Heteroepitaxial Strain Engineering and Interfacial Energy Transfer Boosting Optoelectronic Properties in C ₆₀ /WS ₂ van der Waals Heterostructures

Engineered van der Waals (vdW) heterostructures, combining molecular semiconductors and atomically flat nanomaterials, offer vast opportunities to tailor optoelectronic properties at heterointerfaces. Here, the heteroepitaxial assembly of C₆₀ molecules on monolayer tungsten disulfide (ML-WS₂), where an anisotropic compression strain within the C₆₀ lattice at the heterointerface induces the formation of 1D polymeric C₆₀ strings and activates otherwise symmetry-forbidden S₁ → S₀ optical transitions, is reported. This, coupled with interfacial energy transfer from ML-WS₂ to C₆₀, results in a remarkable 310% enhancement in the PL intensity compared to disordered C₆₀ aggregates. The resulting C₆₀/ML-WS₂ transistors exhibit superior electrical and optoelectronic performance, achieving a charge carrier mobility of 10.4 cm² V^-1 s^-1, facilitated by an ultralow 230 meV contact barrier with Au electrodes. These devices demonstrate a superior photoresponsivity of 46.4 A W^-1 and a detectivity of 3.6 × 10¹² Jones, greatly outperforming pristine ML-WS₂ counterpart devices.