Graphene wrinkle effects on molecular resonance states

Abstract

Wrinkles are a unique class of surface corrugations present over diverse length scales from Kinneyia-type wrinkles in Archean-era sedimentary fossils to nanoscopic crinkling in two-dimensional crystals. Lately, the role of wrinkles on graphene has been subject to debate as devices based on graphene progress towards commercialization. While the topology and electronic structure of graphene wrinkles is known, data on wrinkle geometrical effects on molecular adsorption patterns and resonance states is lacking. Here, we report molecular superstructures and enhancement of free-molecular electronic states of pentacene on graphene wrinkles. A new trend is observed where the pentacene energy gap scales with wrinkle height, as wrinkles taller than 2 nm significantly screen metal induced hybridization. Combined with density functional theory calculations, the impact of wrinkles in tuning molecular growth modes and electronic structure is clarified at room-temperature. These results suggest the need to rethink wrinkle engineering in modular devices based on graphene and related 2D materials interfacing with electronically active molecules.