One-Step Solution Phase Growth of Transition Metal Dichalcogenide Thin Films Directly on Solid Substrates

Ultrathin transition metal dichalcogenides (TMDs) have exotic electronic properties. With success in easy synthesis of high quality TMD thin films, the potential applications will become more viable in electronics, optics, energy storage, and catalysis. Synthesis of TMD thin films has been mostly performed in vacuum or by thermolysis. So far, there is no solution phase synthesis to produce large-area thin films directly on target substrates. Here, this paper reports a one-step quick synthesis (within 45–90 s) of TMD thin films (MoS₂, WS₂, MoSe₂, WSe₂, etc.) on solid substrates by using microwave irradiation on a precursor-containing electrolyte solution. The numbers of the quintuple layers of the TMD thin films are precisely controllable by varying the precursor's concentration in the electrolyte solution. A photodetector made of MoS₂ thin film comprising of small size grains shows near-IR absorption, supported by the first principle calculation, exhibits a high photoresponsivity (>300 mA W⁻¹) and a fast response (124 µs). This study paves a robust way for the synthesis of various TMD thin films in solution phases.

A generalized new strategy for solution phase growth of transition metal dichalcogenide thin films is presented. The microwave-assisted bottom-up synthesis approach enables the formation of MoS₂, MoSe₂, WS₂, and WSe₂ uniform thin films directly on solid substrates within 45–90 s. The MoS₂-based thin film photodetector shows a high photoresponsivity over a broad spectral range and a quick photoresponse time.

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