• Title/Summary/Keyword: hole transport

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Solvent-vapor surface treatment induced performance improvement of organic solar cells

  • Kim, Chang-Su;Kang, Jae-Wook;Kim, Do-Geun;Kim, Jong-Kuk
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2011.05a
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    • pp.42-43
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    • 2011
  • Improvement of the photovoltaic efficiency via exposure of organic solar cells to solvent-vapor at room temperature is reported. Carbon disulfide ($CS_2$) vapor treatment can induce Poly(3-hexylthiophene) (P3HT) self-organization into ordered structure leading to enhanced hole transport and light absorption. The power conversion efficiency (PCE) of the organic solar cells can be increased from 0.89 to 1.67% by solvent-vapor treatment.

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Surface characteristics of ITO treated with $UV/O_3-O_3$ and OLED device properties ($UV/O_3$$O_3$로 처리된 ITO의 표면 특성과 OLED 소자 특성)

  • Kim, Il;You, D.H.;Park, G.B.;Yuk, J.H.;Park, J.K.;Jo, G.S.;Lee, D.C.
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1361-1362
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    • 2006
  • In this research We investigated the effect of UV/O3, $O_3$ treatments of Indium-tin oxide(ITO) surface on the performance of organic light emitting devices(OLEDs). The fundamental structure of OLEDs was ITO(anode) / TPD(Hole Transport Layer) / $Alq_3$ / Al(cathode). We performed UV/O3, $O_3$ treatments and found that both treatments enhanced the performance of OLEDs. Current-Voltage, Luminance-Voltage characteristics were measured at room temperature.

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Measurement of Drifting Mobility and Transit Time of Holes and Electrons in Stabilized a-Se Film

  • Kim, Jae-Hyung;Park, Chang-Hee;Nam, Sang-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.362-363
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    • 2007
  • The transport property of stabilized amorphous selenium typical of the material used in direct conversion x-ray imaging devices was studied using the moving photo-carrier grating (MPG) technique and time-of-flight (TOF) measurements. For MPG measurement, the electron and hole mobility, and recombination lifetime of a-Se films with arsenic (As) additions have been obtained. For TOF measurement, a laser beam with pulse duration of 5ns and wavelength of 350 nm was illuminated on the surface of a-Se with thickness of $400{\mu}m$.

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Effects of Hole Transport Layer Using Au-ionic Doping SWNT on Efficiency of Organic Solar Cells

  • Min, Hyung-Seob;Jeong, Myung-Sun;Choi, Won-Kook;Kim, Sang-Sig;Lee, Jeon-Kook
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.434-434
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    • 2012
  • Despite recent efforts for fabricating flexible transparent conducting films (TCFs) with low resistance and high transmittance, several obstacles to meet the requirement of flexible displays still remain. Indium tin oxide (ITO) thin films, which have been traditionally used as the TCFs, have a serious obstacle in TCFs applications. SWNTs are the most appropriate materials for conductive films for displays due to their excellent high mechanical strength and electrical conductivity. Recently, it has been demonstrated that acid treatment is an efficient method for surfactant removal. However, the treatment has been reported to destroy most SWNT. In this work, the fabrication by the spraying process of transparent SWNT films and reduction of its sheet resistance by Au-ionic doping treatment on PET substrates is researched. Arc-discharge SWNTs were dispersed in deionized water by adding sodium dodecyl sulfate (SDS) as surfactant and sonicated, followed by the centrifugation. The dispersed SWNT was spray-coated on PET substrate and dried on a hotplate. When the spray process was terminated, the TCF was immersed into deionized water to remove the surfactant and then it was dried on hotplate. The TCF film was then was doped with Au-ionic doping treatment, rinsed with deionized water and dried. The surface morphology of TCF was characterized by field emission scanning electron microscopy. The sheet resistance and optical transmission properties of the TCF were measured with a four-point probe method and a UV-visible spectrometry, respectively. This was confirmed and discussed on the XPS and UPS studies. We show that 87 ${\Omega}/{\Box}$ sheet resistances with 81% transmittance at the wavelength of 550 nm. The changes in electrical and optical conductivity of SWNT film before and after Au-ionic doping treatments were discussed. The effects of hole transport interface layer using Au-ionic doping SWNT on the performance of organic solar cells were investigated.

