Emerging novel technologies, such as flexible, foldable, and wearable electronics, need to meet their special requirements such as ease of controlling electronic properties, flexibility, and transparency. To date, metal and semiconducting materials have been used for conventional electronics, but the materials are brittle and nontransparent. In contrast, two-dimensional (2D) materials such as graphene and transition dichalcogenides have demonstrated great potential for flexible electronics and transparent electrodes due to their unique mechanical and electronic properties. In order to fully utilize the unique properties of 2D materials, geometric micropatterns of 2D materials on flexible substrates such as polymer substrates are essential to achieve technological purposes. However, due to harsh conditions such as cleaning, developing, and etching processes in the existing lithography procedures, defining elaborate micropatterns of 2D materials using the conventional photolithography processes on polymer substrates is difficult to achieve.
In this presentation, novel strategies to obtain micropatterned graphene on flexible substrates are discussed. After research on self-heating graphene micropatterns[1], direct polymer curing (DPC) transfer method was developed to overcome the low yield process. With the DPC method, entirely flexible, transparent, and self-activated graphene sensor arrays are stably fabricated on 4-inch wafer-scale polymer substrates. A sensor array composed of four graphene microchannels with different noble‐metal decoration provides sufficient sensing information to discriminate gas species.[2-3] Finite element method simulations are employed to investigate the potential self-heating effect of this patterning technique. The calculation results demonstrate that the performance of the sensors can be highly enhanced when the active channels are suspended and nanopatterned. The DPC method is a state-of-the-art technique to define micropatterns of 2D materials on large-scale polymer substrates with a great potential for next-generation flexible electronics composed of 2D materials.