Interfacial dipolar interactions drive giant second-harmonic generation in 2D organic–inorganic heterostructures
摘要
Interfacial coupling governs the emergent functionality of two-dimensional (2D) organic–inorganic heterostructures, underpinning advances in linear optoelectronics such as photovoltaics. However, extending this control to the nonlinear optical regime remains elusive, as it requires driving the coherent nonlinear polarization of the inorganic lattice using molecular states, which is distinct from the incoherent charge transfer exploited in linear devices. Here we report a giant second-harmonic generation (SHG) response driven purely by interfacial near-field dipole coupling in an α‑perylene organic crystal (α‑Pe)/WS2 heterostructure. We show that the specific crystalline anisotropy of the organic layer creates a polarization-tunable antenna, where anisotropic dipole–dipole coupling efficiently channels excitation energy into the WS2 layer to drive the nonlinear process. This mechanism yields a spatially uniform, giant effective second-order susceptibility