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Fabrication and Characterization of High Performance Green OLEDs using $Alq_3$-C545T Systems ($Alq_3$-C545T시스템을 이용한 고성능 녹색 유기발광다이오드의 제작과 특성 평가)

  • Jang Ji-Geun;Kim Hee-Won;Shin Se-Jin;Kang Eui-Jung;Ahn Jong-Myong;Lim Yong-Gyu
    • Journal of the Microelectronics and Packaging Society
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    • v.13 no.1 s.38
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    • pp.51-55
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    • 2006
  • The green emitting high performance OLEDs using the $Alq_3$-C545T fluorescent system have been fabricated and characterized. In the device fabrication, 2-TNATA [4,4',4'-tris(2-naphthylphenyl-phenylamino)-triphenylamine] as a hole injection material and NPB [N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] as a hole transport material were deposited on the ITO(indium thin oxide)/glass substrate by vacuum evaporation. And then, green color emission layer was deposited using $Alq_3$ as a host material and C-545T[10-(2-benzothiazolyl)-1,1,7,7- tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]/benzopyrano[6,7,8-ij]-quinolizin-11-one] as a dopant. Finally, small molecule OLEDs with structure of ITO/2-TNATA/NPB/$Alq_3$:C545T/$Alq_3$/LiF/Al were obtained by in-situ deposition of $Alq_3$, LiF and Al as the electron transport material, electron injection material and cathode, respectively. Green OLEDs fabricated in our experiments showed the color coordinate of CIE(0.29, 0.65) and the maximum power efficiency of 7.3 lm/W at 12 V with the peak emission wavelength of 521 nm.

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Preparation and Properties of Organic Electroluminescent Devices (유기 전계발광소자의 제작과 특성 연구)

  • 노준서;장호정
    • Journal of the Microelectronics and Packaging Society
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    • v.9 no.1
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    • pp.9-13
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    • 2002
  • Recently, Organic electroluminescent devices (OELDs) have been demonstrated the medium sized full color display with effective multi-layer thin films. In this study, the multi-layer OELDs were prepared on the patterened ITO (indium tin oxide)/glass substrates by the vacuum thermal evaporation method. The low molecule compounds such as $Alq_3$(trim-(8-hydroxyquinoline)aluminum) and CTM (carrier transfer material) as the electron transport and injection layers as well as TPD (triphenyl-diamine) and CuPc (copper phthalocyanine) as the hole transport and injection layers were used. The luminance was rapidly increased above the threshold voltage of 10 V. The luminance and emission spectrum for the OELDs samples with $A1/CTM/Alq_3$/TPD/1TO structures were found to be 430 cd/$m^2$and 512 nm at 17 V showing green color emission. In contrast, the samples with $Li-A1/Alq_3$/TPD/CuPC/1TO multi-structures showed 508 nm in emission spectrum and 650 cd/$m^2$at 17 V in the luminance. The increment of luminance may be ascribed to the improved efficiency of recombination in the region of the emission layers by the deposition of CuPc as hole injection layer and the low work function of the Li-Al electrode compared to the Al electrode.

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Fabrication and characteristics for the organic light emitting device from single layer poly(N-vinylcarbazole) (단층 poly(N-vinylcarbazole) 유기물 전기발광 소자의 제작 및 특성)

  • 윤석범;오환술
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.11
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    • pp.55-61
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    • 1998
  • Organic light emitting devices from a single layer thin film with a hole transport polymer, poly(N-vinylcarbazole) (PVK) doped with 2-(4-bi phenyl)-5-(4-t-butyl-phenyl) -1,3,4-oxadiazole (Bu-PBD) as electron transporting molecules and Coumurine 6(C6), 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), Rhodamine B as a emitter dye were fabricated. The sing1e layer structure and the use of soluble materials simplify the fabrication of devices by spin coating technique. The active layer consists of one polymer layer that is simply sandwiched between two electrodes, indium-tin oxide (ITO), and aluminum. In this structure, electron and hole inject from the electrodes to the PVK : Bu-PBD active layer. Respectively, Blue, green and orange colored emission spectrum by the use of TPB, C6, Rhodamine B dye emitted at 481nm, 500nm and 585nm were achieved during applied voltages. PVK materials can be useful as the host polymer to be molecularly doped with other organic dyes of the different luminescence colors. And EL color can be tuned to the full visible wavelength.

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Inverted CdSe@ZnS Quantum Dots Light-Emitting Diode using Low-Work Function Polyethylenimine Ethoxylated (PEIE) modified ZnO

  • Kim, Choong Hyo;Kim, Hong Hee;Hwang, Do Kyung;Suh, Kwang S;Park, Cheol Min;Choi, Won Kook
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.148-148
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    • 2015
  • Over the past several years, Colloidal core/shell type quantum dots lighting-emitting diodes (QDLEDs) have been developed for the future of optoelectronic applications. An inverted-type quantum-dot light-emitting-diode (QDLED), employing low work function organic material polyethylenimine ethoxylated(PEIE) (<10 nm)[1] modified ZnO nanoparticles (NPs) as electron injection and transport layer, was fabricated by all solution processing method, instead of electrode in the device. The PEIE surface modifier incorporated on the top of the ZnO NPs film, facilitates the enhancement of both electorn injection into the CdSe-ZnS QD emissive layer by lowering the workfunction of ZnO from 3.58eV to 2.87eV and charge balance on the QD emitter. In this inverted QDLEDs, blend of poly (9,9-di-n-octyl-fluorene-alt-benzothiadiazolo) and poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] are used as hole transporting layer (HTL) to improve hole transporting property. At the operating voltage of 7.5 V, the QDLED device emitted spectrally orange color lights with high luminance up to 11110 cd/m2, and showed current efficiency of 2.27 cd/A.[2]

