We demonstrated room temperature near infrared (NIR) region random lasing (RL) (800–950 nm), with a threshold of nearly 500 μW, in ∼200 nm thick MoS 2 /Au nanoparticles (NPs)/ZnO heterostructures using photoluminescence spectroscopy. The RL in the above system arises mainly due to the following three reasons: (1) enhanced multiple scattering because of Au/ZnO disordered structure, (2) exciton–plasmon coupling because of Au NPs, and (3) enhanced charge transfer from ZnO to thick MoS 2 flakes. RL has recently attracted tremendous interest because of its wide applications in the field of telecommunication, spectroscopy, and specifically in biomedical tissue imaging. This work provides new dimensions toward realization of low power on-chip NIR random lasers made up of biocompatible materials.

In the present work, we report plasmon induced brightening of dark excitons (XD) in Au nanoparticle (Au-NP) coated monolayer (1L) WSe2. We observed one order enhancement in photoluminescence (PL) intensity and surface enhanced Raman scattering in Au-NP/1L-WSe2 at room temperature (RT). Temperature dependent PL measurements showed enhanced PL emission from RT down to 100 K in contrast to reduced PL emission which is generally observed for pristine 1L-WSe2. We attribute this effect to the out-of-plane electric field induced by the scattering from Au-NPs, which results in the out-of-plane dipole moment and spin-flip of conduction band electrons in Au-NP/1L-WSe2, making XD bright. Our approach provides a facile way to harness excitonic properties in low-dimensional semiconductors, offering simple strategies for quantum optoelectronics.

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