Molybdenum disulfide (MoS₂) is one of the most studied layered TMDCs due to its excellent optical, electrochemical, and electrical properties. Monolayer MoS₂ is a semiconductor with a direct band gap of 1.8 eV, but it has an indirect band gap in its bulk form, and make it possible to use 2D materials in the next generation of switching and optoelectronic devices.

Many research groups have attempted to synthesize MoS₂ with different methods to make good MoS₂ quality. Mechanical exfoliation has been known as an uncomplicated way for flakes extracted from single crystals. However, several restrictions that method had to come up with were small and random flake size then extreme difficulty in the alignment for device fabrication. Chemical vapor deposition (CVD) have been used to prepare MoS₂ thin layers in large scale. Nevertheless, this method demanded vacuum, the use of Mo or MoO₃ thin films as precursors included in four-step CVD process for reduction and sulfurization resulted in expensive MoS₂ films. Solution based methods, by contrast, is promising for large area formation of controllable MoS₂ film with simple equipment, time-saving at low cost. No report has been published using jet printing technology from MoS₂ precursor solution but our group.

Therefore, the goal of this research was to develop a new drop-on demand printing method for MoS₂ atomic layers based on sol-gel synthesis method. We developed a unique solution process to obtain large-size and uniform MoS₂ atomic layers without CVD. The sulfurization process is omitted to simplify the entire process, and wafer-scale and larger-scale synthesis of MoS₂ can be achieved by simple thermal treatment. The atomic layers of the synthesized MoS₂ were identified as 2 layers, 3 layers, and 5 layers for MoS₂ concentrations. MoS₂ patterns were made with highly uniform coverage using electrohydrodynamic (EHD)-jet printing for the first time. The EHD jet-printed MoS₂ TFTs show good electrical properties of 19.4 cm² V^-1 s^-1.