Illumination of exciton migration in rodlike luminescent conjugated polymers by single-molecule spectroscopy

Wang, C. F.; White, J. D.; Lim, Thong Leng; Hsu, Jui-Hung; Yang, Shu-Chun; Fann, Wunshain; Peng, Kang-Yung; Chen, S. A.

doi:10.1103/physrevb.67.035202

Cited by 42 publications

(23 citation statements)

References 32 publications

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“…The intramolecular interchain energy transfer is significantly faster, [5] in some estimates by more than an order of magnitude, [6] than the intrachain process due to the proximity and relative orientation of the interacting conjugated segments. The fluorescence intermittency indicating excitation localization has since become an almost universal feature of the emission of single chains of conjugated polymers and has been observed for other derivatives of PPV such as DOO-PPV [7][8][9] , for ladder-type poly(para-phenylene) conjugated polymers of MeLPPP, [10,11] and for polyfluorenes (A. Hattori and M. Vacha, unpublished results) and their derivatives such as end-capped polyindenofluorene. [12,13] Recently, fluctuations of fluorescence transition dipole in single molecules of polythiophene with bulky side groups were interpreted as evidence of emission from multiple conjugated segments.…”

Section: Introductionmentioning

confidence: 91%

“…PT-R shows behaviour typically seen in most other conjugated polymers. [3,4,[7][8][9][10][11][12][13] The emission intensity oscillates between the background level and one or, in a few cases, several intensity levels before complete photobleaching takes place. On the other hand, the emission intensity of most PT-PS molecules decays gradually without any apparent quantization effect.…”

Section: Single-molecule Photobleaching and Blinkingmentioning

confidence: 98%

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Structure‐Dependent Photophysics Studied in Single Molecules of Polythiophene Derivatives

et al. 2007

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We report on the photophysical characterization at the single-molecule level of a graft copolymer consisting of a polythiophene backbone and long polystyrene branches. The presence of the branches prevents the polymer chain from forming a collapsed conformational state. The photophysical properties of the resulting solution-like conformation are studied by measuring single-molecule photobleaching dynamics, emission polarization anisotropy and emission spectra. The results are compared with those obtained on the same polythiophene derivative without the branches. It is found that the presence of the branches is a decisive factor in determining the photophysical properties of the polymers on the single-molecule level.

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Section: Introductionmentioning

confidence: 91%

Section: Single-molecule Photobleaching and Blinkingmentioning

confidence: 98%

Structure‐Dependent Photophysics Studied in Single Molecules of Polythiophene Derivatives

et al. 2007

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“…The glass plate spin-coated with the sample was mounted on a modified confocal optical microscope (E600; Nikon) for inspection (37). Excitation of the sample was made through a ϫ100 objective (Plan Fluor, N.A.…”

Section: Methodsmentioning

confidence: 99%

Characterization and application of single fluorescent nanodiamonds as cellular biomarkers

