Synthesis of uniform two-dimensional MoS2 films via thermal evaporation

Two-dimensional (2D) molybdenum disulfide (MoS2) holds great potential for various applications such as electronic devices, catalysis, lubrication, anti-corrosion and so on. Thermal evaporation is a versatile thin film deposition technique, however, the conventional thermal evaporation techniques face challenges in producing uniform thin films of MoS2 due to its high melting temperature of 1375 °C. As a result, only thick and rough MoS2 films can be obtained using these methods. To address this issue, we have designed a vacuum thermal evaporation system specifically for large-scale preparation of MoS2 thin films. By using K2MoS4 as the precursor, we achieved reliable deposition of uniform polycrystalline MoS2 thin films with a size of 50 mm × 50 mm and controllable thickness ranging from 0.8 to 2.4 nm. This approach also allows for patterned deposition of MoS2 using shadow masks and sequential deposition of MoS2 and tungsten disulfide (WS2), similar to conventional thermal evaporation techniques. Moreover, we have demonstrated the potential applications of the obtained MoS2 thin films in field effect transistors (FETs), memristors and electrocatalysts for hydrogen evolution reaction (HER).