Electric Field Induced Fluorescence Modulation of Single Molecules in PMMA Based on Electron Transfer

Chen, Ruiyun; Gao, Yubing; Zhang, Guofeng; Wu, Ruixiang; Liu, Xiao; Jia, Suotang

doi:10.3390/ijms130911130

Cited by 10 publications

(6 citation statements)

References 32 publications

(34 reference statements)

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“…Electron transfer between organic fluorophores and the surrounding media has been intensively discussed as an origin of their fluorescence blinking 53. In particular the reported sensitivity of fluorescence brightness and blinking of single organic molecules embedded in PMMA and similar hosts to external electric field is a strong indication of formation of fluorescence quenching charge‐transfer states 54, 55. Another possibility is that a CP segment might be reduced by filling up the electron vacancy in the HOMO state of the excited polymer segment by electron transfer from the surrounding (or from a neighboring segment of the same chain), which should make the whole segment non‐emissive.…”

Section: Resultsmentioning

confidence: 99%

Cyclodextrin Insulation Prevents Static Quenching of Conjugated Polymer Fluorescence at the Single Molecule Level

Thomsson

Camacho

Tian

et al. 2013

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Conjugated polymers (CPs) are promising materials for fluorescence imaging application. However, a significant problem in this field is the unexplained abnormally low fluorescence brightness (or number of fluorescence photons detected per one excitation photon) exhibited by most of CP single chains in solid polymer hosts. Here it is shown that this detrimental effect can be fully avoided for short chains of polyfluorene-bis-vinylphenylene (PFBV) embedded in a host polymer matrix of PMMA, if the conjugated backbone is insulated by cyclodextrin rings to form a polyrotaxane (PFBV-Rtx). Fluorescence kinetics and quantum yields are measured for the polymers in liquid solutions, pristine films, and solid PMMA blends. The fluorescence brightness of PFBV-Rtx single chains dispersed in a solid PMMA is very close to that expected for a chain with 100% fluorescence quantum yield, while the unprotected PFBV chains of the same length possess 4 times lower brightness. Despite this, the fluorescence decay kinetics are the same for both polymers, suggesting the presence of static or ultrafast fluorescence quenching in the unprotected polymer. About 80% of an unprotected PFBV chain is estimated to be completely quenched. The hypothesis is that the cyclodextrin rings prevent the quenching by working as 'bumpers' reducing the mechanical forces applied by the host polymer to the conjugated backbone and help retaining its conformational freedom. While providing a recipe for making CP fluorescence bright at the single-molecule level, these results identify a lack of fundamental understanding in the community of the influence of the environment on excited states in conjugated materials.

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Section: Resultsmentioning

confidence: 99%

Cyclodextrin Insulation Prevents Static Quenching of Conjugated Polymer Fluorescence at the Single Molecule Level

Thomsson

Camacho

Tian

et al. 2013

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“…In our opinion this study provides an alternative theoretical–computational viewpoint, amendable both in the quality of the calculations and in the level of the approximations, for reaching a valid setup able to quantitatively design and optimize organic dyes in interaction with the actual working environment. − …”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Toward a Realistic Modeling of the Photophysics of Molecular Building Blocks for Energy Harvesting: The Charge-Transfer State in 4,7-Dithien-2-yl-2,1,3-benzothiadiazole As a Case Study

et al. 2013

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Theoretical modeling of the photophysical properties of materials (both low-weighted and polymeric) for energy harvesting represents an attractive area fundamental and applied research. In this area meaningful results can be obtained only in the presence of realistic models keeping intact the atomistic complexity which, in this system, is usually very high. Herein we propose a model study, carried out on a typical building block for energy harvesting materials, 4,7-dithien-2-yl-2,1,3-benzothiadiazole (DTB), with the precise aim to theoretically reproduce the charge-transfer S-0-S-1 UV-vis signal in different solvents and also to provide some hints for interpreting the large Stokes-shift observed in its fluorescence spectra. Results show that the DUB spectral (absorption) features are the result of an intimate interplay between chromophore thermal fluctuations and environmental dynamical (electrostatic) perturbation. Deep inspection of the results also confirms the possibility of modulating the chromophore low-energy photophysics acting on the thermal, electrical, and chemical properties of the molecular surrounding environment

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“…A potential contributor to the low emission efficiency is field-induced quenching (FIQ). In this process, the electric field used to drive the device also promotes nonradiative decay. − FIQ has been studied in many different molecular systems, − particularly by Ohta et al − Herein, the focus will be specifically on FIQ associated with oligomeric and polymeric systems.…”

Section: Introductionmentioning

confidence: 99%

Modeling Field-Induced Quenching in Poly(p-phenylene vinylene) Polymers and Oligomers

2015

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Field-induced fluorescence quenching of poly(p-phenylene vinylene) (PPV) oligomers due to nonradiative relaxation through free electron-hole pair (FEHP) states is modeled using singles configuration interaction computations with the intermediate neglect of differential overlap Hamiltonian. The computations find FEHP states with energies that drop linearly with applied field and undergo avoided crossings with the fluorescent state. The coupling between the FEHP and fluorescent state, computed for multiple FEHP states on a variety of oligomer lengths, is found to depend primarily on the field strength required for the state to cross the fluorescent state. The rate of decay to these dark FEHP states is then calculated from Marcus theory, which is modified to take into account dielectric in addition to other bulk measurement considerations. The results predict that individual molecules go from being emissive to fully quenched over a small range of applied field strengths. Phenomenological introduction of inhomogeneous broadening for the energies of the FEHP states leads to a more gradual dependence on applied field. The fluorescence quenching mechanism considered here is found to be important for applied fields above about 1 MV cm(-1), which is similar in magnitude to those present in light-emitting diodes.

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Electric Field Induced Fluorescence Modulation of Single Molecules in PMMA Based on Electron Transfer

Cited by 10 publications

References 32 publications

Cyclodextrin Insulation Prevents Static Quenching of Conjugated Polymer Fluorescence at the Single Molecule Level

Cyclodextrin Insulation Prevents Static Quenching of Conjugated Polymer Fluorescence at the Single Molecule Level

Toward a Realistic Modeling of the Photophysics of Molecular Building Blocks for Energy Harvesting: The Charge-Transfer State in 4,7-Dithien-2-yl-2,1,3-benzothiadiazole As a Case Study

Modeling Field-Induced Quenching in Poly(p-phenylene vinylene) Polymers and Oligomers

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