Optical Materials: Size-Dependent Nonlinear Optical Properties of Atomically Thin Transition Metal Dichalcogenide Nanosheets (Small 6/2015)

A gradient centrifugation method developed by H.-L. Zhang and co-workers allows the preparation of atomically thin transition metal dichalcogenide (TMD) samples. Z-scan measurements show on page 694 that a dispersion of 50–60 nm MoS2 and WS2 nanosheets exhibits reverse saturable absorption, in contrast to the saturable absorption of larger samples. Such a size-dependent nonlinear optical property implies that the same TMD materials can be used in different applications simply by varying their sheet sizes.