• 연구논문집
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• s.28
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• pp.39-47
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• 1998

Industrial electrostatic precipitation is a very complex process, which involves multiple-way interaction between the electric field, the fluid flow, and the particulate motion. This paper describes a strongly coupled calculation procedure for the rigorous computation of particle dynamics during electrostatic precipitation. The turbulent gas flow and the particle motion under electrostatic forces are calculated by using the commercial computational fluid dynamics (CFD) package FLUENT linked to a finite-volume solver for the electric field and ion charge. Particle charge is determined from both local electrical conditions and the cell residence time which the particle has experienced through its path. Particle charge density and the particle velocity are averaged in a control volume to use Lagrangian information of the particle motion in calculating the gas and electric fields. The turbulent particulate transport and the effects of particulate space charge on the electrical current flow are investigated. The calculated results for poly-dispersed particles are compared with those for mono-dispersed particles, and significant differences are demonstrated.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.97-101
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• 2009

A new approach was applied to examine the charge generation and transport in organic photoconductive devices by Monte‐Carlo simulation utilizing multiple site interactions of carriers with all other charges within Coulomb radius. Stepwise generation frame was considered first by a charge separation process that was counted in two separate transactions, i.e., hopping against physical decay and dissociation against recombination. Thereafter, diffusion/ drifting process of free carriers was counted to follow. This method enables to examine readily the photocurrent generated alongside the charge generation efficiency. The field and temperature dependences of the efficiency and photocurrent were obtained comparable to Onsager’s and experimental data.

• Journal of Adhesion and Interface
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• v.23 no.2
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• pp.17-24
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• 2022

Colloidal quantum dots (QDs) have gained attention for applications in quantum dot light emitting diodes (QLEDs) due to their high photoluminescence quantum yield, narrow emission spectra, and tunable bandgap. Nevertheless, non-radiative recombination induced by electron and hole imbalance deteriorates the device efficiency and stability. To overcome the problem, researchers have been trying to enhance hole transport properties of hole transporting layers (HTL) and/or slow down the electron injection in electron transport layer (ETL). Here, we summarize two approaches: i) development of interfacial materials between QD and ETL (or HTL); ii) engineering of HTL by blending or multi-layer approaches.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.3
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• pp.53-59
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• 2011

Charge transfer through DNA oligonucleotides has been investigated for potential applications of DNA into molecular electrooptic switching devices. Electrons were injected using gold electrode probes where DNA oligomers were adsorbed that are separated in medium. The results show that increased adsorption of DNA reduces the ionization current due to the combined effect of charge transfer through DNA and surface-limited charge transport. The probe-based charge injection was extended to examine the capability of extinguishing fluorescence of Cy3 dye molecules attached to DNA. It is expected that the results may be employed to implementing a novel electrooptic switching device based on DNA molecules.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.5
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• pp.409-417
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• 2003

We have studied electrical properties and luminous efficiency of organic light-emitting diodes(OLEDs) with different buffer layer and cathodes in a temperature range of 10 K and 300 K. Four different device structures were made. The OLEDs are based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinato) aluminum(III) (Alq$_3$) as an electron transport and omissive layer, and poly(3,4-ethylenedioxythiophene) :poly (styrenesulfonate) (PEDOT:PSS ) as a buffer layer. And LiAl was used as a cathode. Among the devices, the ITO/PEDOT:PSS/TPD/Alq$_3$/LiAl structure has a low energy-barrier height for charge injection and show a good luminous efficiency. We have got a highly efficient and low-voltage operating device using the conductive PEDOT:PSS and low work-function LiAl. From current-voltage characteristics with temperature variation, conduction mechanisms are explained SCLC (space charge limited current) and tunneling one. We have also studied energy barrier height and luminous efficiency at various temperature.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.229-229
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• 2006

Recently there has been significant interest in utilizing functional semiconductor polymers for electronic and opto-electronic devices such as Light-emitting diodes, thin film field effect transistors, solar cells, displays, and chemical and biosensors. However, better materials and further understanding of their electronic properties are critical for devices based on these materials. In this work, we use various scanning probe techniques, spectroscopy, and device fabrication to study the molecular interactions, optical and charge transport properties in conjugated polyelectrolytes. Using chemical synthesis approach, we are able to tune the molecular packing and interactions in these materials, which in turn, influence their electronic properties and device performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.198-201
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• 2002

We have studied the temperature dependence of current-voltage and luminance-voltage characteristics of Organic Light Emitting Diodes(OLEDs). The OLEDS are based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole transport, tris(8-hydroxyquinolinoline) aluminum(III) (Alq$_3$) as an electron transport, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a buffer layer. The current-voltage and luminance-voltage characteristics were measured in the temperature range of 10[K] and 300[K]. A conduction mechanism in OLEDs has been interpreted in terms of space-charge-limited current(SCLC) and tunneling mechanism.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.179.2-179.2
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• 2014

Carbon nanotubes (CNT)-metal contacts play an important role in nanoelectronics applications such as field-effect transistor (FET) devices. Using Al and (10,0) CNT, we have recently showed that the CNT-metal contacts mediated via topological defects within CNT exhibits intrinsically low contact resistance, thanks to the preservation of the sp2 bonding network at the metal-CNT contacts.[1] It is well-established that metals with good wetting property such as Pd consistently yield good contacts to both metallic and semiconducting CNTs. In this work, the electronic and charge transport properties of the interfaces between capped CNT and Pd will be investigated based on first-principles computations and compared with previous results obtained for the Al electrodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.492-496
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• 2001

Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e,g. As, Cl). In this paper, We investigated dopants(As, Cl) composition rate to improve dark resistivity and transport properties of charge carrier in amorphous selenium using by direct X-ray conversion material. Alloying a-Se with As inhibits the recrystallization of a-Se but introduces undesirable deep hole traps. then doping with Cl(in the ppm range) compensates for the deep hole traps. We investigated their composition rate in various doping conditions and then obtained optimum dopant composition rate. The result was Se-As 0.3%-Cl 30 ppm and X-ray Sensitivity was 0.57 pc/pixel$.$mR at 137 $\mu\textrm{m}$ x 137 $\mu\textrm{m}$ Pixel area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.533-534
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• 2005

Temperature-dependent current-voltage characteristics of organic light-emitting diodes(OLEDs) were studied in a device structure of ITO/TPD/$Alq_3$/Al. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-l,1'-diphenyl-4,4'-diamine(TPD) as a hole transport and tris(8-hydroxyquinoline) aluminum($Alq_3$) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10K and 300K. We analyzed an electrical conduction mechanism of the OLEDs using space-charge-limited current(SCLC) and Fowler-Nordheim tunneling.