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

Abstract

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 (MoS , WS , MoSe , WSe , 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 MoS thin film comprising of small size grains shows near-IR absorption, supported by the first principle calculation, exhibits a high photoresponsivity (>300 mA W ) and a fast response (124 µs). This study paves a robust way for the synthesis of various TMD thin films in solution phases.

Synthesis of 2D Metal Chalcogenide Thin Films through the Process Involving Solution‐Phase Deposition

“…Currently, the materials reported are mostly TMDCs (MoS 2 , WS 2 , MoSe 2 , WSe 2 and Mo x W 2− x S 2 , etc. ) and PTMCs (SnS 2− x Se x , CuInSe 2 , In 2 Se 3 , etc.) .…”

“…If a one‐step thin film growth is possible it will provide genuine advantage of the solution‐phase growth such as low‐temperature synthesis, versatile scale‐up into massive amount, rich chemistry during the synthesis, and possibility of all‐in‐one printed production. In a very recent study, Jeong and co‐workers demonstrated a one‐step synthesis of metal chalcogenide thin films (MoS 2 , MoSe 2 , WS 2 , WSe 2 ) in a solution phase directly on Si substrates . They adopted the microwave‐assisted crystal growth.…”

“…d) Raman spectra of MoS 2 , MoSe 2 , WS 2 , and WSe 2 thin films showing the characteristic vibrational modes. a–d) Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

“…Ozkan group and Kim group also demonstrated FET devices made of a solution‐based MoS 2 thin films, however, the average field‐effect mobility (0.1 and 0.24 cm 2 V −1 s −1 , respectively) and the on/off current ratio (10 2 and 10 4 , respectively) were too low for practical uses . Jeong and co‐workers recently demonstrated a broadband photodetector based on small grain multilayer MoS 2 thin films (Figure c). The device showed a high photoresponsivity in a wide spectral range of 300–1100 nm (maximum of ≈300 mA W −1 at 600 nm).…”

“…2D Metal chalcogenide thin films have mostly been obtained by the exfoliation and CVD growth. Very recently, synthesis through a process involving solution phase deposition directly on a substrate has been emerging as a promising alternative approach . The solution‐based process has several technological attractions: low temperature synthesis under atmospheric conditions, more choices of substrates including polymer substrates, and more diversity in the material species to be synthesized, and the use of conventional printing techniques .…”