Processing of Monolayer Molybdenum disulfide

Many techniques have been used to prepare monolayer films of MoS2. Below is a brief review of the most common. Mechanical exfoliation: This method, known as the ‘Scotch-tape method,’ was first used to isolate graphene layers. Applying sticky tape to a bulk crystal sample and then peeling it off will result in thin layers of crystal sticking to the tape. This is due to greater mutual adhesion than the interlayer adhesion. This sticking-and-peeling process can be repeated until single monolayers are produced. These can then be transferred onto a substrate (e.g., by a PDMS stamp). While this process has a low monolayer yield, it produces high-quality crystalline monolayers that can be >10’s microns in size. Despite being ‘low-tech,’ it is still a preferred processing method for TMDC research. Solvent exfoliation: Bulk crystals can be sonicated in an organic solvent that breaks them down into thin layers. A distribution in the size and thickness of the layers is obtained, with a surfactant often added to stop the layers from restacking. While the thin-film yield of this method is high, the monolayer yield is low. Flakes tend to be small, with sizes of 100nm. Intercalation: Sometimes classed as a form of solvent exfoliation, intercalation of MoS2 that is monolayers long predates the current research trend in 2D materials, first demonstrated in 1986. Bulk crystals are placed in a solution that acts as a source of lithium ions (commonly n-butyllithium dissolved in hexane), which diffuse between the crystal layers. Water is added – which then interacts with the lithium ions to produce hydrogen, pushing the layers apart. This method requires careful control over the experimental parameters to obtain a high monolayer yield. The resulting layers also tend to have a less desirable metallic 1T structure than the semiconducting 2H structure (although the 1T structure has found a potential application in supercapacitor electrodes – see above). However, the 1T structure can be converted to 2H through thermal annealing. If you are looking for high quality, high purity, and cost-effective Molybdenum disulfide, or if you require the latest price of Molybdenum disulfide, please feel free to email contact mis-asia.