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111.
Inverse opal scaffolds presenting an embossed‐pattern surface are prepared from colloidal crystal assemblies of uniformly sized golf‐ball‐shaped microparticles. Post‐treatments, such as thermal annealing during the bridging of the microparticles for opal preparation, are avoided to prevent deterioration of surface patterns of the sacrificial template. This presents a new approach to increase the surface‐area‐to‐volume ratio (SAV) by the alteration of morphological features in sophisticated 3D structures that remain largely unexamined owing to difficulties in their preparation. Previous results observed in 2D surfaces that show effective performance improvement through an increase in contact area, especially in biomedical applications, also appear applicable to patterned inverse opal scaffolds based on comparable results obtained from cell cultures. As the field of application of opal and inverse opal structures is expanding due to their unique structural advantages, such as 3D interconnectivity and periodic structures, our strategy opens the door for the use of patterned surfaces on highly sophisticated 3D structures, improving their performance via an increase in SAV. 相似文献
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115.
Jeonghun Kim Jong Kwan Koh Byeonggwan Kim Sung Hoon Ahn Hyungju Ahn Du Yeol Ryu Jong Hak Kim Eunkyoung Kim 《Advanced functional materials》2011,21(24):4633-4639
An iodine‐free solid‐state dye‐sensitized solar cell (ssDSSC) is reported here, with 6.8% energy conversion efficiency—one of the highest yet reported for N719 dye—as a result of enhanced light harvesting from the increased transmittance of an organized mesoporous TiO2 interfacial layer and the good hole conductivity of the solid‐state‐polymerized material. The organized mesoporous TiO2 (OM‐TiO2) interfacial layer is prepared on large‐area substrates by a sol‐gel process, and is confirmed by scanning electron microscopy (SEM) and grazing incidence small‐angle X‐ray scattering (GISAXS). A 550‐nm‐thick OM‐TiO2 film coated on fluorine‐doped tin oxide (FTO) glass is highly transparent, resulting in transmittance increases of 8 and 4% compared to those of the bare FTO and conventional compact TiO2 film on FTO, respectively. The high cell performance is achieved through careful control of the electrode/hole transport material (HTM) and nanocrystalline TiO2/conductive glass interfaces, which affect the interfacial resistance of the cell. Furthermore, the transparent OM‐TiO2 film, with its high porosity and good connectivity, exhibits improved cell performance due to increased transmittance in the visible light region, decreased interfacial resistance ( Ω ), and enhanced electron lifetime ( τ ). The cell performance also depends on the conductivity of HTMs, which indicates that both highly conductive HTM and the transparent OM‐TiO2 film interface are crucial for obtaining high‐energy conversion efficiencies in I2‐free ssDSSCs. 相似文献
116.
Kum Hee LeeJae Nam You Jiyeon WonJin Yong Lee Ji Hoon SeoYoung Kwan Kim Seung Soo Yoon 《Thin solid films》2011,520(1):95-100
This paper reports the synthesis and electroluminescent properties of a series of blue emitting materials with arylamine and diphenylvinylbiphenyl groups for applications to efficient blue organic light-emitting diodes (OLEDs). All devices exhibited blue electroluminescence with electroluminescent properties that were quite sensitive to the structural features of the dopants in the emitting layers. In particular, the device using dopant 4 exhibited sky-blue emission with a maximum luminance, luminance efficiency, power efficiency, external quantum efficiency and CIE coordinates of 39,000 cd/m2, 12.3 cd/A, 7.45 lm/W, 7.71% at 20 mA/cm2 and (x = 0.17, y = 0.31) at 8 V, respectively. In addition, a blue OLED using dopant 2 with CIE coordinates (x = 0.16, y = 0.18) at 8 V exhibited a luminous efficiency, power efficiency and external quantum efficiency of 4.39 cd/A, 2.46 lm/W and 2.97% at 20 mA/cm2, respectively. 相似文献
117.
