Surface Directed Self-Assembly of Organic Semiconductors on Atomically Thin Graphene Templates

High-performance organic electronic devices rely on organic semiconductor (OSC) thin films with precisely controlled microstructures. One effective strategy for achieving such control is the use of graphene as a template to direct the self-assembly and crystallization of OSC molecules. Unlike conventional substrates, where the growth behavior is primarily dictated by surface structure and morphology, the growth modes of OSCs on graphene are also governed by its distinctive electronic properties. This presentation delves into the mechanisms underlying OSC molecule assembly on graphene, driven by the interplay between molecular interactions and the electronic structure of the graphene substrate. Specifically, charge transfer interactions between the OSC molecules and the graphene surface, in conjunction with van der Waals forces, critically influence the self-assembly dynamics and subsequent growth modes of the OSC films. The investigation focuses on the formation of graphene–OSC heterostructures, utilizing fullerene (C60) and pentacene as model systems. By employing in situ electrical doping of the graphene template to modulate charge transfer between C60 ad-molecules and graphene, a layer-by-layer growth of C60 films can be achieved. Experimental results further reveal that OSC films fabricated under optimized conditions exhibit superior vertical and lateral transport pathways for charge carriers and excitons, substantially enhancing the performance metrics of optoelectronic devices.