Tailoring light emission in hybrid WS2 monolayer-coupled polystyrene microsphere/Au microcavities

Abstract

Transition metal dichalcogenide (TMD) monolayers provide a versatile platform for nanophotonic and optoelectronic devices due to their direct bandgap and strong excitonic response. However, tailoring their emission characteristics beyond the intrinsically narrow excitonic linewidth remains a key challenge. Here, we report a hybrid microcavity platform consisting of a WS₂ monolayer coupled to polystyrene microspheres (PS-MSs) on a gold substrate under continuous-wave excitation. In this system, light emission can be tailored through the interplay between cavity-enhanced local electromagnetic fields and photoinduced changes in the microcavity optical response. At low excitation powers, the emission evolves from neutral-exciton-dominated to trion-dominated photoluminescence with a continuously tunable intensity ratio, reflecting changes in the relative exciton-trion contributions under laser excitation. At higher excitation powers, the system transitions to a broadband-emission regime, which is associated with irradiation-induced modifications of the microcavity optical properties and is further enhanced by the cavity configuration. The incorporation of the WS₂ monolayer is correlated with enhanced broadband emission and improved performance under continuous-wave excitation, while also influencing the interfacial excitonic emission behavior. Furthermore, extending this approach to multiple-microsphere assemblies enables larger-area broadband emission, suggesting the potential scalability of this strategy toward planar white-light sources. These results establish a simple strategy for tailoring light emission in hybrid microcavities and provide insights into cavity-enhanced optical processes in coupled two-dimensional material-polymer systems, with potential applications in integrated photonic devices and broadband light sources.