Electro-optical studies of a soluble conjugated polymer with particularly low intrachain disorder

Harrison, Mark; Möller, Sven; Weiser, G.; Urbasch, G.; Mahrt, Rainer F.; Bäßler, H.; Scherf, Ullrich

doi:10.1103/physrevb.60.8650

Cited by 59 publications

(43 citation statements)

References 35 publications

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“…We therefore make the testable prediction that there should occur in these systems a lower energy PA at ϳ0.7 eV that is considerably stronger than the PAs in the 1.5-1.8-eV range. The scaled PA2 energy from our PPP oligomer calculations, 0.6-0.8ϫE(1B u ), with experimental E(1B u )ϭ2.7 eV in m-LPPP, 58 corresponds to 1.6 -2.1 eV, once again reasonably close to the experimental value.…”

Section: Conclusion and Discussionsupporting

confidence: 84%

“…We therefore believe that the observed lowest energy PA features actually correspond to PA2 of Frolov et al, and this is why charge separation occurs upon excitation to this energy. This assignment is supported by the observation of EA, 58 as well as TPA, 59 to a different lower energy two-photon state that occurs ϳ0.7 eV above the 1B u exciton in the polymer. We therefore make the testable prediction that there should occur in these systems a lower energy PA at ϳ0.7 eV that is considerably stronger than the PAs in the 1.5-1.8-eV range.…”

Section: Conclusion and Discussionmentioning

confidence: 67%

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Theory of excited-state absorption in phenylene-basedπ-conjugated polymers

2003

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Within a rigid-band correlated electron model for oligomers of poly-͑paraphenylene͒ ͑PPP͒ and poly͑paraphenylenevinylene͒ ͑PPV͒, we show that there exist two fundamentally different classes of two-photon A g states in these systems to which photoinduced absorption ͑PA͒ can occur. At relatively lower energies there occur A g states which are superpositions of one electron-one hole (1e -1h) and two electron-two hole (2e -2h) excitations, that are both comprised of the highest delocalized valence-band and the lowest delocalized conduction-band states only. The dominant PA is to one specific member of this class of states ͑the mA g ). In addition to the above class of A g states, PA can also occur to a higher energy kA g state whose 2e -2h component is different and has significant contributions from excitations involving both delocalized and localized bands. Our calculated scaled energies of the mA g and the kA g agree reasonably well to the experimentally observed low-and high-energy PA's in PPV. The calculated relative intensities of the two PA's are also in qualitative agreement with experiment. In the case of ladder-type PPP and its oligomers, we predict from our theoretical work an intense PA at an energy considerably lower than the region where PA's have been observed currently. Based on earlier work that showed that efficient charge-carrier generation occurs upon excitation to odd-parity states that involve both delocalized and localized bands, we speculate that it is the characteristic electronic nature of the kA g that leads to charge generation subsequent to excitation to this state, as found experimentally.

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Section: Conclusion and Discussionsupporting

confidence: 84%

Section: Conclusion and Discussionmentioning

confidence: 67%

Theory of excited-state absorption in phenylene-basedπ-conjugated polymers

2003

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“…4,5 From previous studies on m-LPPP a comprehensive picture of the generation of polarons [6][7][8] and triplet excitons 8,9 ͑TE's͒ from singlet excitons ͑SE's͒ was drawn. It is well known that polarons, as found in OLED's upon injection of carriers, 10 recombine to form SE's, which generate the electroluminescence ͑EL͒.…”

Section: Introductionmentioning

confidence: 99%

Interaction of singlet excitons with polarons in wide band-gap organic semiconductors: A quantitative study

et al. 2001

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The steady-state photoinduced absorption ͑PA͒, photoluminescence ͑PL͒, PL-detected magnetic resonance ͑PLDMR͒, and PA-detected magnetic resonance ͑PADMR͒ of poly-and oligo-͑para-phenylenes͒ films is described. In particular, the excitation density ͑laser power͒ N 0 dependence of the PA, PL, and PLDMR signals is analyzed by means of a rate equation model, which describes the dynamics of singlet excitons ͑SE's͒ and polarons in all three experiments quantitatively with the same set of parameters. The model is based on the observations that mobile SE's are quenched by trapped and free polarons and that the spin-1 2 magnetic resonance conditions reduce the total polaron population. Since the sublinear N 0 dependences of the positive ͑PL-enhancing͒ spin-1 2 PLDMR and the polaron PA band are essentially the same, we conclude that PLDMR is due to a reduced quenching of SE's by polarons. The agreement between the model, the current results, and results from other spectroscopic techniques provides strong evidence for this quenching mechanism. This also suggests that it is a very significant process in luminescent -conjugated materials and organic light-emitting devices. Consequently, the quenching mechanism needs to be taken into account, especially at high excitation densities, which is of great importance for the development of electrically pumped polymer laser diode structures.

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“…In contrast, the ladder-type poly-p-phenylenes (LPPP) [1] offer the opportunity to study large, rod-like chains of planarised phenylene units. As a consequence, the π-system might spread out over an entire polymer and a vibronic resolution of the S 1 ← S 0 transition is discernible [2]. In order to deduce some characteristics of the polymeric films [3], like the effective conjugation length, several oligomers have been synthesized in the past to study the low-lying electronic excited states of the polymer [4,5].…”

Section: Introductionmentioning

confidence: 99%

Excited states of ladder-type poly-p-phenylene oligomers

et al. 2001

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Ground state properties and excited states of ladder-type paraphenylene oligomers are calculated applying semiempirical methods for up to eleven phenylene rings. The results are in qualitative agreement with experimental data. A new scheme to interpret the excited states is developed which reveals the excitonic nature of the excited states. The electron-hole pair of the S 1 -state has a mean distance of approximately 4Å.

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Electro-optical studies of a soluble conjugated polymer with particularly low intrachain disorder

Cited by 59 publications

References 35 publications

Theory of excited-state absorption in phenylene-basedπ-conjugated polymers

Theory of excited-state absorption in phenylene-basedπ-conjugated polymers

Interaction of singlet excitons with polarons in wide band-gap organic semiconductors: A quantitative study

Excited states of ladder-type poly-p-phenylene oligomers

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