High-Quality Monolithic Graphene Films via Laterally Stitched Growth and Structural Repair of Isolated Flakes for Transparent Electronics

Exfoliation of graphene flakes in solution is a high-yield and low-cost synthesis method, but the quality of the obtained graphene flakes is not high, because of the presence of functional groups and structural defects. Therefore, the ability to synthesize high-quality graphene with excellent electrical properties is desirable for electronic applications. Here, we present a facile and rapid annealing approach with nickel for structural repair in isolated graphene flakes on rough insulating substrates, accompanied by lateral stitching of the isolated parts to form a continuous and monolithic film. This process involves the active carbon species being coalesced at the desaturation edge of graphene flakes. Meanwhile, the defects in graphene can be also repaired to improve its crystal quality and electrical properties. Significantly, the carrier mobility of graphene with excellent structural properties is >1000 cm² V^-1 s^-1 on average, nearly 10 times higher than that of the process with copper or 100 times higher than that of graphene via mere annealing. This approach to high-quality graphene on rough insulating substrates, with transfer-free and well-adapted characteristics, is promising for electronic and optoelectronic applications.