Dal-Ho Kim
Hanyang University
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Featured researches published by Dal-Ho Kim.
Nanotechnology | 2009
Su-Hwan Lee; Dal-Ho Kim; Tae-Hun Shim; Jea-Gun Park
In organic photovoltaic (OPV) devices fabricated with a double small-molecular layer, the power conversion efficiency strongly depends on the thickness of the organic donor layer (here, copper phthalocyanine). In other words, the power conversion efficiency increases with the donor layer thickness up to a specific thickness ( approximately 12.7 nm) and then decreases beyond that thickness. This trend is associated with the light absorption and carrier transport resistance of the small-molecular donor layer, both of which strongly depend on the layer thickness. Experimental and calculated results showed that the short-circuit current due to light absorption increased with the donor layer thickness, while that due to current through the donor layer decreased with 1/R. Since the total short-circuit current is the product of the light absorption current and current through the donor layer, there is a trade-off, and the maximum power conversion efficiency occurs at a specific organic donor layer thickness (e.g. approximately 12.7 nm in this experiment).
Nanotechnology | 2012
Dal-Ho Kim; Jea-Gun Park
In the current study, we fabricated polymer (poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C(61) butyric-acid methyl-ester (PCBM) blend) photovoltaic (PV) cells embedded with p-type single walled carbon nanotubes (SWCNTs) with tangled hair morphology. The power conversion efficiency (PCE) rapidly increased with SWCNT concentration of up to 6.83% coverage, and then decreased and saturated with increasing SWCNT concentration; i.e., the PCE peaks at 5.379%. This tendency is mainly associated with hole transport efficiency toward the transparent electrode (indium-tin-oxide (ITO)) via SWCNTs, directly determining the series resistance and shunt resistance of the polymer PV cells embedded with SWCNTs: the PV cell is increasing shunt resistance and decreasing series resistance.
Nanotechnology | 2009
Su-Hwan Lee; Dal-Ho Kim; Ji-Heon Kim; Katoh Takeo; Gon-Sub Lee; Jea-Gun Park
For applications such as solar cells and displays, transparent single-crystal Si membranes were fabricated on a silicon-on-insulator (SOI) wafer. The SOI wafer included a buried layer of SiO2 and Si3N4 as an etch-stop layer. The etch-stop layer enabled fabrication of transparent single-crystal Si membranes with various thicknesses, and the thinning technology is described. For membranes with thicknesses of 18, 72 and 5000 nm, the respective optical transparent were 96.9%, 93.7% and 9% for R (red, lambda = 660 nm), 96.9%, 91.4% and 1% for G (green, lambda = 525 nm), and 97.0%, 93.2% and 0% for B (blue, lambda = 470 nm). Organic light-emitting diodes (OLEDs) were then fabricated on transparent single-crystal Si membranes with various top Si thicknesses. OLEDs fabricated on 18, 72 and 5000 nm thick membranes and operated at 6 V demonstrated a luminance of 1350, 443 and 27 cd m(-2) at the current densities of 148, 131 and 1.5 mA cm(-2), respectively.
Journal of Physical Chemistry C | 2009
Su-Hwan Lee; Dal-Ho Kim; Ji-Heon Kim; Gon-Sub Lee; Jea-Gun Park
Solar Energy Materials and Solar Cells | 2010
Zhen Yi Wang; Su-Hwan Lee; Dal-Ho Kim; Ji-Heon Kim; Jea-Gun Park
Synthetic Metals | 2009
Su-Hwan Lee; Dal-Ho Kim; Ji-Heon Kim; Tae-Hun Shim; Jea-Gun Park
Archive | 2008
Jae-Gun Park; Gon-Sub Lee; Su-Hwan Lee; Sung-Ho Seo; Woo-Sik Nam; Dong-Won Shin; Dal-Ho Kim; Hyun-Min Seung; Jong-Dae Lee
Journal of the Korean Physical Society | 2013
Dal-Ho Kim; Ji-Heon Kim; Yeon-Hee Hwang; Jae-Woo Shin; Jea-Gun Park
Journal of the Korean Physical Society | 2012
Dal-Ho Kim; Jea-Gun Park
Archive | 2010
Jea-Gun Park; Su-Hwan Lee; Ji-Heon Kim; Dal-Ho Kim