Tuning of fluorescence in films and nanoparticles of oligo-phenylenevinylenes

Oelkrug, D.; Tompert, Alfred; Gierschner, Johannes; Egelhaaf, Hans‐Joachim; Hanack, Michael; Hohloch, Michael; Steinhuber, Elke

doi:10.1117/12.284148

Cited by 58 publications

(105 citation statements)

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“…10,15 With thiophene oligomers, this was found to be strongly dependent on the type of solid material considered. For example, it was reported that for R3 in a polymer matrix the φ F value (at room temperature) increases to 0.2, 16 whereas for R5 in a CHCl 3 solution it was found to be 0.32 and where aggregates (presumably Haggregates) are present to be equal to 0.0011. 16 Moreover, with this same R5, a change of φ F from 10 -4 to 10 -2 was observed between oriented and disordered ultrathin films.…”

Section: Discussionmentioning

confidence: 99%

“…For example, it was reported that for R3 in a polymer matrix the φ F value (at room temperature) increases to 0.2, 16 whereas for R5 in a CHCl 3 solution it was found to be 0.32 and where aggregates (presumably Haggregates) are present to be equal to 0.0011. 16 Moreover, with this same R5, a change of φ F from 10 -4 to 10 -2 was observed between oriented and disordered ultrathin films. 16 Finally, no significant changes are observed in the fluorescence quantum yield upon going to low temperatures (Table 2), possibly suggesting any changes in emission processes resulting from shifts in fluorescence maxima are paralleled by corresponding changes in the nonradiative rates.…”

Section: Discussionmentioning

confidence: 99%

“…This does not, however, seem to be the general rule with the oligothiophene counterparts, where the fluorescence quantum yields in ultrathin films are found to be strongly quenched relative to solution media. 16 However, this also depends on several other factors such as film thickness, structure, and orientation, 16 which were found to increase upon increasing layer thickness or cooling. 17 …”

Section: Introductionmentioning

confidence: 99%

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Spectral and Photophysical Studies on Cruciform Oligothiophenes in Solution and the Solid State

et al. 2006

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The photophysical and spectroscopic properties of a new class of oligothiophene derivatives, designated as cruciform oligomers, have been investigated in solution (room and low temperature) and in the solid state (as thin films in Zeonex matrixes). The study comprises absorption, emission, and triplet-triplet absorption spectra, together with quantitative measurements of quantum yields (fluorescence, intersystem crossing, internal conversion, and singlet oxygen formation) and lifetimes. The overall data allow the determination of the rate constants for all decay processes. From these, several conclusions are drawn. First, in solution, the main deactivation channels for the compounds are the radiationless processes: S 1 ' S 0 internal conversion and S 1 ' T 1 intersystem crossing. Second, in general, in the solid state, the fluorescence quantum yields decrease relative to solution. A comparison is made with the analogous linear R-oligothiophenes, revealing a lower fluorescence quantum efficiency and, in contrast to the normal oligothiophenes, that internal conversion is an important channel for the deactivation of the singlet excited state. Replacement of thiophene by 1,4-phenylene units in the longer-sized cruciform oligomer increases the fluorescence efficiency. The highly efficient generation of singlet oxygen through energy transfer from the triplet state (S ∆ ≈ 1) provides support for the measured intersystem crossing quantum yields and suggests that reaction with this may be an important pathway to consider for degradation of devices produced with these compounds.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectral and Photophysical Studies on Cruciform Oligothiophenes in Solution and the Solid State

et al. 2006

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“…48,49 It is clear from Eq. ͑2͒ that smaller exciton bandwidth and/or increased disorder yields more intense 0-0 emission relative to 0-1 emission.…”

Section: Spectroscopic Characterizationmentioning

confidence: 97%

Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

et al. 2006

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Interchain interactions have a profound effect on the optical as well as charge transport properties of conjugated polymer thin films. In contrast to oligomeric model systems in solution-deposited polymer thin films the study of such effects is complicated by the complex microstructure. We present here a detailed study of interchain interaction effects on both charged polarons as well as neutral excitons in highly crystalline, high-mobility poly-3-hexylthiophene ͑P3HT͒ as a function of molecular weight. We find experimental evidence for reduced exciton bandwidth and increased polaron delocalization with increasing conjugation length and crystalline quality. From comparative studies of field-effect transistor characteristics, film morphology, and optical properties our study provides a microscopic understanding of the factors which limit the charge transport in P3HT to field-effect mobilities around 0.1 cm 2 / V s, and which will need to be addressed to improve mobility further.

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“…Davydov splitting effects are well known in thin films of conjugated oligomers such as sexithiophene and hexaphenyl. 25,26 In these materials the degree of Davydov splitting can be controlled by altering the film deposition conditions leading to strong variations in absorption spectra.…”

Section: A Linear Absorption Spectramentioning

confidence: 99%

Linear and nonlinear optical properties of the conjugated polymers PPV and MEH-PPV

et al. 1999

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We have used absorption and electroabsorption spectroscopy to investigate the electronic structure of poly͑para-phenylene vinylene͒ ͑PPV͒ and poly "2-methoxy, 5-(2Ј-͑ethyl͒hexyloxy͒-p-phenylene vinylene… ͑MEH-PPV͒. In particular we examine the often used assumption that the electronic structure of PPV and its dialkoxy substituted derivatives are essentially the same. The absorption spectrum of PPV consists of three peaks, while that of MEH-PPV has four peaks. We discuss the controversial origin of the extra peak as well as evidence for Davydov splitting effects in the absorption spectrum of PPV. The analysis of the nonlinear spectra shows further differences between the two materials. First, the binding energy of the 1B u exciton for PPV is some 0.1 eV higher than for MEH-PPV. Second, the peak value of Im͕ (3) (Ϫ ;0,0, )͖ for PPV is approximately 40 times higher than that of MEH-PPV. We also found that the sum-over-states modeling of the electroabsorption spectra indicates that the transition dipole moment between the mA g and nB u states is of opposite sign in the two polymers. ͓S0163-1829͑99͒02523-0͔

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Tuning of fluorescence in films and nanoparticles of oligo-phenylenevinylenes

Cited by 58 publications

References 0 publications

Spectral and Photophysical Studies on Cruciform Oligothiophenes in Solution and the Solid State

Spectral and Photophysical Studies on Cruciform Oligothiophenes in Solution and the Solid State

Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

Linear and nonlinear optical properties of the conjugated polymers PPV and MEH-PPV

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