Browsing by Author "Duvail, Jean-Luc"

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Induced Chain Alignment of Conjugated Polymers Within Nanoporous Template
(2011-07-22)
Lo, Kuan-Hsin
;
Ho, Rong-Ming
;
Liao, Yung-Ming
;
Hsu, Chain-Shu
;
Massuyeau, Florian
This work presents a simple method to generate ordered conjugated polymer nanoarrays through a pore-filling process for nanoporous polymer templates so as to enhance the efficiency of photoluminescence (PL). PL results combined with the morphological evolution examined by scanning probe microscopy revealed that the enhanced PL reaches maximum intensity as the template pores are completely filled by conjugated polymers. Polarized PL spectroscopy and grazing incidence Fourier transform infrared spectroscopy were used to determine the chain orientation of templated conjugated polymer; the spectroscopic results indicate a parallel chain orientation along the cylindrical direction of nanopores. The induced alignment of the polymer chains is attributed to a nanoscale spatial effect that increases the PL intensity and the lifetime of the conjugated polymer. The enhanced luminescence of nanostructured conjugated polymers is highly promising for use in designing luminescent nanodevices.
Luminescence Enhancement of Pyrene/Dispersant Nanoarrays Driven by the Nanoscale Spatial Effect on Mixing
(2013-02-05)
Lo, Kuan-Hsin
;
Li, Ming-Chia
;
Ho, Rong-Ming
;
Zhao, Yuan-Chun
;
Massuyeau, Florian
This work presents a simple method to generate ordered chromophore/dispersant nanoarrays through a pore-filling process for a nanoporous polymer template to enhance chromophore luminescence. Fluorescence results combining with the morphological evolution examined by scanning probe microscopy reveal that the enhanced luminescence intensity reaches the maximum intensity as the nanopores of the template are completely filled by the chromophore/dispersant mixture. The variation is attributed to nanoscale spatial effect on the enhanced mixing efficiency of chromophore and dispersant, that is, the alleviation of self-quenching problem, as evidenced by the results of attenuated total reflection Fourier transform IR spectroscopy combining with grazing incident wide-angle X-ray diffraction. The enhanced luminescence of the chromophore/dispersant nanoarrays driven by the nanoscale spatial effect is highly promising for use in designing luminescent nanodevices.
Preservation of Photoluminescence Efficiency in the Ordered phases of Poly(2,3-diphenyl-1,4-phenylenevinylene) via Disturbing the Intermolecular pi-pi Interactions with Dendritic Aliphatic Side Chains
(2012-06-12)
Wu, Yu-Chun
;
Ren, Xiang-Kui
;
Chen, Er-Qiang
;
Lee, Hsun-Mei
;
Duvail, Jean-Luc
To understand the relation between the solid-state phase structures and the photophysical properties of poly(2,3-diphenyl-1,4-phenylenevinylene) (DP-PPV) derivatives, three DP-PPV derivatives, P1-P3, were designed, synthesized via Gilch polymerization and characterized. Among the polymers, PI is a reported highly emissive poly(2,3-diphenyl-5-hexyl-p-phenylenevinylene), and P2 and P3 are novel DP-PPV derivatives, which are purposely designed to bear hydrophobic and hydrophilic Percec-type dendrons as side chains. The bulkiness and hydrophobic hydrophilic natures of the side chains show strong effects on photophysical properties of the polymers. The solutions and as-casted films of P1-F3 all show remarkably high photoluminescence (PL) efficiency (Phi(PL)) (>80% in chloroform solution, and >63% for the as-casted films). However, Phi(PL) of P1 and P3 decrease significantly to 30% after cooled their polymer melts to room temperature. Through the phase behavior analysis by differential scanning calorimetry (DSC), and phase structure analysis by wide-angle X-ray diffraction (WAXD), the decrease of Phi(PL) can be elucidated and attributed to the ordering of the solid-state structures of PI and P3. To our surprise, Phi(PL) of P2 is preserved even in an ordered solid-state phase, and it is insensitive to the structural ordering. Structural analysis of P2 revealed that the aliphatic dendritic side chains of P2 effectively disturbing the intermolecular pi-pi interactions among the conjugated backbones, which allows the preservation of Phi(PL) in the environment with ordered packing of DP-PPV molecules. The results of time-resolved PL decay experiments also confirmed that P2 possesses long-lived decay time because of excitons confined more effectively for emissive relaxation.