Interface-Driven Evolution of Interlayer and Hybrid Excitons in CVD-Grown Large-Area MoS2/WS2 Vertical Heterostructures

Van der Waals heterostructures grown by chemical vapor deposition (CVD) offer a scalable platform for optoelectronic applications. However, understanding and accurately assigning their excitonic spectral features remain challenging. This is due to variable interfacial quality arising from interfacial disorder and interlayer coupling, as well as overlapping spectral signatures. Here, we synthesize continuous, large-area (up to 600 μm) MoS2/WS2 vertical heterostructures using two distinct single-step CVD processes. This approach enables a systematic comparison of excitonic behavior across varying interface qualities. Temperature-dependent photoluminescence, supported by ultra-low-frequency Raman spectroscopy, resolves the evolution of distinct interlayer exciton (ILE) spectral features. In heterobilayers, the ILE evolves from localized states in the presence of interfacial disorder to delocalized states stabilized by uniform interlayer coupling. Notably, we identify a hybrid exciton, arising from strong interlayer electronic hybridization, centered at ∼1.90 eV between the neutral A-excitons of MoS2 and WS2. Importantly, hybrid exciton formation correlates with a suppression of ILE radiative emission. By systematically disentangling disorder-trapped, delocalized, and hybrid excitonic regimes, this work provides clear experimental evidence of interface-driven excitonic transitions. These findings highlight the critical role of interfacial quality in governing excitonic behavior in scalable MoS2/WS2 heterostructures.