Kyeong K Lee

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A new low-band gap polymer containing thiophene and cyclopentadiene, poly(5,2,2'-dioctyldithio-phenylcyclopentadiene) (PDTCP), has been synthesized via the FeCl3 oxidative polymerization. PDTCP showed a broad absorption band and a low energy band gap of 1.82 eV. The photoluminescence (PL) of PDTCP is completely quenched upon addition of PCBM indicative of(More)
The acetylene reduction assay for the measurement of N(2) fixation in a water-saturated paddy soil is limited by the slow diffusion of acetylene and ethylene. In laboratory incubation tests, vigorous shaking after the assay period is needed to release ethylene into the gas within the assay vials. Shaking prior to the incubation is also effective for(More)
A promising possibility for the quantitative analysis of X-ray absorption near edge structure (XANES) spectra of nanosized electrode materials is demonstrated. We used a 2D map representation technique, which utilizes the values of the first derivatives of the absorbance with respect to the inserted Li(+) content plotted over the two-dimensional space(More)
A series of fluorene-thiophene-based pi-conjugated copolymers, PFT2, PFT4, and PFT2BP, have been synthesized using the Suzuki coupling reaction. Compared to PFT2 and PFT2BP, PFT4 film showed clearly red-shifted UV-visible absorption and photoluminescence (PL) spectra with maxima at 474 and 597 nm, respectively. The optical and electrochemical properties of(More)
The regioregular hexyl-substituted poly(3,4-ethylenedioxy-2-thiophenylthiophene) (PEDOTt), structurally alternating copolymer of EDOT and thiophene, was synthesized via the Grignard Metathesis (GRIM) using catalytic amounts of Ni(dppp)Cl2. The products were characterized by 1H NMR spectroscopy, UV-vis spectroscopy and XRD. The alkyl-substituted conjugated(More)
In order to increase the solubility of PEDOT, we introduced an alkyl chain into polymer backbone. Depending on the position of the alkyl bond, the steric hindrance between the alkyl chains can also leads to regioregularity in the polymer. The regioregular polymers can easily occur self-assembly, both in solution and in the solid state, resulting in highly(More)
An electron-transporting triazole (Tz) unit was introduced into the fluorene-thiophene-based copolymer backbone via a Suzuki coupling reaction. The resulting copolymer, poly[9,9'-dioctyl-fluorene-co-5, 5-(4', 7'-di-2-thienyl-2', 1',3'-benzothiadiazole)-co-(4-(4-butyl-phenyl)-3, 5-diphenyl-4H-1,2,4]triazole)] (PF3TBTz), was soluble in common organic solvents(More)
New conjugated polymers based on benzo[1,2-b:4,5-b']dithiophene, poly(benzo[1,2-b:4,5-b'] dithiophene-alt-bithiophene) (PBT-2T) and poly(benzo[1,2-b:4,5-b']dithiophene-alt-terthiophene) (PBT-3T), have been synthesized via the Stille coupling reaction and their optical and electrochemical properties were characterized by UV-vis, photoluminescence (PL) and(More)
A white light-emitting diode was fabricated by preparing multilayer emitting films with an inserted buffer layer. The device structures are ITO/PEDOT:PSS/Emissive layer/LiF/Al. The emissive layer comprises a yellow-emitting layer of Poly[9,9-dioctylfluorenyl-2,7-diyl]-co-1,4-benzo-(2,1,3)-thiadiazole (F8BT), a blue-emitting layer of(More)