Sputter-patterned ITO-based organic light-emitting diodes with leakage current cut-off layers

Park, Jongwoon; Ham, Hyokyun

doi:10.1016/j.orgel.2011.07.024

Cited by 6 publications

(7 citation statements)

References 16 publications

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“…[ 9–11 ] Moreover, in the electrode patterning process (photolithography), the steep step of the electrode edge, the resist residue after development, and resist mist on the substrate in photolithography are factors that can cause short‐circuit defects. To prevent these problems, the formation of edge covers using insulators [ 12,13 ] and optimization of the photolithography process [ 14 ] have been reported. Furthermore, it has been reported that dust particles exist on the substrate before deposition in the vacuum deposition process.…”

Section: Introductionmentioning

confidence: 99%

Coverage Performance of PEDOT:PSS Against Particles on a Substrate for OLEDs

Kurosawa

Murakami

Takahashi

et al. 2022

Adv Materials Inter

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OLEDs, the manufacturing process and production yields should be improved to reduce the overall cost.The structure of an OLED device consists of an organic thin film layered between two electrodes (anode and cathode), and is a self-emitting device that emits light when holes and electrons injected from the electrodes recombine in the light-emitting layer upon application of a DC voltage. [1] A transparent anode (e.g., indium-tin-oxide (ITO)) is formed on a glass or other substrate, on which a hole injection layer (HIL), hole transport layer (HTL), emission layer (EML), electron transport layer (ETL), electron injection layer (EIL), and cathode (e.g., aluminum (Al)) are stacked. An organic layer is fabricated by a vacuum process such as vacuum deposition [2] or a solution process using spin-coating, slot-die coating, and ink-jet printing. [3][4][5][6] Each organic layer is very thin, with a total thickness of ≈100-200 nm. However, in contrast to the film thickness, it has a large emitting area of ≈10 × 10 cm 2 , especially for lighting applications. Owing to the low thickness of the device, even a small amount of microscale dust particles on such a large substrate causes defects, such as electrical short circuits and lower production yields of OLED panels. [7,8] Therefore, to solve this problem in OLED panel manufacturing, a system that strictly controls the microscale particles throughout the manufacturing process is needed.Although dust-induced short-circuit defects are a significant issue in the production of OLED panels, there are few reports on the mechanism. Based on the existing literature on the shortcircuit defects reported, we classified the factors of shortcircuit defects in OLED panels and their prevention methods by their fabrication process (Table 1). Several phenomena can cause short-circuit defects in the series of processes used for the fabrication of OLEDs. First, in the anodic sputtering process on a clean substrate, the flake particles generated from the sputtering target cause short-circuit defects. It has been reported that these factors can be prevented by smoothing the spattering anode (R peak-to-valley (R pv ) < 20 nm). [9][10][11] Moreover, in the electrode patterning process (photolithography), the steep step of the electrode edge, the resist residue after development, and resist mist on the substrate in photolithography are factors that can cause short-circuit defects. To prevent these problems, the formation of edge covers using insulators [12,13] and optimization of the photolithography process [14] have been reported.Short-circuit defects caused by microscale dust particles in organic lightemitting diodes (OLEDs) cause a decrease in production yield and hinder cost reduction. An organic layer coating by solution process is used to prevent short-circuit defects of particles on a substrate. In this study, the coverage properties of a coated organic layer on size-controlled particles are revealed. The surface of the substrate with size-controlled SiO 2 particles with a diameter of 0.2-5...

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Section: Introductionmentioning

confidence: 99%

Coverage Performance of PEDOT:PSS Against Particles on a Substrate for OLEDs

Kurosawa

Murakami

Takahashi

et al. 2022

Adv Materials Inter

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“…It is apparent that in order to solve the problem, a low-cost transparent submount in a stacked LED module must be chosen. In addition, the indium tin oxide (ITO) wiring coated on glass substrate is an effective way to reduce the reflection [ 18 , 19 ]. Furthermore, when multi-chips stack together in a high-power operation, the parasitic heat accumulation must also be solved simultaneously because one major factor in determining the lumen output of an LED is its junction temperature.…”

Section: Introductionmentioning

confidence: 99%

RGB-Stack Light Emitting Diode Modules with Transparent Glass Circuit Board and Oil Encapsulation

Chang

Singh

et al. 2018

Materials

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The light emitting diode (LED) is widely used in modern solid-state lighting applications, and its output efficiency is closely related to the submounts’ material properties. Most submounts used today, such as low-power printed circuit boards (PCBs) or high-power metal core printed circuit boards (MCPCBs), are not transparent and seriously decrease the output light extraction. To meet the requirements of high light output and better color mixing, a three-dimensional (3-D) stacked flip-chip (FC) LED module is proposed and demonstrated. To realize light penetration and mixing, the mentioned 3-D vertically stacking RGB LEDs use transparent glass as FC package submounts called glass circuit boards (GCB). Light emitted from each GCB stacked LEDs passes through each other and thus exhibits good output efficiency and homogeneous light-mixing characteristics. In this work, the parasitic problem of heat accumulation, which caused by the poor thermal conductivity of GCB and leads to a serious decrease in output efficiency, is solved by a proposed transparent cooling oil encapsulation (OCP) method.

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“…Leakage current flows toward spiked structures on ITO layer surfaces, causing short circuiting between the anode and cathode. This causes dark spots in OLED displays owing to the resulting absence of light emission [9,10]. Because rough ITO surfaces promote the generation of defects, a smooth ITO surface morphology allows the preparation of OLEDs with long lifetimes [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…However, a comprehensive study on the abrasiveness and surface resistance of ITO layers remains lacking. ITO layers sputtered during thermal treatment in oxygen plasma contain no surface projections, allowing flat ITO thin layers to be fabricated [9,10]. However, such treatments tend to increase the sheet resistance [10], and high ITO sheet resistances are unfavorable in liquid crystal devices, solar cells, and OLEDs.…”

Section: Introductionmentioning

confidence: 99%

“…ITO layers sputtered during thermal treatment in oxygen plasma contain no surface projections, allowing flat ITO thin layers to be fabricated [9,10]. However, such treatments tend to increase the sheet resistance [10], and high ITO sheet resistances are unfavorable in liquid crystal devices, solar cells, and OLEDs. Because ITO thin films of low sheet resistance and flatness cannot readily be formed by sputtering, newly formed ITO thin layers are typically polished when fabricating devices.…”

Section: Introductionmentioning

confidence: 99%

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