Mechanical exfoliation is a facile way for the preparation of two-dimensional (2D) nanoflakes. However, the quality of obtained flakes still needs to be further improved, e.g., the exfoliated size and production yield, which plays a crucial role in practical applications. Here, solvent-assisted method is proposed by introducing chemical solvents in the exfoliations. The impacts of wrinkles and defects existed in the outmost layer of bulk MoS2 crystal are overcome due to the capillary and diffusion forces driven by solvent molecules underlying flakes. Hence, the size and yield of nanoflakes are promoted manifestly. The MoS2 nanoflakes are obtained with the largest area of similar to 1.5 mm(2) that is three orders of magnitude bigger than conventional mechanical exfoliation. In addition, the characterizations verify the existence of monolayer which may exhibit intrinsic properties of the MoS2 flakes. Subsequently, MoS2 field-effect transistors are conveniently fabricated by one-step mechanical shadow-mask process. The field-effect mobility of similar to 26 cm(2)V(-1)s(-1) and on/off ratio of similar to 10(6) are achieved. All results indicate that the solvent-assisted exfoliations provide a universal path in the preparation of 2D nanoflakes, which is a fundamental support for the studies of 2D materials and devices. GRAPHICS .
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