White-emitting conjugated polymer nanoparticles with cross-linked shell for mechanical stability and controllable photometric properties in color-conversion LED applications
Author
Park, Eun-Ju
Erdem, T.
Ibrahimova, V.
Nizamoglu, S.
Demir, Hilmi Volkan
Tuncel, D.
Date
2011Source Title
ACS Nano
Print ISSN
1936-0851
Electronic ISSN
1936-086X
Volume
5
Issue
4
Pages
2483 - 2492
Language
English
Type
ArticleItem Usage Stats
161
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Abstract
We report on the synthesis and characterization of water-dispersible, mechanically
stable conjugated polymer nanoparticles (CPNs) in shelled architecture with tunable emission and
controllable photometric properties via cross-linking. Using a reprecipitation method, whiteemitting polymer nanoparticles are prepared in different sizes by varying the concentration of
polymer; the emission kinetics are tuned by controlling the shell formation. For this purpose,
polyfluorene derivatives containing azide groups are selected that can be decomposed under UV
light to generate very reactive species, which opportunely facilitate the inter- and intra-cross-linking
of polymer chains to form shells. Nanoparticles before and after UV treatment are characterized by
various techniques. Their size and morphologies are determined by using dynamic light scattering
(DLS) measurements and imaging techniques including scanning electron microscopy (SEM) and
atomic force microscopy (AFM). For optical characterization, UV vis and steady-state and timeresolved fluorescent spectroscopies are performed. Solid-state behaviors of these CPNs are also
investigated by forming films through drop-casting. Moreover, the photometric calculations are also
performed for films and dispersions to determine the color quality. A device has been constructed to
show proof-of-principle white light generation from these nanoparticles. Additionally, mechanical
stability studies are performed and demonstrated that these nanoparticles are indeed mechanically
stable by removing the solvent after cross-linking using a freeze-dryer and redispersing in water and
THF. Optical and imaging data confirm that the redispersed particles preserve their shapes and sizes
after cross-linking.
Keywords
Color conversionConjugated polymer nanoparticles
Cross-linked shell
White light emission
Azide group
Before and after
Color conversions
Color quality
Conjugated polymer nanoparticles
Cross-linked shells
Different sizes
Drop-casting
Emitting polymers
Imaging data
Mechanically stable
Optical characterization
Photometric properties
Polyfluorene derivative
Polymer chains
Polymer nanoparticles
Proof of principles
Reactive species
Reprecipitation methods
SEM
Shell formation
State behavior
Time-resolved fluorescent spectroscopy
Tunable emissions
UV light
UV treatment
Water dispersible
White light emission
White-light generation
Atomic force microscopy
Casting
Color
Dynamic light scattering
Imaging techniques
Light emission
Mechanical properties
Mechanical stability
Nanoparticles
Photometry
Scanning electron microscopy
Shells (structures)
Conjugated polymers
Permalink
http://hdl.handle.net/11693/21952Published Version (Please cite this version)
http://dx.doi.org/10.1021/nn103598qCollections
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