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Effect of Hfe Deficiency on Memory Capacity and Motor Coordination after Manganese Exposure by Drinking Water in Mice

  • Alsulimani, Helal Hussain;Ye, Qi;Kim, Jonghan
    • Toxicological Research
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    • v.31 no.4
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    • pp.347-354
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    • 2015
  • Excess manganese (Mn) is neurotoxic. Increased manganese stores in the brain are associated with a number of behavioral problems, including motor dysfunction, memory loss and psychiatric disorders. We previously showed that the transport and neurotoxicity of manganese after intranasal instillation of the metal are altered in Hfe-deficient mice, a mouse model of the iron overload disorder hereditary hemochromatosis (HH). However, it is not fully understood whether loss of Hfe function modifies Mn neurotoxicity after ingestion. To investigate the role of Hfe in oral Mn toxicity, we exposed Hfe-knockout ($Hfe^{-/-}$) and their control wild-type ($Hfe^{+/+}$) mice to $MnCl_2$ in drinking water (5 mg/mL) for 5 weeks. Motor coordination and spatial memory capacity were determined by the rotarod test and the Barnes maze test, respectively. Brain and liver metal levels were analyzed by inductively coupled plasma mass spectrometry. Compared with the water-drinking group, mice drinking Mn significantly increased Mn concentrations in the liver and brain of both genotypes. Mn exposure decreased iron levels in the liver, but not in the brain. Neither Mn nor Hfe deficiency altered tissue concentrations of copper or zinc. The rotarod test showed that Mn exposure decreased motor skills in $Hfe^{+/+}$ mice, but not in $Hfe^{-/-}$ mice (p = 0.023). In the Barns maze test, latency to find the target hole was not altered in Mn-exposed $Hfe^{+/+}$ compared with water-drinking $Hfe^{+/+}$ mice. However, Mn-exposed $Hfe^{-/-}$ mice spent more time to find the target hole than Mn-drinking $Hfe^{+/+}$ mice (p = 0.028). These data indicate that loss of Hfe function impairs spatial memory upon Mn exposure in drinking water. Our results suggest that individuals with hemochromatosis could be more vulnerable to memory deficits induced by Mn ingestion from our environment. The pathophysiological role of HFE in manganese neurotoxicity should be carefully examined in patients with HFE-associated hemochromatosis and other iron overload disorders.

Biogenic Opal Production and Paleoclimate Change in the Wilkes Land Continental Rise (East Antarctica) during the Mid-to-late Miocene (IODP Exp 318 Site U1359) (동남극 윌크스랜드 대륙대의 마이오세 중-후기 동안 생물기원 오팔 생산과 고기후 변화(IODP Exp 318 Site U1359))

  • Song, Buhan;Khim, Boo-Keun
    • Ocean and Polar Research
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    • v.37 no.1
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    • pp.23-35
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    • 2015
  • A 450 m-long sediment section was recovered from Hole U1359D located at the eastern levee of the Jussieau submarine channel on the Wilkes Land continental rise (East Antarctica) during IODP Expedition 318. The age model for Hole U1359D was established by paleomagnetic stratigraphy and biostratigraphy, and the ages of core-top and core-bottom were estimated to be about 5 Ma and 13 Ma, respectively. Biogenic opal content during this period varied between 3% and 60%. In the Southern Ocean, high biogenic opal content generally represents warm climate characterized by the increased light availability due to the decrease of sea-ice distribution. The surface water productivity change in terms of biogenic opal content at about 10.2 Ma in the Wilkes Land continental rise was related to the development of Northern Component Water. After about 10.2 Ma, more production of Northern Component Water in the North Atlantic caused to increase heat transport to the Southern Ocean, resulting in the enhanced diatom production. Miocene isotope events (Mi4~Mi7), which are intermittent cooling intervals during the Miocene, appeared to be correlated to the low biogenic opal contents, but further refinement was required for precise correlation. Biogenic opal content decreased abruptly during 6 Ma to 5.5 Ma, which most likely corresponds to the Messinian salinity crisis. Short-term variation of biogenic opal content was related to the extent of sea-ice distribution associated with the location of Antarctic Polar Front that was controlled by glacial-interglacial paleoclimate change, although more precise dating and correlation will be necessary. Diatom production in the Wilkes Land continental rise increased during the interglacial periods because of the reduced sea-ice distribution and the southward movement of Antarctic Polar Front.