Browsing by Author "Yang, Chung-He"

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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.
Encapsulated cores: A new approach to solution-processable phosphorescent organic light-emitting diodes based on chromophoric amphiphile/silica nanocomposite
(2007)
Yang, Chung-He
;
Hsu, Chain-Shu
;
應用化學系
;
Department of Applied Chemistry
Here we report the synthesis and characterization of cyclometallated iridium complex which emits sky-blue light. The hybrid meso-structured nanocomposites by sol-gel co-assembly with tetraethyl ortho-silicate and corresponding molecular interactions within mesopores were also demonstrated. Electroluminescent devices were fabricated using carbazole-based monomer and iridium complex as active layer, which act as host/guest system through co-assembled sol-gel process. Devices based on this nanocomposite showed improved luminescent efficiencies several times. higher than that of similar chromophore elaborated in the literature. The designed chromophoric amphiphiles can act as photonically active materials as well as structure-directing agents.
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.
Hybrid white-light emitting-LED based on luminescent polyfluorene polymer and quantum dots
(2007-08-01)
Chou, Cheng-Hsuan
;
Yang, Chung-He
;
Hsu, Chain-Shu
;
Chen, Teng-Ming
;
應用化學系
We report the fabrication and electroluminescence (EL) characterization of a white-emitting hybrid organic/inorganic light emitting device (LED) by integrating core-shell CdSe/ZnS quantum dots (QDs) acting as a yellow emitter and polyfluorenes as the blue emitter in a multilayered structure. The hybrid white-emitting device was fabricated by spin-coating QDs in varied concentrations onto the layer of polyfluorenes with different functional groups (i.e., sulfur-containing PF1 and PFO). Depending on the QDs concentrations and the design of the hybrid LED, our device is able to exhibit either electroluminescence from QDs or a combination of both PF and QD. The EL spectra at different driving voltages, I-V characteristics, and EL chromaticity of the LEDs based on PF1/QD and PFO/QD LEDs have been measured, investigated, and compared, respectively.
Solution-processable phosphorescent to organic light-emitting diodes based on chromophoric amphiphile/silica nanocomposite
(2009-08-05)
Yang, Chung-He
;
Yang, Sheng-Hsiung
;
Hsu, Chain-Shu
;
應用化學系
;
Department of Applied Chemistry
We report the synthesis of a tris-cyclometalated iridium complex which emits sky-blue light and its potential use in phosphorescent light-emitting devices. The hybrid meso-structured nanocomposites by sol-gel co-assembly with tetraethyl ortho-silicate and corresponding molecular interactions within mesopores were also demonstrated. Electroluminescent devices were fabricated using carbazole-based monomers and iridium complex as the active layer, acting as a host/guest system through a co-assembled sol-gel process. Devices based on this nanocomposite showed improved luminescent efficiencies several times higher than that of similar chromophores elaborated in the literature. A triple-layer electroluminescence device with the configuration of ITO/PEDOT/Ir(F2OC11ppy)(3):CA-C11:PBD nanocomposite/TPBI/Ca/Al showed a maximum brightness of 1389 cd m(-2) at 12 V and a maximum efficiency of 3.29 cd A(-1).
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.