Excited state energy dynamics of poly(2,5-diethynylthiophene) copolymers with different effective conjugation lengths

In Wook Hwang, Nam Woong Song, Young Tae Park, Dongho Kim, Yong Rok Kim

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The relaxation dynamics of photoexcitation of poly(2,5-diethynylthiophene) copolymers (PDETs) with different repeating unit numbers (n = 12, 16, 18) were investigated by steady-state fluorescence spectroscopy and picosecond time-resolved fluorescence decay measurements. All three copolymers presented two peaks in a fluorescence spectrum; however, the position and the intensity of each peak changed, depending upon polymer size. These two peaks were assigned as radiative relaxations from a self-trapped (polaronic) exciton state and a conformational kink state, in comparison with the results of polydiacetylenes and polythiophenes. A bathochromic shift in the fluorescence spectra occurred between the PDET with n = 12 and the PDET with n = 16, but it was negligible for the PDETs with n between 16 and 18. The ratio of the populational relaxation at the conformational kink state to the relaxation at the self-trapped (polaronic) exciton state is larger in the PDET with n = 12 than in PDETs with n = 16 or n = 18. From the results of iterative least-squares fitting of time-resolved fluorescence decay data at different emission wavelengths, we obtained the relaxation lifetimes of 139 ± 5 psec and 205 ± 3 psec for each state and fluorescence build-up times of 18 ± 2 psec and 51 ± 5 psec, depending on the size of the copolymers; values which are attributed to charge carrier recombination times.

Original languageEnglish
Pages (from-to)335-339
Number of pages5
JournalEuropean Polymer Journal
Volume34
Issue number3-4
Publication statusPublished - 1998 Mar 1

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conjugation
Excited states
copolymers
Copolymers
Fluorescence
fluorescence
excitation
Excitons
energy
excitons
Photoexcitation
Fluorescence spectroscopy
Polymers
Charge carriers
decay
photoexcitation
charge carriers
Wavelength
life (durability)
shift

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

Cite this

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title = "Excited state energy dynamics of poly(2,5-diethynylthiophene) copolymers with different effective conjugation lengths",
abstract = "The relaxation dynamics of photoexcitation of poly(2,5-diethynylthiophene) copolymers (PDETs) with different repeating unit numbers (n = 12, 16, 18) were investigated by steady-state fluorescence spectroscopy and picosecond time-resolved fluorescence decay measurements. All three copolymers presented two peaks in a fluorescence spectrum; however, the position and the intensity of each peak changed, depending upon polymer size. These two peaks were assigned as radiative relaxations from a self-trapped (polaronic) exciton state and a conformational kink state, in comparison with the results of polydiacetylenes and polythiophenes. A bathochromic shift in the fluorescence spectra occurred between the PDET with n = 12 and the PDET with n = 16, but it was negligible for the PDETs with n between 16 and 18. The ratio of the populational relaxation at the conformational kink state to the relaxation at the self-trapped (polaronic) exciton state is larger in the PDET with n = 12 than in PDETs with n = 16 or n = 18. From the results of iterative least-squares fitting of time-resolved fluorescence decay data at different emission wavelengths, we obtained the relaxation lifetimes of 139 ± 5 psec and 205 ± 3 psec for each state and fluorescence build-up times of 18 ± 2 psec and 51 ± 5 psec, depending on the size of the copolymers; values which are attributed to charge carrier recombination times.",
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Excited state energy dynamics of poly(2,5-diethynylthiophene) copolymers with different effective conjugation lengths. / Hwang, In Wook; Song, Nam Woong; Park, Young Tae; Kim, Dongho; Kim, Yong Rok.

In: European Polymer Journal, Vol. 34, No. 3-4, 01.03.1998, p. 335-339.

Research output: Contribution to journalArticle

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T1 - Excited state energy dynamics of poly(2,5-diethynylthiophene) copolymers with different effective conjugation lengths

AU - Hwang, In Wook

AU - Song, Nam Woong

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AU - Kim, Dongho

AU - Kim, Yong Rok

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N2 - The relaxation dynamics of photoexcitation of poly(2,5-diethynylthiophene) copolymers (PDETs) with different repeating unit numbers (n = 12, 16, 18) were investigated by steady-state fluorescence spectroscopy and picosecond time-resolved fluorescence decay measurements. All three copolymers presented two peaks in a fluorescence spectrum; however, the position and the intensity of each peak changed, depending upon polymer size. These two peaks were assigned as radiative relaxations from a self-trapped (polaronic) exciton state and a conformational kink state, in comparison with the results of polydiacetylenes and polythiophenes. A bathochromic shift in the fluorescence spectra occurred between the PDET with n = 12 and the PDET with n = 16, but it was negligible for the PDETs with n between 16 and 18. The ratio of the populational relaxation at the conformational kink state to the relaxation at the self-trapped (polaronic) exciton state is larger in the PDET with n = 12 than in PDETs with n = 16 or n = 18. From the results of iterative least-squares fitting of time-resolved fluorescence decay data at different emission wavelengths, we obtained the relaxation lifetimes of 139 ± 5 psec and 205 ± 3 psec for each state and fluorescence build-up times of 18 ± 2 psec and 51 ± 5 psec, depending on the size of the copolymers; values which are attributed to charge carrier recombination times.

AB - The relaxation dynamics of photoexcitation of poly(2,5-diethynylthiophene) copolymers (PDETs) with different repeating unit numbers (n = 12, 16, 18) were investigated by steady-state fluorescence spectroscopy and picosecond time-resolved fluorescence decay measurements. All three copolymers presented two peaks in a fluorescence spectrum; however, the position and the intensity of each peak changed, depending upon polymer size. These two peaks were assigned as radiative relaxations from a self-trapped (polaronic) exciton state and a conformational kink state, in comparison with the results of polydiacetylenes and polythiophenes. A bathochromic shift in the fluorescence spectra occurred between the PDET with n = 12 and the PDET with n = 16, but it was negligible for the PDETs with n between 16 and 18. The ratio of the populational relaxation at the conformational kink state to the relaxation at the self-trapped (polaronic) exciton state is larger in the PDET with n = 12 than in PDETs with n = 16 or n = 18. From the results of iterative least-squares fitting of time-resolved fluorescence decay data at different emission wavelengths, we obtained the relaxation lifetimes of 139 ± 5 psec and 205 ± 3 psec for each state and fluorescence build-up times of 18 ± 2 psec and 51 ± 5 psec, depending on the size of the copolymers; values which are attributed to charge carrier recombination times.

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