Exciton and biexciton signatures in femtosecond transient absorption of π-conjugated oligomers

Victor I Klimov, D. McBranch, N. Barashkov, J. Ferraris

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

We report femtosecond transient-absorption studies of a five-ring oligomer of polyphenylenevinylene (PPV) prepared in two different forms: As solid-state films and dilute solutions. Both types of samples exhibit a photoinduced absorption (PA) band with dynamics which closely match those of the stimulated emission (SE), demonstrating unambiguously that these features originate from the same species, namely from intrachain singlet excitons. Photochemical degradation of the solid-state samples is demonstrated to dramatically shorten the SE dynamics above a moderate incident pump fluence, whereupon the dynamics of the SE and the long-wavelength PA no longer coincide. In contrast to solutions, solid-state films exhibit an additional short-wavelength PA band with pump-independent dynamics, indicating the efficient formation of non-emissive inter-chain excitons. Correlations in the subpicosecond dynamics of the two PA features, as well as the pump intensity-dependence provide strong evidence that the formation of inter-chain excitons is mediated by intrachain two-exciton states. At high pump levels, we see a clear indication of interaction between excited states also in dilute solutions. This is manifested as a superlinear pump-dependence and shortening of the decay dynamics of the SE. We attribute this behavior to the formation of biexcitons resulting from coherent interaction between two excitons on a single chain.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsZ.V. Vardeny, L.J. Rothberg
Pages58-68
Number of pages11
Volume3145
DOIs
Publication statusPublished - 1997
EventOptical Probes of Conjugated Polymers - San Diego, CA, United States
Duration: Jul 28 1997Jul 30 1997

Other

OtherOptical Probes of Conjugated Polymers
CountryUnited States
CitySan Diego, CA
Period7/28/977/30/97

Fingerprint

oligomers
Oligomers
Excitons
Stimulated emission
excitons
signatures
stimulated emission
Pumps
pumps
solid state
Absorption spectra
absorption spectra
Wavelength
Excited states
wavelengths
Solid solutions
fluence
indication
interactions
degradation

Keywords

  • π-conjugated oligomers
  • Biexcitons
  • Excitons
  • Transient absorption

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Klimov, V. I., McBranch, D., Barashkov, N., & Ferraris, J. (1997). Exciton and biexciton signatures in femtosecond transient absorption of π-conjugated oligomers. In Z. V. Vardeny, & L. J. Rothberg (Eds.), Proceedings of SPIE - The International Society for Optical Engineering (Vol. 3145, pp. 58-68) https://doi.org/10.1117/12.295539

Exciton and biexciton signatures in femtosecond transient absorption of π-conjugated oligomers. / Klimov, Victor I; McBranch, D.; Barashkov, N.; Ferraris, J.

Proceedings of SPIE - The International Society for Optical Engineering. ed. / Z.V. Vardeny; L.J. Rothberg. Vol. 3145 1997. p. 58-68.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Klimov, VI, McBranch, D, Barashkov, N & Ferraris, J 1997, Exciton and biexciton signatures in femtosecond transient absorption of π-conjugated oligomers. in ZV Vardeny & LJ Rothberg (eds), Proceedings of SPIE - The International Society for Optical Engineering. vol. 3145, pp. 58-68, Optical Probes of Conjugated Polymers, San Diego, CA, United States, 7/28/97. https://doi.org/10.1117/12.295539
Klimov VI, McBranch D, Barashkov N, Ferraris J. Exciton and biexciton signatures in femtosecond transient absorption of π-conjugated oligomers. In Vardeny ZV, Rothberg LJ, editors, Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3145. 1997. p. 58-68 https://doi.org/10.1117/12.295539
Klimov, Victor I ; McBranch, D. ; Barashkov, N. ; Ferraris, J. / Exciton and biexciton signatures in femtosecond transient absorption of π-conjugated oligomers. Proceedings of SPIE - The International Society for Optical Engineering. editor / Z.V. Vardeny ; L.J. Rothberg. Vol. 3145 1997. pp. 58-68
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N2 - We report femtosecond transient-absorption studies of a five-ring oligomer of polyphenylenevinylene (PPV) prepared in two different forms: As solid-state films and dilute solutions. Both types of samples exhibit a photoinduced absorption (PA) band with dynamics which closely match those of the stimulated emission (SE), demonstrating unambiguously that these features originate from the same species, namely from intrachain singlet excitons. Photochemical degradation of the solid-state samples is demonstrated to dramatically shorten the SE dynamics above a moderate incident pump fluence, whereupon the dynamics of the SE and the long-wavelength PA no longer coincide. In contrast to solutions, solid-state films exhibit an additional short-wavelength PA band with pump-independent dynamics, indicating the efficient formation of non-emissive inter-chain excitons. Correlations in the subpicosecond dynamics of the two PA features, as well as the pump intensity-dependence provide strong evidence that the formation of inter-chain excitons is mediated by intrachain two-exciton states. At high pump levels, we see a clear indication of interaction between excited states also in dilute solutions. This is manifested as a superlinear pump-dependence and shortening of the decay dynamics of the SE. We attribute this behavior to the formation of biexcitons resulting from coherent interaction between two excitons on a single chain.

AB - We report femtosecond transient-absorption studies of a five-ring oligomer of polyphenylenevinylene (PPV) prepared in two different forms: As solid-state films and dilute solutions. Both types of samples exhibit a photoinduced absorption (PA) band with dynamics which closely match those of the stimulated emission (SE), demonstrating unambiguously that these features originate from the same species, namely from intrachain singlet excitons. Photochemical degradation of the solid-state samples is demonstrated to dramatically shorten the SE dynamics above a moderate incident pump fluence, whereupon the dynamics of the SE and the long-wavelength PA no longer coincide. In contrast to solutions, solid-state films exhibit an additional short-wavelength PA band with pump-independent dynamics, indicating the efficient formation of non-emissive inter-chain excitons. Correlations in the subpicosecond dynamics of the two PA features, as well as the pump intensity-dependence provide strong evidence that the formation of inter-chain excitons is mediated by intrachain two-exciton states. At high pump levels, we see a clear indication of interaction between excited states also in dilute solutions. This is manifested as a superlinear pump-dependence and shortening of the decay dynamics of the SE. We attribute this behavior to the formation of biexcitons resulting from coherent interaction between two excitons on a single chain.

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