Interchain Electronic Excitations in Poly(phenylenevinylene) (PPV) Aggregates

Tretiak, Sergei; Saxena, Avadh; Martin, and R. L.; Bishop, A. R.

doi:10.1021/jp000397t

Cited by 87 publications

(84 citation statements)

References 64 publications

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“…Points lying higher (lower) than the diagonal of the plot indicate that the computed value is blue-(red-) shifted compared to experiment. Excitation energies of dierent oligomers are well separated since band-gap transition energy-shifts to the red with increasing chain length and gradually saturates to a constant for long chains [19,20]. This trend can be understood by analogy with the particle-in-a-box model.…”

Section: Conjugated Oligomersmentioning

confidence: 89%

“…It has been successfully used in calculations of the optical properties of a variety of conjugated chromophores such as porphyrins, dendrimers, donor/acceptor polymers, biological light-harvesting complexes, etc. [16,19,20]. By focusing only on the spectroscopically relevant observables, the CEO approach enables calculations on excited electronic states of molecules with hundreds of heavy atoms.…”

Section: Introductionmentioning

confidence: 99%

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CEO/semiempirical calculations of UV–visible spectra in conjugated molecules

Tretiak

Saxena

Martin

et al. 2000

Chemical Physics Letters

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The collective electronic oscillators (CEO) approach based on the TDHF approximation is combined with INDO/S, MNDO, AM1, and PM3 semiempirical Hamiltonians. This technique is applied to compute and analyze the electronic structure of acceptor-substituted oligomers and conjugated polymers. Calculated excited-state energies and oscillator strengths agree well with the experimental data and with each other. In particular, the results using the Hamiltonians parameterized for ground-state calculations such as AM1 and PM3 agree well with the INDO/S results. In addition, a two-dimensional analysis of the corresponding transition density matrices provides an ecient way for tracing the origin of various optical transitions by identifying the underlying changes in charge densities and bond-orders. Ó

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Section: Conjugated Oligomersmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

CEO/semiempirical calculations of UV–visible spectra in conjugated molecules

Tretiak

Saxena

Martin

et al. 2000

Chemical Physics Letters

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“…Most of existing theoretical work has been focused on the characteristics of optical and transport properties of isolated PFO oligomers, 5,20,21 with few efforts on studying intermolecular interactions in crystalline packing. 14,[22][23][24] Unfortunately, simulations of realistic disordered materials as used in devices are scarce. 19 The main reason is the computationally unmanageable number of atoms in realistic amorphous polymer systems.…”

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confidence: 99%

Electronic Structure of Self-Assembled Amorphous Polyfluorenes

et al. 2008

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We investigate the role of conformational disorder and intermolecular interactions on the electronic structure of amorphous clusters of polyfluorenes. Classical molecular dynamics simulations are used to determine probable molecular geometries and chain packing, and first-principles density functional theory calculations are employed to determine electronic structure and orbital localization properties. Intramolecular and intermolecular effects are disentangled by contrasting results for densely packed oligomer clusters and for ensembles of isolated oligomers with the same intramolecular geometries. Our simulations show that intermolecular disorder allows for nearly planar configurations of interacting fluorenes compared to the isolated molecules. This rationalizes the experimentally detected formation of the planar crystalline morphologies that frequently accompany twisted glassy configurations in fluorene films. The energy gap (HOMO−LUMO gap) significantly decreases for planar configurations. The electron and hole orbital energies are strongly dependent on both torsional angles and intermolecular interactions. This leads to strong localization of electronic states in amorphous polymer aggregates, which is analyzed by examining the respective orbital participation ratios. Notably, the energies of unoccupied levels show stronger dependence on the conformational disorder, compared to that of occupied levels. This results in the more probable formation of trap states near the edge of the conduction band than near the valence band.

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“…calculate optical properties in both conjugated molecules and molecular aggregates (Tretiak et al, 1996(Tretiak et al, , 2000.…”

Section: Methodsmentioning

confidence: 99%

Geometry Relaxation of Photoexcited States in Conjugated Molecules

et al. 2002

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The random phase approximation combined with semiempirical Hamiltonians is applied to compute and analyze electronic structure and excited state adiabatic potentials of several conjugated molecules. Calculated excited state energies and parameters of molecular adiabatic surfaces characterize the coupled dynamics of vibrational and electronic degrees of freedom. The analysis identifies the specific torsional and bond-stretching nuclear motions that dominate the excited state relaxation and lead to self-localized excitations. This approach is an inexpensive and numerically efficient method of computing molecular excited state adiabatic surfaces and modeling femto-to-pico second time-dependent photoexcitation processes along chosen trajectories.

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Interchain Electronic Excitations in Poly(phenylenevinylene) (PPV) Aggregates

Cited by 87 publications

References 64 publications

CEO/semiempirical calculations of UV–visible spectra in conjugated molecules

CEO/semiempirical calculations of UV–visible spectra in conjugated molecules

Electronic Structure of Self-Assembled Amorphous Polyfluorenes

Geometry Relaxation of Photoexcited States in Conjugated Molecules

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