Theoretical investigation of the low-lying electronic structure of poly(<b><i>p</i></b>-phenylene vinylene)

Lavrentiev, M. Yu.; Barford, William; Martin, Simon J.; Daly, Helen; Bursill, Robert J.

doi:10.1103/physrevb.59.9987

Cited by 51 publications

(36 citation statements)

References 32 publications

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“…The wavefunction descriptions make it clear that very qualitatively these wavefunctions can also be described within the effective linear chain model [40], but with less precision than the 2A g . Our calculated relative intensities of the 2A g and the mA g are in qualitative agreement with other recent calculations for polyphenylenes that used a basis space of only the d 1 and d * 1 bands [41,42]. Above band III in the calculated spectra we always have a state that is qualitatively different from lower energy A g states.…”

Section: Correlated Electron Calculations Of Pa Spectrasupporting

confidence: 90%

Ultrafast excited state absorption and charge separation in phenylene-based conjugated polymers

2004

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Ultrafast pump-probe spectroscopy of phenylene-based -conjugated polymers give low and high energy photoinduced absorptions (PAs) to final states with very different relaxation behavior. While the low energy two-photon state that is reached in PA relaxes to the optical exciton in ultrafast times, the higher energy two-photon state violates the Vavilov-Kasha rule and instead of relaxing to the optical exciton undergoes interchain dissociation to a polaron pair state. We have calculated the excited state absorptions of long oligomers of poly-paraphenylene and poly-paraphenylenevinylene within a rigid band correlated electron Hamiltonian, using the complete -electron basis and the powerful multi-reference singles and double configuration interaction technique. Our calculated PA spectra well reproduce the experimental PA. We further show that there exists a fundamental difference in the natures of the wavefunctions of the final states that are reached in low and high energy PA, and the difference originates from the existence of multiple kinds of bands in phenylene-based systems within one-electron theory. We speculate that the violation of the Vavilov-Kasha rule and charge separation into polaron pairs upon excitation to the high energy two-photon state is a consequence of its specific electronic structure, and discuss an earlier work on wavelength dependent photoconductivity of poly-paraphenylenevinylene to support this conjecture.

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Section: Correlated Electron Calculations Of Pa Spectrasupporting

confidence: 90%

Ultrafast excited state absorption and charge separation in phenylene-based conjugated polymers

2004

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“…So for brevity we shall present TPA (as well as EA) data only for the highest oligomer length studied, PPV7. Our calculated TPA, EA resembles well with other theoretical calculations [34]. Although that is a highly approximated calculation but as we show that in larger oligomer limits higher energy excited states involve dominantly excitations involving only d 1 electrons, thus the present calculation shows similarity with the approximated one [34].…”

Section: Correlated Electron Calculation Of Nonlinear Optical Prsupporting

confidence: 87%

Ground and excited state nonlinear optical properties of poly(-para phenylene vinylene)

Ghosh

2008

Synthetic Metals

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We investigate theoretically the nature of higher energy excited even as well as odd parity states, for various sizes of oligomers of PPV. We study in detail various nonlinear optical properties, like third harmonic generation (THG), two photon absorption (TPA), electro absorption (EA) of oligomers of PPV within a rigid band correlated Pariser-Parr-Pople (PPP) model Hamiltonian, using the π-electron basis and the powerful multireference single and double configuration interaction (MRSDCI) method. We also use single-double-triple-quadruple configuration interaction (SDTQCI) in limited cases. We show that in THG three kinds of one photon states 1Bu, jBu and nBu (where j < n) whereas three kinds of even parity states 2Ag, mAg and kAg appear. The even parity states 2Ag, mAg and kAg also appear in TPA. While mAg absorptions appear just after the nBu, the 2Ag appears immediately after the jBu absorptions. A detailed analysis of the wavefunctions of higher energy excited states with conjugation length are presented. We show that beyond certain conjugation length that both mAg and kAg states mainly involve excitations between the lowest delocalized valance and conductance bands. Our study indicate middle order exciton binding energy. Finally, we theoretically predict that by optically exciting PPV at one wavelength equivalent to the optical gap for a sufficiently long time to perform nonlinear optical measurement, the values of χ can be enhanced by three orders-of-magnitude.

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“…[6][7][8] The Hamiltonian in Eq. V(r) is the average over all pairwise atom-atom Coulombic interactions within the two unit cells separated by |r|, 6-8 including also the effects of dielectric screening.…”

Section: The Modelmentioning

confidence: 99%

Vibronic coupling in quantum wires: Applications to polydiacetylene

Yamagata

Spano

2011

The Journal of Chemical Physics

115

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A theory describing vibronic coupling in direct band gap, one-dimensional semiconductors is developed to account for the photophysical properties of isolated, defect-free conjugated polymers. A Holstein-like Hamiltonian represented in a multi-particle basis set is used to evaluate absorption and emission due to Wannier-Mott excitons. The photophysical properties of such quantum wires are shown to strongly resemble those of Frenkel exciton J-aggregates. The 1(1)B(u) exciton coherence length and effective mass are readily determined from the ratio of the 0-0 and 0-1 line strengths, I(0 - 0)/I(0 - 1), in the photoluminescence spectrum. I(0 - 0)/I(0 - 1) is shown to follow a T(-1/2) dependence, in an excellent agreement with experiments on the red-phase of polydiacteylene.

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Theoretical investigation of the low-lying electronic structure of poly(p-phenylene vinylene)

Cited by 51 publications

References 32 publications

Ultrafast excited state absorption and charge separation in phenylene-based conjugated polymers

Ultrafast excited state absorption and charge separation in phenylene-based conjugated polymers

Ground and excited state nonlinear optical properties of poly(-para phenylene vinylene)

Vibronic coupling in quantum wires: Applications to polydiacetylene

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