Exciton dissociation dynamics in a conjugated polymer containing aggregate states

Haugeneder, A.; Lemmer, Uli; Scherf, Ullrich

doi:10.1016/s0009-2614(01)01343-4

Cited by 40 publications

(17 citation statements)

References 26 publications

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“…Conversely, the PFO NPs showed a QY value of 51.8%, which was lower than that of the free polymer chains in good solvent (63.1%). This reduction in emission efficiency was attributed to aggregation-induced depopulation of excitons resulting in quenching. , The QY of the as-prepared PFO NPs was higher than that reported for PFO NPs (40%), owing to residual THF in the mixture.…”

Section: Resultsmentioning

confidence: 74%

“…Furthermore, certain unique fluorescence properties, arising from the discrete structure of oligomers, show promise for applications in sensing, imaging, antibacterial agents, drug/gene delivery, and controlled release. − Nevertheless, both conjugated polymers and oligomers suffer from aggregation-caused quenching (ACQ) when transferred from solution to a nanoparticle (NP) form or a solid film. This effect is attributed to aggregation-induced depopulation of excitons. , The ACQ problem greatly reduces the emission efficiency of such materials and restricts their applications in the solid state.…”

Section: Introductionmentioning

confidence: 99%

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Ultrabright Fluorescent Silica Nanoparticles Embedded with Conjugated Oligomers and Their Application in Latent Fingerprint Detection

Zhang

Liu

Cui

et al. 2017

ACS Appl. Mater. Interfaces

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Fluorescent micro- and nanosized particles have a broad range of applications in biology, medicine, and engineering. For these uses, the materials should have high emission efficiency and good photostability. However, many organic fluorophores suffer from aggregation-induced quenching effects and photobleaching. Here, we used a simple method based on covalently blending a fluorescent conjugated oligomer with silica nanoparticles to achieve emission quantum yields as high as 97%. The resulting system also showed excellent stability under continuous light illumination, in a range of pH values and temperatures, and in common solvents. This fluorescent material showed outstanding properties, including highly efficient blue emission, low cost, low toxicity, and easy synthesis. Furthermore, its effectiveness for latent fingerprint detection was demonstrated as a proof of concept on various substrates. The obtained emissive fingerprint powder gave good optical/fluorescent images with high contrast and resolution between the ridges and spaces.

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Section: Resultsmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Ultrabright Fluorescent Silica Nanoparticles Embedded with Conjugated Oligomers and Their Application in Latent Fingerprint Detection

Zhang

Liu

Cui

et al. 2017

ACS Appl. Mater. Interfaces

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“…A key acquisition of these conjugated polymers is the capability of their nanoparticle formation resulting in increased dispersibility in water, low toxicity, and reduced sensitivity of the optical features to environmental changes such as thin film formation . However, the problem of significant decrease in the quantum yield (QY) after solution to nanoparticle (NP) and film transition, which is attributed to the aggregate-induced depopulation of the excitons, − still persists and strongly restricts the use of conjugated polymers in solid film.…”

mentioning

confidence: 99%

High-Stability, High-Efficiency Organic Monoliths Made of Oligomer Nanoparticles Wrapped in Organic Matrix

et al. 2016

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Oligomer nanoparticles (OL NPs) have been considered unsuitable for solid-state lighting due to their low quantum yields and low temperature stability of their emission. Here, we address these problems by forming highly emissive and stable OL NPs solids to make them applicable in lighting. For this purpose, we incorporated OL NPs into sucrose matrix and then prepared their all-organic monoliths. We show that wrapping the OL NPs in sucrose significantly increases their quantum yield up to 44%, while the efficiency of their dispersion and direct solid-film remain only at ∼6%. We further showed ∼3-fold improved temperature stability of OL NP emission within these monoliths. Our experiments revealed that a physical passivation mechanism is responsible from these improvements. As a proof-of-concept demonstration, we successfully employed these high-stability, high-efficiency monoliths as color converters on a blue LED chip. Considering the improved optical features, low cost, and simplicity of the presented methodology, we believe that this study holds great promise for a ubiquitous use of organic OL NPs in lighting and possibly in other photonic applications.

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“…Also, the presence of interchain coupled states induces an efficient energy transfer from higher energy intrachain singlet excitons to lower lying eigenstates that are delocalized over several polymer chains in intimate contact with each other (through dispersive relaxation processes). However, such aggregate-induced depopulation of the initially excited intrachain excitons also undesirably result in a significant red shift in the emission band, accompanied with a substantial reduction in the fluorescence quantum efficiency (Φ PL ) of typically more than 50% in the film state [7][8][9][10][11]. In this work, to address this problem, we propose and demonstrate the formation of organic nanoparticles (NPs) from π -conjugated polymers to exhibit higher fluorescence quantum efficiencies and reduced shifts in their emission bands in their NP films compared to their polymer thin films without forming NPs.…”

mentioning

confidence: 99%

Quantum efficiency enhancement in film by making nanoparticles of polyfluorene

Huyal¹,

Özel²,

Tuncel³

et al. 2008

Opt. Express

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Abstract:We report on conjugated polymer nanoparticles of polyfluorene that were formed to exhibit higher fluorescence quantum efficiency in film (68%) and reduce undesired emission peak wavelength shifts in film (by 20 nm), compared to the solid-state polymer thin film made directly out of the same polymer solution without forming nanoparticles. Using the facile reprecipitation method, solutions of poly[9,9-dihexyl-9H-fluorene] in THF were added at different volume ratios to obtain different size distributions of nanoparticle dispersions in water. This allowed us to control the sizedependent optical emission of our polyfluorene nanoparticles. Such organic nanoparticles hold great promise for use as efficient emitters in optoelectronic device applications.

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Exciton dissociation dynamics in a conjugated polymer containing aggregate states

Cited by 40 publications

References 26 publications

Ultrabright Fluorescent Silica Nanoparticles Embedded with Conjugated Oligomers and Their Application in Latent Fingerprint Detection

Ultrabright Fluorescent Silica Nanoparticles Embedded with Conjugated Oligomers and Their Application in Latent Fingerprint Detection

High-Stability, High-Efficiency Organic Monoliths Made of Oligomer Nanoparticles Wrapped in Organic Matrix

Quantum efficiency enhancement in film by making nanoparticles of polyfluorene

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