Spectroscopy of Defects in Organic Crystals

Ostapenko, N. I.; Sugakov, V. I.; Shpak, M. T.

doi:10.1007/978-94-011-1675-6

Cited by 15 publications

(18 citation statements)

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“…In reality organic molecular crystals and aggregates are disordered due to point and structural defects. [45][46][47][48][49][50][51] Defects have the most profound affect on emission ͑see Sec. VI͒; in absorption they are manifest primarily in the form of inhomogeneously broadened line shapes.…”

Section: The Noninteracting Domains Model "Ndm…mentioning

confidence: 99%

“…In organic molecular crystals, point defects due to misaligned molecules and impurities as well as structural defects, such as dislocations, stacking faults, and grain boundaries are common, and are responsible for continuous and quasi-discrete emission bands. [45][46][47][48][49][50][51] FIG. 11.…”

Section: The Effects Of Defects On Emissionmentioning

confidence: 99%

“…We employ the noninteracting domains model ͑NDM͒ to approximate spatially correlated site-energy disorder in evaluating the nanoaggregate absorption spectrum. In order to account for the aforementioned Stokes shift structural disorder, including stacking faults and dislocations, [45][46][47][48][49][50][51] is investigated.…”

Section: Introductionmentioning

confidence: 99%

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Absorption and emission in oligo-phenylene vinylene nanoaggregates: The role of disorder and structural defects

Spano¹

2002

The Journal of Chemical Physics

164

230

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Absorption and emission in pinwheel aggregates of oligo-phenylene vinylene moleculesThe impact of exciton-phonon coupling and defect states on the photophysical properties of p-distyrylbenzene nanoaggregates is studied numerically. Molecular packing within aggregates is based on the known crystal structures of poly-p-phenylene vinylene ͑Type I͒ and the five phenyl group oligomer ͑Type II͒. Calculations of absorption and emission are conducted using a reduced basis set consisting of all one-and two-particle vibronic states. The calculated spectra are very similar for both aggregate types, the only substantial difference being the polarization directions for the J-band and 0-0 emission line. Under the noninteracting domains approximation the calculated nanoaggregate absorption spectrum is in excellent agreement with experiment, assuming an exciton coherence length of approximately 20 Å. In the calculated emission spectrum the 0-0 emission is uniquely polarized compared with the rest of the vibronic progression, also in agreement with experiment. The 0-0 emission intensity in defect-free Type I and II aggregates is linearly proportional to the total number of molecules, becoming superradiant beyond a certain size threshold. The 0-0 emission is highly sensitive to stacking faults and dislocations. These defects account for the measured Stokes shift, but quench the 0-0 emission ͑and superradiance͒ while only slightly affecting the rest of the vibronic progression. Adding orientational point defects to an aggregate with stacking faults and/or dislocations enhances the 0-0 oscillator strength, bringing the 0-0 emission intensity into good agreement with experiment.

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Section: The Noninteracting Domains Model "Ndm…mentioning

confidence: 99%

Section: The Effects Of Defects On Emissionmentioning

confidence: 99%

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Absorption and emission in oligo-phenylene vinylene nanoaggregates: The role of disorder and structural defects

Spano¹

2002

The Journal of Chemical Physics

164

230

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“…For these excitations the matrix elements of resonant interaction M are small (0.1 to 1.0 cm-'). The order of magnitude of the interaction contribution to the difference between the exciton band and exciton trap levels is about M [2]. Thus, for triplet excitons this contribution can be neglected.…”

Section: The Exciton Traps On Dipole Centersmentioning

confidence: 96%

Exciton and Electron Traps on Structural Defects in Molecular Crystals with Dipolar Molecules

Izvekov

Sugakov

1995

Physica Status Solidi (b)

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“…In this respect, another 'difficulty is bound to emerge for higher dopant concentrations (which are also of experimental interest [9,10]), since the cases, where two or more impurity molecules are close to each other, would be practically impossible to handle in that way.…”

Section: O Conclusionmentioning

confidence: 99%

Cluster Model of Charge Transfer Excitons in Molecular Crystals. II. Local Frenkel Excitons in Doped Crystals

Eilmes

1993

Acta Phys. Pol. A

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Spectroscopy of Defects in Organic Crystals

Cited by 15 publications

References 0 publications

Absorption and emission in oligo-phenylene vinylene nanoaggregates: The role of disorder and structural defects

Absorption and emission in oligo-phenylene vinylene nanoaggregates: The role of disorder and structural defects

Exciton and Electron Traps on Structural Defects in Molecular Crystals with Dipolar Molecules

Cluster Model of Charge Transfer Excitons in Molecular Crystals. II. Local Frenkel Excitons in Doped Crystals

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