• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1018-1021
• /
• 2003

We have synthesized poly(3-hexylthiophene) and studied the optical properties of P3HT for applying to the red emitting materials of organic electroluminescent device. Usually, an organic EL device is composed of single layer like anode/emitting layer/cathode, but additional layer such as hole transport, electron transport and buffer layer is deposited to improve device efficiency. In this study, Multilayer EL devices were fabricated using tris(8-hydroxyquinolinate) aluminum($Alq_3$) as electron transport material, (N,N'-diphenyl-N,,N'(3-methylphenyl)-1,1'-biphenyl-4,4'diamine))(TPD) as hole transport/electron blocking materials and LiF as buffer layer. That is, a device structure of ITO/blending layer(TPD+P3HT)/$Alq_3$/LiF/Al was employed. In the Multilayer device, the luminance of $10{\mu}W/cm^2$ obtained at 10V. And, we present the experimental evidence of the enhancement of the Foster energy transfer interaction in emitting layer.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.492-495
• /
• 2008

Efficient top-emitting organic light-emitting diodes were fabricated using copper iodide (CuI) doped NPB as a p-doped hole injection layer to improve hole injection from a silver bottom electrode. The enhanced hole injection is originated from the formation of the charge transfer complex between CuI and NPB. The devices result in high efficiency of 69 cd/A with almost Lambertian emission pattern.

• The Research Journal of the Costume Culture
• /
• v.25 no.6
• /
• pp.880-892
• /
• 2017

In this study, the appearance change and the heat moisture transfer properties of knitted fabric by yarn shrinkage were examined to obtain useful data on the development of thermo-sensitive functional materials. Eleven types of knitted fabric were knitted using highly bulky acrylic-blended yarn. After shrinking the specimens using dry heat treatment, the appearance change and thickness were measured. An HEC simulator was adopted for measuring the heat moisture transfer properties of specimens by yarn shrinkage. When holes were arranged vertically in the mesh structure, the specimens with 2,500 and 5,000 holes showed high percent change of hole area, appearance, and thickness. When holes were diagonally arranged in the mesh structure, the percent change of hole area in the specimen with 1,250 holes was larger than the one with 2,500 holes. However, the dimensional stability of the specimen with 2,500 holes was better because of its smaller appearance and thickness change. In the tuck structure, the percent change of hole area in the specimen with 625 and 416 holes was relatively large compared with the appearance and thickness change. Furthermore, the hole size in the tuck structure was smaller than that in the mesh structure but the percent change of hole area was larger. Therefore, it was proved that the tuck structure is more suitable than the mesh structure for developing thermo-sensitive functional materials. Heat moisture transfer property test verified that the change of hole area by yarn shrinkage enabled obtaining the thermal effect due to the distinct temperature difference in the inner layer.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.2
• /
• pp.288-297
• /
• 2000

This paper describes the results of an experimental investigation of the flow characteristics and the heat transfer rate on a surface by interaction of a pair of vortices. The test facility consists of a boundary-layer wind tunnel with a vortex introduced into the flow by half-delta wings(vortex generators) protruding from the surface. In order to control the strength of the two longitudinal vortices, the angles of attack of the vortex generators are varied from 20 degree to 45 degree, but spacings between the vortex generators are fixed to 4 cm. The 3-dimensional mean velocity downstream of the vortex generators is measured by a five-hole pressure probe, and the hue-capturing method using the thermochromatic liquid crystals has been used to provide the local distribution of the heat transfer coefficient. By using the method mentioned above, the following conclusions are obtained from the present experiment. The boundary layer is thinned in the regions where the secondary flow is directed toward the wall and thickened where it is directed away from the wall. The peak augmentation of the local heat transfer coefficient occurs in the downwash region near the point of minimum boundary-layer thickness. Streamwise distributions of averaged Stanton number on the measurement planes show very similar trends for all the cases(${\beta}=20^{circ},\;30^{\circ}\;and\;45^{\circ}$).

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.1
• /
• pp.165-173
• /
• 1997

The present study investigates heat/mass transfer for flow through perforated plates for application to combustor wall and turbine blade film cooling. The experiments are conducted for hole length to diameter ratios of 0.68 to 1.5, for hole pitch-to-diameter ratios of 1.5 and 3.0, for gap distance between two parallel perforated plates of 1 to 3 hole diameters, and for Reynolds numbers of 60 to 13, 700. Local heat/mass transfer coefficients near and inside the cooling holes are obtained using a naphthalene sublimation technique. Detailed knowledge of the local transfer coefficients is essential to analyze thermal stress in turbine components. The results indicate that the heat/mass transfer coefficients inside the hole surface vary significantly due to flow separation and reattachment. The transfer coefficient near the reattachment point is about four and half times that for a fully developed circular tube flow. The heat/mass transfer coefficient on the leeward surface has the same order as that on the windward surface because of a strong recirculation flow between neighboring jets from the array of holes. For flow through two perforated plate layers, the transfer coefficients on the target surface (windward surface of the second wall) affected by the gap spacing are approximately three to four times higher than that with a single layer.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.2
• /
• pp.298-305
• /
• 2000

