Dr. Eui-Tae Kim, Professor, Department of Materials Science & Engineering, Chungnam National University, Korea

Title: Lift-Off Patterning of Graphene and Graphene-Ag Nanowire Hybrid Films for Flexible Transparent Electrode Applications

Abstract: Flexible transparent conductive films (TCFs) have been extensively studied because of their applications in emerging soft electronic and optoelectronic devices, such as flexible and wearable solar cells, organic light-emitting diodes, displays, and touch-screen panels. Recently, graphene and metal nanowire (NW) based TCFs have been emerged one of promising candidates. However, the complex and high-cost micropatterning process of graphene-metal composites limit their practical device applications. The most simple and cost-effective approach can be based on conventional photolithography, which is well established in the semiconductor industry. However, lithography is accompanied by etching processes, which are harsh to vulnerable soft materials, such as organic compounds. Herein, we present a simple and non-damaging approach to fabricate the micron-scale patterns of graphene and graphene-Ag NW hybrid films by utilizing a lift-off technique assisted by ultrasonic vibration. A 20 m-width pattern with uniform and smooth pattern edges was neatly defined on various rigid and flexible substrates. The patterned graphene-Ag NW electrodes showed a low sheet resistance of 19 /sq with a high transmittance of 93% at 550 nm, a robust stability against oxidation, and a high reliability under a bending test. Given its low-cost, high-throughput, and non-damaging effect, this simple and reliable patterning approach stimulates the practical applications of graphene-based flexible transparent electrodes in soft electronic and optoelectronic devices.

Keywords: patterning, lift-off, graphene, Ag nanowires, flexible transparent conductors