Gravure Printing of Graphene for Large‐area Flexible Electronics

Abstract

Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large-area printed and flexible electronics.

Conductivity Enhancement of Binder‐Based Graphene Inks by Photonic Annealing and Subsequent Compression Rolling

“…The presence of a binder with a glass transition point above room temperature may lower the particle mobility even under high force applied, obstruct sheet-to-sheet interactions, and thereby render the application of compression rolling inefficient. Nevertheless, taking into account the two main aspects of performance an ink should provide, i.e., good printability with high printing definition and sufficiently low sheet resistance, e.g., less than 5 Ω & À1 , it becomes clear from previous works [16,[18][19][20]22,25,26,[28][29][30] that the use of a binder, surfactant, or rheology modifier is necessary. These rheological modifications should be compatible with the commonly used R2R-friendly flexible substrates and comply with already existing high-speed technologies.…”

“…To increase the conductivity of final structures, post-processing methods, such as long-time thermal annealing [19,20,24] or compression rolling, [23,26] can be employed, thus, increasing the application potential of graphene-based printable conductors. In particular, thermal annealing is known to be a very efficient method to improve the conductivity of graphene, [19,20,24,27] as it results in desorption of the surface contaminants and degradation of binders and other ink components, e.g., rheology modifiers. However, the commonly used substrates, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and paper, do not tolerate long-time treatment at temperatures above 150 C, thus, preventing conventional thermal annealing approaches.…”

“…[11][12][13] Even though the field of printable conductors is still mainly focused on metalbased (Ag, Cu, %50 mΩ & À1 at 25 mm thickness) [13,14] inks and PEDOT:PSS dispersions (%50 Ω & À1 ), [15] graphene-based conductive inks are gaining attention both from science [16][17][18][19][20][21][22][23][24] and technology. [25] Unfortunately, the conductive properties of graphene inks and printed structures thereof are still far from being a replacement for silver and copper inks.…”

Conductive Screen Printing Inks by Gelation of Graphene Dispersions

“…The conditions of post-treatment defi ne the substrate that can be used for printing. For example, ink annealing at 250 °C and higher for 30 min [ 18,24,25 ] signifi cantly limits the range of suitable substrates and fundamentally limits high speed R2R industrial realization. Thus, the design of graphene inks that meet the requirements of current R2R applications is still to be accomplished.…”

“…For example, ink annealing at 250 °C and higher for 30 min [ 18,24,25 ] signifi cantly limits the range of suitable substrates and fundamentally limits high speed R2R industrial realization. Thus, the design of graphene inks that meet the requirements of current R2R applications is still to be accomplished.There are several reports on the preparation of graphene-based inks comprising either graphene oxide (GO), [ 17,19,23,[27][28][29][30] or graphite exfoliated with [ 13,16,18,22,24,25 ] and without [ 20 ] surface active agents. The preparation of inks based on GO is relatively simple.…”