• Transactions on Electrical and Electronic Materials
• /
• v.16 no.3
• /
• pp.124-129
• /
• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Journal of Sensor Science and Technology
• /
• v.30 no.5
• /
• pp.309-313
• /
• 2021

Organic semiconductors have received tremendous attention for their research because of their tunable electrical and optical properties that can be achieved by changing their molecular structure. However, organic materials are inherently unstable in the presence of oxygen and moisture. Therefore, it is necessary to develop moisture and air stable semiconducting materials that can replace conventional organic semiconductors. In this study, we developed a NiO_x thin film through a solution process. The electrical characteristics of the NiO_x thin film, depending on the thermal annealing temperature and UV-ozone treatment, were determined by applying them to the hole injection layer of an organic light-emitting diode. A high annealing temperature of 500 ℃ and UV-ozone treatment enhanced the conductivity of the NiO_x thin films. The optimized NiO_x exhibited beneficial hole injection properties comparable those of 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN), a conventional organic hole injection layer. As a result, both devices exhibited similar power efficiencies and the comparable electroluminescent spectra. We believe that NiO_x could be a potential solution which can provide robustness to conventional organic semiconductors.

• Journal of Information Display
• /
• v.2 no.3
• /
• pp.1-5
• /
• 2001

The effect of doping on the energy transfer and charge carrier trapping processes has been studied in organic light-emitting diodes (OLEDs) doped with a fluorescent laser dye. The devices consisted of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1-biphenyl-4,4'-diamine (TPD) as a hole transporting layer, tris(8-hydroxyquinoline) aluminum ($Alq_3$) as the host, and a fluorescent dye, 4-dicyanomethylene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1 H,5H-benzo[i,j]quinolizin-8-yl) vinyl]-4H-pyran) (DCM2) as the dopant. Temperature dependence of the current-voltage-luminescence (I-V-L) characteristics, the electroluminescence (EL) and photoluminescence (PL) spectra are studied in the temperature ranging between 15 K and 300 K. The emission from DCM2 was seen to be much stronger compared with the emission from $Alq_3$, indicative of efficient energy transfer from $Alq_3$ to DCM2. In addition, the EL emission from DCM2 increasd with increasing temperature while the emission from the host $Alq_3$ decreased. The result indicates that direct charge carrier trapping becomes efficient with increasing temperature. The EL emission from DCM2 shows a slightly sublinear dependence on the current density, implying the enhanced quenching of excitons at high current densities due to the exciton-exciton annihilation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1511-1513
• /
• 2005

The polymer-light emtting diodes(PLEDs) were comprised a design of OLED array, process develop by using ITO thin glass, and fabrication of PDMS stamp by using nanocontact printing. In the study, we describe a different approach for building OLEDs, which is based on physical lamination of thin metal electrodes supported by a PDMS stamp layer against an electroluminescent organic. We develop that devices fabricated in this manner have better performance than those constructed with standard processing techniques. The lamination approach avoids forms of disruption that can be introduced at the electrode organic interface by metal evaporation and has a reduced sensitivity to pinhole or partial pinhole defects. Also, it is easy to build patterned PLED with feature sizes into the nanometer regime. This method provides a new route to PLED for applications ranging from high performance displays to storage and lithography systems, and PLED can used for organic electronics and flexible display.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1573-1576
• /
• 2007

ABCV-Py, a new red fluorescent material, in which two identical electron donor (dimethylamino group) and acceptor (cyano group) moieties are linked to two independent biphenyl groups which share the same core phenyl, has been synthesized for use in OLED application. Performance of red doped electroluminescent devices using ABCV-Py as dopant were measured with various host materials, $Alq_3$, CBP, DPVBi, and p-terphenyl. The performance of device with DPVBi host material was better than those with other host materials and high doping concentration could be applied on device with ABCV-Py as dopant.

• Transactions on Electrical and Electronic Materials
• /
• v.3 no.2
• /
• pp.16-19
• /
• 2002

In this study, a novel red emitting organic electroluminescent (EL) device was fabricated with the bis(8-oxyquinolino)zinc II (Znq2) doped dye as an emitting layer. The Znq2 was synthesized successfully from zinc chloride (ZnC1$_2$) as an initial material. Then, we fabricated the red organic EL device with a dye (DCJTB) doped and inserted Znq2 between emission layer and cathode for increasing EL efficiency. The hole transporting layer is a N,N'-diphenyl-N,N'-bis-(3-methylphenyl)-1,1'-diphenyl-4,4-diamine (TPD), and the host material of emission layer is Znq2. And the electrical and luminance characteristics of the device were measured. We found that the EL device with Znq2 inserting layer results in the increasing luminance efficiency.

