Papers by Author: Gee Keun Chang

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Authors: Gee Keun Chang
Abstract: With new models of AM1 solar spectra and Si refractive indices in the wavelength range of 0.4  0.97  , effective absorption powers of Si solar cells coated with the single and double AR layers were theoretically calculated for the first time. The SiO2, Si3N4 and SiO2/Si3N4 easily obtainable in the standard Si process were used as the AR layers of Si solar cell. Optimum thicknesses showing the maximum absorption power for AR layers of SiO2, Si3N4 and SiO2/Si3N4 were as follows: d(SiO2)=10001, d(Si3N4)=7001 and d(SiO2/Si3N4) =500 1 /3001 . Effective absorption powers in the solar cells of SiO2-Si, Si3N4-Si and SiO2/Si3N4-Si were 520W/m2, 565W/m2 and 607W/m2 at AM1 in the optimum conditions of AR coating, respectively
1013
Authors: Jae Hyouk Yoo, Ho Jung Chang, Su Cheol Gong, In Jae Baek, Hyun Seong Lim, Gee Keun Chang, Young Chol Chang, Hee Joon Kim
Abstract: Polymer light emitting diodes (PLEDs) with ITO/PEDOT:PSS/MEH-PPV/LiF/Al structures were prepared by spin coating method on the patterned ITO(indium tin oxide)/glass substrates. MEH-PPV [Poly(2-methoxy-5(2-ethylhexoxy)-1,4-phenylenevinyle)] and PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)] polymers were used as the light emitting and hole transport materials. The dependence of the plasma treatment of ITO anode films on the optical and electrical properties of the PLEDs was investigated. The sheet resistances increased with increasing the plasma intensities from 40W to 300W in RF power. In contrast, the surface roughness was improved as the plasma intensity increased. The maximum current density and luminance were found to be about 97.5 mA/ and 55 cd/m2 at 8 V for the PLED sample coated on ITO/glass substrate with plasma treatment of 100W for 30s under 40 mtorr O2 pressure.
1699
Authors: Jae Hyouk Yoo, Su Cheol Gong, In Jae Baek, Hyun Seong Lim, Sang Baie Shin, Young Chol Chang, Gee Keun Chang, Ho Jung Chang
Abstract: Polymer light emitting diodes (PLEDs) with ITO/PEDOT:PSS/PVK/PFO-poss/LiF/Al structure were prepared by spin coating method on the plasma-treated ITO(indium tin oxide)/glass substrates. PVK(N-vinylcabozole) and PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)] polymers were used as hole injection and transport materials. As blue light emitting material, PFO-poss(poly(9,9-dioctylfluorence) polymer was used. The dependence of the plasma treatment of ITO films on the optical and electrical properties of the PLEDs was investigated. The sheet resistance of ITO films increased slightly with increasing the plasma intensity from 20W to 300W in RF power. In contrast, the surface roughness was improved as the plasma intensity increased. The maximum current density and luminance were about 20 mA/cm2 and 250 cd/m2 at 9 V for the PLED sample coated on ITO/glass substrate with plasma treatment of 100W for 30s under 40 mtorr O2 pressure. The maximum emission spectrum of the PLEDs was 441 nm showing blue color.
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