Browsing by Author "Bhongale, Chetan Jagdish"

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Bergman cyclopolymerization within the channels of functional hybrid nanocomposites formed by co-assembly of silica and polymerizable surfactant monomer
(2006)
Bhongale, Chetan Jagdish
;
Yang, Chung-He
;
Hsu, Chain-Shu
;
應用化學系
;
Department of Applied Chemistry
The Bergman cyclopolymerization of polymerizable surfactant monomer was carried out within the hexagonal channels of functional hybrid nanocomposite formed by co-assembly with silica.
Fabrication of hybrid chromophoric amphiphile/silica nanocomposite-based light emitting devices with enhanced performance
(2007)
Yang, Chung-He
;
Bhongale, Chetan Jagdish
;
Liao, Yung-Ming
;
Hsu, Chain-Shu
;
應用化學系
Organic semiconductors show efficient electroluminescence which has led to their commercialization in light-emitting diodes (LEDs), however, they have been marred by the thorniest problem of solid-state quenching. Here, we report the synthesis and characterization of two fluorene-based blue amphiphile emitters containing triphenylamine or anthracene side groups and demonstrate formation of their hybrid meso-structured nanocomposites by sol - gel co-assembly with tetraethyl orthosilicate; and study the molecular interactions within the mesophases formed. The chromophore amphiphiles designed act as photonic active materials as well as structure-directing agents. The new blue luminescent fluorene-based amphiphile/silica co-assembled nanocomposite films have been successfully prepared with enhanced emission. Different kinds of light emitting devices based on these nanocomposites show efficiencies which are improved by several times compared with the corresponding pristine chromophore amphiphiles.
Relaxation Dynamics and Structural Characterization of Organic Nanobelts with Aggregation-Induced Emission
(1970-01-01)
Chang, Chih-Wei
;
Bhongale, Chetan Jagdish
;
Lee, Chi-Shen
;
Huang, Wei-Kai
;
Hsu, Chain-Shu
"We prepared the fluorescent nanobelts of cyano-substituted 1,4-distyrylbenzene derivative (CNDSB) with the reprecipitation method. CNDSB is nonemissive in solution but with strong aggregation-induced emission (AIE) in belt-like structure. The molecular structure predicted by quantum chemical calculations indicates a twisted conformation of CNDSB monomer, while the solid-state X-ray structure of the CNDSB crystal features herringbone-type arrangement and three benzene rings arrange in nearly planar conformation. Femto- and picosecond time-resolved fluorescence spectroscopy are implemented to study the photophysics and the origin of the ME effect in CNDSB nanobelts. The fluorescence quenching of CNDSB in THF solution arises from the efficient nonradiative isomerization channel. In this study, the fluorescence decay of CNDSB embedded in poly(methyl methacrylate) matrix is slowed down due to the restriction of intra:molecular motions in the solid matrix. In nanobelt structure, the fluorescence lifetime further increases due to the intermolecular interaction between H-type aggregates. Both the steady-state and time-resolved studies suggests that there are at least two different packing structures might exist in nanobelts, and the relative composition of these two different structures gradually changes in different sizes of nanobelts."
Synthesis and light emitting properties of sulfide-containing polyfluorenes and their nanocomposites with CdSe nanocrystals: A simple process to suppress keto-defect
(2007-01-05)
Yang, Chung-He
;
Bhongale, Chetan Jagdish
;
Chou, Cheng-Hsuan
;
Yang, Sheng-Hsiung
;
Lo, Chih-Nan
A new series of sulfide-containing polyfluorene homopolymers and copolymers (PFS, PF1, PF3 and PF4) comprising 9,9-di[11-(decylsulfanyl)undecyl] fluorene, 9,9-dihexylfluorene, triphenylamine or benzothiadiazole moieties were synthesized by Ni(O)-mediated Yamarnoto-coupling and palladium-catalyzed Suzuki polymerizations. Three other polyfluorenes (PF2, PF5 and PFC6) without sulfur atom in the alkyl side chains were also synthesized by a similar method for comparison purpose. These fluorene-based polymers were characterized using Ff-IR spectroscopy, elemental analysis, DSC, TGA, photoluminescence (PL) and electroluminescence (EL) spectroscopies. The synthesized polymers PFS and PF1-PF3 emit blue light at around 440-468 nm, while copolymers PF4 and PF5 emit green light at around 540 nm. In annealing experiments, these polymer films show better stability against thermal oxidation than polymer PFC6. Sulfide-containing polymers show not only good electroluminescent color stability, but their EL spectra also remain unchanged at high driving voltage. A multi-layer electroluminescent device with the configuration of ITO/PEDOT/PF1/CsF/A1 exhibited a stable sky-blue emission with color coordinates (0.21, 0.23) at 10 V, which showed a maximum brightness of 2991 cd/m(2) at 8 V (75 mA/cm(2)) and a maximum efficiency of 1.36 cd/A. Finally, by ligand exchange process, the sulfur element could form coordination bonding with quantum dots, and PLED devices using these new QDs-containing organic/inorganic hybrid materials as light-emitting layers exhibit superior or comparable EL performance compared to those without quantum dots. (c) 2006 Elsevier Ltd. All rights reserved.