Introductionmentioning

confidence: 99%

“…Of particular importance to the study reported here is the ability to vary the extent of the formation of conjugated sequences by controlling the temperature at, and time for which the conversion of the initially non-conjugated precursor (I) is carried out. 'Full conversion' to I11 (as judged by an absence of the precursor C-S stretching vibrational mode (632 cm-') from the infrared spectrum) requires heating at 300 "C. A t lower conversion temperatures a copolymer (11) of conjugated and non-conjugated sequences is generated in which the degree of conjugation increases with the temperature and heating time (for further details see Bradley (1987b)). The corresponding expected increase in x-electron delocalisation is confirmed experimentally by electron energy loss dispersion (Fink eta1 1987) and infraredintensity (Bradley 1987b and references therein) measurements.…”

Section: Introductionmentioning

confidence: 99%

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Light-induced luminescence quenching in precursor-route poly(p-phenylene vinylene)

Bradley

Friend

1989

J. Phys.: Condens. Matter

107

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Light-induced luminescence quenching in precursor-route poly(p-phenylene vinylene)

Bradley

Friend

1989

J. Phys.: Condens. Matter

107

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“…These include polaron pairs and excimers, but also aggregates with an associated ground state interaction ͑physical dimers͒ have been considered. [15][16][17][18][19][20][21][22] The basis for the physical aggregate is a sufficiently strong interchain interaction predominantly via a dipole-dipole interaction. If this interaction is strong enough, there will be a significant impact on the electronic transition ͑1A g → 2B u ͒ leading to a Davydov splitting of the absorption band.…”

Section: Introductionmentioning

confidence: 99%

Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Pålsson

Vaughan

Monkman

2006

The Journal of Chemical Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Two related poly͑phenylene-vinylene͒ ͑PPV͒ light-emitting polymers have been investigated by means of polarized optical spectroscopy. The purpose of the investigation was to investigate the nature of the interactions in thin films and to examine what impact the difference in side chain structure and molecular weight in poly͑2Ј-methoxy-5-2-ethyl-hexoxy͒-1,4-phenylene vinylene ͑MEH-PPV͒ and poly͑2-͑3Ј ,7Ј-dimethyloctyloxy͒-5-methoxy-1,4-phenylene-vinylene͒ ͑OC 1 C 10 -PPV͒ has on the electronic and optical properties of the two polymers. Aligning the polymers by dispersing them in anisotropic solvents and stretched films shows that the side chains have an impact on the relative orientations of the transition dipole moments. In anisotropic solvents the linear dichroism is larger for MEH-PPV than for the related polymer OC 1 C 10 -PPV, while in stretched films the opposite situation prevails. A lower polarization of the luminescence from OC 1 C 10 -PPV, relative to MEH-PPV, was also obtained independent of alignment medium used. The data therefore suggest that while mechanical stretching may align the OC 1 C 10 -PPV to a greater degree, the emitting species is distinct from the absorbing species. The circular dichroism ͑CD͒ spectra of both polymers undergo dramatic changes when the liquid phase and the solid state ͑film͒ are compared. The solution CD spectra shows no evidence of interchain interactions; instead the spectra of both systems indicate a helical conformation of the polymers. The CD spectra of films are dramatically different with the strong Cotton effect being observed. This points to the formation of an aggregate in the film, with an associated ground state interaction, an interchain species such as a physical dimer, or a more complex higher aggregate.

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“…36 This photoinduced infrared difference spectrum of PPV (Figure 6d) resembles those observed in the previous studies. [65][66][67] The spectrum in Figure 6e was obtained by subtracting the spectrum of a neutral PPV film from the spectrum of the same film doped with H 2 SO 4 . 62 It is worth pointing out that in any of the transient infrared absorption spectra (Figure 6a-c) and the photoinduced and doping-induced infrared difference spectra (Figure 6d,e), no negative (bleach) bands due to the neutral PPV in the groundstate were observed.…”

Section: Methodsmentioning

confidence: 99%

Picosecond Time-Resolved Polarized Infrared Spectroscopic Study of Photoexcited States and Their Dynamics in Oriented Poly(p-phenylenevinylene)

2008

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The picosecond time-resolved polarized infrared absorption spectra of the photoexcited states of an oriented poly(p-phenylenevinylene) [-(C6H4CH=CH)n-, PPV] film have been recorded in the 3600-1050 cm(-1) region. The time-resolved photoinduced infrared absorptions due to an electronic transition in the wavenumber region of 3600-1700 cm(-1) and vibrational transitions in the region of 1700-1050 cm(-1) have fast and slow decay components under all polarization conditions of the pump and probe pulses with respect to the orientation of PPV. The picosecond time-resolved infrared absorption spectra are analyzed by reference to the photoinduced and doping-induced infrared difference spectra of PPV. The long-lived transient species, observed with the pump polarization perpendicular and the probe polarization parallel to the orientation of PPV, are assigned to positive and negative polarons. The short-lived transient species under the same polarization condition is assigned to bound polaron pairs. It is likely that singlet excitons are observed with both the pump and probe polarizations parallel to the orientation of PPV. The singlet excitons show fast decay due to the exciton-exciton annihilation under the high excitation density used in the present study.

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Photoinduced Absorption in Poly(p-phenylene vinylene)

Cited by 9 publications

References 15 publications

Light-induced luminescence quenching in precursor-route poly(p-phenylene vinylene)

Light-induced luminescence quenching in precursor-route poly(p-phenylene vinylene)

Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Picosecond Time-Resolved Polarized Infrared Spectroscopic Study of Photoexcited States and Their Dynamics in Oriented Poly(p-phenylenevinylene)

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