Interfacial Electric Fields Acting on Molecules at Solid Interfaces

Charge transfer at solid interfaces and ensuing interfacial electric fields on the order of 10⁹ V/m are ubiquitous in nanostructures and hybrid materials. Here, we address how intrinsic interfacial electric fields alter the structural properties of intercalated molecules considering the optically transparent and atomically flat graphene–mica interface and confined rhodamine 6G dyes as a model system. Using a combination of Raman spectroscopy and atomistic simulations based on density-functional theory and classical molecular dynamics, we show that the observed softening of Raman-active modes of the confined molecules is due to mechanical deformations within the latter and to the action of interfacial electric fields exceeding 10⁹ V/m. Our findings contribute to the general understanding of the role of interfacial electric fields in molecule/solid interfaces, thereby opening new perspectives for controlling catalytic activities of such complex systems.