Lee

Chen

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

804

455

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Type Ib diamonds emit bright fluorescence at 550 -800 nm from nitrogen-vacancy point defects, (N-V) 0 and (N-V) ؊ , produced by high-energy ion beam irradiation and subsequent thermal annealing. The emission, together with noncytotoxicity and easiness of surface functionalization, makes nano-sized diamonds a promising fluorescent probe for single-particle tracking in heterogeneous environments. We present the result of our characterization and application of single fluorescent nanodiamonds as cellular biomarkers. We found that, under the same excitation conditions, the fluorescence of a single 35-nm diamond is significantly brighter than that of a single dye molecule such as Alexa Fluor 546. The latter photobleached in the range of 10 s at a laser power density of 10 4 W/cm 2 , whereas the nanodiamond particle showed no sign of photobleaching even after 5 min of continuous excitation. Furthermore, no fluorescence blinking was detected within a time resolution of 1 ms. The photophysical properties of the particles do not deteriorate even after surface functionalization with carboxyl groups, which form covalent bonding with polyL-lysines that interact with DNA molecules through electrostatic forces. The feasibility of using surface-functionalized fluorescent nanodiamonds as single-particle biomarkers is demonstrated with both fixed and live HeLa cells.blinking ͉ photobleaching ͉ single-molecule detection ͉ single-particle tracking ͉ live cell O ne of the key avenues to understanding how biological systems function at the molecular level is to probe biomolecules individually and observe how they interact with each other directly in vivo. Laser-induced fluorescence is a technique widely adopted for this purpose owing to its ultrahigh sensitivity and capabilities of performing multiple-probe detection (1-3). However, in applying this technique to imaging and tracking a single molecule or particle in a biological cell, progress is often hampered by the presence of ubiquitous endogenous components such as flavins, nicotinamide adenine dinucleotides, collagens, and porphyrins that produce high fluorescence background signals (4-6). These biomolecules typically absorb light at wavelengths in the range of 300-500 nm and fluoresce at 400-550 nm (Fig. 1). To avoid such interference, a good biological fluorescent probe should absorb light at a wavelength longer than 500 nm and emit light at a wavelength longer than 600 nm, at which the emission has a long penetration depth through cells and tissues (5, 7). Organic dyes and fluorescent proteins are two types of molecules often used to meet such a requirement (1,8,9); however, the detrimental photophysical properties of these molecules, such as photobleaching and blinking, inevitably restrict their applications for long-term in vitro or in vivo observations. Fluorescent semiconductor nanocrystals (or quantum dots), on the other hand, have gained considerable attention in recent years because they hold a number of advantageous features including high photobleaching thresholds a...

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“…[1][2][3][4][5][6][7][8][9][10][11] Unlike inorganic electronic materials that are crystalline and highly ordered, conjugated polymer materials are typically amorphous and exhibit varying degrees of disorder. These properties, in conjunction with their processibility and low-cost fabrication, make them important candidate materials for field-effect transistors, light-emitting diodes, and other electro-optic applications.…”

Section: Introductionmentioning

confidence: 99%

Modeling outer-sphere disorder in the symmetry breaking of PPV

Liu

Yaron

2009

The Journal of Chemical Physics

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Disorder plays an important role in the photophysics of conjugated polymers such as poly(para-phenylene vinylene) (PPV). The dipole moments measured by electroabsorption spectroscopy for a centrosymmetric system such as PPV provide a direct quantitative measure of disorder-induced symmetry breaking. Although inner-sphere (structural) disorder is present, outer-sphere (environmental) disorder dominates the symmetry breaking in PPV. This paper develops and compares six models of outer-sphere disorder that differ in their representation of the electrostatic environment of PPV in glassy solvents. The most detailed model is an all-atom description of the solvent glass and this model forms the basis for comparison of the less detailed models. Four models are constructed in which multipoles are placed at points on a lattice. These lattice models differ in the degree to which they include correlation between the lattice spacings and the orientations of the multipoles. A simple model that assigns random Gaussian-distributed electrostatic potentials to each atom in the PPV molecule is also considered. Comparison of electronic structure calculations of PPV in these electrostatic environments using the all-atom model as a benchmark reveals that dipole and quadrupole lattices provide reasonable models of organic glassy solvents. Including orientational correlation among the solvent molecules decreases the effects of outer-sphere disorder, whereas including correlation in the lattice spacings increases the effects. Both the dipole and quadrupole moments of the solvent molecules can have significant effects on the symmetry breaking and these effects are additive. This additivity provides a convenient means for predicting the effects of various glassy solvents based on their multipole moments. The results presented here suggest that electrostatic disorder can account for the observed symmetry breaking in organic glasses. Furthermore, the lattice models are in general agreement with the dipole and quadrupole lattice models used to explain the Poole-Frenkel behavior in charge transport through disordered organic materials.

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Illumination of exciton migration in rodlike luminescent conjugated polymers by single-molecule spectroscopy

Cited by 42 publications

References 32 publications

Structure‐Dependent Photophysics Studied in Single Molecules of Polythiophene Derivatives

Structure‐Dependent Photophysics Studied in Single Molecules of Polythiophene Derivatives

Characterization and application of single fluorescent nanodiamonds as cellular biomarkers

Modeling outer-sphere disorder in the symmetry breaking of PPV

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