When light is incident on 2D transition
metal dichalcogenides (TMDCs), it engages in multiple reflections
within underlying substrates, producing interferences that lead to
enhancement or attenuation of the incoming and outgoing strength of
light. Here, we report a simple method to engineer the light outcoupling
in semiconducting TMDCs by modulating their dielectric surroundings.
We show that by modulating the thicknesses of underlying substrates
and capping layers, the interference caused by substrate can significantly
enhance the light absorption and emission of WSe<sub>2</sub>, resulting
in a ∼11 times increase in Raman signal and a ∼30 times
increase in the photoluminescence (PL) intensity of WSe<sub>2</sub>. On the basis of the interference model, we also propose a strategy
to control the photonic and optoelectronic properties of thin-layer
WSe<sub>2</sub>. This work demonstrates the utilization of outcoupling
engineering in 2D materials and offers a new route toward the realization
of novel optoelectronic devices, such as 2D LEDs and solar cells