• Transactions on Electrical and Electronic Materials
• /
• v.10 no.6
• /
• pp.208-211
• /
• 2009

The authors have demonstrated the various characteristics of hybrid white organic light-emitting diodes (HWOLED) using fluorescent blue and phosphorescent red emitters. We also demonstrated that two devices showed different characteristics in accordance with thickness of the 4,4′-N,N′-dicarbazole-biphenyl (CBP) spacer (CS) inserted between the blue and the red emitting layer. It was found that the device with a CS thickness of 70 $\AA$ showed a current efficiency 2.5 times higher than that of the control device with a CS thickness of 30 $\AA$ by preventing the triplet Dexter energy transfer from the red to the blue emitting layer. The HWOLED with the CS thickness of 70 $\AA$ exhibited a maximum luminance of 24500 cd/$m^2$, a maximum current efficiency of 42.9 cd/A, a power efficiency of 37.5 lm/W, and Commission Internationale de I'Eclairage coordinates of (0.37, 0.42).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.95-95
• /
• 2014

An OLED(Organic Light-Emitting Diode) device based on the emissive electroluminescent layer a film of organic materials. OLED is used for many electronic devices such as TV, mobile phones, handheld games consoles. ULVAC's mass production systems are indispensable to the manufacturing of OLED device. ULVAC is a manufacturer and worldwide supplier of equipment and vacuum systems for the OLED, LCD, Semiconductor, Electronics, Optical device and related high technology industries. The SMD Series are single-substrate sputtering systems for deposition of films such as metal films and TCO (Transparent Conductive Oxide) films. ULVAC has delivered a large number of these systems not only Organic Evaporating systems but also LTPS CVD systems. The most important technology of thin-film encapsulation (TFE) is preventing moisture($H_2O$) and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass substrate, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This report provides a review of promising thin-film barrier technologies as well as the WVTR(Water Vapor Transmission Rate) properties. Multilayer thin-film deposition technology of organic and inorganic layer is very effective method for increasing barrier performance of OLED device. Gases and water in the organic evaporating system is having a strong influence as impurities to OLED device. CRYO pump is one of the very useful vacuum components to reduce above impurities. There for CRYO pump is faster than conventional TMP exhaust velocity of gases and water. So, we suggest new method to make a good vacuum condition which is CRYO Trap addition on OLED evaporator. Alignment accuracy is one of the key technologies to perform high resolution OLED device. In order to reduce vibration characteristic of CRYO pump, ULVAC has developed low vibration CRYO pumps to achieve high resolution alignment performance between Metal mask and substrate. This report also includes ULVAC's approach for these issues.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2011.03a
• /
• pp.63-63
• /
• 2011

The donor-${\pi}$-acceptor (D-${\pi}$-A) chromophoric dye system has received great attention in variety fields such as electroluminescent materials, sensors and optoelectronic devices. There are many research activities focused on the development for abovementioned application materials with the high-performance properties. In the previous work, we are reported that novel D-${\pi}$-A dye, 2-[4-(9H-carbazol-9-yl)benzylidene]-2,3-dihydroinden-1-one, is successfully attained and exhibited a positive fluorescence solvatochromism. In this work, the molecular structure and packing geometry of 2-[4-(9H-carbazol-9-yl)benzylidene]-2,3-dihydroinden-1-one was discussed by their conformational structure. Their single yellow prism crystal having approximate dimensions of $0.30{\times}0.10{\times}0.10$ mm was carried out with a Rigaku RAXIS RAPID imaging plate area detector with graphite monochromated $CuK_{\alpha}$ radiation. Their crystal structure were solved by using the CrystalStructure crystallographic software package.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1466-1468
• /
• 2001

For the full color organic electro-luminescent device, essentially, red, green, and blue emissions are required. But red emission is not to reach minimum level of practical use 31[lm/W]. In order to optimize color purity and power consumption requirements, it is important for the materials development efforts to search for improvements in red emission effisiency. In this study, the bis(8-oxyquinolino)zinc II ($Znq_2$) were synthesized successfully from zinc chloride($ZnCl_2$) as a initial material. Then, we fabricated red organic electroluminescent device with a dye(DCJTB)-doped and inserted $Znq_2$ between emission layer and cathode layer for increasing EL efficiency. 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 material of emission layer is $Znq_2$. For the inserting of $Znq_2$, efficiency increased.