Room-Temperature Trion Emission Enhancement in Monolayer WS ₂ /CsPbBr ₃ Perovskite Heterostructures

Monolayer tungsten disulfide (WS2) is a promising candidate for exploring exciton and trion physics thanks to its strong light-matter interactions and large exciton binding energy at room temperature (RT). Trions, in particular, offer intriguing prospects for optoelectronic and valleytronic applications. However, trion stability at RT and a low excitation density are limited by the inherently low free-electron concentration in monolayer WS2. Here we demonstrate a robust approach to enhance trion emission by constructing a type-II heterostructure between monolayer WS2 and the CsPbBr3 perovskite. Through band engineering, we achieve efficient n-doping of WS2 by electron transfer from CsPbBr3, facilitating a pronounced enhancement of trion emission at RT. Under low-power excitation, trions dominate the photoluminescence (PL) spectra. Time-resolved PL measurements reveal distinct lifetimes of excitons and trions in WS2, perovskites, and heterostructures, confirming the charge-transfer dynamics. Helicity-resolved PL spectra show that trions preserve valley polarization in heterostructures. By integrating this heterostructure into an optical microcavity, we further amplify trion emission via the Purcell effect. Our findings present a viable strategy for achieving stable RT trion emission, advancing the development of transition metal dichalcogenide-perovskite hybrid systems for optoelectronic applications.