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Components and Devices
Published in Katsuyuki Sakuma, Krzysztof Iniewski, Flexible, Wearable, and Stretchable Electronics, 2020
Due to the sensitivity of SMOLED materials to oxygen and moisture, as well as the sensitivity of device performance upon layer thickness, vacuum deposition tools are typically used for fabrication. Such tools are capable of uniform layer deposition with accuracy in the nm range, which is required for optimal device performance. Many PLED materials can be deposited by solution processes, and even in ambient conditions [169]. However, obtaining uniform films of precise thickness is challenging and solvent compatibility between layers may limit material options. For applications where additive patterning is not required, coating methods such as slot die [170–172] and blade [169] coating are commonly used. If additive fabrication with patterning is desired, OLED fabrication has been demonstrated using gravure [173, 174] and inkjet [175] printing.
Fabrication of Nanomaterials
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
R. Preethi, Leena Maria, J.A. Moses, C. Anandharamakrishnan
This method is also called thin film process, and is an atomistic deposition process, where the material is vaporized from liquid or solid source to form atoms and transferred in the form of vapor through low-pressure plasma or vacuum environment to the substrate, and then it condenses. This method is commonly used to deposit films with various thicknesses in the range of nanometers. The shape can vary from flat to geometries with a variety of 1–10 nm. Vacuum deposition, sputter deposition, arc vapor deposition, and ion plating are various PVD methods. Vacuum deposition is used to form permeation barrier films on flexible packaging materials and water- and corrosion-resistant coatings in the food industry. In this vacuum deposition process, the substrate after thermal vaporization crosses with little or no collision with a gas molecule, which reduces the gaseous contamination at a low level.
Charging Up the Future by Organic Solar Cells
Published in Toshio Naito, Functional Materials, 2019
Soluble polymers are attractive for large-area and low-cost OPVs due to easy fabrication by solution process, such as spin-coating or printing techniques, although they are difficult to purify and are well defined. On the other hand, small molecules are also attractive for OPVs based on highly purified materials of well-defined structures, leading to high mobilities compared to those of polymers. However, vacuum deposition techniques are not suitable for fabricating large-area and low-cost devices. Thus, there is a requirement to design and develop small molecules in order to provide large-area and low-cost OPVs fabricated by solution process. There are two classes of solution-processable small molecules: small molecules with solubilizing groups (Section 8.3.4) and small molecules with thermally or photochemically removable groups (latent pigments) (Section 8.5).
Recent progress in the development of backplane thin film transistors for information displays
Published in Journal of Information Display, 2021
Dongseob Ji, Jisu Jang, Joon Hui Park, Dasol Kim, You Seung Rim, Do Kyung Hwang, Yong-Young Noh
This paper has reviewed the current state of research on backplane TFTs for rigid and flexible OLED displays, including amorphous metal oxides, CNTs, TMDCs, and organic semiconductors. Existing LTPS TFTs suffer from high manufacturing cost, high Ioff and low uniformity of electrical characteristics over large areas. These demerits provide the main motivation for the development of new TFT materials. Mechanical flexibility of semiconducting materials is required for flexible OLED backplane but this requirement is not strict because the effective TFT area in OLED display is small. Replacement of conventional vacuum-deposition methods by solution-based techniques has recently been pursued, particularly towards cost-effective manufacturing. Many pioneering display-panel companies have recently run pilot lines that use inkjet printing to manufacture front panels for OLED displays. After front-panel production using inkjet printing is commercialized, the next goal would be back plane production. With this goal in mind, printable channel materials have been studied for a decade and should be optimized in the future.
Microstructural and Tribological Behavior of Pulse Electroplated Nickel Barrier on Copper Conductors
Published in Tribology Transactions, 2019
Electroplating is a versatile and economical process for the fabrication of a wide range of micro- and nanostructured coatings and bulk materials (Sharma, et al. (1)–(3)). Traditionally these materials are prepared by various approaches, such as vacuum deposition, magnetron sputtering, evaporation, sol-gel, spray deposition, ball milling, chemical precipitation methods, etc. (Sharma, et al. (3); Kim, et al. (4); Park, et al. (5); Loffer, et al. (6)). All of these methods need a great deal of precision and control, making the processes highly expensive and generating huge waste deposits. Copper plating has been used in microelectronic packaging and devices for years (Sharma, et al. (7); Davis (8)). Ni is plated over Cu in order to protect the electrical bonding of interconnection assemblies from thermal and corrosive attacks and Cu maintains the excellent conductivity necessary for the efficient electrical and thermal conduction in electric wiring boards (Aniekwe and Utigard (9); Harput (10)). For instance, high-thickness Ni-plated Cu films are useful in continuous high-temperature operation up to 450 °C (National Research Council (11)). The major applications of Ni-plated Cu include aircraft circuitries exposed to wind and mist, automotive engines and exhaust systems, high-temperature electrical appliances, heating furnaces/coils, spreaders, etc. (Aniekwe and Utigard (9); Harput (10); National Research Council (11)). In addition, pulse-plated Ni on Cu conductors serves as a promising barrier to tin whisker growth in microelectronic industries (Brusse, et al. (12)).