摘要： The emergence of nanomaterials with their often superior mechanical, electronic and optical properties compared with bulk form demands a robust technology that can synthesize, modify and pattern scalably and cost effectively. This can be fulfilled via laser processing protocols which produce such materials with both high precision and excellent spatial controllability [1]. Direct laser synthesis of nanomaterials such as graphene and nano-structured metal oxides have been explored thoroughly for a wide range of applications [2,3]. However, to date, there are only a few reports associated with the laser processing of two-dimensional transition metal dichalcogenides (2D-TMDCs) [4]. These mainly utilize laser radiation for thinning TMDC films through sublimation down to a single molecular thickness [1]. However, this top-down approach is not practical for large- area and scalable production. In addition, further processing steps such as lithographic patterning are then required for discrete device fabrication. Here we present a novel method for the local synthesis and patterning of two-dimensional MoS2 and WS2 layers. The synthesis of these materials is achieved by spatially selective, visible laser irradiation of suitable precursors coated on the surface of planar substrates under ambient, room temperature conditions. The non- exposed precursor regions are then completely removed in a single step, revealing the synthesised 2D-TMDCs. This method can produce micro-patterned films with lateral dimensions that approach the diffraction limit of the focused laser beam. An example of such laser synthesised MoS2 tracks can be seen in the optical microscopy image of Figure 1(a) where it clearly shows a well-defined micro-pattern without any precursor residue. Using this method, we have achieved local synthesis of of MoS2 and WS2 with thickness down to three molecular layers for MoS2 and monolayer WS2 on various glass and crystalline substrates. The quality and thickness of the resulting films can be tuned by modifying the precursor chemistry and laser parameters. Different microprobe and spectroscopic spectroscopy, photoluminescence spectroscopy (PL) and X-ray photoelectron spectroscopy (XPS) have been used to assess the quality and thickness of the deposited MoS2 and WS2 structures. Finally, we have demonstrated the electronic functionality of our films by fabricating a thin film transistor (TFT). The transfer characteristics (source-drain current vs gate voltage) of such a TFT using a laser-synthesised MoS2 channel is shown in Figure 1(b).