2D MoS2 Pattern from Sol-Gel-Processed Precursors Using Jet Printer for TFT Application

Abstract

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.