Interfacial Configuration Engineering in Organic/2D Heterostructures for Tailored Exciton Dynamics

The van der Waals (vdW) heterostructures composed of organic and two-dimensional transition metal dichalcogenides (2D TMDs) combine the advantages of both components, demonstrating exceptional optoelectronic properties. Current research efforts on organic/2D TMD heterostructures primarily focus on exploring diverse material combinations and their fundamental properties. However, the universal mechanisms by which interfacial effects determine interfacial configurations and modulate light-matter interactions remain unexplored. Here, we demonstrate that controlled epitaxial growth of vanadyl phthalocyanine/tungsten diselenide (VOPc/WSe2) enables on-demand programming of exciton pathways. Deposition kinetics dictates a reversible transition between layered growth and acicular growth of VOPc on WSe2. The epitaxy is driven by a dual-coupling mechanism involving adsorbate dipole moments and local symmetry breaking. In-depth characterization and calculations reveal the critical role of interfacial configurations in modulating exciton dynamics: the face-to-face configuration in VOPc/WSe2 exhibits an ultrafast recombination of 757 fs, 11.7 times faster than the edge-to-edge configuration in WSe2/VOPc (8887 fs), enabling superior photogenerated carrier separation efficiency and transport in VOPc/WSe2. Temperature-dependent studies further unveil thermally activated interlayer energy transfer. This work shows the great promise of interfacial configuration engineering for tailoring exciton dynamics in organic 2D TMD heterostructures and provides guidance for device design from controlled growth to customized functionalities.