The flow characteristics and the heat transfer rate on a surface by interaction of a pair of vortices were studied experimentally. The test facility consisted of a boundary-layer wind tunnel with a vortex introduced into the flow by half-delta wings protruding from the surface. In order to control the strength of the longitudinal vortices, the angles of attack of the vortex generators were varied from - 20 degree to - 45 degree, but spacings between the vortex generators were fixed to 4 cm. The 3-dimensional mean velocity measurements were made using a five-hole pressure probe. Heat transfer measurements were made using the thermochromatic liquid to provide the local distribution of the heat transfer coefficient. Unlike common flow down, common flow up vortices moved toward the centerline as they developed and interacted strongly with each other but not with the boundary layer. Spanwise profiles of Stanton number were similar for ${\beta}=-20^{\circ}\;and\;-35^{\circ}$, but not similar for ${\beta}=-45^{\circ}$. The case of ${\beta}=-20^{\circ}\;and\;-35^{\circ}$ showed the two peak Stanton number, but the case of ${\beta}=-45^{\circ}$ showed the only one peak Stanton number.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.784-786
• /
• 2009

Thermal transfer of emitting layer from the donor film to the substrates depends on the physical interaction between the donor film, the emitting layer, and the hole-transport layer (HTL). The interfacial adhesion between the donor film and the EML, the cohesive force of the EML, and the interfacial adhesion between the EML and the HIL have to be optimized to achieve good LITI pattern quality. It was found that surface pretreatment of the donor plate was important on the laser induced thermal transfer of the emitting layer onto the HIL layer of the OLED devices.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.6
• /
• pp.17-23
• /
• 2000

In this study, we prepared red organic light-emitting-diode(OLED) with a fluorescent dye(Sq)-doped and inserted between emission and cathode layer 1,3-bis(5-p-t-butylphenyl)-1,3,4-oxadiazol-2-yl)benzene (OXD7) or/and tris(8-hydroxyquinoline) aluminum ($Alq_3$) layers for increasing electroluminescent(EL) efficiency. This inserting effect has been observed and EL mechanism characteristics have been examined. The hole transfer layer is a N,N'-diphenyl-N,N'-bis-(3-methyl phenyl)-1,1'-diphenyl-4,4'-diamine (TPD), and the host and guest materials of emission layer is $Alq_3$ and bis[1-methyl-3,3'-dimethyl-2-indorindiylmethyl] squaraine (Sq), respectively. For the inserting of $Alq_3$, emission efficiency increased. But we can not obtained highly pure red emission owing to the emission of inserting $Alq_3$ layer. The inserting of OXD7 makes hole block and accumulate. Because of increasing recombination probability of electron and hole, highly pure red color can be held. Simultaneously brightness characteristics and emission efficiency could improve.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.239.2-239.2
• /
• 2016

Numerous studies and approaches have been performed for solar cells to improve their photoelectric conversion efficiencies. Among them, the study for electrode containing transparent conducting oxide (TCO) layers is one of issues as well as for the cell structure based on band theory. In this study, we focused on an interfacial layer between p-type silicon and indium tin oxide (ITO) well-known as TCO materials. According to current-voltage characteristics for the sample with the interfacial layers, the improvement of band alignment between p-type silicon and ITO was observed, and their ohmic properties were enhanced in the proper condition of deposition. To investigate cause of this improvement, spectroscopic ellipsometry and ultraviolet photoelectron spectroscopy were utilized. Using these techniques, band alignment and defect in the band gap were examined. The major materials of the interfacial layer are vanadium oxide and tungsten oxide, which are notable as a hole transfer layer in the organic solar cells. Finally, the interfacial layer was applied to silicon solar cells to see the actual behavior of carriers in the solar cells. In the case of vanadium oxide, we found 10% of improvement of photoelectric conversion efficiencies, compared to solar cells without interfacial layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.939-942
• /
• 2001

We fabricated Red Organic light-emitting devices(OLED). The Basic Device Structure is ITO/hole transfer layer, TPD(50nm)/red emitting layer, Alq3 doped with DCM2 or DCM2:rubrene(xnm)/electorn transfer layer, Alq3(50-xnm)/LiF(0.8nm)/Al(8nm) . The thickness of emitting layer(xnm) changed 5, 10, 20nm. we demonstrate red emitting OLED with dependent on the thickness and concentrators of Alq3 layer doped with DCM2 or co-doped with DCM2:ruberene. The Emission color and Brightness are changed with doping or co-doping condition, dopant concentarton. In the case of rubrene:DCM2 co-doped layer structure, the red color Purity and device efficiency is improved. The CIE index of rubrene co-doped OLED is x=0.67, y=0.31. By co-doping the Alq3 layer with DCM2, rubrene, EL efficiency improved from 0.38cd/A to 0.44cd/A in comparison whit DCM2 doped Alq3 layer.