Simple, Fast, and Scalable Reverse-Offset Printing of Micropatterned Copper Nanowire Electrodes with Sub-10 μm Resolution

Abstract

Copper nanowires (CuNWs) possess key characteristics for realizing flexible transparent electronics. High-quality CuNW micropatterns with high resolution and uniform thickness are required to realize integrated transparent electronic devices. However, patterning high-aspect-ratio CuNWs is challenging because of their long length, exceeding the target pattern dimension. This work reports a novel reverse-offset printing technology that enables the sub-10 μm high-resolution micropatterning of CuNW transparent conducting electrodes (TCEs). The CuNW ink for reverse-offset printing was formulated to control viscoelasticity, cohesive force, and adhesion by adjusting the ligands, solvents, surface energy modifiers, and leveling additives. An inexpensive commercial adhesive handroller achieved a simple, fast, and scalable micropatterning of CuNW TCEs. Easy production of high-quality CuNW micropatterns with various curvatures and shapes was possible, regardless of the printing direction. The reverse-offset-printed CuNW micropatterns exhibited a minimum of 7 μm line width and excellent pattern qualities such as fine line spacing, sharp edge definition, and outstanding pattern uniformity. In addition, they exhibited excellent sheet resistance, high optical transparency, outstanding mechanical durability, and long-term stability. Flexible light-emitting diode (LED) circuits, transparent heaters, and organic LEDs (OLEDs) can be fabricated using high-resolution reverse-offset-printed CuNW micropatterns for applications in flexible transparent electronic devices.

High-Quality Microprintable and Stretchable Conductors for High-Performance 5G Wireless Communication

“…To transfer the semidry film from the silicone blanket to the cliché or the target substrate without any residue, the AgNP/AgNW hybrid ink must have an adequate cohesive force that is greater than the adhesion between the blanket and semidry film and lower than the adhesion between the cliché and semidry film. , The cohesive force of the ink was finely tuned by adjusting the relative proportions of PGMEA, polyacrylate-based binder, and polyurethane (PU) diol. Moreover, the AgNP/AgNW hybrid ink must exhibit stronger tackiness than the AgNW ink, which has an inherent cohesion owing to its structural properties, such as wire entanglement.…”

Copper inks for printed electronics: a review

“…Screen printing, gravure printing, spray-coating, and other non-digital printing methods can be done at high speed using a mask, but the disadvantage is that it is difficult to achieve high-resolution manufacturing (<10 μm). Recently, Kim et al reported a reverse-offset printing technology, 151 in which CuNWs were coated by Mayer rod and then transferred to a gravure plate. They used a commercial adhesive hand-roller to achieve the directional transfer of patterned ink to obtain CuNW patterns with a minimum line width of 7 μm.…”

“…[144][145][146] Table 2 lists the materials, capping agents, sintering methods, aspect ratio, and resistivity of some CuNWs inks. The hydrothermal method generally uses deionized water as the reaction medium, with hexadecylamine (HDA), [147][148][149][150][151] ethylenediamine (EDA), [152][153][154] octadecylamine (ODA) [155][156][157] and PVP 69,158,159 as the limiting ligand. By controlling the heating temperature, limiting ligand concentration and reaction time, CuNWs with different lengths and diameters can be obtained (Fig.…”

Emerging low-cost, large-scale photonic platforms with soft lithography and self-assembly

“…Although existing transfer printing can be compatible with various materials, it fails to offer high-resolution/quality patterning. Kim et al proposed a novel reverse-offset printing technology by patterning sub-10 µm copper nanowire (CuNW) transparent conducting electrodes [80] . The intaglio trench allows only the desired pattern to remain on the stamp, without any morphological changes [Fig.…”