| Summary: | Random lasers have attracted much attention in recent years owing to their advantages of a simple fabrication process, low processing cost, and material flexibility for any lasing wavelengths. They provide a roadmap for the design of ultra-bright lighting, displays, etc. However, the threshold reduction in random nanolasers remains a challenge in practical applications. In this work, lower-threshold random laser action from monolayer molybdenum disulfide film-encapsulated Au nanoparticles (MoS<sub>2</sub>/Au NPs) is demonstrated. The observed laser action of the MoS<sub>2</sub>/Au NPs shows a lower threshold of about 0.564 µJ/mm<sup>2</sup>, which is about 46.2% lower than the threshold of random lasers based on Au NPs. We proposed that the charge transfer between MoS<sub>2</sub> and the gain material is the main reason for the reduction in the random laser threshold. The finite-difference time-domain (FDTD) method was used to calculate the lasing action of these two nanostructures. When charge transfer is taken into account, the theoretically calculated threshold of the MoS<sub>2</sub>/Au NPs is reduced by 46.8% compared to Au NP samples, which is consistent with the experimental results. This study provides a new mechanism to achieve low-threshold and high-quality random lasers, which has the potential to facilitate the application of random lasers and the development of high-performance optoelectronic devices.
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