Fluorescence depolarization of chromophores in polymeric solids

Peterson, Kara J.; Zimmt, Matthew B.; Fayer, M. D.; Jeng, Y.H.; Frank, C. W.

doi:10.1021/ma00192a060

Cited by 14 publications

(14 citation statements)

References 4 publications

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“…This method follows theoretical and experimental studies of exciton diffusion via Förster energy transfer in an ensemble of randomly oriented chromophores. 37 The singlet excitons diffuse in these materials by incoherent hopping and there is some loss of polarization memory with each hop. Dendrimers are not expected to pack with any significant short range order, therefore, a single hop is sufficient to cause a loss of polarisation by a factor of 1 / e and an average hopping rate can be estimated as k h =1/ dep .…”

Section: Excitation Energy Transfer In Filmsmentioning

confidence: 99%

Influence of the dendron chemical structure on the photophysical properties of bisfluorene-cored dendrimers

Ribierre

Ruseckas

Samuel

et al. 2008

The Journal of Chemical Physics

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A detailed study of the photophysics of a family of bisfluorene-cored dendrimers is reported. Polarized time-resolved fluorescence, singlet-singlet exciton annihilation and fluorescence quantum yield measurements were performed and used to understand how the dendron structure affects the light-emitting properties of the materials. The exciton diffusion rate is similar in all films studied. An increase in the nonradiative deactivation rate by nearly one order of magnitude is observed in films of dendrimers with stilbenyl and carbazolyl based dendrons as compared to solutions, whereas the dendrimers with biphenyl and diphenylethylenyl dendrons showed highly efficient emission (photoluminescence quantum yields of 90%) in both solution and the solid state. The results of the materials that show fluorescence quenching can be explained by the presence of quenching sites at a concentration of just a fraction of a percent of all macromolecules. A possible explanation of this quenching is hole transfer from the emissive chromophore to the dendron in a face-to-face geometry. These results are important for the design of efficient blue emitters for optoelectronic applications.

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Section: Excitation Energy Transfer In Filmsmentioning

confidence: 99%

Influence of the dendron chemical structure on the photophysical properties of bisfluorene-cored dendrimers

Ribierre

Ruseckas

Samuel

et al. 2008

The Journal of Chemical Physics

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“…Rapid depolarization due to early time exciton hopping leads to fundamental anisotropy values (anisotropy at t = 0) below the theoretical value of 0.4 and is not captured in the time window of our experiment. Rather, given the relatively large size of the complexes, we primarily capture the depolarization due to exciton migration, as well as segmental motion. , By the latter, we mean rotational motion of chromophores about the chain contour. , Figure a shows that the TRPLA decay of pristine aqueous raPTAK is fairly rapid, reflecting the ensemble of intrachain π-stacking interactions, which lead to relatively fast scrambling of the transition dipole moment orientation. However, raPTAK within the complex shows a clear slowing and eventual flattening of the decay with increasing temperature relative to its native CPE state.…”

Section: Resultsmentioning

confidence: 99%

Semiconducting Eggs and Ladders: Understanding Exciton Landscape Formation in Aqueous π-Conjugated Inter-Polyelectrolyte Complexes

2020

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Conjugated polymers display remarkable optoelectronic properties that emerge from the strong coupling between delocalized π-electrons, leading to highly mobile excited states. This is a very useful property from a light-harvesting perspective. We showed previously that a promising and environmentally attractive approach to formation of an ultrafast light-harvesting antenna is to use aqueous ionic assembly of oppositely charged conjugated polyelectrolytes (CPEs). However, to rationally design the excited-state transfer efficiency, the basic physical chemistry of inter-CPE assembly must be elucidated. We demonstrate that the delocalization of π-electrons and the orientation of ionic sidechains relative to the conjugation plane together dictate the complexation kinetics and thermodynamics, and thus the resulting structure. We find that the enthalpy of complexation is substantially larger than previously observed with nonconjugated polyelectrolytes. We further show that the reaction enthalpy changes sign with increasing temperature. We argue that the interaction between the water solvation shell and the polarizable aromatic backbone is key to understanding both the activation energy and the reaction enthalpy.

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“…They involve the measurement of the decay of luminescence intensity [5,12,13], the decay of fluorescence polarization anisotropy for organic molecular systems [14][15][16], the time-dependent emission spectra by spectral energy transfer in inhomogeneously broadened lines using the time-resolved fluorescence line narrowing [17][18][19], or site-selective laser excitation spectroscopy of cooperative luminescence [11]. These techniques are useful to shed light on the distribution of luminescent ions or molecules inside a material, but they often require a model describing the excitation probability of a collection of ions in the presence of traps and energy migration.…”

Section: Introductionmentioning

confidence: 99%

Probability density function of the rate of energy transfer from luminescent ions to a random distribution of traps in the static limit

Bisson¹

2015

J. Opt. Soc. Am. B

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The transfer of excitation of luminescent ions to a random distribution of traps is revisited in the static limit, with the emphasis on the probability density function (PDF) of the decay rate. Knowledge of the PDF is advantageous for situations when the time evolution of an individual ion's excited state differs from an exponential decay or when no closed-form solution for the ensemble average exists, because it allows one to reconstruct an ensemble average from the knowledge of the behavior of a single class of ions. A model with dipole-dipole interactions with no minimum distance leads, in the continuum limit, to an inverse gamma (IG) PDF with shape parameter α 1∕2, which has infinite moments. With a minimum nearest trap distance, closed-form solutions of the moments of the actual PDF are well matched with those of a smoothly truncated IG distribution.

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Fluorescence depolarization of chromophores in polymeric solids

Cited by 14 publications

References 4 publications

Influence of the dendron chemical structure on the photophysical properties of bisfluorene-cored dendrimers

Influence of the dendron chemical structure on the photophysical properties of bisfluorene-cored dendrimers

Semiconducting Eggs and Ladders: Understanding Exciton Landscape Formation in Aqueous π-Conjugated Inter-Polyelectrolyte Complexes

Probability density function of the rate of energy transfer from luminescent ions to a random distribution of traps in the static limit

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