The photophysics of phenyl disubstituted polyacetylenes: picosecond photoluminescence and femtosecond photoinduced absorption studies of PDPA-n-Bu

Gustafson, Terry L.; Kyllo, Erica; Frost, Tony; Sun, Rong; Lim, Henry C.; Wang, Daike K; Epstein, Arthur J.; Lefumeux, Christophe; Burdziński, Gotard; Buntinx, G.; Poizat, O.

doi:10.1016/s0379-6779(00)00509-9

Cited by 13 publications

(12 citation statements)

References 21 publications

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“…Several previous studies have detected photogenerated polarons in solutions, but they disagree about the photogeneration mechanism (due to polymer aggregates in solution, 17,23 to charge transfer to the solvent, 22,39,40 to exciton dissociation 19 or direct generation 24 ). In addition, the reported efficiencies for charge pair generation and the dynamics of charge recombination vary considerably.…”

Section: Discussionmentioning

confidence: 91%

“…47 However, one would naively expect that recombination on isolated chains in dilute solution would be faster than for chains close-packed in a polymer film; confining the charges to diffusion along a onedimensional (1D) chain would facilitate charge recombination with respect to the three-dimensional (3D) carrier diffusion expected for films. In fact, earlier studies (in the ns to the ms time scale) 19,22,24 have found that charge recombination is faster for polymer chains solution than in solid films. Measurements in the ps range have also suggested that charge recombination is faster in aggregated solutions than in polymer films, 17 although this experiment might actually be probing charge transfer excitons.…”

Section: Discussionmentioning

confidence: 97%

“…12 The ultrafast ͑Ͻ250 fs͒ nature of polaron photogeneration is inconsistent with the possibility of charges being created by thermal dissociation of relatively long lived excitons. 19 It has been proposed that polarons can be generated by "hotexciton" dissociation, i.e., excitons in a vibrationally excited state right after photoexcitation can be dissociated within the vibrational cooling time. 44 Since the vibrational relaxation occurs within a few hundred femtoseconds, it could in principle explain ultrafast polaron photogeneration.…”

Section: Discussionmentioning

confidence: 99%

“…In experiments, the role played by interchain interactions on charge photogeneration has been addressed by time-resolved [15][16][17][18][19][20] and steady-state spectroscopy, [21][22][23] and by time-resolved microwave conductivity. 24 Although most of the solution studies have detected photogenerated polarons, they disagree regarding the photogeneration mechanism, the efficiency for charge pair generation, and the dynamics of charge recombination.…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast photogeneration of charged polarons on conjugated polymer chains in dilute solution

2004

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Ultrafast photoinduced absorption by infrared-active vibrational modes is used to study the photogeneration of polarons on semiconducting polymer chains in dilute solutions and in solid films of a soluble derivative of poly(para-phenylene vinylene). In dilute solutions, polaron pairs are photogenerated on the conjugated polymer within less than 250 fs with quantum efficiencies ch ϳ 3%, about one-third of that for solid films of the same polymer. The excitation spectra of ch for both solutions and films show that ch is weakly dependent on photon energy between 2.2 eV (the onset of absorption) and 4.7 eV. The recombination dynamics of polarons is very fast and highly dependent on the excitation density for polymer films, but it is significantly slower and less sensitive to pump intensity for the semiconducting polymer in dilute solution. We conclude that the positive and negative polarons on a single chain in solution are typically separated by hundreds of monomer repeat units and that their one-dimensional diffusion along the chain is inhibited by the intervening excitons. This, together with the suppression of interchain recombination, explains the surprisingly slower polaron recombination in isolated chains.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrafast photogeneration of charged polarons on conjugated polymer chains in dilute solution

2004

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“…As to polydiphenylacetylenes (i.e., poly(diphenylvinylene)s, PDV), only a few ring-substituted PDVs have been studied [23][24][25][26] because the parent polymer, unsubstituted PDV, is infusible and insoluble in any solvent [14,15,27]. Recently, the photogeneration of longlived polarons was observed in photooxidized n-butyl substituted PDVs [23,24], which was explained by the presence of carbonyl groups in the photo-degraded polymer, as these groups can be expected to increase the probability of exciton dissociation into free charge carriers.…”

Section: Introductionmentioning

confidence: 99%