Jae Kwan Lee Ue Jin LeeMyung-Ki Kim Sang Ho LeeKyung-Tae Kang 《Thin solid films》2011,519(16):5649-5653
The direct writing approach of poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) composite from bulk-heterojunction (BHJ) solar cell was efficiently addressed by inkjet printing technology using conventional chlorobenzene ink solution. The structure of inkjet-printed P3TH:PCBM BHJ film was fabricated by the repetitive direct writing of new line overlapped partially on former line. The best structure of P3HT:PCBM film for BHJ solar cell was observed from inkjet printing condition of around 50% of droplet overlaps with 2 wt.% BHJ ink at 25 °C of substrate temperature. The maximum power conversion efficiency reached 2.83% with an open circuit voltage of 0.62 V, a short circuit current density of 8.60 mA/cm2, and a fill factor of 0.53 under air mass 1.5 G irradiation (100 mW/cm2). 相似文献
118.
Ji Hoon Seo Jung Sun Park Suk Jae Lee Bo Min Seo Kum Hee Lee Jung Keun Park Seung Soo Yoon Young Kwan Kim 《Journal of Mechanical Science and Technology》2011,25(1):17-19
The authors demonstrated phosphorescent white organic light-emitting diodes (PHWOLED) with mixed electron transporting layers
(M-ETL) using 4,7-diphenyl-1,10-phenanthroline (BPhen)/4,4′-bis (carbazol-9-yl)biphenyl (CBP). The M-ETL PHWOLED exhibited
the optimum balance of holes and electrons, owing to the low electron mobility of the CBP M-ETL. The optimized PHWOLED showed
a peak current efficiency of 16.85 cd/A and a peak external quantum efficiency of 7.32%. 相似文献
119.
Abhilash Suryan Yong Kwan Yoon Dong Sun Kim Heuy Dong Kim 《Journal of Mechanical Science and Technology》2011,25(4):839-845
Increasing power demands have necessitated the development of energy efficient systems in the industrial sector. At present,
about 10% of the overall electric power used by large industrial plants is consumed by high-capacity compressors supplying
compressed air. Likewise, in a gas turbine power plant, nearly half the generated power is used for driving the compressor.
The work of compression is proportional to inlet air temperature, and cooling the inlet air can save considerable amount of
power in large turbo machines during hot summer months. Inlet fogging is a popular means of inlet air cooling, and fog nozzles
are the most critical components in an inlet fogging installation. Majority of these installations employ impaction pin nozzles.
In the present work, experiments are conducted over a wide range of operating parameters in variable length wind tunnels of
different cross sections in order to investigate the performance of impaction pin nozzle in inlet fogging. Flow visualization
and measurements are carried out to analyze the fog behavior and identify suitable nozzle locations in typical air ducts.
The results show that impaction pin nozzles are suitable for inlet fogging applications. 相似文献
120.
Highly Fluorescent and Color‐Tunable Exciplex Emission from Poly(N‐vinylcarbazole) Film Containing Nanostructured Supramolecular Acceptors
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Jong H. Kim Byeong‐Kwan An Seong‐Jun Yoon Sang Kyu Park Ji Eon Kwon Chang‐Keun Lim Soo Young Park 《Advanced functional materials》2014,24(19):2746-2753
Highly fluorescent excited‐state charge‐transfer complexes (exciplexes) formed at the interfacial region between a polymeric donor matrix, here, poly(N‐vinylcarbazole), and embedded nanostructured acceptors are characterized for their photophysical properties. Exciplex‐to‐exciton emission switching is observed after solvent vapor annealing (SVA) due to the size evolution of the nanostructures beyond the exciton diffusion length. Color‐tunable exiplex emission (sky blue, green, and orange) is demonstrated for three different nanostructured acceptors with the same HOMO–LUMO gap (i.e., the same blue excitonic emission) but with different electron affinity. White‐emitting poly(N‐vinylcarbazole) film is also fabricated, simply by incorporating mixed supramolecular acceptors, which provide independent exciplex emissions. This study presents important insights into the excited‐state intermolecular interaction at the well‐defined nanoscale interface and suggests an efficient way to obtain multicolored exciplex emissions. 相似文献